gnome-shell/js/ui/calendar.js

// -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-

const Clutter = imports.gi.Clutter;
const Gio = imports.gi.Gio;
const GLib = imports.gi.GLib;
const Lang = imports.lang;
const St = imports.gi.St;
const Signals = imports.signals;
const Pango = imports.gi.Pango;
const Gettext_gtk30 = imports.gettext.domain('gtk30');
const Mainloop = imports.mainloop;
const Shell = imports.gi.Shell;

const MSECS_IN_DAY = 24 * 60 * 60 * 1000;
const SHOW_WEEKDATE_KEY = 'show-weekdate';

// in org.gnome.desktop.interface
const CLOCK_FORMAT_KEY        = 'clock-format';

function _sameDay(dateA, dateB) {
    return (dateA.getDate() == dateB.getDate() &&
            dateA.getMonth() == dateB.getMonth() &&
            dateA.getYear() == dateB.getYear());
}

function _sameYear(dateA, dateB) {
    return (dateA.getYear() == dateB.getYear());
}

/* TODO: maybe needs config - right now we assume that Saturday and
 * Sunday are non-work days (not true in e.g. Israel, it's Sunday and
 * Monday there)
 */
function _isWorkDay(date) {
    return date.getDay() != 0 && date.getDay() != 6;
}

function _getBeginningOfDay(date) {
    let ret = new Date(date.getTime());
    ret.setHours(0);
    ret.setMinutes(0);
    ret.setSeconds(0);
    ret.setMilliseconds(0);
    return ret;
}

function _getEndOfDay(date) {
    let ret = new Date(date.getTime());
    ret.setHours(23);
    ret.setMinutes(59);
    ret.setSeconds(59);
    ret.setMilliseconds(999);
    return ret;
}

function _formatEventTime(event, clockFormat) {
    let ret;
    if (event.allDay) {
        /* Translators: Shown in calendar event list for all day events
         * Keep it short, best if you can use less then 10 characters
         */
        ret = C_("event list time", "All Day");
    } else {
        switch (clockFormat) {
        case '24h':
            /* Translators: Shown in calendar event list, if 24h format,
               \u2236 is a ratio character, similar to : */
            ret = event.date.toLocaleFormat(C_("event list time", "%H\u2236%M"));
            break;

        default:
            /* explicit fall-through */
        case '12h':
            /* Translators: Shown in calendar event list, if 12h format,
               \u2236 is a ratio character, similar to : and \u2009 is
               a thin space */
            ret = event.date.toLocaleFormat(C_("event list time", "%l\u2236%M\u2009%p"));
            break;
        }
    }
    return ret;
}

function _getCalendarWeekForDate(date) {
    // Based on the algorithms found here:
    // http://en.wikipedia.org/wiki/Talk:ISO_week_date
    let midnightDate = new Date(date.getFullYear(), date.getMonth(), date.getDate());
    // Need to get Monday to be 1 ... Sunday to be 7
    let dayOfWeek = 1 + ((midnightDate.getDay() + 6) % 7);
    let nearestThursday = new Date(midnightDate.getFullYear(), midnightDate.getMonth(),
                                   midnightDate.getDate() + (4 - dayOfWeek));

    let jan1st = new Date(nearestThursday.getFullYear(), 0, 1);
    let diffDate = nearestThursday - jan1st;
    let dayNumber = Math.floor(Math.abs(diffDate) / MSECS_IN_DAY);
    let weekNumber = Math.floor(dayNumber / 7) + 1;

    return weekNumber;
}

function _getCalendarDayAbbreviation(dayNumber) {
    let abbreviations = [
        /* Translators: Calendar grid abbreviation for Sunday.
         *
         * NOTE: These grid abbreviations are always shown together
         * and in order, e.g. "S M T W T F S".
         */
        C_("grid sunday", "S"),
        /* Translators: Calendar grid abbreviation for Monday */
        C_("grid monday", "M"),
        /* Translators: Calendar grid abbreviation for Tuesday */
        C_("grid tuesday", "T"),
        /* Translators: Calendar grid abbreviation for Wednesday */
        C_("grid wednesday", "W"),
        /* Translators: Calendar grid abbreviation for Thursday */
        C_("grid thursday", "T"),
        /* Translators: Calendar grid abbreviation for Friday */
        C_("grid friday", "F"),
        /* Translators: Calendar grid abbreviation for Saturday */
        C_("grid saturday", "S")
    ];
    return abbreviations[dayNumber];
}

function _getEventDayAbbreviation(dayNumber) {
    let abbreviations = [
        /* Translators: Event list abbreviation for Sunday.
         *
         * NOTE: These list abbreviations are normally not shown together
         * so they need to be unique (e.g. Tuesday and Thursday cannot
         * both be 'T').
         */
        C_("list sunday", "Su"),
        /* Translators: Event list abbreviation for Monday */
        C_("list monday", "M"),
        /* Translators: Event list abbreviation for Tuesday */
        C_("list tuesday", "T"),
        /* Translators: Event list abbreviation for Wednesday */
        C_("list wednesday", "W"),
        /* Translators: Event list abbreviation for Thursday */
        C_("list thursday", "Th"),
        /* Translators: Event list abbreviation for Friday */
        C_("list friday", "F"),
        /* Translators: Event list abbreviation for Saturday */
        C_("list saturday", "S")
    ];
    return abbreviations[dayNumber];
}

// Abstraction for an appointment/event in a calendar

const CalendarEvent = new Lang.Class({
    Name: 'CalendarEvent',

    _init: function(date, end, summary, allDay) {
        this.date = date;
        this.end = end;
        this.summary = summary;
        this.allDay = allDay;
    }
});

// Interface for appointments/events - e.g. the contents of a calendar
//

// First, an implementation with no events
const EmptyEventSource = new Lang.Class({
    Name: 'EmptyEventSource',

    _init: function() {
        this.isLoading = false;
        this.isDummy = true;
        this.hasCalendars = false;
    },

    destroy: function() {
    },

    requestRange: function(begin, end) {
    },

    getEvents: function(begin, end) {
        let result = [];
        return result;
    },

    hasEvents: function(day) {
        return false;
    }
});
Signals.addSignalMethods(EmptyEventSource.prototype);

const CalendarServerIface = <interface name="org.gnome.Shell.CalendarServer">
<method name="GetEvents">
    <arg type="x" direction="in" />
    <arg type="x" direction="in" />
    <arg type="b" direction="in" />
    <arg type="a(sssbxxa{sv})" direction="out" />
</method>
<property name="HasCalendars" type="b" access="read" />
<signal name="Changed" />
</interface>;

const CalendarServerInfo  = Gio.DBusInterfaceInfo.new_for_xml(CalendarServerIface);

function CalendarServer() {
    return new Gio.DBusProxy({ g_connection: Gio.DBus.session,
                               g_interface_name: CalendarServerInfo.name,
                               g_interface_info: CalendarServerInfo,
                               g_name: 'org.gnome.Shell.CalendarServer',
                               g_object_path: '/org/gnome/Shell/CalendarServer' });
}

function _datesEqual(a, b) {
    if (a < b)
        return false;
    else if (a > b)
        return false;
    return true;
}

function _dateIntervalsOverlap(a0, a1, b0, b1)
{
    if (a1 <= b0)
        return false;
    else if (b1 <= a0)
        return false;
    else
        return true;
}

// an implementation that reads data from a session bus service
const DBusEventSource = new Lang.Class({
    Name: 'DBusEventSource',

    _init: function() {
        this._resetCache();
        this.isLoading = false;
        this.isDummy = false;

        this._initialized = false;
        this._dbusProxy = new CalendarServer();
        this._dbusProxy.init_async(GLib.PRIORITY_DEFAULT, null, Lang.bind(this, function(object, result) {
            try {
                this._dbusProxy.init_finish(result);
            } catch(e) {
                log('Error loading calendars: ' + e.message);
                return;
            }

            this._dbusProxy.connectSignal('Changed', Lang.bind(this, this._onChanged));

            this._dbusProxy.connect('notify::g-name-owner', Lang.bind(this, function() {
                if (this._dbusProxy.g_name_owner)
                    this._onNameAppeared();
                else
                    this._onNameVanished();
            }));

            this._dbusProxy.connect('g-properties-changed', Lang.bind(this, function() {
                this.emit('notify::has-calendars');
            }));

            this._initialized = true;
            this.emit('notify::has-calendars');
            this._onNameAppeared();
        }));
    },

    destroy: function() {
        this._dbusProxy.run_dispose();
    },

    get hasCalendars() {
        if (this._initialized)
            return this._dbusProxy.HasCalendars;
        else
            return false;
    },

    _resetCache: function() {
        this._events = [];
        this._lastRequestBegin = null;
        this._lastRequestEnd = null;
    },

    _onNameAppeared: function(owner) {
        this._resetCache();
        this._loadEvents(true);
    },

    _onNameVanished: function(oldOwner) {
        this._resetCache();
        this.emit('changed');
    },

    _onChanged: function() {
        this._loadEvents(false);
    },

    _onEventsReceived: function(results, error) {
        let newEvents = [];
        let appointments = results ? results[0] : null;
        if (appointments != null) {
            for (let n = 0; n < appointments.length; n++) {
                let a = appointments[n];
                let date = new Date(a[4] * 1000);
                let end = new Date(a[5] * 1000);
                let summary = a[1];
                let allDay = a[3];
                let event = new CalendarEvent(date, end, summary, allDay);
                newEvents.push(event);
            }
            newEvents.sort(function(event1, event2) {
                return event1.date.getTime() - event2.date.getTime();
            });
        }

        this._events = newEvents;
        this.isLoading = false;
        this.emit('changed');
    },

    _loadEvents: function(forceReload) {
        // Ignore while loading
        if (!this._initialized)
            return;

        if (this._curRequestBegin && this._curRequestEnd){
            let callFlags = Gio.DBusCallFlags.NO_AUTO_START;
            if (forceReload)
                callFlags = Gio.DBusCallFlags.NONE;
            this._dbusProxy.GetEventsRemote(this._curRequestBegin.getTime() / 1000,
                                            this._curRequestEnd.getTime() / 1000,
                                            forceReload,
                                            Lang.bind(this, this._onEventsReceived),
                                            callFlags);
        }
    },

    requestRange: function(begin, end, forceReload) {
        if (forceReload || !(_datesEqual(begin, this._lastRequestBegin) && _datesEqual(end, this._lastRequestEnd))) {
            this.isLoading = true;
            this._lastRequestBegin = begin;
            this._lastRequestEnd = end;
            this._curRequestBegin = begin;
            this._curRequestEnd = end;
            this._loadEvents(forceReload);
        }
    },

    getEvents: function(begin, end) {
        let result = [];
        for(let n = 0; n < this._events.length; n++) {
            let event = this._events[n];
            if (_dateIntervalsOverlap (event.date, event.end, begin, end)) {
                result.push(event);
            }
        }
        return result;
    },

    hasEvents: function(day) {
        let dayBegin = _getBeginningOfDay(day);
        let dayEnd = _getEndOfDay(day);

        let events = this.getEvents(dayBegin, dayEnd);

        if (events.length == 0)
            return false;

        return true;
    }
});
Signals.addSignalMethods(DBusEventSource.prototype);

const Calendar = new Lang.Class({
    Name: 'Calendar',

    _init: function() {
        this._weekStart = Shell.util_get_week_start();
        this._settings = new Gio.Settings({ schema: 'org.gnome.shell.calendar' });

        this._settings.connect('changed::' + SHOW_WEEKDATE_KEY, Lang.bind(this, this._onSettingsChange));
        this._useWeekdate = this._settings.get_boolean(SHOW_WEEKDATE_KEY);

        // Find the ordering for month/year in the calendar heading
        this._headerFormatWithoutYear = '%B';
        switch (Gettext_gtk30.gettext('calendar:MY')) {
        case 'calendar:MY':
            this._headerFormat = '%B %Y';
            break;
        case 'calendar:YM':
            this._headerFormat = '%Y %B';
            break;
        default:
            log('Translation of "calendar:MY" in GTK+ is not correct');
            this._headerFormat = '%B %Y';
            break;
        }

        // Start off with the current date
        this._selectedDate = new Date();

        this.actor = new St.Table({ homogeneous: false,
                                    style_class: 'calendar',
                                    reactive: true });

        this.actor.connect('scroll-event',
                           Lang.bind(this, this._onScroll));

        this._buildHeader ();
    },

    // @eventSource: is an object implementing the EventSource API, e.g. the
    // requestRange(), getEvents(), hasEvents() methods and the ::changed signal.
    setEventSource: function(eventSource) {
        this._eventSource = eventSource;
        this._eventSource.connect('changed', Lang.bind(this, function() {
            this._update(false);
        }));
        this._update(true);
    },

    // Sets the calendar to show a specific date
    setDate: function(date, forceReload) {
        if (!_sameDay(date, this._selectedDate)) {
            this._selectedDate = date;
            this._update(forceReload);
            this.emit('selected-date-changed', new Date(this._selectedDate));
        } else {
            if (forceReload)
                this._update(forceReload);
        }
    },

    _buildHeader: function() {
        let offsetCols = this._useWeekdate ? 1 : 0;
        this.actor.destroy_all_children();

        // Top line of the calendar '<| September 2009 |>'
        this._topBox = new St.BoxLayout();
        this.actor.add(this._topBox,
                       { row: 0, col: 0, col_span: offsetCols + 7 });

        this._backButton = new St.Button({ style_class: 'calendar-change-month-back',
                                           can_focus: true });
        this._topBox.add(this._backButton);
        this._backButton.connect('clicked', Lang.bind(this, this._onPrevMonthButtonClicked));

        this._monthLabel = new St.Label({style_class: 'calendar-month-label'});
        this._topBox.add(this._monthLabel, { expand: true, x_fill: false, x_align: St.Align.MIDDLE });

        this._forwardButton = new St.Button({ style_class: 'calendar-change-month-forward',
                                              can_focus: true });
        this._topBox.add(this._forwardButton);
        this._forwardButton.connect('clicked', Lang.bind(this, this._onNextMonthButtonClicked));

        // Add weekday labels...
        //
        // We need to figure out the abbreviated localized names for the days of the week;
        // we do this by just getting the next 7 days starting from right now and then putting
        // them in the right cell in the table. It doesn't matter if we add them in order
        let iter = new Date(this._selectedDate);
        iter.setSeconds(0); // Leap second protection. Hah!
        iter.setHours(12);
        for (let i = 0; i < 7; i++) {
            // Could use iter.toLocaleFormat('%a') but that normally gives three characters
            // and we want, ideally, a single character for e.g. S M T W T F S
            let customDayAbbrev = _getCalendarDayAbbreviation(iter.getDay());
            let label = new St.Label({ style_class: 'calendar-day-base calendar-day-heading',
                                       text: customDayAbbrev });
            this.actor.add(label,
                           { row: 1,
                             col: offsetCols + (7 + iter.getDay() - this._weekStart) % 7,
                             x_fill: false, x_align: St.Align.MIDDLE });
            iter.setTime(iter.getTime() + MSECS_IN_DAY);
        }

        // All the children after this are days, and get removed when we update the calendar
        this._firstDayIndex = this.actor.get_n_children();
    },

    _onScroll : function(actor, event) {
        switch (event.get_scroll_direction()) {
        case Clutter.ScrollDirection.UP:
        case Clutter.ScrollDirection.LEFT:
            this._onPrevMonthButtonClicked();
            break;
        case Clutter.ScrollDirection.DOWN:
        case Clutter.ScrollDirection.RIGHT:
            this._onNextMonthButtonClicked();
            break;
        }
    },

    _onPrevMonthButtonClicked: function() {
        let newDate = new Date(this._selectedDate);
        let oldMonth = newDate.getMonth();
        if (oldMonth == 0) {
            newDate.setMonth(11);
            newDate.setFullYear(newDate.getFullYear() - 1);
            if (newDate.getMonth() != 11) {
                let day = 32 - new Date(newDate.getFullYear() - 1, 11, 32).getDate();
                newDate = new Date(newDate.getFullYear() - 1, 11, day);
            }
        }
        else {
            newDate.setMonth(oldMonth - 1);
            if (newDate.getMonth() != oldMonth - 1) {
                let day = 32 - new Date(newDate.getFullYear(), oldMonth - 1, 32).getDate();
                newDate = new Date(newDate.getFullYear(), oldMonth - 1, day);
            }
        }

        this._backButton.grab_key_focus();

        this.setDate(newDate, false);
    },

    _onNextMonthButtonClicked: function() {
        let newDate = new Date(this._selectedDate);
        let oldMonth = newDate.getMonth();
        if (oldMonth == 11) {
            newDate.setMonth(0);
            newDate.setFullYear(newDate.getFullYear() + 1);
            if (newDate.getMonth() != 0) {
                let day = 32 - new Date(newDate.getFullYear() + 1, 0, 32).getDate();
                newDate = new Date(newDate.getFullYear() + 1, 0, day);
            }
        }
        else {
            newDate.setMonth(oldMonth + 1);
            if (newDate.getMonth() != oldMonth + 1) {
                let day = 32 - new Date(newDate.getFullYear(), oldMonth + 1, 32).getDate();
                newDate = new Date(newDate.getFullYear(), oldMonth + 1, day);
            }
        }

        this._forwardButton.grab_key_focus();

        this.setDate(newDate, false);
    },

    _onSettingsChange: function() {
        this._useWeekdate = this._settings.get_boolean(SHOW_WEEKDATE_KEY);
        this._buildHeader();
        this._update(false);
    },

    _update: function(forceReload) {
        let now = new Date();

        if (_sameYear(this._selectedDate, now))
            this._monthLabel.text = this._selectedDate.toLocaleFormat(this._headerFormatWithoutYear);
        else
            this._monthLabel.text = this._selectedDate.toLocaleFormat(this._headerFormat);

        // Remove everything but the topBox and the weekday labels
        let children = this.actor.get_children();
        for (let i = this._firstDayIndex; i < children.length; i++)
            children[i].destroy();

        // Start at the beginning of the week before the start of the month
        //
        // We want to show always 6 weeks (to keep the calendar menu at the same
        // height if there are no events), so we pad it according to the following
        // policy:
        //
        // 1 - If a month has 6 weeks, we place no padding (example: Dec 2012)
        // 2 - If a month has 5 weeks and it starts on week start, we pad one week
        //     before it (example: Apr 2012)
        // 3 - If a month has 5 weeks and it starts on any other day, we pad one week
        //     after it (example: Nov 2012)
        // 4 - If a month has 4 weeks, we pad one week before and one after it
        //     (example: Feb 2010)
        //
        // Actually computing the number of weeks is complex, but we know that the
        // problematic categories (2 and 4) always start on week start, and that
        // all months at the end have 6 weeks.

        let beginDate = new Date(this._selectedDate);
        beginDate.setDate(1);
        beginDate.setSeconds(0);
        beginDate.setHours(12);
        let year = beginDate.getYear();

        let daysToWeekStart = (7 + beginDate.getDay() - this._weekStart) % 7;
        let startsOnWeekStart = daysToWeekStart == 0;
        let weekPadding = startsOnWeekStart ? 7 : 0;

        beginDate.setTime(beginDate.getTime() - (weekPadding + daysToWeekStart) * MSECS_IN_DAY);

        let iter = new Date(beginDate);
        let row = 2;
        // nRows here means 6 weeks + one header + one navbar
        let nRows = 8;
        while (row < 8) {
            let button = new St.Button({ label: iter.getDate().toString(),
                                         can_focus: true });
            let rtl = button.get_text_direction() == Clutter.TextDirection.RTL;

            if (this._eventSource.isDummy)
                button.reactive = false;

            let iterStr = iter.toUTCString();
            button.connect('clicked', Lang.bind(this, function() {
                this._shouldDateGrabFocus = true;

                let newlySelectedDate = new Date(iterStr);
                this.setDate(newlySelectedDate, false);

                this._shouldDateGrabFocus = false;
            }));

            let hasEvents = this._eventSource.hasEvents(iter);
            let styleClass = 'calendar-day-base calendar-day';

            if (_isWorkDay(iter))
                styleClass += ' calendar-work-day'
            else
                styleClass += ' calendar-nonwork-day'

            // Hack used in lieu of border-collapse - see gnome-shell.css
            if (row == 2)
                styleClass = 'calendar-day-top ' + styleClass;

            let leftMost = rtl ? iter.getDay() == (this._weekStart + 6) % 7
                               : iter.getDay() == this._weekStart;
            if (leftMost)
                styleClass = 'calendar-day-left ' + styleClass;

            if (_sameDay(now, iter))
                styleClass += ' calendar-today';
            else if (iter.getMonth() != this._selectedDate.getMonth())
                styleClass += ' calendar-other-month-day';

            if (hasEvents)
                styleClass += ' calendar-day-with-events'

            button.style_class = styleClass;

            let offsetCols = this._useWeekdate ? 1 : 0;
            this.actor.add(button,
                           { row: row, col: offsetCols + (7 + iter.getDay() - this._weekStart) % 7 });

            if (_sameDay(this._selectedDate, iter)) {
                button.add_style_pseudo_class('active');

                if (this._shouldDateGrabFocus)
                    button.grab_key_focus();
            }

            if (this._useWeekdate && iter.getDay() == 4) {
                let label = new St.Label({ text: _getCalendarWeekForDate(iter).toString(),
                                           style_class: 'calendar-day-base calendar-week-number'});
                this.actor.add(label,
                               { row: row, col: 0, y_align: St.Align.MIDDLE });
            }

            iter.setTime(iter.getTime() + MSECS_IN_DAY);

            if (iter.getDay() == this._weekStart)
                row++;
        }
        // Signal to the event source that we are interested in events
        // only from this date range
        this._eventSource.requestRange(beginDate, iter, forceReload);
    }
});

Signals.addSignalMethods(Calendar.prototype);

const EventsList = new Lang.Class({
    Name: 'EventsList',

    _init: function() {
        this.actor = new St.BoxLayout({ vertical: true, style_class: 'events-header-vbox'});
        this._date = new Date();
        this._desktopSettings = new Gio.Settings({ schema: 'org.gnome.desktop.interface' });
        this._desktopSettings.connect('changed', Lang.bind(this, this._update));
        this._weekStart = Shell.util_get_week_start();
    },

    setEventSource: function(eventSource) {
        this._eventSource = eventSource;
        this._eventSource.connect('changed', Lang.bind(this, this._update));
    },

    _addEvent: function(dayNameBox, timeBox, eventTitleBox, includeDayName, day, time, desc) {
        if (includeDayName) {
            dayNameBox.add(new St.Label( { style_class: 'events-day-dayname',
                                           text: day } ),
                           { x_fill: true } );
        }
        timeBox.add(new St.Label( { style_class: 'events-day-time',
                                    text: time} ),
                    { x_fill: true } );
        eventTitleBox.add(new St.Label( { style_class: 'events-day-task',
                                          text: desc} ));
    },

    _addPeriod: function(header, begin, end, includeDayName, showNothingScheduled) {
        let events = this._eventSource.getEvents(begin, end);

        let clockFormat = this._desktopSettings.get_string(CLOCK_FORMAT_KEY);;

        if (events.length == 0 && !showNothingScheduled)
            return;

        let vbox = new St.BoxLayout( {vertical: true} );
        this.actor.add(vbox);

        vbox.add(new St.Label({ style_class: 'events-day-header', text: header }));
        let box = new St.BoxLayout({style_class: 'events-header-hbox'});
        let dayNameBox = new St.BoxLayout({ vertical: true, style_class: 'events-day-name-box' });
        let timeBox = new St.BoxLayout({ vertical: true, style_class: 'events-time-box' });
        let eventTitleBox = new St.BoxLayout({ vertical: true, style_class: 'events-event-box' });
        box.add(dayNameBox, {x_fill: false});
        box.add(timeBox, {x_fill: false});
        box.add(eventTitleBox, {expand: true});
        vbox.add(box);

        for (let n = 0; n < events.length; n++) {
            let event = events[n];
            let dayString = _getEventDayAbbreviation(event.date.getDay());
            let timeString = _formatEventTime(event, clockFormat);
            let summaryString = event.summary;
            this._addEvent(dayNameBox, timeBox, eventTitleBox, includeDayName, dayString, timeString, summaryString);
        }

        if (events.length == 0 && showNothingScheduled) {
            let now = new Date();
            /* Translators: Text to show if there are no events */
            let nothingEvent = new CalendarEvent(now, now, _("Nothing Scheduled"), true);
            let timeString = _formatEventTime(nothingEvent, clockFormat);
            this._addEvent(dayNameBox, timeBox, eventTitleBox, false, "", timeString, nothingEvent.summary);
        }
    },

    _showOtherDay: function(day) {
        this.actor.destroy_all_children();

        let dayBegin = _getBeginningOfDay(day);
        let dayEnd = _getEndOfDay(day);

        let dayString;
        let now = new Date();
        if (_sameYear(day, now))
            /* Translators: Shown on calendar heading when selected day occurs on current year */
            dayString = day.toLocaleFormat(C_("calendar heading", "%A, %B %d"));
        else
            /* Translators: Shown on calendar heading when selected day occurs on different year */
            dayString = day.toLocaleFormat(C_("calendar heading", "%A, %B %d, %Y"));
        this._addPeriod(dayString, dayBegin, dayEnd, false, true);
    },

    _showToday: function() {
        this.actor.destroy_all_children();

        let now = new Date();
        let dayBegin = _getBeginningOfDay(now);
        let dayEnd = _getEndOfDay(now);
        this._addPeriod(_("Today"), dayBegin, dayEnd, false, true);

        let tomorrowBegin = new Date(dayBegin.getTime() + 86400 * 1000);
        let tomorrowEnd = new Date(dayEnd.getTime() + 86400 * 1000);
        this._addPeriod(_("Tomorrow"), tomorrowBegin, tomorrowEnd, false, true);

        let dayInWeek = (dayEnd.getDay() - this._weekStart + 7) % 7;

        if (dayInWeek < 5) {
            /* If now is within the first 5 days we show "This week" and
             * include events up until and including Saturday/Sunday
             * (depending on whether a week starts on Sunday/Monday).
             */
            let thisWeekBegin = new Date(dayBegin.getTime() + 2 * 86400 * 1000);
            let thisWeekEnd = new Date(dayEnd.getTime() + (6 - dayInWeek) * 86400 * 1000);
            this._addPeriod(_("This week"), thisWeekBegin, thisWeekEnd, true, false);
        } else {
            /* otherwise it's one of the two last days of the week ... show
             * "Next week" and include events up until and including *next*
             * Saturday/Sunday
             */
            let nextWeekBegin = new Date(dayBegin.getTime() + 2 * 86400 * 1000);
            let nextWeekEnd = new Date(dayEnd.getTime() + (13 - dayInWeek) * 86400 * 1000);
            this._addPeriod(_("Next week"), nextWeekBegin, nextWeekEnd, true, false);
        }
    },

    // Sets the event list to show events from a specific date
    setDate: function(date) {
        if (!_sameDay(date, this._date)) {
            this._date = date;
            this._update();
        }
    },

    _update: function() {
        if (this._eventSource.isLoading)
            return;

        let today = new Date();
        if (_sameDay (this._date, today)) {
            this._showToday();
        } else {
            this._showOtherDay(this._date);
        }
    }
});