var api_base_url_sensors = '/api/1/sensor/type/Wassertemperatur?mode=consolidated&format=c3';
var api_base_url_weather = '/api/1/openweathermap/city/3319578?mode=consolidated&format=c3';

function dayschart(element, title, days, xtickformat) {
	var chartdata;
	if (element.substr(0, 7) == 'chart_w') {
		chartdata = {
				url: api_base_url_sensors + beginend(days),
				mimeType: 'json',
				xs: {
					'0416a1ac66ff': '0416a1ac66ff_x',
					'0516a207a4ff': '0516a207a4ff_x',
					'0416a1bab9ff': '0416a1bab9ff_x'
				},
				names: {
					'0416a1ac66ff': 'Wassertemperatur in 30 cm Tiefe',
					'0516a207a4ff': 'Wassertemperatur in 50 cm Tiefe',
					'0416a1bab9ff': 'Wassertemperatur in 1 m Tiefe'
				},
				xFormat: '%Y-%m-%d %H:%M:%S',
				colors: {
					'0416a1ac66ff': 'lightskyblue',
					'0516a207a4ff': 'royalblue',
					'0416a1bab9ff': 'midnightblue'
				},
				/*
				xSort: false,
				order: function (a, b) {
					// gets 2 x objects. seems to be a "sort function" for js's sort()
					// -1: a before b etc.
					// only handle cases that appear in the wild
					// console.log("a.id", a.id, "b.id", b.id);
					if (a.id == '0416a1ac66ff') {return -1};
					if (a.id == '0416a1bab9ff') {return  1};
				}
				*/
		};
	} else {
		chartdata = {
				url: api_base_url_weather + beginend(days),
				mimeType: 'json',
				xs: {
					'3319578': '3319578_x'
				},
				names: {
					'3319578': 'Lufttemperatur in Obsteig'
				},
				xFormat: '%Y-%m-%d %H:%M:%S',
				colors: {
					'3319578': 'red'
				}
		};
	};
	var chart = c3.generate({
		bindto: '#' + element,
		size: {
			width: document.getElementById(element).parentElement.clientWidth * 80 / 100
		},
		transition: {
			duration: null
		},
		title: {
			text: title
		},
		data: chartdata,
		point: {
			r: 1.5 // default 2.5
		},
		axis: {
			x: {
				type: 'timeseries',
				tick: {
					format: xtickformat,
					fit: false,
					multiline: true, // broken? so →
					rotate: -90
				}
			},
			y: {
				label: {
					text: 'Temperatur in °C',
					position: 'outer-middle'
				},
				tick: {
					format: function (d) {
						return d.toFixed(1) + '°';
					}
				}
			}
		},
		zoom: {
			enabled: true,
			onzoomend: function (domain) {
				// UNIX epoch
				var start = domain[0].getTime()/1000;
				var end   = domain[1].getTime()/1000;
				var duration = end - start;
				// duration is now the diff of the "viewport in seconds"
				// FIXME
				var days = Math.round(duration / 86400 / 2);
				if (days > 0) {
					loaddays(this, element, days); // this = chart
				}
			}
		},
		tooltip: {
			format: {
				// TODO: maybe move to top
				name: function (name, ratio, id, index) {
					var prefix = '';
					if (element.substr(0, 7) == 'chart_w') {
						var re = /\d+ c?m/;
						prefix = 'Wasser ';
					} else {
						var re = /Luft/;
					};
					var result = re.exec(name);
					return prefix + result;
				},
				value: function (value, ratio, id, index) {
					return value.toFixed(2) + '°';
				},
				title: function (x) {
					// TODO: format datetime into something readable
					return x;
				}
			}
		},
		grid: {
			y: {
				show: true
			}
		},
		regions: [
			{axis: 'y', start: -999, end:   0, class: 'region-frozen'},
			{axis: 'y', start:    0, end:  25, class: 'region-ok'},
			{axis: 'y', start:   25, end: 100, class: 'region-warm'},
			{axis: 'y', start:  100, end: 999, class: 'region-boiling'}
		]
	});
};

function loaddays(chart, element, days) {
	// TODO: maybe move to top or factor out somehow
	if (element.substr(0, 7) == 'chart_w') {
		chart.load({
			url: api_base_url_sensors + beginend(days),
			mimeType: 'json'
		});
	} else {
		chart.load({
			url: api_base_url_weather + beginend(days),
			mimeType: 'json'
		});
	}
}

function beginend(days) {
	var now = Date.now();

	// TODO: this timezone calculation relies on the browser being in Europe/Vienna
	var refdate = new Date(now);
	var offset = refdate.getTimezoneOffset(); // -120 for UTC+2

	var end = new Date(now - offset * 60 * 1000).toISOString().substr(0, 19); // 2018-06-13T16:52:30.995Z
	var begin = new Date(now - days * 60*60*24 * 1000 - offset * 60 * 1000).toISOString().substr(0, 19);
	return '&begin=' + begin + '&end=' + end;
}

dayschart('chart_water_1',   'Der See (Tag)',     1, '%H:%M');
dayschart('chart_water_7',   'Der See (Woche)',   7, '%a %d');
dayschart('chart_water_31',  'Der See (Monat)',  31, 'Woche %V');
dayschart('chart_water_365', 'Der See (Jahr)',  365, '%b %Y');

dayschart('chart_air_1',     'Die Luft (Tag)',     1, '%H:%M');
dayschart('chart_air_7',     'Die Luft (Woche)',   7, '%a %d');
dayschart('chart_air_31',    'Die Luft (Monat)',  31, 'Woche %V');
dayschart('chart_air_365',   'Die Luft (Jahr)',  365, '%b %Y');