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

    µBlock - a browser extension to block requests.
    Copyright (C) 2014 The µBlock authors

    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://github.com/gorhill/uMatrix
*/

'use strict';

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

this.EXPORTED_SYMBOLS = ['contentObserver'];

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

const hostName = Services.io.newURI(Components.stack.filename, null, null).host;

// Cu.import('resource://gre/modules/devtools/Console.jsm');

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

const getMessageManager = function(win) {
    return win
        .QueryInterface(Ci.nsIInterfaceRequestor)
        .getInterface(Ci.nsIDocShell)
        .sameTypeRootTreeItem
        .QueryInterface(Ci.nsIDocShell)
        .QueryInterface(Ci.nsIInterfaceRequestor)
        .getInterface(Ci.nsIContentFrameMessageManager);
};

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

const contentObserver = {
    classDescription: 'content-policy for ' + hostName,
    classID: Components.ID('{c84283d4-9975-41b7-b1a4-f106af56b51d}'),
    contractID: '@' + hostName + '/content-policy;1',
    ACCEPT: Ci.nsIContentPolicy.ACCEPT,
    MAIN_FRAME: Ci.nsIContentPolicy.TYPE_DOCUMENT,
    contentBaseURI: 'chrome://' + hostName + '/content/js/',
    uniqueSandboxId: 1,

    get componentRegistrar() {
        return Components.manager.QueryInterface(Ci.nsIComponentRegistrar);
    },

    get categoryManager() {
        return Components.classes['@mozilla.org/categorymanager;1']
                .getService(Ci.nsICategoryManager);
    },

    QueryInterface: XPCOMUtils.generateQI([
            Ci.nsIFactory,
            Ci.nsIObserver,
            Ci.nsIContentPolicy,
            Ci.nsISupportsWeakReference
    ]),

    createInstance: function(outer, iid) {
        if ( outer ) {
            throw Components.results.NS_ERROR_NO_AGGREGATION;
        }

        return this.QueryInterface(iid);
    },

    register: function() {
        Services.obs.addObserver(this, 'document-element-inserted', true);

        this.componentRegistrar.registerFactory(
            this.classID,
            this.classDescription,
            this.contractID,
            this
        );
        this.categoryManager.addCategoryEntry(
            'content-policy',
            this.contractID,
            this.contractID,
            false,
            true
        );
    },

    unregister: function() {
        Services.obs.removeObserver(this, 'document-element-inserted');

        this.componentRegistrar.unregisterFactory(this.classID, this);
        this.categoryManager.deleteCategoryEntry(
            'content-policy',
            this.contractID,
            false
        );
    },

    // https://bugzil.la/612921
    shouldLoad: function(type, location, origin, context) {
        return this.ACCEPT;
    },

    initContentScripts: function(win, sandbox) {
        let messager = getMessageManager(win);
        let sandboxId = hostName + ':sb:' + this.uniqueSandboxId++;

        if ( sandbox ) {
            let sandboxName = [
                win.location.href.slice(0, 100),
                win.document.title.slice(0, 100)
            ].join(' | ');

            sandbox = Cu.Sandbox([win], {
                sandboxName: sandboxId + '[' + sandboxName + ']',
                sandboxPrototype: win,
                wantComponents: false,
                wantXHRConstructor: false
            });

            sandbox.injectScript = function(script) {
                Services.scriptloader.loadSubScript(script, sandbox);
            };
        }
        else {
            sandbox = win;
        }

        sandbox._sandboxId_ = sandboxId;
        sandbox.sendAsyncMessage = messager.sendAsyncMessage;

        sandbox.addMessageListener = function(callback) {
            if ( sandbox._messageListener_ ) {
                sandbox.removeMessageListener();
            }

            sandbox._messageListener_ = function(message) {
                callback(message.data);
            };

            messager.addMessageListener(
                sandbox._sandboxId_,
                sandbox._messageListener_
            );
            messager.addMessageListener(
                hostName + ':broadcast',
                sandbox._messageListener_
            );
        };

        sandbox.removeMessageListener = function() {
            try {
                messager.removeMessageListener(
                    sandbox._sandboxId_,
                    sandbox._messageListener_
                );
                messager.removeMessageListener(
                    hostName + ':broadcast',
                    sandbox._messageListener_
                );
            } catch (ex) {
                // It throws sometimes, mostly when the popup closes
            }

            sandbox._messageListener_ = null;
        };

        return sandbox;
    },

    observe: function(doc) {
        let win = doc.defaultView;
        if ( !win ) {
            return;
        }

        let loc = win.location;
        if ( !loc ) {
            return;
        }

        if ( loc.protocol !== 'http:' && loc.protocol !== 'https:' && loc.protocol !== 'file:' ) {
            if ( loc.protocol === 'chrome:' && loc.host === hostName ) {
                this.initContentScripts(win);
            }

            // What about data: and about:blank?
            return;
        }

        let lss = Services.scriptloader.loadSubScript;
        let sandbox = this.initContentScripts(win, true);

        lss(this.contentBaseURI + 'vapi-client.js', sandbox);
        lss(this.contentBaseURI + 'contentscript-start.js', sandbox);

        let docReady = (e) => {
            let doc = e.target;
            doc.removeEventListener(e.type, docReady, true);
            lss(this.contentBaseURI + 'contentscript-end.js', sandbox);
        };

        if ( doc.readyState === 'loading') {
            doc.addEventListener('DOMContentLoaded', docReady, true);
        } else {
            docReady({ target: doc, type: 'DOMContentLoaded' });
        }
    }
};

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

contentObserver.register();

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