/*******************************************************************************

    ηMatrix - a browser extension to black/white list requests.
    Copyright (C) 2014-2019 The uMatrix/uBlock Origin authors
    Copyright (C) 2019 Alessio Vanni

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see {http://www.gnu.org/licenses/}.

    Home: https://gitlab.com/vannilla/ematrix
    uMatrix Home: https://github.com/gorhill/uMatrix
*/

/* jshint bitwise: false, esnext: true */
/* global self, Components, punycode */

// For background page

'use strict';

/******************************************************************************/

(function () {
    const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
    const {Services} = Cu.import('resource://gre/modules/Services.jsm', null);

    let vAPI = self.vAPI = self.vAPI || {};
    
    vAPI.firefox = true;
    vAPI.modernFirefox =
	Services.appinfo.ID === '{ec8030f7-c20a-464f-9b0e-13a3a9e97384}'
	&& Services.vc.compare(Services.appinfo.version, '44') > 0;

    let deferUntil = function (testFn, mainFn, details) {
	let dtls = (typeof details !== 'object') ? {} : details;
	let now = 0;
	let next = dtls.next || 200;
	let until = dtls.until || 2000;

	let check = function () {
            if (testFn() === true || now >= until) {
		mainFn();
		return;
            }
            now += next;
            vAPI.setTimeout(check, next);
	};

	if ('sync' in dtls && dtls.sync === true) {
            check();
	} else {
            vAPI.setTimeout(check, 1);
	}
    };

    vAPI.app = {
	name: 'eMatrix',
	version: location.hash.slice(1),
	
	start: function () {
	    return;
	},
	stop: function () {
	    return;
	},
	restart: function () {
	    Cc['@mozilla.org/childprocessmessagemanager;1']
		.getService(Ci.nsIMessageSender)
		.sendAsyncMessage(location.host + '-restart');
	},
    };


    // List of things that needs to be destroyed when disabling the extension
    // Only functions should be added to it

    let cleanupTasks = [];

    // This must be updated manually, every time a new task is added/removed
    // eMatrix: do we?
    let expectedNumberOfCleanups = 7;

    window.addEventListener('unload', function () {
	// if (typeof vAPI.app.onShutdown === 'function') {
        //     vAPI.app.onShutdown();
	// }

	// IMPORTANT: cleanup tasks must be executed using LIFO order.
	for (let i=cleanupTasks.length-1; i>=0; --i) {
	    try {
		cleanupTasks[i]();
	    } catch (e) {
		// Just in case a clean up task ends up throwing for
		// no reason
		console.error(e);
	    }
	}

	// eMatrix: temporarily disabled
	// if (cleanupTasks.length < expectedNumberOfCleanups) {
        //     console.error
	//     ('eMatrix> Cleanup tasks performed: %s (out of %s)',
        //      cleanupTasks.length,
        //      expectedNumberOfCleanups);
	// }

	// frameModule needs to be cleared too
	let frameModuleURL = vAPI.getURL('frameModule.js');
	let frameModule = {};
	
	Cu.import(frameModuleURL, frameModule);
	frameModule.contentObserver.unregister();
	Cu.unload(frameModuleURL);
    });

    vAPI.browserSettings = {
	// For now, only booleans.
	originalValues: {},

	rememberOriginalValue: function (path, setting) {
            let key = path + '.' + setting;
            if (this.originalValues.hasOwnProperty(key)) {
		return;
            }
	    
            let hasUserValue;
            let branch = Services.prefs.getBranch(path + '.');
	    
            try {
		hasUserValue = branch.prefHasUserValue(setting);
            } catch (ex) {
		// Ignore
            }
	    
            if (hasUserValue !== undefined) {
		this.originalValues[key] = hasUserValue
		    ? this.getValue(path, setting)
		    : undefined;
            }
	},
	clear: function (path, setting) {
            let key = path + '.' + setting;

            // Value was not overriden -- nothing to restore
            if (this.originalValues.hasOwnProperty(key) === false) {
		return;
            }

            let value = this.originalValues[key];
	    
            // https://github.com/gorhill/uBlock/issues/292#issuecomment-109621979
            // Forget the value immediately, it may change outside of
            // uBlock control.
            delete this.originalValues[key];

            // Original value was a default one
            if (value === undefined) {
		try {
                    Services.prefs.getBranch(path + '.').clearUserPref(setting);
		} catch (ex) {
		    // Ignore
		}
		return;
            }

            // Reset to original value
            this.setValue(path, setting, value);
	},
	getValue: function (path, setting) {
            let branch = Services.prefs.getBranch(path + '.');

	    try {
		switch (branch.getPrefType(setting)) {
		case branch.PREF_INT:
		    return branch.getIntPref(setting);
		case branch.PREF_BOOL:
		    return branch.getBoolPref(setting);
		default:
		    // not supported
		    return;
		}
	    } catch (e) {
		// Ignore
	    }
	},
	setValue: function (path, setting, value) {
	    let branch = Services.prefs.getBranch(path + '.');
	    
	    try {
		switch (typeof value) {
		case 'number':
		    return branch.setIntPref(setting, value);
		case 'boolean':
		    return branch.setBoolPref(setting, value);
		default:
		    // not supported
		    return;
		}
	    } catch (e) {
		// Ignore
	    }
	},
	setSetting: function (setting, value) {
            switch (setting) {
            case 'prefetching':
		this.rememberOriginalValue('network', 'prefetch-next');
		// https://bugzilla.mozilla.org/show_bug.cgi?id=814169
		// Sigh.
		// eMatrix: doesn't seem the case for Pale
		// Moon/Basilisk, but let's keep this anyway
		this.rememberOriginalValue('network.http', 'speculative-parallel-limit');
		
		// https://github.com/gorhill/uBlock/issues/292
		// "true" means "do not disable", i.e. leave entry alone
		if (value) {
                    this.clear('network', 'prefetch-next');
                    this.clear('network.http', 'speculative-parallel-limit');
		} else {
                    this.setValue('network', 'prefetch-next', false);
                    this.setValue('network.http',
				  'speculative-parallel-limit', 0);
		}
		break;
            case 'hyperlinkAuditing':
		this.rememberOriginalValue('browser', 'send_pings');
		this.rememberOriginalValue('beacon', 'enabled');
		
		// https://github.com/gorhill/uBlock/issues/292
		// "true" means "do not disable", i.e. leave entry alone
		if (value) {
                    this.clear('browser', 'send_pings');
                    this.clear('beacon', 'enabled');
		} else {
                    this.setValue('browser', 'send_pings', false);
                    this.setValue('beacon', 'enabled', false);
		}
		break;
            case 'webrtcIPAddress':
		let prefName;
		let prefVal;
		
		// https://github.com/gorhill/uBlock/issues/894
		// Do not disable completely WebRTC if it can be avoided. FF42+
		// has a `media.peerconnection.ice.default_address_only` pref which
		// purpose is to prevent local IP address leakage.
		if (this.getValue('media.peerconnection',
				  'ice.default_address_only') !== undefined) {
                    prefName = 'ice.default_address_only';
                    prefVal = true;
		} else {
                    prefName = 'enabled';
                    prefVal = false;
		}

		this.rememberOriginalValue('media.peerconnection', prefName);
		if (value) {
                    this.clear('media.peerconnection', prefName);
		} else {
                    this.setValue('media.peerconnection', prefName, prefVal);
		}
		break;
            default:
		break;
            }
	},
	set: function (details) {
            for (let setting in details) {
		if (details.hasOwnProperty(setting) === false) {
                    continue;
		}
		this.setSetting(setting, !!details[setting]);
            }
	},
	restoreAll: function () {
            let pos;
            for (let key in this.originalValues) {
		if (this.originalValues.hasOwnProperty(key) === false) {
                    continue;
		}
		
		pos = key.lastIndexOf('.');
		this.clear(key.slice(0, pos), key.slice(pos + 1));
            }
	},
    };

    cleanupTasks.push(vAPI.browserSettings.restoreAll.bind(vAPI.browserSettings));

    // API matches that of chrome.storage.local:
    // https://developer.chrome.com/extensions/storage
    vAPI.storage = (function () {
	let db = null;
	let vacuumTimer = null;

	let close = function () {
            if (vacuumTimer !== null) {
		clearTimeout(vacuumTimer);
		vacuumTimer = null;
            }
	    
            if (db === null) {
		return;
            }
	    
            db.asyncClose();
            db = null;
	};

	let open = function () {
            if (db !== null) {
		return db;
            }
	    
            // Create path
            let path = Services.dirsvc.get('ProfD', Ci.nsIFile);
            path.append('ematrix-data');
            if (!path.exists()) {
		path.create(Ci.nsIFile.DIRECTORY_TYPE, parseInt('0774', 8));
            }
            if (!path.isDirectory()) {
		throw Error('Should be a directory...');
            }

	    let path2 = Services.dirsvc.get('ProfD', Ci.nsIFile);
	    path2.append('extension-data');
	    path2.append(location.host + '.sqlite');
	    if (path2.exists()) {
		path2.moveTo(path, location.host+'.sqlite');
	    }

	    path.append(location.host + '.sqlite');

            // Open database
            try {
		db = Services.storage.openDatabase(path);
		if (db.connectionReady === false) {
                    db.asyncClose();
                    db = null;
		}
            } catch (ex) {
		// Ignore
            }

            if (db === null) {
		return null;
            }

            // Database was opened, register cleanup task
            cleanupTasks.push(close);

            // Setup database
            db.createAsyncStatement('CREATE TABLE IF NOT EXISTS '
				    +'"settings" ("name" '
				    +'TEXT PRIMARY KEY NOT NULL, '
				    +'"value" TEXT);')
		.executeAsync();

            if (vacuum !== null) {
		vacuumTimer = vAPI.setTimeout(vacuum, 60000);
            }

            return db;
	};

	// Vacuum only once, and only while idle
	let vacuum = function () {
            vacuumTimer = null;
            if (db === null) {
		return;
            }
            let idleSvc =
		Cc['@mozilla.org/widget/idleservice;1']
		.getService(Ci.nsIIdleService);
	    
            if (idleSvc.idleTime < 60000) {
		vacuumTimer = vAPI.setTimeout(vacuum, 60000);
		return;
            }
	    
            db.createAsyncStatement('VACUUM').executeAsync();
            vacuum = null;
	};

	// Execute a query
	let runStatement = function (stmt, callback) {
            let result = {};

            stmt.executeAsync({
		handleResult: function (rows) {
                    if (!rows || typeof callback !== 'function') {
			return;
                    }

                    let row;
                    while ((row = rows.getNextRow())) {
			// we assume that there will be two columns, since we're
			// using it only for preferences
			// eMatrix: the above comment is obsolete
			// (it's not used just for preferences
			// anymore), but we still expect two columns.
			let res = row.getResultByIndex(0);
			result[res] = row.getResultByIndex(1);
                    }
		},
		handleCompletion: function (reason) {
                    if (typeof callback === 'function' && reason === 0) {
			callback(result);
                    }
		},
		handleError: function (error) {
                    console.error('SQLite error ', error.result, error.message);
		    
                    // Caller expects an answer regardless of failure.
                    if (typeof callback === 'function' ) {
			callback(null);
                    }
		},
            });
	};

	let bindNames = function (stmt, names) {
            if (Array.isArray(names) === false || names.length === 0) {
		return;
            }
	    
            let params = stmt.newBindingParamsArray();
	    
	    for (let i=names.length-1; i>=0; --i) {
		let bp = params.newBindingParams();
		bp.bindByName('name', names[i]);
		params.addParams(bp);
            }
	    
            stmt.bindParameters(params);
	};

	let clear = function (callback) {
            if (open() === null) {
		if (typeof callback === 'function') {
                    callback();
		}
		return;
            }
	    
            runStatement(db.createAsyncStatement('DELETE FROM "settings";'),
			 callback);
	};

	let getBytesInUse = function (keys, callback) {
            if (typeof callback !== 'function') {
		return;
            }

            if (open() === null) {
		callback(0);
		return;
            }

            let stmt;
            if (Array.isArray(keys)) {
		stmt = db.createAsyncStatement('SELECT "size" AS "size", '
					       +'SUM(LENGTH("value")) '
					       +'FROM "settings" WHERE '
					       +'"name" = :name');
		bindNames(keys);
            } else {
		stmt = db.createAsyncStatement('SELECT "size" AS "size", '
					       +'SUM(LENGTH("value")) '
					       +'FROM "settings"');
            }

            runStatement(stmt, function (result) {
		callback(result.size);
            });
	};

	let read = function (details, callback) {
            if (typeof callback !== 'function') {
		return;
            }

            let prepareResult = function (result) {
		for (let key in result) {
                    if (result.hasOwnProperty(key) === false) {
			continue;
                    }
		    
                    result[key] = JSON.parse(result[key]);
		}
		
		if (typeof details === 'object' && details !== null) {
                    for (let key in details) {
			if (result.hasOwnProperty(key) === false) {
                            result[key] = details[key];
			}
                    }
		}
		
		callback(result);
            };

            if (open() === null) {
		prepareResult({});
		return;
            }

            let names = [];
            if (details !== null) {
		if (Array.isArray(details)) {
                    names = details;
		} else if (typeof details === 'object') {
                    names = Object.keys(details);
		} else {
                    names = [details.toString()];
		}
            }

            let stmt;
            if (names.length === 0) {
		stmt = db.createAsyncStatement('SELECT * FROM "settings"');
            } else {
		stmt = db.createAsyncStatement('SELECT * FROM "settings" '
					       +'WHERE "name" = :name');
		bindNames(stmt, names);
            }
	    
            runStatement(stmt, prepareResult);
	};

	let remove = function (keys, callback) {
            if (open() === null) {
		if (typeof callback === 'function') {
                    callback();
		}
		return;
            }
	    
            var stmt = db.createAsyncStatement('DELETE FROM "settings" '
					       +'WHERE "name" = :name');
            bindNames(stmt, typeof keys === 'string' ? [keys] : keys);
            runStatement(stmt, callback);
	};
	
	let write = function (details, callback) {
            if (open() === null) {
		if (typeof callback === 'function') {
                    callback();
		}
		return;
            }
	    
            let stmt = db.createAsyncStatement('INSERT OR REPLACE INTO '
					       +'"settings" ("name", "value") '
					       +'VALUES(:name, :value)');
            let params = stmt.newBindingParamsArray();
	    
            for (let key in details) {
		if (details.hasOwnProperty(key) === false) {
                    continue;
		}
		
		let bp = params.newBindingParams();
		bp.bindByName('name', key);
		bp.bindByName('value', JSON.stringify(details[key]));
		params.addParams(bp);
            }
	    
            if (params.length === 0) {
		return;
            }

            stmt.bindParameters(params);
            runStatement(stmt, callback);
	};

	// Export API
	var api = {
            QUOTA_BYTES: 100 * 1024 * 1024,
            clear: clear,
            get: read,
            getBytesInUse: getBytesInUse,
            remove: remove,
            set: write
	};
	
	return api;
    })();

    vAPI.cacheStorage = vAPI.storage;

    // This must be executed/setup early.
    let winWatcher = (function () {
	let windowToIdMap = new Map();
	let windowIdGenerator = 1;
	let api = {
            onOpenWindow: null,
            onCloseWindow: null
	};

	// https://github.com/gorhill/uMatrix/issues/586 This is
	// necessary hack because on SeaMonkey 2.40, for unknown
	// reasons private windows do not have the attribute
	// `windowtype` set to `navigator:browser`. As a fallback, the
	// code here will also test whether the id attribute is
	// `main-window`.
	api.toBrowserWindow = function (win) {
            let docElement = win && win.document
		&& win.document.documentElement;
	    
            if (!docElement) {
		return null;
            }
            if (vAPI.thunderbird) {
		return docElement.getAttribute('windowtype') === 'mail:3pane'
		    ? win
		    : null;
            }
	    
            return docElement.getAttribute('windowtype') === 'navigator:browser'
		|| docElement.getAttribute('id') === 'main-window'
		? win
		: null;
	};

	api.getWindows = function () {
            return windowToIdMap.keys();
	};

	api.idFromWindow = function (win) {
            return windowToIdMap.get(win) || 0;
	};

	api.getCurrentWindow = function () {
            return this.toBrowserWindow(Services.wm.getMostRecentWindow(null));
	};

	let addWindow = function (win) {
            if (!win || windowToIdMap.has(win)) {
		return;
            }
	    
            windowToIdMap.set(win, windowIdGenerator++);
	    
            if (typeof api.onOpenWindow === 'function') {
		api.onOpenWindow(win);
            }
	};

	let removeWindow = function (win) {
            if (!win || windowToIdMap.delete(win) !== true) {
		return;
            }
	    
            if (typeof api.onCloseWindow === 'function') {
		api.onCloseWindow(win);
            }
	};

	// https://github.com/gorhill/uMatrix/issues/357
	// Use nsIWindowMediator for being notified of opened/closed windows.
	let listeners = {
            onOpenWindow: function (aWindow) {
		let win;
		try {
                    win = aWindow.QueryInterface(Ci.nsIInterfaceRequestor)
                        .getInterface(Ci.nsIDOMWindow);
		} catch (e) {
		    // Ignore
		}
		
		addWindow(win);
            },
            onCloseWindow: function (aWindow) {
		let win;
		try {
                    win = aWindow.QueryInterface(Ci.nsIInterfaceRequestor)
                        .getInterface(Ci.nsIDOMWindow);
		} catch (e) {
		    // Ignore
		}
		
		removeWindow(win);
            },
            observe: function (aSubject, topic) {
		let win;
		try {
                    win = aSubject.QueryInterface(Ci.nsIInterfaceRequestor)
                        .getInterface(Ci.nsIDOMWindow);
		} catch (e) {
		    // Ignore
		}
		
		if (!win) {
		    return;
		}

		switch (topic) {
		case 'domwindowopened':
		    addWindow(win);
		    break;
		case 'domwindowclosed':
		    removeWindow(win);
		    break;
		default:
		    console.error('unknown observer topic');
		    break;
		}
            }
	};

	(function() {
            let winumerator;

            winumerator = Services.wm.getEnumerator(null);
            while (winumerator.hasMoreElements()) {
		let win = winumerator.getNext();
		
		if (!win.closed) {
                    windowToIdMap.set(win, windowIdGenerator++);
		}
            }

            winumerator = Services.ww.getWindowEnumerator();
            while (winumerator.hasMoreElements()) {
		let win = winumerator.getNext()
                    .QueryInterface(Ci.nsIInterfaceRequestor)
                    .getInterface(Ci.nsIDOMWindow);
		
		if (!win.closed) {
                    windowToIdMap.set(win, windowIdGenerator++);
		}
            }

            Services.wm.addListener(listeners);
            Services.ww.registerNotification(listeners);
	})();

	cleanupTasks.push(function() {
            Services.wm.removeListener(listeners);
            Services.ww.unregisterNotification(listeners);
            windowToIdMap.clear();
	});

	return api;
    })();

    let getTabBrowser = function (win) {
	return win && win.gBrowser || null;
    };

    let getOwnerWindow = function (target) {
	if (target.ownerDocument) {
            return target.ownerDocument.defaultView;
	}
	
	return null;
    };

    vAPI.isBehindTheSceneTabId = function (tabId) {
	return tabId.toString() === '-1';
    };

    vAPI.noTabId = '-1';

    // Tabs and related functions
    vAPI.tabs = {};

    vAPI.tabs.registerListeners = function() {
	tabWatcher.start();
    };

    vAPI.tabs.get = function (tabId, callback) {
	// eMatrix: the following might be obsoleted (though probably
	// still relevant at least for Pale Moon.)
	// 
	// Firefox:
	//
	// browser -> ownerDocument -> defaultView -> gBrowser -> browsers --+
	//    ^                                                              |
	//    |                                                              |
	//    +--------------------------------------------------------------+
	//
	// browser (browser)
	//   contentTitle
	//   currentURI
	//   ownerDocument (XULDocument)
	//     defaultView (ChromeWindow)
	//     gBrowser (tabbrowser OR browser)
	//       browsers (browser)
	//       selectedBrowser
	//       selectedTab
	//       tabs (tab.tabbrowser-tab)
	//
	// Fennec: (what I figured so far)
	//
	//   tab -> browser     windows -> window -> BrowserApp -> tabs --+
	//    ^     window                                                |
	//    |                                                           |
	//    +-----------------------------------------------------------+
	//
	// tab
	//   browser
	// [manual search to go back to tab from list of windows]
	let browser;

	if (tabId === null) {
            browser = tabWatcher.currentBrowser();
            tabId = tabWatcher.tabIdFromTarget(browser);
	} else {
            browser = tabWatcher.browserFromTabId(tabId);
	}

	// For internal use
	if (typeof callback !== 'function') {
            return browser;
	}

	if (!browser || !browser.currentURI) {
            callback();
            return;
	}

	let win = getOwnerWindow(browser);
	let tabBrowser = getTabBrowser(win);

	callback({
            id: tabId,
            windowId: winWatcher.idFromWindow(win),
            active: tabBrowser !== null
		&& browser === tabBrowser.selectedBrowser,
            url: browser.currentURI.asciiSpec,
            title: browser.contentTitle
	});
    };

    vAPI.tabs.getAllSync = function (window) {
	let win;
	let tabs = [];

	for (let win of winWatcher.getWindows()) {
            if (window && window !== win) {
		continue;
            }

            let tabBrowser = getTabBrowser(win);
            if (tabBrowser === null) {
		continue;
            }

            // This can happens if a tab-less window is currently opened.
            // Example of a tab-less window: one opened from clicking
            //   "View Page Source".
            if (!tabBrowser.tabs) {
		continue;
            }

            for (let tab of tabBrowser.tabs) {
		tabs.push(tab);
            }
	}

	return tabs;
    };

    vAPI.tabs.getAll = function (callback) {
	let tabs = [];

	for (let browser of tabWatcher.browsers()) {
            let tab = tabWatcher.tabFromBrowser(browser);
	    
            if (tab === null) {
		continue;
            }
	    
            if (tab.hasAttribute('pending')) {
		continue;
            }
	    
            tabs.push({
		id: tabWatcher.tabIdFromTarget(browser),
		url: browser.currentURI.asciiSpec
            });
	}

	callback(tabs);
    };

    vAPI.tabs.open = function (details) {
	// properties of the details object:
	// + url - the address that will be opened    
	// + tabId:- the tab is used if set, instead of creating a new one
	// + index: - undefined: end of the list, -1: following tab, or
	// after index
	// + active: - opens the tab in background - true and undefined:
	// foreground
	// + select: - if a tab is already opened with that url, then
	// select it instead of opening a new one
	if (!details.url) {
            return null;
	}
	
	// extension pages
	if (/^[\w-]{2,}:/.test(details.url) === false) {
            details.url = vAPI.getURL(details.url);
	}

	if (details.select) {
            let URI = Services.io.newURI(details.url, null, null);

            for (let tab of this.getAllSync()) {
		let browser = tabWatcher.browserFromTarget(tab);
		
		// https://github.com/gorhill/uBlock/issues/2558
		if (browser === null) {
		    continue;
		}

		// Or simply .equals if we care about the fragment
		if (URI.equalsExceptRef(browser.currentURI) === false) {
                    continue;
		}

		this.select(tab);

		// Update URL if fragment is different
		if (URI.equals(browser.currentURI) === false) {
                    browser.loadURI(URI.asciiSpec);
		}
		
		return;
            }
	}

	if (details.active === undefined) {
            details.active = true;
	}

	if (details.tabId) {
            let tab = tabWatcher.browserFromTabId(details.tabId);
	    
            if (tab) {
		tabWatcher.browserFromTarget(tab).loadURI(details.url);
		return;
            }
	}

	// Open in a standalone window
	if (details.popup === true) {
            Services.ww.openWindow(self,
				   details.url,
				   null,
				   'location=1,menubar=1,personalbar=1,'
				   +'resizable=1,toolbar=1',
				   null);
            return;
	}

	let win = winWatcher.getCurrentWindow();
	let tabBrowser = getTabBrowser(win);
	
	if (tabBrowser === null) {
            return;
	}

	if (details.index === -1) {
            details.index =
		tabBrowser.browsers.indexOf(tabBrowser.selectedBrowser) + 1;
	}

	let tab = tabBrowser.loadOneTab(details.url, {
	    inBackground: !details.active
	});

	if (details.index !== undefined) {
            tabBrowser.moveTabTo(tab, details.index);
	}
    };

    vAPI.tabs.replace = function (tabId, url) {
	// Replace the URL of a tab. Noop if the tab does not exist.
	let targetURL = url;

	// extension pages
	if (/^[\w-]{2,}:/.test(targetURL) !== true) {
            targetURL = vAPI.getURL(targetURL);
	}

	let browser = tabWatcher.browserFromTabId(tabId);
	if (browser) {
            browser.loadURI(targetURL);
	}
    };

    vAPI.tabs._remove = function (tab, tabBrowser) {
	if (tabBrowser) {
            tabBrowser.removeTab(tab);
	}
    };
    function removeInternal(tab, tabBrowser) {
	if (tabBrowser) {
	    tabBrowser.removeTab(tab);
	}
    }

    vAPI.tabs.remove = function (tabId) {
	let browser = tabWatcher.browserFromTabId(tabId);
	if (!browser) {
            return;
	}
	
	let tab = tabWatcher.tabFromBrowser(browser);
	if (!tab) {
            return;
	}
	
	removeInternal(tab, getTabBrowser(getOwnerWindow(browser)));
    };

    vAPI.tabs.reload = function (tabId) {
	let browser = tabWatcher.browserFromTabId(tabId);
	if (!browser) {
            return;
	}

	browser.webNavigation.reload(Ci.nsIWebNavigation.LOAD_FLAGS_BYPASS_CACHE);
    };

    vAPI.tabs.select = function (tab) {
	if (typeof tab !== 'object') {
            tab = tabWatcher.tabFromBrowser(tabWatcher.browserFromTabId(tab));
	}
	if (!tab) {
            return;
	}

	// https://github.com/gorhill/uBlock/issues/470
	let win = getOwnerWindow(tab);
	win.focus();

	let tabBrowser = getTabBrowser(win);
	if (tabBrowser) {
            tabBrowser.selectedTab = tab;
	}
    };

    vAPI.tabs.injectScript = function (tabId, details, callback) {
	let browser = tabWatcher.browserFromTabId(tabId);
	if (!browser) {
            return;
	}

	if (typeof details.file !== 'string') {
            return;
	}

	details.file = vAPI.getURL(details.file);
	browser.messageManager.sendAsyncMessage(location.host + ':broadcast',
						JSON.stringify({
						    broadcast: true,
						    channelName: 'vAPI',
						    msg: {
							cmd: 'injectScript',
							details: details
						    }
						}));

	if (typeof callback === 'function') {
            vAPI.setTimeout(callback, 13);
	}
    };

    let tabWatcher = (function () {
	// TODO: find out whether we need a janitor to take care of stale entries.

	// https://github.com/gorhill/uMatrix/issues/540
	// Use only weak references to hold onto browser references.
	let browserToTabIdMap = new WeakMap();
	let tabIdToBrowserMap = new Map();
	let tabIdGenerator = 1;

	let indexFromBrowser = function (browser) {
            if (!browser) {
		return -1;
            }

	    let win = getOwnerWindow(browser);
            if (!win) {
		return -1;
            }
	    
            let tabBrowser = getTabBrowser(win);
            if (tabBrowser === null) {
		return -1;
            }
	    
            // This can happen, for example, the `view-source:`
            // window, there is no tabbrowser object, the browser
            // object sits directly in the window.
            if (tabBrowser === browser) {
		return 0;
            }
	    
            return tabBrowser.browsers.indexOf(browser);
	};

	let indexFromTarget = function (target) {
            return indexFromBrowser(browserFromTarget(target));
	};

	let tabFromBrowser = function (browser) {
            let i = indexFromBrowser(browser);
            if (i === -1) {
		return null;
            }
	    
            let win = getOwnerWindow(browser);
            if (!win) {
		return null;
            }
	    
            let tabBrowser = getTabBrowser(win);
            if (tabBrowser === null) {
		return null;
            }
	    
            if (!tabBrowser.tabs || i >= tabBrowser.tabs.length) {
		return null;
            }
	    
            return tabBrowser.tabs[i];
	};

	let browserFromTarget = function (target) {
            if (!target) {
		return null;
            }
	    
            if (target.linkedPanel) {
		// target is a tab
		target = target.linkedBrowser;
            }
	    
            if (target.localName !== 'browser') {
		return null;
            }
	    
            return target;
	};

	let tabIdFromTarget = function (target) {
            let browser = browserFromTarget(target);
            if (browser === null) {
		return vAPI.noTabId;
            }
	    
            let tabId = browserToTabIdMap.get(browser);
            if (tabId === undefined) {
		tabId = '' + tabIdGenerator++;
		browserToTabIdMap.set(browser, tabId);
		tabIdToBrowserMap.set(tabId, Cu.getWeakReference(browser));
            }
	    
            return tabId;
	};

	let browserFromTabId = function (tabId) {
            let weakref = tabIdToBrowserMap.get(tabId);
            let browser = weakref && weakref.get();
	    
            return browser || null;
	};

	let currentBrowser = function () {
            let win = winWatcher.getCurrentWindow();
	    
            // https://github.com/gorhill/uBlock/issues/399
            // getTabBrowser() can return null at browser launch time.
            let tabBrowser = getTabBrowser(win);
            if (tabBrowser === null) {
		return null;
            }
	    
            return browserFromTarget(tabBrowser.selectedTab);
	};

	let removeBrowserEntry = function (tabId, browser) {
            if (tabId && tabId !== vAPI.noTabId) {
		vAPI.tabs.onClosed(tabId);
		delete vAPI.toolbarButton.tabs[tabId];
		tabIdToBrowserMap.delete(tabId);
            }
	    
            if (browser) {
		browserToTabIdMap.delete(browser);
            }
	};

	let removeTarget = function (target) {
            onClose({
		target: target
	    });
	};

	let getAllBrowsers = function () {
            let browsers = [];

	    for (let [tabId, weakref] of tabIdToBrowserMap) {
		let browser = weakref.get();
		
		// TODO: Maybe call removeBrowserEntry() if the
		// browser no longer exists?
		if (browser) {
                    browsers.push(browser);
		}
            }
	    
            return browsers;
	};

	// var onOpen = function (target) {
	//     var tabId = tabIdFromTarget(target);
	//     var browser = browserFromTabId(tabId);
	//     vAPI.tabs.onNavigation({
	// 	frameId: 0,
	// 	tabId: tabId,
	// 	url: browser.currentURI.asciiSpec,
	//     });
	// };

	var onShow = function ({target}) {
            tabIdFromTarget(target);
	};

	var onClose = function ({target}) {
            // target is tab in Firefox, browser in Fennec
            let browser = browserFromTarget(target);
            let tabId = browserToTabIdMap.get(browser);
            removeBrowserEntry(tabId, browser);
	};

	var onSelect = function ({target}) {
	    // This is an entry point: when creating a new tab, it is
	    // not always reported through onLocationChanged...
	    // Sigh. It is "reported" here however.
            let browser = browserFromTarget(target);
            let tabId = browserToTabIdMap.get(browser);

	    if (tabId === undefined) {
		tabId = tabIdFromTarget(target);
		vAPI.tabs.onNavigation({
                    frameId: 0,
                    tabId: tabId,
                    url: browser.currentURI.asciiSpec
		});
            }
	    
            vAPI.setIcon(tabId, getOwnerWindow(target));
	};

	let locationChangedMessageName = location.host + ':locationChanged';

	let onLocationChanged = function (e) {
            let details = e.data;

            // Ignore notifications related to our popup
            if (details.url.lastIndexOf(vAPI.getURL('popup.html'), 0) === 0) {
		return;
            }

            let browser = e.target;
            let tabId = tabIdFromTarget(browser);
            if (tabId === vAPI.noTabId) {
		return;
            }

            // LOCATION_CHANGE_SAME_DOCUMENT = "did not load a new document"
            if (details.flags
		& Ci.nsIWebProgressListener.LOCATION_CHANGE_SAME_DOCUMENT) {
		vAPI.tabs.onUpdated(tabId, {url: details.url}, {
                    frameId: 0,
                    tabId: tabId,
                    url: browser.currentURI.asciiSpec
		});
		return;
            }

            // https://github.com/chrisaljoudi/uBlock/issues/105
            // Allow any kind of pages
            vAPI.tabs.onNavigation({
		frameId: 0,
		tabId: tabId,
		url: details.url
            });
	};

	let attachToTabBrowser = function (window) {
            if (typeof vAPI.toolbarButton.attachToNewWindow === 'function') {
		vAPI.toolbarButton.attachToNewWindow(window);
            }

            let tabBrowser = getTabBrowser(window);
            if (tabBrowser === null) {
		return;
            }

            let tabContainer;
            if (tabBrowser.deck) {
                // Fennec
		tabContainer = tabBrowser.deck;
            } else if (tabBrowser.tabContainer) {
		// Firefox
		tabContainer = tabBrowser.tabContainer;
		vAPI.contextMenu.register(document);
            }

            // https://github.com/gorhill/uBlock/issues/697
            // Ignore `TabShow` events: unfortunately the `pending`
            // attribute is not set when a tab is opened as a result
            // of session restore -- it is set *after* the event is
            // fired in such case.
            if (tabContainer) {
		tabContainer.addEventListener('TabShow', onShow);
		tabContainer.addEventListener('TabClose', onClose);
		// when new window is opened TabSelect doesn't run on
		// the selected tab?
		tabContainer.addEventListener('TabSelect', onSelect);
            }
	};
	
	var canAttachToTabBrowser = function (window) {
	    // https://github.com/gorhill/uBlock/issues/906
	    // Ensure the environment is ready before trying to attaching.
            let document = window && window.document;
            if (!document || document.readyState !== 'complete') {
		return false;
            }

            // On some platforms, the tab browser isn't immediately
            // available, try waiting a bit if this 	   
            // https://github.com/gorhill/uBlock/issues/763
            // Not getting a tab browser should not prevent from
            // attaching ourself to the window.
            let tabBrowser = getTabBrowser(window);
            if (tabBrowser === null) {
		return false;
            }

            return winWatcher.toBrowserWindow(window) !== null;
	};

	let onWindowLoad = function (win) {
            deferUntil(canAttachToTabBrowser.bind(null, win),
		       attachToTabBrowser.bind(null, win));
	};

	let onWindowUnload = function (win) {
            vAPI.contextMenu.unregister(win.document);

            let tabBrowser = getTabBrowser(win);
            if (tabBrowser === null) {
		return;
            }

            let tabContainer = tabBrowser.tabContainer;
            if (tabContainer) {
		tabContainer.removeEventListener('TabShow', onShow);
		tabContainer.removeEventListener('TabClose', onClose);
		tabContainer.removeEventListener('TabSelect', onSelect);
            }

            // https://github.com/gorhill/uBlock/issues/574
            // To keep in mind: not all windows are tab containers,
            // sometimes the window IS the tab.
            let tabs;
            if (tabBrowser.tabs) {
		tabs = tabBrowser.tabs;
            } else if (tabBrowser.localName === 'browser') {
		tabs = [tabBrowser];
            } else {
		tabs = [];
            }

            let browser;
	    let URI;
	    let tabId;
	    for (let i=tabs.length-1; i>=0; --i) {
		let tab = tabs[i];
		browser = browserFromTarget(tab);
		if (browser === null) {
                    continue;
		}
		
		URI = browser.currentURI;
		// Close extension tabs
		if (URI.schemeIs('chrome') && URI.host === location.host) {
                    removeInternal(tab, getTabBrowser(win));
		}
		
		tabId = browserToTabIdMap.get(browser);
		if (tabId !== undefined) {
                    removeBrowserEntry(tabId, browser);
                    tabIdToBrowserMap.delete(tabId);
		}
		browserToTabIdMap.delete(browser);
            }
	};

	var start = function () {
	    // Initialize map with existing active tabs
            let tabBrowser;
	    let tabs;

            for (let win of winWatcher.getWindows()) {
		onWindowLoad(win);
		
		tabBrowser = getTabBrowser(win);
		if (tabBrowser === null) {
                    continue;
		}
		
		for (let tab of tabBrowser.tabs) {
                    if (!tab.hasAttribute('pending')) {
			tabIdFromTarget(tab);
                    }
		}
            }

            winWatcher.onOpenWindow = onWindowLoad;
            winWatcher.onCloseWindow = onWindowUnload;

            vAPI.messaging.globalMessageManager
		.addMessageListener(locationChangedMessageName,
				    onLocationChanged);
	};

	let stop = function () {
            winWatcher.onOpenWindow = null;
            winWatcher.onCloseWindow = null;

            vAPI.messaging.globalMessageManager
		.removeMessageListener(locationChangedMessageName,
				       onLocationChanged);

            for (let win of winWatcher.getWindows()) {
		onWindowUnload(win);
            }

            browserToTabIdMap = new WeakMap();
            tabIdToBrowserMap.clear();
	};

	cleanupTasks.push(stop);

	return {
            browsers: getAllBrowsers,
            browserFromTabId: browserFromTabId,
            browserFromTarget: browserFromTarget,
            currentBrowser: currentBrowser,
            indexFromTarget: indexFromTarget,
            removeTarget: removeTarget,
            start: start,
            tabFromBrowser: tabFromBrowser,
            tabIdFromTarget: tabIdFromTarget
	};
    })();

    // Icon-related stuff
    vAPI.setIcon = function (tabId, iconId, badge) {
	// If badge is undefined, then setIcon was called from the
	// TabSelect event
	let win;
	if (badge === undefined) {
            win = iconId;
	} else {
            win = winWatcher.getCurrentWindow();
	}
	
	let tabBrowser = getTabBrowser(win);
	if (tabBrowser === null) {
            return;
	}
	
	let curTabId = tabWatcher.tabIdFromTarget(tabBrowser.selectedTab);
	let tb = vAPI.toolbarButton;

	// from 'TabSelect' event
	if (tabId === undefined) {
            tabId = curTabId;
	} else if (badge !== undefined) {
            tb.tabs[tabId] = {
		badge: badge, img: iconId
	    };
	}

	if (tabId === curTabId) {
            tb.updateState(win, tabId);
	}
    };

    // Internal message passing mechanism
    vAPI.messaging = {
	get globalMessageManager() {
            return Cc['@mozilla.org/globalmessagemanager;1']
                .getService(Ci.nsIMessageListenerManager);
	},
	frameScript: vAPI.getURL('frameScript.js'),
	listeners: {},
	defaultHandler: null,
	NOOPFUNC: function(){},
	UNHANDLED: 'vAPI.messaging.notHandled'
    };

    vAPI.messaging.listen = function (listenerName, callback) {
	this.listeners[listenerName] = callback;
    };

    vAPI.messaging.onMessage = function ({target, data}) {
	let messageManager = target.messageManager;

	if (!messageManager) {
            // Message came from a popup, and its message manager is
            // not usable.  So instead we broadcast to the parent
            // window.
            messageManager =
		getOwnerWindow(target.webNavigation
			       .QueryInterface(Ci.nsIDocShell)
			       .chromeEventHandler).messageManager;
	}

	let channelNameRaw = data.channelName;
	let pos = channelNameRaw.indexOf('|');
	let channelName = channelNameRaw.slice(pos + 1);

	let callback = vAPI.messaging.NOOPFUNC;
	if (data.requestId !== undefined) {
            callback = CallbackWrapper.factory(messageManager,
					       channelName,
					       channelNameRaw.slice(0, pos),
					       data.requestId).callback;
	}

	let sender = {
            tab: {
		id: tabWatcher.tabIdFromTarget(target)
            }
	};

	// Specific handler
	let r = vAPI.messaging.UNHANDLED;
	let listener = vAPI.messaging.listeners[channelName];
	
	if (typeof listener === 'function') {
            r = listener(data.msg, sender, callback);
	}
	if (r !== vAPI.messaging.UNHANDLED) {
            return;
	}

	// Default handler
	r = vAPI.messaging.defaultHandler(data.msg, sender, callback);
	if (r !== vAPI.messaging.UNHANDLED) {
            return;
	}

	console.error('eMatrix> messaging > unknown request: %o', data);

	// Unhandled: Need to callback anyways in case caller expected
	// an answer, or else there is a memory leak on caller's side
	callback();
    };

    vAPI.messaging.setup = function (defaultHandler) {
	// Already setup?
	if (this.defaultHandler !== null) {
            return;
	}

	if (typeof defaultHandler !== 'function') {
            defaultHandler = function () {
		return vAPI.messaging.UNHANDLED;
	    };
	}
	
	this.defaultHandler = defaultHandler;
	this.globalMessageManager.addMessageListener(location.host
						     + ':background',
						     this.onMessage);
	this.globalMessageManager.loadFrameScript(this.frameScript, true);

	cleanupTasks.push(function () {
            let gmm = vAPI.messaging.globalMessageManager;

            gmm.removeDelayedFrameScript(vAPI.messaging.frameScript);
            gmm.removeMessageListener(location.host + ':background',
				      vAPI.messaging.onMessage);
	});
    };

    vAPI.messaging.broadcast = function (message) {
	this.globalMessageManager
	    .broadcastAsyncMessage(location.host + ':broadcast',
				   JSON.stringify({
				       broadcast: true,
				       msg: message}));
    };

    let CallbackWrapper = function (messageManager, channelName,
				    listenerId, requestId) {
	// This allows to avoid creating a closure for every single
	// message which expects an answer. Having a closure created
	// each time a message is processed has been always bothering
	// me. Another benefit of the implementation here is to reuse
	// the callback proxy object, so less memory churning.
	//
	// https://developers.google.com/speed/articles/optimizing-javascript
	// "Creating a closure is significantly slower then creating
	// an inner function without a closure, and much slower than
	// reusing a static function"
	//
	// http://hacksoflife.blogspot.ca/2015/01/the-four-horsemen-of-performance.html
	// "the dreaded 'uniformly slow code' case where every
	// function takes 1% of CPU and you have to make one hundred
	// separate performance optimizations to improve performance
	// at all"
	//
	// http://jsperf.com/closure-no-closure/2
	this.callback = this.proxy.bind(this); // bind once
	this.init(messageManager, channelName, listenerId, requestId);
    };

    CallbackWrapper.junkyard = [];

    CallbackWrapper.factory = function (messageManager, channelName,
					listenerId, requestId) {
	let wrapper = CallbackWrapper.junkyard.pop();
	if (wrapper) {
            wrapper.init(messageManager, channelName, listenerId, requestId);
            return wrapper;
	}
	
	return new CallbackWrapper(messageManager, channelName,
				   listenerId, requestId);
    };

    CallbackWrapper.prototype.init = function (messageManager, channelName,
					       listenerId, requestId) {
	this.messageManager = messageManager;
	this.channelName = channelName;
	this.listenerId = listenerId;
	this.requestId = requestId;
    };

    CallbackWrapper.prototype.proxy = function (response) {
	let message = JSON.stringify({
            requestId: this.requestId,
            channelName: this.channelName,
            msg: response !== undefined ? response : null
	});

	if (this.messageManager.sendAsyncMessage) {
            this.messageManager.sendAsyncMessage(this.listenerId, message);
	} else {
            this.messageManager.broadcastAsyncMessage(this.listenerId, message);
	}

	// Mark for reuse
	this.messageManager = this.channelName =
	    this.requestId = this.listenerId = null;
	
	CallbackWrapper.junkyard.push(this);
    };

    let httpRequestHeadersFactory = function (channel) {
	let entry = httpRequestHeadersFactory.junkyard.pop();
	if (entry) {
            return entry.init(channel);
	}
	
	return new HTTPRequestHeaders(channel);
    };

    httpRequestHeadersFactory.junkyard = [];

    let HTTPRequestHeaders = function (channel) {
	this.init(channel);
    };

    HTTPRequestHeaders.prototype.init = function (channel) {
	this.channel = channel;
	this.headers = new Array();
	this.originalHeaderNames = new Array();
	
	channel.visitRequestHeaders({
	    visitHeader: function (name, value) {
		this.headers.push({name: name, value: value});
		this.originalHeaderNames.push(name);
	    }.bind(this)
	});
	
	return this;
    };

    HTTPRequestHeaders.prototype.dispose = function () {
	this.channel = null;
	this.headers = null;
	this.originalHeaderNames = null;
	httpRequestHeadersFactory.junkyard.push(this);
    };

    HTTPRequestHeaders.prototype.update = function () {
	let newHeaderNames = new Set();
	for (let header of this.headers) {
            this.setHeader(header.name, header.value, true);
            newHeaderNames.add(header.name);
	}
	
	//Clear any headers that were removed
	for (let name of this.originalHeaderNames) {
            if (!newHeaderNames.has(name)) {
		this.channel.setRequestHeader(name, '', false);
            }
	}
    };

    HTTPRequestHeaders.prototype.getHeader = function (name) {
	try {
            return this.channel.getRequestHeader(name);
	} catch (e) {
	    // Ignore
	}
	
	return '';
    };

    HTTPRequestHeaders.prototype.setHeader = function (name, newValue, create) {
	let oldValue = this.getHeader(name);
	if (newValue === oldValue) {
            return false;
	}
	
	if (oldValue === '' && create !== true) {
            return false;
	}
	
	this.channel.setRequestHeader(name, newValue, false);
	return true;
    };

    let httpObserver = {
	classDescription: 'net-channel-event-sinks for ' + location.host,
	classID: Components.ID('{5d2e2797-6d68-42e2-8aeb-81ce6ba16b95}'),
	contractID: '@' + location.host + '/net-channel-event-sinks;1',
	REQDATAKEY: location.host + 'reqdata',
	ABORT: Components.results.NS_BINDING_ABORTED,
	ACCEPT: Components.results.NS_SUCCEEDED,
	// Request types:
	// https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Reference/Interface/nsIContentPolicy#Constants
	// eMatrix: we can just use nsIContentPolicy's built-in
	// constants, can we?
	frameTypeMap: {
            6: 'main_frame',
            7: 'sub_frame'
	},
	typeMap: {
            1: 'other',
            2: 'script',
            3: 'image',
            4: 'stylesheet',
            5: 'object',
            6: 'main_frame',
            7: 'sub_frame',
            9: 'xbl',
            10: 'ping',
            11: 'xmlhttprequest',
            12: 'object',
            13: 'xml_dtd',
            14: 'font',
            15: 'media',
            16: 'websocket',
            17: 'csp_report',
            18: 'xslt',
            19: 'beacon',
            20: 'xmlhttprequest',
            21: 'imageset',
            22: 'web_manifest'
	},
	mimeTypeMap: {
            'audio': 15,
            'video': 15
	},
	get componentRegistrar () {
            return Components.manager.QueryInterface(Ci.nsIComponentRegistrar);
	},
	get categoryManager () {
            return Cc['@mozilla.org/categorymanager;1']
                .getService(Ci.nsICategoryManager);
	},
	QueryInterface: (function () {
            var {XPCOMUtils} =
		Cu.import('resource://gre/modules/XPCOMUtils.jsm', null);

            return XPCOMUtils.generateQI([
		Ci.nsIFactory,
		Ci.nsIObserver,
		Ci.nsIChannelEventSink,
		Ci.nsISupportsWeakReference
            ]);
	})(),
	createInstance: function (outer, iid) {
            if (outer) {
		throw Components.results.NS_ERROR_NO_AGGREGATION;
            }

            return this.QueryInterface(iid);
	},
	register: function () {
            this.pendingRingBufferInit();
	    
            Services.obs.addObserver(this, 'http-on-modify-request', true);
            Services.obs.addObserver(this, 'http-on-examine-response', true);
            Services.obs.addObserver(this, 'http-on-examine-cached-response', true);

            // Guard against stale instances not having been unregistered
            if (this.componentRegistrar.isCIDRegistered(this.classID)) {
		try {
                    this.componentRegistrar
			.unregisterFactory(this.classID,
					   Components.manager
					   .getClassObject(this.classID,
							   Ci.nsIFactory));
		} catch (ex) {
                    console.error('eMatrix> httpObserver > '
				  +'unable to unregister stale instance: ', ex);
		}
            }

            this.componentRegistrar.registerFactory(this.classID,
						    this.classDescription,
						    this.contractID,
						    this);
            this.categoryManager.addCategoryEntry('net-channel-event-sinks',
						  this.contractID,
						  this.contractID,
						  false,
						  true);
	},
	unregister: function () {
            Services.obs.removeObserver(this, 'http-on-modify-request');
            Services.obs.removeObserver(this, 'http-on-examine-response');
            Services.obs.removeObserver(this, 'http-on-examine-cached-response');

            this.componentRegistrar.unregisterFactory(this.classID, this);
            this.categoryManager.deleteCategoryEntry('net-channel-event-sinks',
						     this.contractID,
						     false);
	},
	PendingRequest: function () {
            this.rawType = 0;
            this.tabId = 0;
            this._key = ''; // key is url, from URI.spec
	},
	// If all work fine, this map should not grow indefinitely. It
	// can have stale items in it, but these will be taken care of
	// when entries in the ring buffer are overwritten.
	pendingURLToIndex: new Map(),
	pendingWritePointer: 0,
	pendingRingBuffer: new Array(256),
	pendingRingBufferInit: function () {
            // Use and reuse pre-allocated PendingRequest objects =
            // less memory churning.
            for (let i=this.pendingRingBuffer.length-1; i>=0; --i) {
		this.pendingRingBuffer[i] = new this.PendingRequest();
            }
	},
	createPendingRequest: function (url) {
	    // Pending request ring buffer:
	    // +-------+-------+-------+-------+-------+-------+-------
	    // |0      |1      |2      |3      |4      |5      |...      
	    // +-------+-------+-------+-------+-------+-------+-------
	    //
	    // URL to ring buffer index map:
	    // { k = URL, s = ring buffer indices }
	    //
	    // s is a string which character codes map to ring buffer
	    // indices -- for when the same URL is received multiple times
	    // by shouldLoadListener() before the existing one is serviced
	    // by the network request observer.  I believe the use of a
	    // string in lieu of an array reduces memory churning.
            let bucket;
            let i = this.pendingWritePointer;
            this.pendingWritePointer = i + 1 & 255;
	    
            let preq = this.pendingRingBuffer[i];
            let si = String.fromCharCode(i);
	    
            // Cleanup unserviced pending request
            if (preq._key !== '') {
		bucket = this.pendingURLToIndex.get(preq._key);
		if (bucket.length === 1) {
                    this.pendingURLToIndex.delete(preq._key);
		} else {
                    let pos = bucket.indexOf(si);
                    this.pendingURLToIndex.set(preq._key,
					       bucket.slice(0, pos)
					       + bucket.slice(pos + 1));
		}
            }
	    
            bucket = this.pendingURLToIndex.get(url);
            this.pendingURLToIndex.set(url, bucket === undefined
				       ? si
				       : bucket + si);
            preq._key = url;
            return preq;
	},
	lookupPendingRequest: function (url) {
            let bucket = this.pendingURLToIndex.get(url);
            if (bucket === undefined) {
		return null;
            }
	    
            let i = bucket.charCodeAt(0);
            if (bucket.length === 1) {
		this.pendingURLToIndex.delete(url);
            } else {
		this.pendingURLToIndex.set(url, bucket.slice(1));
            }
	    
            let preq = this.pendingRingBuffer[i];
            preq._key = ''; // mark as "serviced"
            return preq;
	},
	handleRequest: function (channel, URI, tabId, rawType) {
            let type = this.typeMap[rawType] || 'other';

            let onBeforeRequest = vAPI.net.onBeforeRequest;
            if (onBeforeRequest.types === null
		|| onBeforeRequest.types.has(type)) {
		let result = onBeforeRequest.callback({
                    parentFrameId: type === 'main_frame' ? -1 : 0,
                    tabId: tabId,
                    type: type,
                    url: URI.asciiSpec
		});

		if (typeof result === 'object') {
                    channel.cancel(this.ABORT);
                    return true;
		}
            }

            let onBeforeSendHeaders = vAPI.net.onBeforeSendHeaders;
            if (onBeforeSendHeaders.types === null
		|| onBeforeSendHeaders.types.has(type)) {
		let requestHeaders = httpRequestHeadersFactory(channel);
		let newHeaders = onBeforeSendHeaders.callback({
                    parentFrameId: type === 'main_frame' ? -1 : 0,
                    requestHeaders: requestHeaders.headers,
                    tabId: tabId,
                    type: type,
                    url: URI.asciiSpec,
                    method: channel.requestMethod
		});
		
		if (newHeaders) {
                    requestHeaders.update();
		}
		requestHeaders.dispose();
            }

            return false;
	},
	channelDataFromChannel: function (channel) {
            if (channel instanceof Ci.nsIWritablePropertyBag) {
		try {
                    return channel.getProperty(this.REQDATAKEY) || null;
		} catch (ex) {
		    // Ignore
		}
            }
	    
            return null;
	},
	// https://github.com/gorhill/uMatrix/issues/165
	// https://developer.mozilla.org/en-US/Firefox/Releases/3.5/Updating_extensions#Getting_a_load_context_from_a_request
	// Not sure `ematrix:shouldLoad` is still needed, eMatrix does
	// not care about embedded frames topography.
	// Also:
	// https://developer.mozilla.org/en-US/Firefox/Multiprocess_Firefox/Limitations_of_chrome_scripts
	tabIdFromChannel: function (channel) {
            let lc;
            try {
		lc = channel.notificationCallbacks.getInterface(Ci.nsILoadContext);
            } catch(ex) {
		// Ignore
            }
	    
            if (!lc) {
		try {
                    lc = channel.loadGroup.notificationCallbacks
			.getInterface(Ci.nsILoadContext);
		} catch(ex) {
		    // Ignore
		}
		
		if (!lc) {
                    return vAPI.noTabId;
		}
            }
	    
            if (lc.topFrameElement) {
		return tabWatcher.tabIdFromTarget(lc.topFrameElement);
            }
	    
            let win;
            try {
		win = lc.associatedWindow;
            } catch (ex) {
		// Ignore
	    }
	    
            if (!win) {
		return vAPI.noTabId;
            }
	    
            if (win.top) {
		win = win.top;
            }
	    
            let tabBrowser;
            try {
		tabBrowser =
		    getTabBrowser(win.QueryInterface(Ci.nsIInterfaceRequestor)
				  .getInterface(Ci.nsIWebNavigation)
				  .QueryInterface(Ci.nsIDocShell).rootTreeItem
				  .QueryInterface(Ci.nsIInterfaceRequestor)
				  .getInterface(Ci.nsIDOMWindow));
            } catch (ex) {
		// Ignore
	    }
	    
            if (!tabBrowser) {
		return vAPI.noTabId;
            }
	    
            if (tabBrowser.getBrowserForContentWindow) {
		return tabWatcher.tabIdFromTarget(tabBrowser.getBrowserForContentWindow(win));
            }
	    
            // Falling back onto _getTabForContentWindow to ensure older
            // versions of Firefox work well.
            return tabBrowser._getTabForContentWindow
		? tabWatcher.tabIdFromTarget(tabBrowser
					     ._getTabForContentWindow(win))
		: vAPI.noTabId;
	},
	rawtypeFromContentType: function (channel) {
            let mime = channel.contentType;
            if (!mime) {
		return 0;
            }
	    
            let pos = mime.indexOf('/');
            if (pos === -1) {
		pos = mime.length;
            }
	    
            return this.mimeTypeMap[mime.slice(0, pos)] || 0;
	},
	observe: function (channel, topic) {
            if (channel instanceof Ci.nsIHttpChannel === false) {
		return;
            }

            let URI = channel.URI;
            let channelData = this.channelDataFromChannel(channel);

            if (topic.lastIndexOf('http-on-examine-', 0) === 0) {
		if (channelData === null) {
                    return;
		}

		let type = this.frameTypeMap[channelData[1]];
		if (!type) {
                    return;
		}

		// topic = ['Content-Security-Policy',
		// 'Content-Security-Policy-Report-Only'];
		// 
		// Can send empty responseHeaders as these headers are
		// only added to and then merged.
		// 
		// TODO: Find better place for this, needs to be set
		// before onHeadersReceived.callback.  Web workers not
		// blocked in Pale Moon as child-src currently
		// unavailable, see:
		//
		// https://github.com/MoonchildProductions/Pale-Moon/issues/949
		//
		// eMatrix: as of Pale Moon 28 it seems child-src is
		// available and depracated(?)
		if (ηMatrix.cspNoWorker === undefined) {
                    // ηMatrix.cspNoWorker = "child-src 'none'; "
		    // 	+"frame-src data: blob: *; "
		    // 	+"report-uri about:blank";
		    ηMatrix.cspNoWorker = "worker-src 'none'; "
			+"frame-src data: blob: *; "
			+"report-uri about:blank";
		}

		let result = vAPI.net.onHeadersReceived.callback({
                    parentFrameId: type === 'main_frame' ? -1 : 0,
                    responseHeaders: [],
                    tabId: channelData[0],
                    type: type,
                    url: URI.asciiSpec
		});

		if (result) {
                    for (let header of result.responseHeaders) {
			channel.setResponseHeader(header.name,
						  header.value,
						  true);
                    }
		}
		
		return;
            }

            // http-on-modify-request
            // The channel was previously serviced.
            if (channelData !== null) {
		this.handleRequest(channel, URI,
				   channelData[0], channelData[1]);
		return;
            }

            // The channel was never serviced.
            let tabId;
            let pendingRequest = this.lookupPendingRequest(URI.asciiSpec);
            let rawType = 1;
            let loadInfo = channel.loadInfo;

            // https://github.com/gorhill/uMatrix/issues/390#issuecomment-155717004
            if (loadInfo) {
		rawType = (loadInfo.externalContentPolicyType !== undefined)
		    ? loadInfo.externalContentPolicyType
		    : loadInfo.contentPolicyType;
		if (!rawType) {
                    rawType = 1;
		}
            }

            if (pendingRequest !== null) {
		tabId = pendingRequest.tabId;
		// https://github.com/gorhill/uBlock/issues/654
		// Use the request type from the HTTP observer point of view.
		if (rawType !== 1) {
                    pendingRequest.rawType = rawType;
		} else {
                    rawType = pendingRequest.rawType;
		}
            } else {
		tabId = this.tabIdFromChannel(channel);
            }

            if (this.handleRequest(channel, URI, tabId, rawType)) {
		return;
            }

            if (channel instanceof Ci.nsIWritablePropertyBag === false) {
		return;
            }

            // Carry data for behind-the-scene redirects
            channel.setProperty(this.REQDATAKEY, [tabId, rawType]);
	},
	asyncOnChannelRedirect: function (oldChannel, newChannel,
					  flags, callback) {
	    // contentPolicy.shouldLoad doesn't detect redirects, this
	    // needs to be used
            // If error thrown, the redirect will fail
            try {
		let URI = newChannel.URI;
		if (!URI.schemeIs('http') && !URI.schemeIs('https')) {
                    return;
		}

		if (newChannel instanceof Ci.nsIWritablePropertyBag === false) {
                    return;
		}

		let channelData = this.channelDataFromChannel(oldChannel);
		if (channelData === null) {
                    return;
		}

		// Carry the data on in case of multiple redirects
		newChannel.setProperty(this.REQDATAKEY, channelData);
            } catch (ex) {
		// console.error(ex);
		// Ignore
            } finally {
		callback.onRedirectVerifyCallback(this.ACCEPT);
            }
	}
    };

    vAPI.net = {};

    vAPI.net.registerListeners = function () {
	this.onBeforeRequest.types = this.onBeforeRequest.types
	    ? new Set(this.onBeforeRequest.types)
	    : null;
	
	this.onBeforeSendHeaders.types = this.onBeforeSendHeaders.types
	    ? new Set(this.onBeforeSendHeaders.types)
	    : null;

	let shouldLoadListenerMessageName = location.host + ':shouldLoad';
	let shouldLoadListener = function (e) {
            let details = e.data;
            let pendingReq = httpObserver.createPendingRequest(details.url);
            pendingReq.rawType = details.rawType;
            pendingReq.tabId = tabWatcher.tabIdFromTarget(e.target);
	};

	// https://github.com/gorhill/uMatrix/issues/200
	// We need this only for Firefox 34 and less: the tab id is derived from
	// the origin of the message.
	if (!vAPI.modernFirefox) {
            vAPI.messaging.globalMessageManager
		.addMessageListener(shouldLoadListenerMessageName,
				    shouldLoadListener);
	}

	httpObserver.register();

	cleanupTasks.push(function () {
            if (!vAPI.modernFirefox) {
		vAPI.messaging.globalMessageManager
		    .removeMessageListener(shouldLoadListenerMessageName,
					   shouldLoadListener);
            }

            httpObserver.unregister();
	});
    };

    vAPI.toolbarButton = {
	id: location.host + '-button',
	type: 'view',
	viewId: location.host + '-panel',
	label: vAPI.app.name,
	tooltiptext: vAPI.app.name,
	tabs: {/*tabId: {badge: 0, img: boolean}*/},
	init: null,
	codePath: ''
    };

    // Non-Fennec: common code paths.
    (function () {
	if (vAPI.fennec) {
            return;
	}

	let tbb = vAPI.toolbarButton;
	let popupCommittedWidth = 0;
	let popupCommittedHeight = 0;

	tbb.onViewShowing = function ({target}) {
            popupCommittedWidth = popupCommittedHeight = 0;
            target.firstChild.setAttribute('src', vAPI.getURL('popup.html'));
	};

	tbb.onViewHiding = function ({target}) {
            target.parentNode.style.maxWidth = '';
            target.firstChild.setAttribute('src', 'about:blank');
	};

	tbb.updateState = function (win, tabId) {
            let button = win.document.getElementById(this.id);

            if (!button) {
		return;
            }

            let icon = this.tabs[tabId];
            button.setAttribute('badge', icon && icon.badge || '');
            button.classList.toggle('off', !icon || !icon.img);

            let iconId = icon && icon.img ? icon.img : 'off';
            icon = 'url(' + vAPI.getURL('img/browsericons/icon19-' + iconId + '.png') + ')';
            button.style.listStyleImage = icon;
	};

	tbb.populatePanel = function (doc, panel) {
            panel.setAttribute('id', this.viewId);

            let iframe = doc.createElement('iframe');
            iframe.setAttribute('type', 'content');

            panel.appendChild(iframe);

            let toPx = function (pixels) {
		return pixels.toString() + 'px';
            };

            let scrollBarWidth = 0;
            let resizeTimer = null;

            let resizePopupDelayed = function (attempts) {
		if (resizeTimer !== null) {
                    return false;
		}

		// Sanity check
		attempts = (attempts || 0) + 1;
		if ( attempts > 1/*000*/ ) {
                    //console.error('eMatrix> resizePopupDelayed: giving up after too many attempts');
                    return false;
		}

		resizeTimer = vAPI.setTimeout(resizePopup, 10, attempts);
		return true;
            };

            let resizePopup = function (attempts) {
		resizeTimer = null;

		panel.parentNode.style.maxWidth = 'none';
		let body = iframe.contentDocument.body;

		// https://github.com/gorhill/uMatrix/issues/301
		// Don't resize if committed size did not change.
		if (popupCommittedWidth === body.clientWidth
		    && popupCommittedHeight === body.clientHeight) {
                    return;
		}

		// We set a limit for height
		let height = Math.min(body.clientHeight, 600);

		// https://github.com/chrisaljoudi/uBlock/issues/730
		// Voodoo programming: this recipe works
		panel.style.setProperty('height', toPx(height));
		iframe.style.setProperty('height', toPx(height));

		// Adjust width for presence/absence of vertical scroll bar which may
		// have appeared as a result of last operation.
		let contentWindow = iframe.contentWindow;
		let width = body.clientWidth;
		if (contentWindow.scrollMaxY !== 0) {
                    width += scrollBarWidth;
		}
		panel.style.setProperty('width', toPx(width));

		// scrollMaxX should always be zero once we know the scrollbar width
		if (contentWindow.scrollMaxX !== 0) {
                    scrollBarWidth = contentWindow.scrollMaxX;
                    width += scrollBarWidth;
                    panel.style.setProperty('width', toPx(width));
		}

		if (iframe.clientHeight !== height
		    || panel.clientWidth !== width) {
                    if (resizePopupDelayed(attempts)) {
			return;
                    }
                    // resizePopupDelayed won't be called again, so commit
                    // dimentsions.
		}

		popupCommittedWidth = body.clientWidth;
		popupCommittedHeight = body.clientHeight;
            };

            let onResizeRequested = function () {
		let body = iframe.contentDocument.body;
		if (body.getAttribute('data-resize-popup') !== 'true') {
                    return;
		}
		body.removeAttribute('data-resize-popup');
		resizePopupDelayed();
            };

            let onPopupReady = function () {
		let win = this.contentWindow;

		if (!win || win.location.host !== location.host) {
                    return;
		}

		if (typeof tbb.onBeforePopupReady === 'function') {
                    tbb.onBeforePopupReady.call(this);
		}

		resizePopupDelayed();

		let body = win.document.body;
		body.removeAttribute('data-resize-popup');
		
		let mutationObserver =
		    new win.MutationObserver(onResizeRequested);
		
		mutationObserver.observe(body, {
                    attributes: true,
                    attributeFilter: [ 'data-resize-popup' ]
		});
            };

            iframe.addEventListener('load', onPopupReady, true);
	};
    })();

    /******************************************************************************/

    (function () {
	// Add toolbar button for not-Basilisk
	if (Services.appinfo.ID === "{ec8030f7-c20a-464f-9b0e-13a3a9e97384}") {
	    return;
	}
	
	let tbb = vAPI.toolbarButton;
	if (tbb.init !== null) {
            return;
	}

	tbb.codePath = 'legacy';
	tbb.viewId = tbb.id + '-panel';

	let styleSheetUri = null;

	let createToolbarButton = function (window) {
            let document = window.document;

            let toolbarButton = document.createElement('toolbarbutton');
            toolbarButton.setAttribute('id', tbb.id);
            // type = panel would be more accurate, but doesn't look as good
            toolbarButton.setAttribute('type', 'menu');
            toolbarButton.setAttribute('removable', 'true');
            toolbarButton.setAttribute('class', 'toolbarbutton-1 '
				       +'chromeclass-toolbar-additional');
            toolbarButton.setAttribute('label', tbb.label);
	    toolbarButton.setAttribute('tooltiptext', tbb.tooltiptext);

            let toolbarButtonPanel = document.createElement('panel');
            // NOTE: Setting level to parent breaks the popup for PaleMoon under
            // linux (mouse pointer misaligned with content). For some reason.
	    // eMatrix: TODO check if it's still true
            // toolbarButtonPanel.setAttribute('level', 'parent');
            tbb.populatePanel(document, toolbarButtonPanel);
            toolbarButtonPanel.addEventListener('popupshowing',
						tbb.onViewShowing);
            toolbarButtonPanel.addEventListener('popuphiding',
						tbb.onViewHiding);
            toolbarButton.appendChild(toolbarButtonPanel);

	    toolbarButtonPanel.setAttribute('tooltiptext', '');

            return toolbarButton;
	};

	let addLegacyToolbarButton = function (window) {
            // eMatrix's stylesheet lazily added.
            if (styleSheetUri === null) {
		var sss = Cc["@mozilla.org/content/style-sheet-service;1"]
                    .getService(Ci.nsIStyleSheetService);
		styleSheetUri = Services.io
		    .newURI(vAPI.getURL("css/legacy-toolbar-button.css"),
			    null, null);

		// Register global so it works in all windows, including palette
		if (!sss.sheetRegistered(styleSheetUri, sss.AUTHOR_SHEET)) {
                    sss.loadAndRegisterSheet(styleSheetUri, sss.AUTHOR_SHEET);
		}
            }

            let document = window.document;

            // https://github.com/gorhill/uMatrix/issues/357
            // Already installed?
            if (document.getElementById(tbb.id) !== null) {
		return;
            }

            let toolbox = document.getElementById('navigator-toolbox')
		|| document.getElementById('mail-toolbox');
	    
            if (toolbox === null) {
		return;
            }

            let toolbarButton = createToolbarButton(window);

            let palette = toolbox.palette;
            if (palette && palette.querySelector('#' + tbb.id) === null) {
		palette.appendChild(toolbarButton);
            }

            // Find the place to put the button.
            // Pale Moon: `toolbox.externalToolbars` can be
            // undefined. Seen while testing popup test number 3:
            // http://raymondhill.net/ublock/popup.html
            let toolbars = toolbox.externalToolbars
		? toolbox.externalToolbars.slice()
		: [];
	    
            for (let child of toolbox.children) {
		if (child.localName === 'toolbar') {
                    toolbars.push(child);
		}
            }

            for (let toolbar of toolbars) {
		let currentsetString = toolbar.getAttribute('currentset');
		if (!currentsetString) {
                    continue;
		}
		
		let currentset = currentsetString.split(/\s*,\s*/);
		let index = currentset.indexOf(tbb.id);
		if (index === -1) {
                    continue;
		}
		
		// This can occur with Pale Moon:
		// "TypeError: toolbar.insertItem is not a function"
		if (typeof toolbar.insertItem !== 'function') {
                    continue;
		}
		
		// Found our button on this toolbar - but where on it?
		let before = null;
		for (let i = index+1; i<currentset.length; ++i) {
		    // The [id=...] notation doesn't work on
		    // space elements as they get a random ID each session
		    // (or something like that)
		    // https://gitlab.com/vannilla/ematrix/issues/5
		    // https://gitlab.com/vannilla/ematrix/issues/6

		    // Based on JustOff's snippet from the Pale Moon
		    // forum.  It was reorganized because I find it
		    // more readable like this, but he did most of the
		    // work.
		    let space = /^(spring|spacer|separator)$/.exec(currentset[i]);
		    if (space !== null) {
			let elems = toolbar.querySelectorAll('toolbar'+space[1]);
			
			let count = currentset.slice(i-currentset.length)
			    .filter(function (x) {return x == space[1];})
			    .length;

			before =
			    toolbar.querySelector('[id="'
						  + elems[elems.length-count].id
						  + '"]');
		    } else {
			before = toolbar.querySelector('[id="'+currentset[i]+'"]');
		    }
                    if ( before !== null ) {
			break;
                    }
		}

		toolbar.insertItem(tbb.id, before);
		break;
            }

            // https://github.com/gorhill/uBlock/issues/763
            // We are done if our toolbar button is already installed
            // in one of the toolbar.
            if (palette !== null && toolbarButton.parentElement !== palette) {
		return;
            }

            // No button yet so give it a default location. If forcing
            // the button, just put in in the palette rather than on
            // any specific toolbar (who knows what toolbars will be
            // available or visible!)
            let navbar = document.getElementById('nav-bar');
            if (navbar !== null
		&& !vAPI.localStorage.getBool('legacyToolbarButtonAdded')) {
		// https://github.com/gorhill/uBlock/issues/264
		// Find a child customizable palette, if any.
		navbar = navbar.querySelector('.customization-target') || navbar;
		navbar.appendChild(toolbarButton);
		navbar.setAttribute('currentset', navbar.currentSet);
		document.persist(navbar.id, 'currentset');
		vAPI.localStorage.setBool('legacyToolbarButtonAdded', 'true');
            }
	};

	let canAddLegacyToolbarButton = function (window) {
            let document = window.document;
            if (!document
		|| document.readyState !== 'complete'
		|| document.getElementById('nav-bar') === null) {
		return false;
            }
	    
            let toolbox = document.getElementById('navigator-toolbox')
		|| document.getElementById('mail-toolbox');
            return toolbox !== null && !!toolbox.palette;
	};

	let onPopupCloseRequested = function ({target}) {
            let document = target.ownerDocument;
            if (!document) {
		return;
            }
	    
            let toolbarButtonPanel = document.getElementById(tbb.viewId);
            if (toolbarButtonPanel === null) {
		return;
            }
	    
            // `hidePopup` reported as not existing while testing
            // legacy button on FF 41.0.2.
            // https://bugzilla.mozilla.org/show_bug.cgi?id=1151796
            if (typeof toolbarButtonPanel.hidePopup === 'function') {
		toolbarButtonPanel.hidePopup();
            }
	};

	let shutdown = function () {
            for (let win of winWatcher.getWindows()) {
		let toolbarButton = win.document.getElementById(tbb.id);
		if (toolbarButton) {
                    toolbarButton.parentNode.removeChild(toolbarButton);
		}
            }

            if (styleSheetUri !== null) {
		var sss = Cc["@mozilla.org/content/style-sheet-service;1"]
                    .getService(Ci.nsIStyleSheetService);
		if (sss.sheetRegistered(styleSheetUri, sss.AUTHOR_SHEET)) {
                    sss.unregisterSheet(styleSheetUri, sss.AUTHOR_SHEET);
		}
		styleSheetUri = null;
            }

            vAPI.messaging.globalMessageManager
		.removeMessageListener(location.host + ':closePopup',
				       onPopupCloseRequested);
	};

	tbb.attachToNewWindow = function (win) {
            deferUntil(canAddLegacyToolbarButton.bind(null, win),
		       addLegacyToolbarButton.bind(null, win));
	};

	tbb.init = function () {
            vAPI.messaging.globalMessageManager
		.addMessageListener(location.host + ':closePopup',
				    onPopupCloseRequested);
	    
            cleanupTasks.push(shutdown);
	};
    })();


    /*
      (function() {
      // Add toolbar button for Basilisk
      if (Services.appinfo.ID !== "{ec8030f7-c20a-464f-9b0e-13a3a9e97384}") {
      return;
      }
      
      var tbb = vAPI.toolbarButton;
      if ( tbb.init !== null ) {
      return;
      }

      if ( Services.vc.compare(Services.appinfo.version, '36.0') >= 0 ) {
      return null;
      }
      var CustomizableUI = null;
      try {
      CustomizableUI = Cu.import('resource:///modules/CustomizableUI.jsm', null).CustomizableUI;
      } catch (ex) {
      }
      if ( CustomizableUI === null ) {
      return;
      }
      tbb.codePath = 'australis';
      tbb.CustomizableUI = CustomizableUI;
      tbb.defaultArea = CustomizableUI.AREA_NAVBAR;

      var styleURI = null;

      var onPopupCloseRequested = function({target}) {
      if ( typeof tbb.closePopup === 'function' ) {
      tbb.closePopup(target);
      }
      };

      var shutdown = function() {
      CustomizableUI.destroyWidget(tbb.id);

      for ( var win of winWatcher.getWindows() ) {
      var panel = win.document.getElementById(tbb.viewId);
      panel.parentNode.removeChild(panel);
      win.QueryInterface(Ci.nsIInterfaceRequestor)
      .getInterface(Ci.nsIDOMWindowUtils)
      .removeSheet(styleURI, 1);
      }

      vAPI.messaging.globalMessageManager.removeMessageListener(
      location.host + ':closePopup',
      onPopupCloseRequested
      );
      };

      tbb.onBeforeCreated = function(doc) {
      var panel = doc.createElement('panelview');

      this.populatePanel(doc, panel);

      doc.getElementById('PanelUI-multiView').appendChild(panel);

      doc.defaultView.QueryInterface(Ci.nsIInterfaceRequestor)
      .getInterface(Ci.nsIDOMWindowUtils)
      .loadSheet(styleURI, 1);
      };

      tbb.onBeforePopupReady = function() {
      // https://github.com/gorhill/uBlock/issues/83
      // Add `portrait` class if width is constrained.
      try {
      this.contentDocument.body.classList.toggle(
      'portrait',
      CustomizableUI.getWidget(tbb.id).areaType === CustomizableUI.TYPE_MENU_PANEL
      );
      } catch (ex) {
      // noop
      }
      };

      tbb.init = function() {
      vAPI.messaging.globalMessageManager.addMessageListener(
      location.host + ':closePopup',
      onPopupCloseRequested
      );

      var style = [
      '#' + this.id + '.off {',
      'list-style-image: url(',
      vAPI.getURL('img/browsericons/icon19-off.png'),
      ');',
      '}',
      '#' + this.id + ' {',
      'list-style-image: url(',
      vAPI.getURL('img/browsericons/icon19.png'),
      ');',
      '}',
      '#' + this.viewId + ', #' + this.viewId + ' > iframe {',
      'width: 160px;',
      'height: 290px;',
      'overflow: hidden !important;',
      '}',
      '#' + this.id + '[badge]:not([badge=""])::after {',
      'position: absolute;',
      'margin-left: -16px;',
      'margin-top: 3px;',
      'padding: 1px 2px;',
      'font-size: 9px;',
      'font-weight: bold;',
      'color: #fff;',
      'background: #000;',
      'content: attr(badge);',
      '}'
      ];

      styleURI = Services.io.newURI(
      'data:text/css,' + encodeURIComponent(style.join('')),
      null,
      null
      );

      this.closePopup = function(tabBrowser) {
      CustomizableUI.hidePanelForNode(
      tabBrowser.ownerDocument.getElementById(this.viewId)
      );
      };

      CustomizableUI.createWidget(this);

      cleanupTasks.push(shutdown);
      };
      })();
    */

    (function() {
	// It appears that this branch actually works on the latest
	// Basilisk.  Maybe we can simply use this one directly instead of
	// making checks like it's done now.

	// It was decided to use this branch unconditionally. It's still
	// experimental though.

	// Add toolbar button for Basilisk
	if (Services.appinfo.ID !== "{ec8030f7-c20a-464f-9b0e-13a3a9e97384}") {
	    return;
	}
	
	let tbb = vAPI.toolbarButton;
	if (tbb.init !== null) {
            return;
	}
	// if ( Services.vc.compare(Services.appinfo.version, '36.0') < 0 ) {
	//     return null;
	// }
	let CustomizableUI = null;
	try {
            CustomizableUI =
		Cu.import('resource:///modules/CustomizableUI.jsm', null)
		.CustomizableUI;
	} catch (ex) {
	    // Ignore
	}
	if (CustomizableUI === null) {
            return null;
	}
	tbb.codePath = 'australis';
	tbb.CustomizableUI = CustomizableUI;
	tbb.defaultArea = CustomizableUI.AREA_NAVBAR;

	let CUIEvents = {};

	let badgeCSSRules = 'background: #000;color: #fff';

	let updateBadgeStyle = function () {
            for (let win of winWatcher.getWindows()) {
		let button = win.document.getElementById(tbb.id);
		if (button === null) {
                    continue;
		}
		let badge = button.ownerDocument
		    .getAnonymousElementByAttribute(button,
						    'class',
						    'toolbarbutton-badge');
		if (!badge) {
                    continue;
		}

		badge.style.cssText = badgeCSSRules;
            }
	};

	let updateBadge = function () {
            let wId = tbb.id;
            let buttonInPanel =
		CustomizableUI.getWidget(wId).areaType
		=== CustomizableUI.TYPE_MENU_PANEL;

            for (let win of winWatcher.getWindows()) {
		let button = win.document.getElementById(wId);
		if (button === null) {
                    continue;
		}
		
		if (buttonInPanel) {
                    button.classList.remove('badged-button');
                    continue;
		}
		
		button.classList.add('badged-button');
            }

            if (buttonInPanel) {
		return;
            }

            // Anonymous elements need some time to be reachable
            vAPI.setTimeout(updateBadgeStyle, 250);
	}.bind(CUIEvents);

	CUIEvents.onCustomizeEnd = updateBadge;
	CUIEvents.onWidgetAdded = updateBadge;
	CUIEvents.onWidgetUnderflow = updateBadge;

	let onPopupCloseRequested = function ({target}) {
            if (typeof tbb.closePopup === 'function') {
		tbb.closePopup(target);
            }
	};

	let shutdown = function () {
            for (let win of winWatcher.getWindows()) {
		let panel = win.document.getElementById(tbb.viewId);
		if (panel !== null && panel.parentNode !== null) {
                    panel.parentNode.removeChild(panel);
		}
		
		win.QueryInterface(Ci.nsIInterfaceRequestor)
                    .getInterface(Ci.nsIDOMWindowUtils)
                    .removeSheet(styleURI, 1);
            }

            CustomizableUI.removeListener(CUIEvents);
            CustomizableUI.destroyWidget(tbb.id);

            vAPI.messaging.globalMessageManager
		.removeMessageListener(location.host + ':closePopup',
				       onPopupCloseRequested);
	};

	let styleURI = null;

	tbb.onBeforeCreated = function (doc) {
            let panel = doc.createElement('panelview');

            this.populatePanel(doc, panel);

            doc.getElementById('PanelUI-multiView').appendChild(panel);

            doc.defaultView.QueryInterface(Ci.nsIInterfaceRequestor)
		.getInterface(Ci.nsIDOMWindowUtils)
		.loadSheet(styleURI, 1);
	};

	tbb.onCreated = function (button) {
            button.setAttribute('badge', '');
            vAPI.setTimeout(updateBadge, 250);
	};

	tbb.onBeforePopupReady = function () {
            // https://github.com/gorhill/uBlock/issues/83
            // Add `portrait` class if width is constrained.
            try {
		this.contentDocument.body
		    .classList.toggle('portrait',
				      CustomizableUI.getWidget(tbb.id).areaType
				      === CustomizableUI.TYPE_MENU_PANEL);
            } catch (ex) {
		// Ignore
            }
	};

	tbb.closePopup = function (tabBrowser) {
            CustomizableUI.hidePanelForNode(tabBrowser
					    .ownerDocument
					    .getElementById(tbb.viewId));
	};

	tbb.init = function () {
            vAPI.messaging.globalMessageManager
		.addMessageListener(location.host + ':closePopup',
				    onPopupCloseRequested);

            CustomizableUI.addListener(CUIEvents);

            var style = [
		'#' + this.id + '.off {',
                'list-style-image: url(',
                vAPI.getURL('img/browsericons/icon19-off.png'),
                ');',
		'}',
		'#' + this.id + ' {',
                'list-style-image: url(',
                vAPI.getURL('img/browsericons/icon19-19.png'),
                ');',
		'}',
		'#' + this.viewId + ', #' + this.viewId + ' > iframe {',
                'height: 290px;',
                'max-width: none !important;',
                'min-width: 0 !important;',
                'overflow: hidden !important;',
                'padding: 0 !important;',
                'width: 160px;',
		'}'
            ];

            styleURI =
		Services.io.newURI('data:text/css,'
				   +encodeURIComponent(style.join('')),
				   null,
				   null);

            CustomizableUI.createWidget(this);

            cleanupTasks.push(shutdown);
	};
    })();

    // No toolbar button.

    (function () {
	// Just to ensure the number of cleanup tasks is as expected: toolbar
	// button code is one single cleanup task regardless of platform.
	// eMatrix: might not be needed anymore
	if (vAPI.toolbarButton.init === null) {
            cleanupTasks.push(function(){});
	}
    })();

    if (vAPI.toolbarButton.init !== null) {
	vAPI.toolbarButton.init();
    }

    vAPI.contextMenu = {
	contextMap: {
            frame: 'inFrame',
            link: 'onLink',
            image: 'onImage',
            audio: 'onAudio',
            video: 'onVideo',
            editable: 'onEditableArea'
	}
    };

    vAPI.contextMenu.displayMenuItem = function ({target}) {
	let doc = target.ownerDocument;
	let gContextMenu = doc.defaultView.gContextMenu;
	if (!gContextMenu.browser) {
            return;
	}

	let menuitem = doc.getElementById(vAPI.contextMenu.menuItemId);
	let currentURI = gContextMenu.browser.currentURI;

	// https://github.com/chrisaljoudi/uBlock/issues/105
	// TODO: Should the element picker works on any kind of pages?
	if (!currentURI.schemeIs('http') && !currentURI.schemeIs('https')) {
            menuitem.setAttribute('hidden', true);
            return;
	}

	let ctx = vAPI.contextMenu.contexts;

	if (!ctx) {
            menuitem.setAttribute('hidden', false);
            return;
	}

	let ctxMap = vAPI.contextMenu.contextMap;

	for (let context of ctx) {
            if (context === 'page'
		&& !gContextMenu.onLink
		&& !gContextMenu.onImage
		&& !gContextMenu.onEditableArea
		&& !gContextMenu.inFrame
		&& !gContextMenu.onVideo
		&& !gContextMenu.onAudio) {
		menuitem.setAttribute('hidden', false);
		return;
            }

            if (ctxMap.hasOwnProperty(context)
		&& gContextMenu[ctxMap[context]]) {
		menuitem.setAttribute('hidden', false);
		return;
            }
	}

	menuitem.setAttribute('hidden', true);
    };

    vAPI.contextMenu.register = (function () {
	let register = function (doc) {
            if (!this.menuItemId) {
		return;
            }

            // Already installed?
            if (doc.getElementById(this.menuItemId) !== null) {
		return;
            }

            let contextMenu = doc.getElementById('contentAreaContextMenu');
	    
            let menuitem = doc.createElement('menuitem');
            menuitem.setAttribute('id', this.menuItemId);
            menuitem.setAttribute('label', this.menuLabel);
            menuitem.setAttribute('image', vAPI.getURL('img/browsericons/icon19-19.png'));
            menuitem.setAttribute('class', 'menuitem-iconic');
            menuitem.addEventListener('command', this.onCommand);
	    
            contextMenu.addEventListener('popupshowing', this.displayMenuItem);
            contextMenu.insertBefore(menuitem, doc.getElementById('inspect-separator'));
	};

	var registerSafely = function (doc, tryCount) {
	    // https://github.com/gorhill/uBlock/issues/906
	    // Be sure document.readyState is 'complete': it could happen
	    // at launch time that we are called by
	    // vAPI.contextMenu.create() directly before the environment
	    // is properly initialized.
            if (doc.readyState === 'complete') {
		register.call(this, doc);
		return;
            }
	    
            if (typeof tryCount !== 'number') {
		tryCount = 0;
            }
	    
            tryCount += 1;
            if ( tryCount < 8) {
		vAPI.setTimeout(registerSafely.bind(this, doc, tryCount), 200);
            }
	};

	return registerSafely;
    })();

    vAPI.contextMenu.unregister = function (doc) {
	if (!this.menuItemId) {
            return;
	}

	let menuitem = doc.getElementById(this.menuItemId);
	if (menuitem === null) {
            return;
	}
	
	let contextMenu = menuitem.parentNode;
	menuitem.removeEventListener('command', this.onCommand);
	contextMenu.removeEventListener('popupshowing', this.displayMenuItem);
	contextMenu.removeChild(menuitem);
    };

    vAPI.contextMenu.create = function (details, callback) {
	this.menuItemId = details.id;
	this.menuLabel = details.title;
	this.contexts = details.contexts;

	if (Array.isArray(this.contexts) && this.contexts.length) {
            this.contexts = this.contexts.indexOf('all') === -1
		? this.contexts
		: null;
	} else {
            // default in Chrome
            this.contexts = ['page'];
	}

	this.onCommand = function () {
            let gContextMenu = getOwnerWindow(this).gContextMenu;
            let details = {
		menuItemId: this.id
            };

            if (gContextMenu.inFrame) {
		details.tagName = 'iframe';
		// Probably won't work with e10s
		// eMatrix: doesn't matter ;)
		details.frameUrl = gContextMenu.focusedWindow.location.href;
            } else if (gContextMenu.onImage) {
		details.tagName = 'img';
		details.srcUrl = gContextMenu.mediaURL;
            } else if (gContextMenu.onAudio) {
		details.tagName = 'audio';
		details.srcUrl = gContextMenu.mediaURL;
            } else if (gContextMenu.onVideo) {
		details.tagName = 'video';
		details.srcUrl = gContextMenu.mediaURL;
            } else if (gContextMenu.onLink) {
		details.tagName = 'a';
		details.linkUrl = gContextMenu.linkURL;
            }

            callback(details, {
		id: tabWatcher.tabIdFromTarget(gContextMenu.browser),
		url: gContextMenu.browser.currentURI.asciiSpec
            });
	};

	for (let win of winWatcher.getWindows()) {
            this.register(win.document);
	}
    };

    vAPI.contextMenu.remove = function () {
	for (let win of winWatcher.getWindows()) {
            this.unregister(win.document);
	}

	this.menuItemId = null;
	this.menuLabel = null;
	this.contexts = null;
	this.onCommand = null;
    };

    let optionsObserver = (function () {
	let addonId = 'eMatrix@vannilla.org';

	let commandHandler = function () {
            switch (this.id) {
            case 'showDashboardButton':
		vAPI.tabs.open({
		    url: 'dashboard.html',
		    index: -1,
		});
		break;
            case 'showLoggerButton':
		vAPI.tabs.open({
		    url: 'logger-ui.html',
		    index: -1,
		});
		break;
            default:
		break;
            }
	};

	let setupOptionsButton = function (doc, id) {
            let button = doc.getElementById(id);
            if (button === null) {
		return;
            }
            button.addEventListener('command', commandHandler);
            button.label = vAPI.i18n(id);
	};

	let setupOptionsButtons = function (doc) {
            setupOptionsButton(doc, 'showDashboardButton');
            setupOptionsButton(doc, 'showLoggerButton');
	};

	let observer = {
            observe: function (doc, topic, id) {
		if (id !== addonId) {
                    return;
		}

		setupOptionsButtons(doc);
            }
	};

	var canInit = function() {
	    // https://github.com/gorhill/uBlock/issues/948
	    // Older versions of Firefox can throw here when looking
	    // up `currentURI`.
            try {
		let tabBrowser = tabWatcher.currentBrowser();
		return tabBrowser
		    && tabBrowser.currentURI
		    && tabBrowser.currentURI.spec === 'about:addons'
		    && tabBrowser.contentDocument
		    && tabBrowser.contentDocument.readyState === 'complete';
            } catch (ex) {
		// Ignore
            }
	};

	// Manually add the buttons if the `about:addons` page is
	// already opened.
	let init = function () {
            if (canInit()) {
		setupOptionsButtons(tabWatcher.currentBrowser().contentDocument);
            }
	};

	let unregister = function () {
            Services.obs.removeObserver(observer, 'addon-options-displayed');
	};

	let register = function () {
            Services.obs.addObserver(observer,
				     'addon-options-displayed',
				     false);
            cleanupTasks.push(unregister);
            deferUntil(canInit, init, { next: 463 });
	};

	return {
            register: register,
            unregister: unregister
	};
    })();

    optionsObserver.register();

    vAPI.lastError = function () {
	return null;
    };

    vAPI.onLoadAllCompleted = function() {
	// This is called only once, when everything has been loaded
	// in memory after the extension was launched. It can be used
	// to inject content scripts in already opened web pages, to
	// remove whatever nuisance could make it to the web pages
	// before uBlock was ready.
	for (let browser of tabWatcher.browsers()) {
            browser.messageManager
		.sendAsyncMessage(location.host + '-load-completed');
	}
    };

    // Likelihood is that we do not have to punycode: given punycode overhead,
    // it's faster to check and skip than do it unconditionally all the time.
    var punycodeHostname = punycode.toASCII;
    var isNotASCII = /[^\x21-\x7F]/;

    vAPI.punycodeHostname = function (hostname) {
	return isNotASCII.test(hostname)
	    ? punycodeHostname(hostname)
	    : hostname;
    };

    vAPI.punycodeURL = function (url) {
	if (isNotASCII.test(url)) {
            return Services.io.newURI(url, null, null).asciiSpec;
	}
	
	return url;
    };

    vAPI.cloud = (function () {
	let extensionBranchPath = 'extensions.' + location.host;
	let cloudBranchPath = extensionBranchPath + '.cloudStorage';

	// https://github.com/gorhill/uBlock/issues/80#issuecomment-132081658
	// We must use get/setComplexValue in order to properly handle strings
	// with unicode characters.
	let iss = Ci.nsISupportsString;
	let argstr = Components.classes['@mozilla.org/supports-string;1']
            .createInstance(iss);

	let options = {
            defaultDeviceName: '',
            deviceName: ''
	};

	// User-supplied device name.
	try {
            options.deviceName = Services.prefs
                .getBranch(extensionBranchPath + '.')
                .getComplexValue('deviceName', iss)
                .data;
	} catch(ex) {
	    // Ignore
	}

	var getDefaultDeviceName = function() {
            var name = '';
            try {
		name = Services.prefs
                    .getBranch('services.sync.client.')
                    .getComplexValue('name', iss)
                    .data;
            } catch(ex) {
		// Ignore
            }

            return name || window.navigator.platform || window.navigator.oscpu;
	};

	let start = function (dataKeys) {
            let extensionBranch =
		Services.prefs.getBranch(extensionBranchPath + '.');
            let syncBranch =
		Services.prefs.getBranch('services.sync.prefs.sync.');

            // Mark config entries as syncable
            argstr.data = '';
            let dataKey;
            for (let i=0; i<dataKeys.length; ++i) {
		dataKey = dataKeys[i];
		if (extensionBranch.prefHasUserValue('cloudStorage.' + dataKey)
		    === false) {
                    extensionBranch.setComplexValue('cloudStorage.' + dataKey,
						    iss, argstr);
		}
		
		syncBranch.setBoolPref(cloudBranchPath + '.' + dataKey, true);
            }
	};

	let push = function (datakey, data, callback) {
            let branch = Services.prefs.getBranch(cloudBranchPath + '.');
            let bin = {
		'source': options.deviceName || getDefaultDeviceName(),
		'tstamp': Date.now(),
		'data': data,
		'size': 0
            };
            bin.size = JSON.stringify(bin).length;
            argstr.data = JSON.stringify(bin);
            branch.setComplexValue(datakey, iss, argstr);
	    
            if (typeof callback === 'function') {
		callback();
            }
	};

	let pull = function (datakey, callback) {
            let result = null;
            let  branch = Services.prefs.getBranch(cloudBranchPath + '.');
	    
            try {
		let json = branch.getComplexValue(datakey, iss).data;
		if (typeof json === 'string') {
                    result = JSON.parse(json);
		}
            } catch(ex) {
		// Ignore
            }
	    
            callback(result);
	};

	let getOptions = function (callback) {
            if (typeof callback !== 'function') {
		return;
            }
	    
            options.defaultDeviceName = getDefaultDeviceName();
            callback(options);
	};

	let setOptions = function (details, callback) {
            if (typeof details !== 'object' || details === null) {
		return;
            }

            let branch = Services.prefs.getBranch(extensionBranchPath + '.');

            if (typeof details.deviceName === 'string') {
		argstr.data = details.deviceName;
		branch.setComplexValue('deviceName', iss, argstr);
		options.deviceName = details.deviceName;
            }

            getOptions(callback);
	};

	return {
            start: start,
            push: push,
            pull: pull,
            getOptions: getOptions,
            setOptions: setOptions
	};
    })();

    vAPI.browserData = {};

    vAPI.browserData.clearCache = function (callback) {
	// PURGE_DISK_DATA_ONLY:1
	// PURGE_DISK_ALL:2
	// PURGE_EVERYTHING:3
	// However I verified that no argument does clear the cache data.
	// There is no cache2 for older versions of Firefox.
	if (Services.cache2) {
            Services.cache2.clear();
	} else if (Services.cache) {
            Services.cache.evictEntries(Services.cache.STORE_ON_DISK);
	}
	
	if (typeof callback === 'function') {
            callback();
	}
    };

    vAPI.browserData.clearOrigin = function(/* domain */) {
	// TODO
    };

    vAPI.cookies = {};
    // https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Reference/Interface/nsICookieManager2
    // https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Reference/Interface/nsICookie2
    // https://developer.mozilla.org/en-US/docs/Observer_Notifications#Cookies

    vAPI.cookies.CookieEntry = function (ffCookie) {
	this.domain = ffCookie.host;
	this.name = ffCookie.name;
	this.path = ffCookie.path;
	this.secure = ffCookie.isSecure === true;
	this.session = ffCookie.expires === 0;
	this.value = ffCookie.value;
    };

    vAPI.cookies.start = function () {
	Services.obs.addObserver(this, 'cookie-changed', false);
	Services.obs.addObserver(this, 'private-cookie-changed', false);
	cleanupTasks.push(this.stop.bind(this));
    };

    vAPI.cookies.stop = function () {
	Services.obs.removeObserver(this, 'cookie-changed');
	Services.obs.removeObserver(this, 'private-cookie-changed');
    };

    vAPI.cookies.observe = function (subject, topic, reason) {
	//if ( topic !== 'cookie-changed' && topic !== 'private-cookie-changed' ) {
	//    return;
	//}
	//
	if (reason === 'cleared' && typeof this.onAllRemoved === 'function') {
            this.onAllRemoved();
            return;
	}
	if (subject === null) {
            return;
	}
	if (subject instanceof Ci.nsICookie2 === false) {
            try {
		subject = subject.QueryInterface(Ci.nsICookie2);
            } catch (ex) {
		return;
            }
	}
	if (reason === 'deleted') {
            if (typeof this.onRemoved === 'function') {
		this.onRemoved(new this.CookieEntry(subject));
            }
            return;
	}
	if (typeof this.onChanged === 'function') {
            this.onChanged(new this.CookieEntry(subject));
	}
    };

    vAPI.cookies.getAll = function(callback) {
	// Meant and expected to be asynchronous.
	if (typeof callback !== 'function') {
            return;
	}
	
	let onAsync = function () {
            let out = [];
            let enumerator = Services.cookies.enumerator;
            let ffcookie;
            while (enumerator.hasMoreElements()) {
		ffcookie = enumerator.getNext();
		if (ffcookie instanceof Ci.nsICookie) {
                    out.push(new this.CookieEntry(ffcookie));
		}
            }
	    
            callback(out);
	};
	
	vAPI.setTimeout(onAsync.bind(this), 0);
    };

    vAPI.cookies.remove = function (details, callback) {
	let uri = Services.io.newURI(details.url, null, null);
	let cookies = Services.cookies;
	cookies.remove(uri.asciiHost, details.name, uri.path, false, {});
	cookies.remove( '.' + uri.asciiHost, details.name, uri.path, false, {});
	
	if (typeof callback === 'function') {
            callback({
		domain: uri.asciiHost,
		name: details.name,
		path: uri.path
            });
	}
    };
})();