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

    ηMatrix - a browser extension to black/white list requests.
    Copyright (C) 2013-2019 Raymond Hill
    Copyright (C) 2019-2020 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
*/

'use strict';

ηMatrix.pageStoreFactory = (function() {

    Cu.import('chrome://ematrix/content/lib/UriTools.jsm');

    let ηm = ηMatrix;

    let BlockedCollapsibles = function () {
        this.boundPruneAsyncCallback = this.pruneAsyncCallback.bind(this);
        this.blocked = new Map();
        this.hash = 0;
        this.timer = null;
    };

    BlockedCollapsibles.prototype = {
        shelfLife: 10 * 1000,

        add: function (type, url, isSpecific) {
            if (this.blocked.size === 0) {
                this.pruneAsync();
            }
            let now = Date.now() / 1000 | 0;
            // The following "trick" is to encode the specifity into
            // the lsb of the time stamp so as to avoid to have to
            // allocate a memory structure to store both time stamp
            // and specificity.
            if (isSpecific) {
                now |= 0x00000001;
            } else {
                now &= 0xFFFFFFFE;
            }
            this.blocked.set(type + ' ' + url, now);
            this.hash = now;
        },
        reset: function () {
            this.blocked.clear();
            this.hash = 0;
            if (this.timer !== null) {
                clearTimeout(this.timer);
                this.timer = null;
            }
        },
        pruneAsync: function () {
            if (this.timer === null) {
                this.timer = vAPI.setTimeout(this.boundPruneAsyncCallback,
                                             this.shelfLife * 2);
            }
        },
        pruneAsyncCallback: function () {
            this.timer = null;
            let obsolete = Date.now() - this.shelfLife;
            for (let entry of this.blocked) {
                if (entry[1] <= obsolete) {
                    this.blocked.delete(entry[0]);
                }
            }
            if (this.blocked.size !== 0) {
                this.pruneAsync();
            }
        }
    };

    // Ref: Given a URL, returns a (somewhat) unique 32-bit value
    // Based on: FNV32a
    // http://www.isthe.com/chongo/tech/comp/fnv/index.html#FNV-reference-source
    // The rest is custom, suited for uMatrix.
    let PageStore = function (tabContext) {
        this.hostnameTypeCells = new Map();
        this.domains = new Set();
        this.blockedCollapsibles = new BlockedCollapsibles();
        this.requestStats = ηm.requestStatsFactory();
        this.off = false;
        this.init(tabContext);
    };

    PageStore.prototype = {
        collapsibleTypes: new Set([ 'image' ]),
        pageStoreJunkyard: [],

        init: function (tabContext) {
            this.tabId = tabContext.tabId;
            this.rawUrl = tabContext.rawURL;
            this.pageUrl = tabContext.normalURL;
            this.pageHostname = tabContext.rootHostname;
            this.pageDomain =  tabContext.rootDomain;
            this.title = '';
            this.hostnameTypeCells.clear();
            this.domains.clear();
            this.allHostnamesString = ' ';
            this.blockedCollapsibles.reset();
            this.requestStats.reset();
            this.distinctRequestCount = 0;
            this.perLoadAllowedRequestCount = 0;
            this.perLoadBlockedRequestCount = 0;
            this.has3pReferrer = false;
            this.hasMixedContent = false;
            this.hasNoscriptTags = false;
            this.hasWebWorkers = false;
            this.incinerationTimer = null;
            this.mtxContentModifiedTime = 0;
            this.mtxCountModifiedTime = 0;
            return this;
        },
        dispose: function () {
            this.rawUrl = '';
            this.pageUrl = '';
            this.pageHostname = '';
            this.pageDomain = '';
            this.title = '';
            this.hostnameTypeCells.clear();
            this.domains.clear();
            this.allHostnamesString = ' ';
            this.blockedCollapsibles.reset();
            if (this.incinerationTimer !== null) {
                clearTimeout(this.incinerationTimer);
                this.incinerationTimer = null;
            }
            if (this.pageStoreJunkyard.length < 8) {
                this.pageStoreJunkyard.push(this);
            }
        },
        cacheBlockedCollapsible: function (type, url, specificity) {
            if (this.collapsibleTypes.has(type)) {
                this.blockedCollapsibles.add(type,
                                             url,
                                             specificity !== 0
                                             && specificity < 5);
            }
        },
        lookupBlockedCollapsibles: function (request, response) {
            let tabContext = ηm.tabContextManager.lookup(this.tabId);
            if (tabContext === null) {
                return;
            }

            let collapseBlacklisted = ηm.userSettings.collapseBlacklisted;
            let collapseBlocked = ηm.userSettings.collapseBlocked;
            let blockedResources = response.blockedResources;

            if (Array.isArray(request.toFilter) && request.toFilter.length !== 0) {
                let roothn = tabContext.rootHostname;
                let hnFromURI = UriTools.hostnameFromURI;
                let tMatrix = ηm.tMatrix;

                for (let entry of request.toFilter) {
                    if (tMatrix.mustBlock(roothn,
                                          hnFromURI(entry.url),
                                          entry.type) === false) {
                        continue;
                    }

                    blockedResources.push([
                        entry.type + ' ' + entry.url,
                        collapseBlocked
                            || collapseBlacklisted
                            && tMatrix.specificityRegister !== 0
                            && tMatrix.specificityRegister < 5
                    ]);
                }
            }

            if (this.blockedCollapsibles.hash === response.hash) {
                return;
            }
            response.hash = this.blockedCollapsibles.hash;

            for (let entry of this.blockedCollapsibles.blocked) {
                blockedResources.push([
                    entry[0],
                    collapseBlocked
                        || collapseBlacklisted
                        && (entry[1] & 1) !== 0
                ]);
            }
        },
        recordRequest: function (type, url, block) {
            if (block !== false) {
                this.perLoadBlockedRequestCount++;
            } else {
                this.perLoadAllowedRequestCount++;
            }

            // Store distinct network requests. This is used to:
            // - remember which hostname/type were seen
            // - count the number of distinct URLs for any given
            //   hostname-type pair
            let hostname = UriTools.hostnameFromURI(url);
            let key = hostname + ' ' + type;
            let uids = this.hostnameTypeCells.get(key);

            if (uids === undefined) {
                this.hostnameTypeCells.set(key, (uids = new Set()));
            } else if (uids.size > 99) {
                return;
            }

            let uid = this.uidFromURL(url);
            if (uids.has(uid)) {
                return;
            }
            uids.add(uid);

            // Count blocked/allowed requests
            this.requestStats.record(type, block);

            // https://github.com/gorhill/httpswitchboard/issues/306
            // If it is recorded locally, record globally
            ηm.requestStats.record(type, block);
            ηm.updateBadgeAsync(this.tabId);

            // this.distinctRequestCount++;
            this.mtxCountModifiedTime = Date.now();

            if (this.domains.has(hostname) === false) {
                this.domains.add(hostname);
                this.allHostnamesString += hostname + ' ';
                this.mtxContentModifiedTime = Date.now();
            }
        },
        uidFromURL: function (uri) {
            var hint = 0x811c9dc5;
            let i = uri.length;
            while (i--) {
                hint ^= uri.charCodeAt(i) | 0;
                hint += (hint<<1) + (hint<<4) + (hint<<7) + (hint<<8) + (hint<<24) | 0;
                hint >>>= 0;
            }
            return hint;
        }
    };

    return function (tabContext) {
        let entry = PageStore.prototype.pageStoreJunkyard.pop();
        if (entry) {
            return entry.init(tabContext);
        }
        return new PageStore(tabContext);
    };
})();