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

    ηMatrix - a browser extension to black/white list requests.
    Copyright (C) 2014-2019 The uMatrix/uBlock Origin authors
    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://libregit.org/heckyel/ematrix
    uMatrix Home: https://github.com/gorhill/uMatrix
*/

'use strict';

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

(function () {
    Cu.import('chrome://ematrix/content/lib/CallbackWrapper.jsm');

    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 =
                vAPI.browser.
                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: vAPI.tabs.manager.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);

        vAPI.addCleanUpTask(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}));
    };
})();