/** Next time we need to query the calendar */
var nextCalendarUpdate = 0;
/** Next time we need to redraw the list because the active item changed */
var nextRender = 0;
var calendars = {};
var locations = {};
var DATENOW, NOW;
var globalTimer;

$(document).ready(function () {
	if (!globalConfig || globalConfig.constructor !== Object) {
		fatalError("Embedded panel config is not valid JSON");
		return;
	}
	initializePanel();
});

function initializePanel() {
	if (!globalConfig.locations || globalConfig.locations.constructor !== Array) {
		fatalError("Requested panel doesn't contain locations / not array");
		return;
	}

	var locs = 0;
	globalConfig.locations.forEach(function (x) {
		// filter out if no numeric id, or id already present
		if (typeof(x.id) !== 'number' || x.id <= 0 || locations[x.id])
			return;
		locs++;
		locations[x.id] = x;
	});

	if (locs === 0) {
		fatalError("List of location ids is empty");
		return;
	}

	if (globalConfig.time) {
		SetUpDate(globalConfig.time);
	}
	delete globalConfig.time;
	delete globalConfig.locations;

	sanitizeAndOverrideConfig(globalConfig);
	if (!globalTimer) {
		mainUpdateLoop();
		if (globalConfig.qrcode) {
			makeQrCode();
		}
	}
}

/**
 * gets Additional Parameters from the URL, and from the
 * downloaded json.
 * also makes sure parameters are in a given range
 */
function sanitizeAndOverrideConfig(config) {
	sanitizeConfigParam(config, 'calupdate', PARAM_INT, 30, 1, 60, 60 * 1000);
	sanitizeConfigParam(config, 'qrcode', PARAM_BOOL, false);
	sanitizeConfigParam(config, 'language', PARAM_STRING, 'en');
}

function updateNow() {
	DATENOW = MyDate();
	NOW = DATENOW.getTime();
}

/**
 * queries the Calendar data
 */
function queryCalendars() {
	console.log('Querying current calendar data');
	if (!PANEL_UUID) return;
	var url = API + "get=calendar&uuid=" + PANEL_UUID;
	$.ajax({
		url: url,
		dataType: 'json',
		cache: false,
		timeout: 30000,
		success: queryCalendarsCallback,
		error: function () {
			// Retry in 5 minutes (300 seconds)
			updateNow();
			nextCalendarUpdate = NOW + 300000;
		}
	});
}

var color;

function queryCalendarsCallback(result) {
	if (result && result.constructor === Array) {
		var l = result.length;
		var timeTable = {};
		color = 'rgb(' + Math.round(Math.random() * 128 + 127) + ', ' + Math.round(Math.random() * 128 + 127) + ', ' + Math.round(Math.random() * 128 + 127) + ')';
		updateNow();
		for (var i = 0; i < l; i++) {
			timeTable[result[i].id] = processSingleCalendar(result[i].calendar);
		}
		calendars = mergeCalendars(timeTable);
		renderUnifiedEvents();
	}
}

const SEVEN_DAYS = 7 * 86400 * 1000;

/**
 * Calendar data will be filtered and sorted.
 * Expired events will be removed, remaining events sorted by start time, up to 7 days in advance.
 *
 * @param {Array} json - The new event data in JSON format to update the calendar.
 */
function processSingleCalendar(json) {
	if (!json || json.constructor !== Array) {
		console.log("Error: Calendar data was empty or malformed.");
		return [];
	}
	if (json.length === 0) {
		console.log("Notice: Calendar already empty from server");
	}
	json = json.filter(function (el) {
		if (!el.title || !el.start || !el.end) return false;
		el.s = new Date(el.start).getTime();
		el.e = new Date(el.end).getTime();
		return !(isNaN(el.s) || isNaN(el.e) || Math.abs(el.s - NOW) > SEVEN_DAYS || Math.abs(el.e) < NOW);
	});
	if (json.length === 0) {
		console.log('Notice: Calendar has no current events');
	}
	json.sort(function (a, b) { return a.s - b.s; });
	for (var i = json.length - 1; i > 0; i--) {
		// if title, start and end are the same, "merge" two events by removing one of them
		if (json[i].title === json[i-1].title && json[i].start === json[i-1].start && json[i].end === json[i-1].end) {
			json.splice(i, 1);
		}
	}
	return json;
}

/**
 * Takes one or more calendars and merges the individual eventsfrom them, sorted ascending
 * by start time. The inputcalendars are assumed to be sorted in ascending order already.
 * If multiple calendars contain an event with matching start/end times and title, it is
 * assumed to be the same event spread across multiple locations, so the event will be
 * merged, and the location names concatenated.
 * @param {Array} calendars - An array of calendars to be merged.
 * @returns {Array} - Returns a new array containing the merged calendars.
 */
function mergeCalendars(calendars) {
	var k, tt, merged = [];
	var nextRefresh = null;
	do {
		var smallest = false;
		for (k in calendars) {
			if (!calendars.hasOwnProperty(k))
				continue;
			tt = calendars[k];
			if (!tt || tt.length === 0 || tt[0].e < NOW)
				continue;
			if (smallest === false || tt[0].s < calendars[smallest][0].s) {
				smallest = k;
			}
		}
		if (smallest) {
			var v = calendars[smallest].shift();
			v.location = locations[smallest] ? locations[smallest].name : '???';
			if (merged.length !== 0) {
				var cur = merged.pop();
				if (cur.s === v.s && cur.e === v.e && cur.title === v.title) {
					v.location += ', ' + cur.location;
				} else {
					merged.push(cur);
				}
			}
			merged.push(v);
		}
	} while (smallest);
	return merged;
}

function pad(number, digits) {
	var s = "00" + number;
	return s.substr(s.length - digits);
}

function formatTime(dateObj) {
	return pad(dateObj.getHours(), 2) + ":" + pad(dateObj.getMinutes(), 2);
}

function makeQrCode() {
	var script = document.createElement('script');
	script.type = 'text/javascript';
	script.src = 'modules/locationinfo/frontend/qrcode.min.js';

	console.log("MakeQR");
	var callback = function() {
		console.log("Script cb");
		var $code = $('<div id="qrcode">');
		$('body').append($code);
		setTimeout(function() {
			new QRCode($code[0], {
				text: window.location.href.replace(/([#&])qrcode=\d+/, '$1').replace(/[&#]+$/, ''),
				width: $code.width() * 4,
				height: $code.height() * 4,
				correctLevel : QRCode.CorrectLevel.L
			});
		}, 1);
	}

	script.onload = function () {
		this.onload = null;
		this.onreadystatechange = null;
		callback();
	};
	script.onreadystatechange = function () {
		if (this.readyState === 'loaded' || this.readyState === 'complete') {
			this.onload = null;
			this.onreadystatechange = null;
			callback();
		}
	};

	document.getElementsByTagName('head')[0].appendChild(script);
}

//

/**
 * Main Update loop, this loop runs every 10 seconds
 */
function mainUpdateLoop() {
	updateNow();
	if (nextCalendarUpdate < NOW) {
		nextCalendarUpdate = NOW + globalConfig.calupdate;
		queryCalendars();
	} else if (nextRender < NOW) {
		renderUnifiedEvents();
	} else {
		queryPanelChange(API, PANEL_UUID, globalConfig);
	}
	var nx = Math.min(nextCalendarUpdate, nextRender) - NOW;
	nx = Math.max(1000, nx);
	nx = Math.min(15000, nx);
	$('#time .date-today').text(t('long' + DATENOW.getDay()) + ', ' + DATENOW.toLocaleDateString(LANGUAGE));
	$('#time .time-today').text(formatTime(DATENOW));
	globalTimer = setTimeout(mainUpdateLoop, nx);
}