/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

Components.utils.import("resource://gre/modules/AddonManager.jsm");
Components.utils.import("resource://gre/modules/Services.jsm");
Components.utils.import("resource://gre/modules/Preferences.jsm");
Components.utils.import("resource://calendar/modules/calUtils.jsm");
Components.utils.import("resource://calendar/modules/calProviderUtils.jsm");

var REGISTRY_BRANCH = "calendar.registry.";
var DB_SCHEMA_VERSION = 10;
var MAX_INT = Math.pow(2, 31) - 1;
var MIN_INT = -MAX_INT;

function calCalendarManager() {
    this.wrappedJSObject = this;
    this.mObservers = new calListenerBag(Components.interfaces.calICalendarManagerObserver);
    this.mCalendarObservers = new calListenerBag(Components.interfaces.calIObserver);
}

var calCalendarManagerClassID = Components.ID("{f42585e7-e736-4600-985d-9624c1c51992}");
var calCalendarManagerInterfaces = [
    Components.interfaces.calICalendarManager,
    Components.interfaces.calIStartupService,
    Components.interfaces.nsIObserver,
];
calCalendarManager.prototype = {
    classID: calCalendarManagerClassID,
    QueryInterface: XPCOMUtils.generateQI(calCalendarManagerInterfaces),
    classInfo: XPCOMUtils.generateCI({
        classID: calCalendarManagerClassID,
        contractID: "@mozilla.org/calendar/manager;1",
        classDescription: "Calendar Manager",
        interfaces: calCalendarManagerInterfaces,
        flags: Components.interfaces.nsIClassInfo.SINGLETON
    }),

    get networkCalendarCount() { return this.mNetworkCalendarCount; },
    get readOnlyCalendarCount() { return this.mReadonlyCalendarCount; },
    get calendarCount() { return this.mCalendarCount; },

    // calIStartupService:
    startup: function ccm_startup(aCompleteListener) {
        AddonManager.addAddonListener(gCalendarManagerAddonListener);
        this.checkAndMigrateDB();
        this.mCache = null;
        this.mCalObservers = null;
        this.mRefreshTimer = {};
        this.setupOfflineObservers();
        this.mNetworkCalendarCount = 0;
        this.mReadonlyCalendarCount = 0;
        this.mCalendarCount = 0;

        Services.obs.addObserver(this, "http-on-modify-request", false);

        // We only add the observer if the pref is set and only check for the
        // pref on startup to avoid checking for every http request
        if (Preferences.get("calendar.network.multirealm", false)) {
            Services.obs.addObserver(this, "http-on-examine-response", false);
        }

        aCompleteListener.onResult(null, Components.results.NS_OK);
    },

    shutdown: function ccm_shutdown(aCompleteListener) {
        for (let id in this.mCache) {
            let calendar = this.mCache[id];
            calendar.removeObserver(this.mCalObservers[calendar.id]);
        }

        this.cleanupOfflineObservers();

        Services.obs.removeObserver(this, "http-on-modify-request");

        AddonManager.removeAddonListener(gCalendarManagerAddonListener);

        // Remove the observer if the pref is set. This might fail when the
        // user flips the pref, but we assume he is going to restart anyway
        // afterwards.
        if (Preferences.get("calendar.network.multirealm", false)) {
            Services.obs.removeObserver(this, "http-on-examine-response");
        }

        aCompleteListener.onResult(null, Components.results.NS_OK);
    },


    setupOfflineObservers: function ccm_setupOfflineObservers() {
        Services.obs.addObserver(this, "network:offline-status-changed", false);
    },

    cleanupOfflineObservers: function ccm_cleanupOfflineObservers() {
        Services.obs.removeObserver(this, "network:offline-status-changed");
    },

    observe: function ccm_observe(aSubject, aTopic, aData) {
        switch (aTopic) {
            case "timer-callback":
                // Refresh all the calendars that can be refreshed.
                var cals = this.getCalendars({});
                for (var calendar of cals) {
                    if (!calendar.getProperty("disabled") && calendar.canRefresh) {
                        calendar.refresh();
                    }
                }
                break;
            case "network:offline-status-changed":
                for (var id in this.mCache) {
                    let calendar = this.mCache[id];
                    if (calendar instanceof calCachedCalendar) {
                        calendar.onOfflineStatusChanged(aData == "offline");
                    }
                }
                break;
            case "http-on-examine-response":
                try {
                    let channel = aSubject.QueryInterface(Components.interfaces.nsIHttpChannel);
                    if (channel.notificationCallbacks) {
                        // We use the notification callbacks to get the calendar interface,
                        // which likely works for our requests since getInterface is called
                        // from the calendar provider context.
                        let authHeader = channel.getResponseHeader("WWW-Authenticate");
                        let calendar = channel.notificationCallbacks
                                              .getInterface(Components.interfaces.calICalendar);
                        if (calendar && !calendar.getProperty("capabilities.realmrewrite.disabled")) {
                            // The provider may choose to explicitly disable the
                            // rewriting, for example if all calendars on a
                            // domain have the same credentials
                            let escapedName = calendar.name.replace(/\\/g, '\\\\')
                                                           .replace(/\"/g, '\\"');
                            authHeader = appendToRealm(authHeader, "(" + escapedName + ")");
                            channel.setResponseHeader("WWW-Authenticate", authHeader, false);
                        }
                    }
                } catch (e) {
                    if (e.result != Components.results.NS_NOINTERFACE &&
                        e.result != Components.results.NS_ERROR_NOT_AVAILABLE) {
                        throw e;
                    }
                    // Possible reasons we got here:
                    // - Its not a http channel (wtf? Oh well)
                    // - The owner is not a calICalendar (looks like its not our deal)
                    // - The WWW-Authenticate header is missing (thats ok)
                }
                break;
            case "http-on-modify-request":
                // Unfortunately, the ability to do this with a general pref has
                // been removed. Calendar servers might still want to know what
                // client is used for access, so add our UA String to each
                // request.
                let httpChannel = aSubject.QueryInterface(Components.interfaces.nsIHttpChannel);
                try {
                    // NOTE: For some reason, this observer call doesn't have
                    // the "cal" namespace defined
                    let ua = httpChannel.getRequestHeader("User-Agent");
                    let calUAString = Preferences.get("calendar.useragent.extra", "").trim();

                    // Don't add an empty string or an already included token.
                    if (calUAString && !ua.includes(calUAString)) {
                        // User-Agent is not a mergeable header. We need to
                        // merge the user agent ourselves.
                        httpChannel.setRequestHeader("User-Agent",
                                                     ua + " " + calUAString,
                                                     false);
                    }
                } catch (e) {
                    if (e.result != Components.results.NS_ERROR_NOT_AVAILABLE) {
                        throw e;
                    }
                    // We swallow this error since it means the User Agent
                    // header is not set. We don't want to force it to be set.
                }
                break;
        }
    },

    //
    // DB migration code begins here
    //

    upgradeDB: function(oldVersion, db) {
        // some common helpers
        function addColumn(db_, tableName, colName, colType) {
            db_.executeSimpleSQL("ALTER TABLE " + tableName + " ADD COLUMN " + colName + " " + colType);
        }

        if (oldVersion < 6) {
            dump ("**** Upgrading calCalendarManager schema to 6\n");

            // Schema changes in v6:
            //
            // - Change all STRING columns to TEXT to avoid SQLite's
            //   "feature" where it will automatically convert strings to
            //   numbers (ex: 10e4 -> 10000). See bug 333688.

            // Create the new tables.

            try {
                db.executeSimpleSQL("DROP TABLE cal_calendars_v6; DROP TABLE cal_calendars_prefs_v6;");
            } catch (e) {
                // We should get exceptions for trying to drop tables
                // that don't (shouldn't) exist.
            }

            db.executeSimpleSQL("CREATE TABLE cal_calendars_v6 " +
                                "(id   INTEGER PRIMARY KEY," +
                                " type TEXT," +
                                " uri  TEXT);");

            db.executeSimpleSQL("CREATE TABLE cal_calendars_prefs_v6 " +
                                "(id       INTEGER PRIMARY KEY," +
                                " calendar INTEGER," +
                                " name     TEXT," +
                                " value    TEXT);");

            // Copy in the data.
            var calendarCols = ["id", "type", "uri"];
            var calendarPrefsCols = ["id", "calendar", "name", "value"];

            db.executeSimpleSQL("INSERT INTO cal_calendars_v6(" + calendarCols.join(",") + ") " +
                                "     SELECT " + calendarCols.join(",") +
                                "       FROM cal_calendars");

            db.executeSimpleSQL("INSERT INTO cal_calendars_prefs_v6(" + calendarPrefsCols.join(",") + ") " +
                                "     SELECT " + calendarPrefsCols.join(",") +
                                "       FROM cal_calendars_prefs");

            // Delete each old table and rename the new ones to use the
            // old tables' names.
            var tableNames = ["cal_calendars", "cal_calendars_prefs"];

            for (var i in tableNames) {
                db.executeSimpleSQL("DROP TABLE " + tableNames[i] + ";" +
                                    "ALTER TABLE " + tableNames[i] + "_v6 " +
                                    "  RENAME TO " + tableNames[i] + ";");
            }

            oldVersion = 8;
        }

        if (oldVersion < DB_SCHEMA_VERSION) {
            dump ("**** Upgrading calCalendarManager schema to 9/10\n");

            if (db.tableExists("cal_calmgr_schema_version")) {
                // Set only once the last time to v10, so the version check works in calendar 0.8.
                // In calendar 0.9 and following, the provider itself will check its version
                // on initialization and notify the calendar whether it's usable or not.
                db.executeSimpleSQL("UPDATE cal_calmgr_schema_version SET version = " + DB_SCHEMA_VERSION + ";");
            } else {
                // Schema changes in v9:
                //
                // - Decouple schema version from storage calendar
                // Create the new tables.
                db.executeSimpleSQL("CREATE TABLE cal_calmgr_schema_version (version INTEGER);");
                db.executeSimpleSQL("INSERT INTO cal_calmgr_schema_version VALUES(" + DB_SCHEMA_VERSION + ")");
            }
        }
    },

    migrateDB: function calmgr_migrateDB(db) {
        let selectCalendars = db.createStatement("SELECT * FROM cal_calendars");
        let selectPrefs = db.createStatement("SELECT name, value FROM cal_calendars_prefs WHERE calendar = :calendar");
        try {
            let sortOrder = {};

            while (selectCalendars.executeStep()) {
                let id = cal.getUUID(); // use fresh uuids
                Preferences.set(getPrefBranchFor(id) + "type", selectCalendars.row.type);
                Preferences.set(getPrefBranchFor(id) + "uri", selectCalendars.row.uri);
                // the former id served as sort position:
                sortOrder[selectCalendars.row.id] = id;
                // move over prefs:
                selectPrefs.params.calendar = selectCalendars.row.id;
                while (selectPrefs.executeStep()) {
                    let name = selectPrefs.row.name.toLowerCase(); // may come lower case, so force it to be
                    let value = selectPrefs.row.value;
                    switch (name) {
                        case "readonly":
                            Preferences.set(getPrefBranchFor(id) + "readOnly", value == "true");
                            break;
                        case "relaxedmode":
                            Preferences.set(getPrefBranchFor(id) + "relaxedMode", value == "true");
                            break;
                        case "suppressalarms":
                            Preferences.set(getPrefBranchFor(id) + "suppressAlarms", value == "true");
                            break;
                        case "disabled":
                        case "cache.supported":
                        case "auto-enabled":
                        case "cache.enabled":
                        case "lightning-main-in-composite":
                        case "calendar-main-in-composite":
                        case "lightning-main-default":
                        case "calendar-main-default":
                            Preferences.set(getPrefBranchFor(id) + name, value == "true");
                            break;
                        case "backup-time":
                        case "uniquenum":
                            // These preference names were migrated due to bug 979262.
                            Preferences.set(getPrefBranchFor(id) + name + "2", "bignum:" + value);
                            break;
                        default: // keep as string
                            Preferences.set(getPrefBranchFor(id) + name, value);
                            break;
                    }
                }
                selectPrefs.reset();
            }

            let sortOrderAr = [];
            for (let id in sortOrder) {
                let s = sortOrder[id];
                sortOrderAr.push(s);
            }
            Preferences.set("calendar.list.sortOrder", sortOrderAr.join(" "));
            flushPrefs();

        } finally {
            selectPrefs.reset();
            selectCalendars.reset();
        }
    },

    checkAndMigrateDB: function calmgr_checkAndMigrateDB() {
        let storageSdb = Services.dirsvc.get("ProfD", Components.interfaces.nsILocalFile);
        storageSdb.append("storage.sdb");
        let db = Services.storage.openDatabase(storageSdb);

        db.beginTransactionAs(Components.interfaces.mozIStorageConnection.TRANSACTION_EXCLUSIVE);
        try {
            if (db.tableExists("cal_calendars_prefs")) {
                // Check if we need to upgrade:
                let version = this.getSchemaVersion(db);
                //cal.LOG("*** Calendar schema version is: " + version);
                if (version < DB_SCHEMA_VERSION) {
                    this.upgradeDB(version, db);
                }

                this.migrateDB(db);

                db.executeSimpleSQL("DROP TABLE cal_calendars; " +
                                    "DROP TABLE cal_calendars_prefs; " +
                                    "DROP TABLE cal_calmgr_schema_version;");
            }

            if (!db.tableExists("cal_calendars")) {
                // create dummy cal_calendars, so previous versions (pre 1.0pre) run into the schema check:
                db.createTable("cal_calendars", "id INTEGER");
                // let schema checks always fail, we cannot take the shared cal_calendar_schema_version:
                db.createTable("cal_calmgr_schema_version", "version INTEGER");
                db.executeSimpleSQL("INSERT INTO cal_calmgr_schema_version VALUES(" + (DB_SCHEMA_VERSION + 1) + ")");
                db.commitTransaction();
            } else {
                db.rollbackTransaction();
            }
        } catch (exc) {
            db.rollbackTransaction();
            throw exc;
        } finally {
            db.close();
        }
    },

    /**
     * @return      db schema version
     * @exception   various, depending on error
     */
    getSchemaVersion: function calMgrGetSchemaVersion(db) {
        var stmt;
        var version = null;

        var table;
        if (db.tableExists("cal_calmgr_schema_version")) {
            table = "cal_calmgr_schema_version";
        } else {
            // Fall back to the old schema table
            table = "cal_calendar_schema_version";
        }

        try {
            stmt = db.createStatement("SELECT version FROM " + table + " LIMIT 1");
            if (stmt.executeStep()) {
                version = stmt.row.version;
            }
            stmt.reset();

            if (version !== null) {
                // This is the only place to leave this function gracefully.
                return version;
            }
        } catch (e) {
            if (stmt) {
                stmt.reset();
            }
            cal.ERROR("++++++++++++ calMgrGetSchemaVersion() error: " + db.lastErrorString);
            Components.utils.reportError("Error getting calendar schema version! DB Error: " + db.lastErrorString);
            throw e;
        }

        throw table + " SELECT returned no results";
    },

    //
    // / DB migration code ends here
    //

    alertAndQuit: function cmgr_alertAndQuit() {
        // We want to include the extension name in the error message rather
        // than blaming Thunderbird.
        var hostAppName = calGetString("brand", "brandShortName", null, "branding");
        var calAppName = calGetString("lightning", "brandShortName", null, "lightning");
        var errorBoxTitle = calGetString("calendar", "tooNewSchemaErrorBoxTitle", [calAppName]);
        var errorBoxText = calGetString("calendar", "tooNewSchemaErrorBoxTextLightning", [calAppName, hostAppName]);
        var errorBoxButtonLabel = calGetString("calendar", "tooNewSchemaButtonRestart", [hostAppName]);

        var promptSvc = Services.prompt;

        var errorBoxButtonFlags = (promptSvc.BUTTON_POS_0 *
                                   promptSvc.BUTTON_TITLE_IS_STRING +
                                   promptSvc.BUTTON_POS_0_DEFAULT);

        var choice = promptSvc.confirmEx(null,
                                         errorBoxTitle,
                                         errorBoxText,
                                         errorBoxButtonFlags,
                                         errorBoxButtonLabel,
                                         null, // No second button text
                                         null, // No third button text
                                         null, // No checkbox
                                         { value: false }); // Unnecessary checkbox state

        // Disable Lightning
        AddonManager.getAddonByID("{e2fda1a4-762b-4020-b5ad-a41df1933103}", function getLightningExt(aAddon) {
            aAddon.userDisabled = true;
            Services.startup.quit(Components.interfaces.nsIAppStartup.eRestart |
                Components.interfaces.nsIAppStartup.eForceQuit);
        });
    },

    /**
     * calICalendarManager interface
     */
    createCalendar: function cmgr_createCalendar(type, uri) {
        try {
            if (!Components.classes["@mozilla.org/calendar/calendar;1?type=" + type]) {
                // Don't notify the user with an extra dialog if the provider
                // interface is missing.
                return null;
            }
            let calendar = Components.classes["@mozilla.org/calendar/calendar;1?type=" + type]
                                     .createInstance(Components.interfaces.calICalendar);
            calendar.uri = uri;
            return calendar;
        } catch (ex) {
            let rc = ex;
            let uiMessage = ex;
            if (ex instanceof Components.interfaces.nsIException) {
                rc = ex.result;
                uiMessage = ex.message;
            }
            switch (rc) {
                case Components.interfaces.calIErrors.STORAGE_UNKNOWN_SCHEMA_ERROR:
                    // For now we alert and quit on schema errors like we've done before:
                    this.alertAndQuit();
                    return null;
                case Components.interfaces.calIErrors.STORAGE_UNKNOWN_TIMEZONES_ERROR:
                    uiMessage = calGetString("calendar", "unknownTimezonesError", [uri.spec]);
                    break;
                default:
                    uiMessage = calGetString("calendar", "unableToCreateProvider", [uri.spec]);
                    break;
            }
            // Log the original exception via error console to provide more debug info
            cal.ERROR(ex);

            // Log the possibly translated message via the UI.
            let paramBlock = Components.classes["@mozilla.org/embedcomp/dialogparam;1"]
                                       .createInstance(Components.interfaces.nsIDialogParamBlock);
            paramBlock.SetNumberStrings(3);
            paramBlock.SetString(0, uiMessage);
            paramBlock.SetString(1, "0x" + rc.toString(0x10));
            paramBlock.SetString(2, ex);
            Services.ww.openWindow(null,
                                   "chrome://calendar/content/calendar-error-prompt.xul",
                                   "_blank",
                                   "chrome,dialog=yes,alwaysRaised=yes",
                                   paramBlock);
            return null;
        }
    },

    registerCalendar: function(calendar) {
        this.assureCache();

        // If the calendar is already registered, bail out
        cal.ASSERT(!calendar.id || !(calendar.id in this.mCache),
                   "[calCalendarManager::registerCalendar] calendar already registered!",
                   true);

        if (!calendar.id) {
            calendar.id = cal.getUUID();
        }

        Preferences.set(getPrefBranchFor(calendar.id) + "type", calendar.type);
        Preferences.set(getPrefBranchFor(calendar.id) + "uri", calendar.uri.spec);

        if ((calendar.getProperty("cache.supported") !== false) &&
            (calendar.getProperty("cache.enabled") ||
             calendar.getProperty("cache.always"))) {
            calendar = new calCachedCalendar(calendar);
        }

        this.setupCalendar(calendar);
        flushPrefs();

        if (!calendar.getProperty("disabled") && calendar.canRefresh) {
            calendar.refresh();
        }

        this.notifyObservers("onCalendarRegistered", [calendar]);
    },

    setupCalendar: function cmgr_setupCalendar(calendar) {
        this.mCache[calendar.id] = calendar;

        // Add an observer to track readonly-mode triggers
        var newObserver = new calMgrCalendarObserver(calendar, this);
        calendar.addObserver(newObserver);
        this.mCalObservers[calendar.id] = newObserver;

        // Set up statistics
        if (calendar.getProperty("requiresNetwork") !== false) {
            this.mNetworkCalendarCount++;
        }
        if (calendar.readOnly) {
            this.mReadonlyCalendarCount++;
        }
        this.mCalendarCount++;

        // Set up the refresh timer
        this.setupRefreshTimer(calendar);
    },

    setupRefreshTimer: function setupRefreshTimer(aCalendar) {
        // Add the refresh timer for this calendar
        let refreshInterval = aCalendar.getProperty("refreshInterval");
        if (refreshInterval === null) {
            // Default to 30 minutes, in case the value is missing
            refreshInterval = 30;
        }

        this.clearRefreshTimer(aCalendar);

        if (refreshInterval > 0) {
            this.mRefreshTimer[aCalendar.id] =
                Components.classes["@mozilla.org/timer;1"]
                          .createInstance(Components.interfaces.nsITimer);

            this.mRefreshTimer[aCalendar.id]
                .initWithCallback(new timerCallback(aCalendar),
                                  refreshInterval * 60000,
                                  Components.interfaces.nsITimer.TYPE_REPEATING_SLACK);
        }
    },

    clearRefreshTimer: function clearRefreshTimer(aCalendar) {
        if (aCalendar.id in this.mRefreshTimer &&
            this.mRefreshTimer[aCalendar.id]) {
            this.mRefreshTimer[aCalendar.id].cancel();
            delete this.mRefreshTimer[aCalendar.id]
        }
    },

    unregisterCalendar: function(calendar) {
        this.notifyObservers("onCalendarUnregistering", [calendar]);

        // calendar may be a calICalendar wrapper:
        if (calendar.wrappedJSObject instanceof calCachedCalendar) {
            calendar.wrappedJSObject.onCalendarUnregistering();
        }

        calendar.removeObserver(this.mCalObservers[calendar.id]);
        Services.prefs.deleteBranch(getPrefBranchFor(calendar.id));
        flushPrefs();

        if (this.mCache) {
            delete this.mCache[calendar.id];
        }

        if (calendar.readOnly) {
            this.mReadonlyCalendarCount--;
        }

        if (calendar.getProperty("requiresNetwork") !== false) {
            this.mNetworkCalendarCount--;
        }
        this.mCalendarCount--;

        this.clearRefreshTimer(calendar);
    },

    // Delete this method for Lightning 4.7 at latest
    deleteCalendar: function(calendar) {
        if (!this.deleteCalendar.warningIssued) {
            cal.WARN("Use of calICalendarManager::deleteCalendar is deprecated" +
                     " and will be removed with the next release. Use" +
                     " ::removeCalendar instead.\n" + cal.STACK(10));
            this.deleteCalendar.warningIssued = true;
        }

        const cICM = Components.interfaces.calICalendarManager;
        this.removeCalendar(calendar, cICM.REMOVE_NO_UNREGISTER);
    },

    removeCalendar: function(calendar, mode=0) {
        const cICM = Components.interfaces.calICalendarManager;

        let removeModes = new Set(calendar.getProperty("capabilities.removeModes") || ["unsubscribe"]);
        if (!removeModes.has("unsubscribe") && !removeModes.has("delete")) {
            // Removing is not allowed
            return;
        }

        if ((mode & cICM.REMOVE_NO_UNREGISTER) && this.mCache &&
            (calendar.id in this.mCache)) {
            throw new Components.Exception("Can't remove a registered calendar");
        } else if (!(mode & cICM.REMOVE_NO_UNREGISTER)) {
            this.unregisterCalendar(calendar);
        }

        // This observer notification needs to be fired for both unsubscribe
        // and delete, we don't differ this at the moment.
        this.notifyObservers("onCalendarDeleting", [calendar]);

        // For deleting, we also call the deleteCalendar method from the provider.
        if (removeModes.has("delete") && (mode & cICM.REMOVE_NO_DELETE) == 0) {
            let wrappedCalendar = cal.wrapInstance(calendar, Components.interfaces.calICalendarProvider);
            if (!wrappedCalendar) {
                throw new Components.Exception("Calendar is missing a provider implementation for delete");
            }

            wrappedCalendar.deleteCalendar(calendar, null);
        }
    },

    getCalendarById: function cmgr_getCalendarById(aId) {
        if (aId in this.mCache) {
            return this.mCache[aId];
        } else {
            return null;
        }
    },

    getCalendars: function cmgr_getCalendars(count) {
        this.assureCache();
        var calendars = [];
        for (var id in this.mCache) {
            let calendar = this.mCache[id];
            calendars.push(calendar);
        }
        count.value = calendars.length;
        return calendars;
    },

    assureCache: function cmgr_assureCache() {
        if (!this.mCache) {
            this.mCache = {};
            this.mCalObservers = {};

            let allCals = {};
            for (let key of Services.prefs.getChildList(REGISTRY_BRANCH)) { // merge down all keys
                allCals[key.substring(0, key.indexOf(".", REGISTRY_BRANCH.length))] = true;
            }

            for (let calBranch in allCals) {
                let id = calBranch.substring(REGISTRY_BRANCH.length);
                let ctype = Preferences.get(calBranch + ".type", null);
                let curi = Preferences.get(calBranch + ".uri", null);

                try {
                    if (!ctype || !curi) { // sanity check
                        Services.prefs.deleteBranch(calBranch + ".");
                        continue;
                    }

                    let uri = cal.makeURL(curi);
                    let calendar = this.createCalendar(ctype, uri);
                    if (calendar) {
                        calendar.id = id;
                        if (calendar.getProperty("auto-enabled")) {
                            calendar.deleteProperty("disabled");
                            calendar.deleteProperty("auto-enabled");
                        }

                        if ((calendar.getProperty("cache.supported") !== false) &&
                            (calendar.getProperty("cache.enabled") ||
                             calendar.getProperty("cache.always"))) {
                            calendar = new calCachedCalendar(calendar);
                        }
                    } else { // create dummy calendar that stays disabled for this run:
                        calendar = new calDummyCalendar(ctype);
                        calendar.id = id;
                        calendar.uri = uri;
                        // try to enable on next startup if calendar has been enabled:
                        if (!calendar.getProperty("disabled")) {
                            calendar.setProperty("auto-enabled", true);
                        }
                        calendar.setProperty("disabled", true);
                    }

                    this.setupCalendar(calendar);
                } catch (exc) {
                    cal.ERROR("Can't create calendar for " + id + " (" + ctype + ", " + curi + "): " + exc);
                }
            }

            // do refreshing in a second step, when *all* calendars are already available
            // via getCalendars():
            for (let id in this.mCache) {
                let calendar = this.mCache[id];
                if (!calendar.getProperty("disabled") && calendar.canRefresh) {
                    calendar.refresh();
                }
            }
        }
    },

    getCalendarPref_: function(calendar, name) {
        cal.ASSERT(calendar, "Invalid Calendar!");
        cal.ASSERT(calendar.id !== null, "Calendar id needs to be set!");
        cal.ASSERT(name && name.length > 0, "Pref Name must be non-empty!");

        let branch = (getPrefBranchFor(calendar.id) + name);
        let value = Preferences.get(branch, null);

        if (typeof value == "string" && value.startsWith("bignum:")) {
            let converted = Number(value.substr(7));
            if (!isNaN(converted)) {
                value = converted;
            }
        }
        return value;
    },

    setCalendarPref_: function(calendar, name, value) {
        cal.ASSERT(calendar, "Invalid Calendar!");
        cal.ASSERT(calendar.id !== null, "Calendar id needs to be set!");
        cal.ASSERT(name && name.length > 0, "Pref Name must be non-empty!");

        let branch = (getPrefBranchFor(calendar.id) + name);

        if (typeof value == "number" && (value > MAX_INT || value < MIN_INT || !Number.isInteger(value))) {
            // This is something the preferences service can't store directly.
            // Convert to string and tag it so we know how to handle it.
            value = "bignum:" + value;
        }

        // Delete before to allow pref-type changes, then set the pref.
        Services.prefs.deleteBranch(branch);
        if (value !== null && value !== undefined) {
            Preferences.set(branch, value);
        }
    },

    deleteCalendarPref_: function(calendar, name) {
        cal.ASSERT(calendar, "Invalid Calendar!");
        cal.ASSERT(calendar.id !== null, "Calendar id needs to be set!");
        cal.ASSERT(name && name.length > 0, "Pref Name must be non-empty!");
        Services.prefs.deleteBranch(getPrefBranchFor(calendar.id) + name);
    },

    mObservers: null,
    addObserver: function(aObserver) { return this.mObservers.add(aObserver); },
    removeObserver: function(aObserver) { return this.mObservers.remove(aObserver); },
    notifyObservers: function(functionName, args) { return this.mObservers.notify(functionName, args); },

    mCalendarObservers: null,
    addCalendarObserver: function(aObserver) { return this.mCalendarObservers.add(aObserver); },
    removeCalendarObserver: function(aObserver) { return this.mCalendarObservers.remove(aObserver); },
    notifyCalendarObservers: function(functionName, args) { return this.mCalendarObservers.notify(functionName, args); }
};

function equalMessage(msg1, msg2) {
    if (msg1.GetString(0) == msg2.GetString(0) &&
        msg1.GetString(1) == msg2.GetString(1) &&
        msg1.GetString(2) == msg2.GetString(2)) {
        return true;
    }
    return false;
}

function calMgrCalendarObserver(calendar, calMgr) {
    this.calendar = calendar;
    // We compare this to determine if the state actually changed.
    this.storedReadOnly = calendar.readOnly;
    this.announcedMessages = [];
    this.calMgr = calMgr;
}

calMgrCalendarObserver.prototype = {
    calendar: null,
    storedReadOnly: null,
    calMgr: null,

    QueryInterface: XPCOMUtils.generateQI([
        Components.interfaces.nsIWindowMediatorListener,
        Components.interfaces.calIObserver
    ]),

    // calIObserver:
    onStartBatch: function() { return this.calMgr.notifyCalendarObservers("onStartBatch", arguments); },
    onEndBatch: function() { return this.calMgr.notifyCalendarObservers("onEndBatch", arguments); },
    onLoad: function(calendar) { return this.calMgr.notifyCalendarObservers("onLoad", arguments); },
    onAddItem: function(aItem) { return this.calMgr.notifyCalendarObservers("onAddItem", arguments); },
    onModifyItem: function(aNewItem, aOldItem) { return this.calMgr.notifyCalendarObservers("onModifyItem", arguments); },
    onDeleteItem: function(aDeletedItem) { return this.calMgr.notifyCalendarObservers("onDeleteItem", arguments); },
    onError: function(aCalendar, aErrNo, aMessage) {
        this.calMgr.notifyCalendarObservers("onError", arguments);
        this.announceError(aCalendar, aErrNo, aMessage);
    },

    onPropertyChanged: function(aCalendar, aName, aValue, aOldValue) {
        this.calMgr.notifyCalendarObservers("onPropertyChanged", arguments);
        switch (aName) {
            case "requiresNetwork":
                this.calMgr.mNetworkCalendarCount += (aValue ? 1 : -1);
                break;
            case "readOnly":
                this.calMgr.mReadonlyCalendarCount += (aValue ? 1 : -1);
                break;
            case "refreshInterval":
                this.calMgr.setupRefreshTimer(aCalendar);
                break;
            case "cache.enabled":
                this.changeCalendarCache.apply(this, arguments);
                break;
            case "disabled":
                if (!aValue && aCalendar.canRefresh) {
                    aCalendar.refresh();
                }
                break;
        }
    },

    changeCalendarCache: function(aCalendar, aName, aValue, aOldValue) {
        const cICM = Components.interfaces.calICalendarManager;
        aOldValue = aOldValue || false;
        aValue = aValue || false;

        // hack for bug 1182264 to deal with calendars, which have set cache.enabled, but in fact do
        // not support caching (like storage calendars) - this also prevents enabling cache again
        if (aCalendar.getProperty("cache.supported") === false) {
            if (aCalendar.getProperty("cache.enabled") === true) {
                aCalendar.deleteProperty("cache.enabled");
            }
            return;
        }

        if (aOldValue != aValue) {
            // Try to find the current sort order
            let sortOrderPref = Preferences.get("calendar.list.sortOrder", "").split(" ");
            let initialSortOrderPos = null;
            for (let i = 0; i < sortOrderPref.length; ++i) {
                if (sortOrderPref[i] == aCalendar.id) {
                    initialSortOrderPos = i;
                }
            }
            // Enabling or disabling cache on a calendar re-creates
            // it so the registerCalendar call can wrap/unwrap the
            // calCachedCalendar facade saving the user the need to
            // restart Thunderbird and making sure a new Id is used.
            this.calMgr.removeCalendar(aCalendar, cICM.REMOVE_NO_DELETE);
            var newCal = this.calMgr.createCalendar(aCalendar.type,aCalendar.uri);
            newCal.name = aCalendar.name;

            // TODO: if properties get added this list will need to be adjusted,
            // ideally we should add a "getProperties" method to calICalendar.idl
            // to retrieve all non-transient properties for a calendar.
            let propsToCopy = [ "color",
                                "disabled",
                                "auto-enabled",
                                "cache.enabled",
                                "refreshInterval",
                                "suppressAlarms",
                                "calendar-main-in-composite",
                                "calendar-main-default",
                                "readOnly",
                                "imip.identity.key"];
            for (let prop of propsToCopy) {
              newCal.setProperty(prop,
                                 aCalendar.getProperty(prop));
            }

            if (initialSortOrderPos != null) {
                newCal.setProperty("initialSortOrderPos",
                                   initialSortOrderPos);
            }
            this.calMgr.registerCalendar(newCal);
        } else {
            if (aCalendar.wrappedJSObject instanceof calCachedCalendar) {
                // any attempt to switch this flag will reset the cached calendar;
                // could be useful for users in case the cache may be corrupted.
                aCalendar.wrappedJSObject.setupCachedCalendar();
            }
        }
    },

    onPropertyDeleting: function(aCalendar, aName) {
        this.onPropertyChanged(aCalendar, aName, false, true);
    },

    // Error announcer specific functions
    announceError: function(aCalendar, aErrNo, aMessage) {

        var paramBlock = Components.classes["@mozilla.org/embedcomp/dialogparam;1"]
                                   .createInstance(Components.interfaces.nsIDialogParamBlock);
        var props = Services.strings.createBundle("chrome://calendar/locale/calendar.properties");
        var errMsg;
        paramBlock.SetNumberStrings(3);
        if (!this.storedReadOnly && this.calendar.readOnly) {
            // Major errors change the calendar to readOnly
            errMsg = props.formatStringFromName("readOnlyMode", [this.calendar.name], 1);
        } else if (!this.storedReadOnly && !this.calendar.readOnly) {
            // Minor errors don't, but still tell the user something went wrong
            errMsg = props.formatStringFromName("minorError", [this.calendar.name], 1);
        } else {
            // The calendar was already in readOnly mode, but still tell the user
            errMsg = props.formatStringFromName("stillReadOnlyError", [this.calendar.name], 1);
        }

        // When possible, change the error number into its name, to
        // make it slightly more readable.
        var errCode = "0x"+aErrNo.toString(16);
        const calIErrors = Components.interfaces.calIErrors;
        // Check if it is worth enumerating all the error codes.
        if (aErrNo & calIErrors.ERROR_BASE) {
            for (var err in calIErrors) {
                if (calIErrors[err] == aErrNo) {
                    errCode = err;
                }
            }
        }

        var message;
        switch (aErrNo) {
            case calIErrors.CAL_UTF8_DECODING_FAILED:
                message = props.GetStringFromName("utf8DecodeError");
                break;
            case calIErrors.ICS_MALFORMEDDATA:
                message = props.GetStringFromName("icsMalformedError");
                break;
            case calIErrors.MODIFICATION_FAILED:
                errMsg = calGetString("calendar", "errorWriting", [aCalendar.name]);
             default:
                message = aMessage;
         }


        paramBlock.SetString(0, errMsg);
        paramBlock.SetString(1, errCode);
        paramBlock.SetString(2, message);

        this.storedReadOnly = this.calendar.readOnly;
        var errorCode = calGetString("calendar","errorCode", [errCode]);
        var errorDescription = calGetString("calendar","errorDescription", [message]);
        var summary = errMsg + " " + errorCode + ". " + errorDescription;

        // Log warnings in error console.
        // Report serious errors in both error console and in prompt window.
        if (aErrNo == calIErrors.MODIFICATION_FAILED) {
            Components.utils.reportError(summary);
            this.announceParamBlock(paramBlock);
        } else {
            cal.WARN(summary);
        }
    },

    announceParamBlock: function(paramBlock) {
        function awaitLoad(event) {
            promptWindow.removeEventListener("load", awaitLoad, false);
            promptWindow.addEventListener("unload", awaitUnload, false);
        }
        let awaitUnload = (event) => {
            promptWindow.removeEventListener("unload", awaitUnload, false);
            // unloaded (user closed prompt window),
            // remove paramBlock and unload listener.
            try {
                // remove the message that has been shown from
                // the list of all announced messages.
                this.announcedMessages = this.announcedMessages.filter((msg) => {
                    return !equalMessage(msg, paramBlock);
                });
            } catch (e) {
                Components.utils.reportError(e);
            }
        };

        // silently don't do anything if this message already has been
        // announced without being acknowledged.
        if (this.announcedMessages.some(equalMessage.bind(null, paramBlock))) {
            return;
        }

        // this message hasn't been announced recently, remember the details of
        // the message for future reference.
        this.announcedMessages.push(paramBlock);

        // Will remove paramBlock from announced messages when promptWindow is
        // closed.  (Closing fires unloaded event, but promptWindow is also
        // unloaded [to clean it?] before loading, so wait for detected load
        // event before detecting unload event that signifies user closed this
        // prompt window.)
        let promptUrl = "chrome://calendar/content/calendar-error-prompt.xul";
        let features = "chrome,dialog=yes,alwaysRaised=yes";
        let promptWindow =  Services.ww.openWindow(null, promptUrl, "_blank", features, paramBlock);
        promptWindow.addEventListener("load", awaitLoad, false);
    }
};

function calDummyCalendar(type) {
    this.initProviderBase();
    this.type = type;
}
calDummyCalendar.prototype = {
    __proto__: cal.ProviderBase.prototype,

    getProperty: function calDummyCalendar_getProperty(aName) {
        switch (aName) {
            case "force-disabled":
                return true;
            default:
                return this.__proto__.__proto__.getProperty.apply(this, arguments);
        }
    }
};

function getPrefBranchFor(id) {
    return (REGISTRY_BRANCH + id + ".");
}

/**
 * Helper function to flush the preferences file. If the application crashes
 * after a calendar has been created using the prefs registry, then the calendar
 * won't show up. Writing the prefs helps counteract.
 */
function flushPrefs() {
    Services.prefs.savePrefFile(null);
}

/**
 * Callback object for the refresh timer. Should be called as an object, i.e
 * let foo = new timerCallback(calendar);
 *
 * @param aCalendar     The calendar to refresh on notification
 */
function timerCallback(aCalendar) {
    this.notify = function refreshNotify(aTimer) {
        if (!aCalendar.getProperty("disabled") && aCalendar.canRefresh) {
            aCalendar.refresh();
        }
    }
}

var gCalendarManagerAddonListener = {
    onDisabling: function(aAddon, aNeedsRestart) {
        if (!this.queryUninstallProvider(aAddon)) {
            // If the addon should not be disabled, then re-enable it.
            aAddon.userDisabled = false;
        }
    },

    onUninstalling: function(aAddon, aNeedsRestart) {
        if (!this.queryUninstallProvider(aAddon)) {
            // If the addon should not be uninstalled, then cancel the uninstall.
            aAddon.cancelUninstall();
        }
    },

    queryUninstallProvider: function(aAddon) {
        const uri = "chrome://calendar/content/calendar-providerUninstall-dialog.xul";
        const features = "chrome,titlebar,resizable,modal";
        let calMgr = cal.getCalendarManager();
        let affectedCalendars =
            calMgr.getCalendars({}).filter(calendar => calendar.providerID == aAddon.id);
        if (!affectedCalendars.length) {
            // If no calendars are affected, then everything is fine.
            return true;
        }

        let args = { shouldUninstall: false, extension: aAddon };

        // Now find a window. The best choice would be the most recent
        // addons window, otherwise the most recent calendar window, or we
        // create a new toplevel window.
        let win = Services.wm.getMostRecentWindow("Extension:Manager") ||
                  cal.getCalendarWindow();
        if (win) {
            win.openDialog(uri, "CalendarProviderUninstallDialog", features, args);
        } else {
            // Use the window watcher to open a parentless window.
            Services.ww.openWindow(null, uri, "CalendarProviderUninstallWindow", features, args);
        }

        // Now that we are done, check if the dialog was accepted or canceled.
        return args.shouldUninstall;
    }
};

function appendToRealm(authHeader, appendStr) {
    let isEscaped = false;
    let idx = authHeader.search(/realm="(.*?)(\\*)"/);
    if (idx > -1) {
        let remain = authHeader.substr(idx + 7); idx += 7;
        while (remain.length && !isEscaped) {
            let m = remain.match(/(.*?)(\\*)"/);
            idx += m[0].length;

            isEscaped = ((m[2].length % 2) == 0);
            if (!isEscaped) {
                remain = remain.substr(m[0].length);
            }
        }
        return authHeader.substr(0, idx - 1) + " " +
                appendStr + authHeader.substr(idx - 1);
    } else {
        return authHeader;
    }
}
