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

function dayschart(element, title, days, xtickformat) {
	var chart = c3.generate({
		bindto: '#' + element,
		size: {
			width: document.getElementById(element).parentElement.clientWidth * 80 / 100
		},
		transition: {
			duration: null
		},
		title: {
			text: title
		},
		data: {
			url: api_base_url_sensors + beginend(days),
			mimeType: 'json',
			xs: {
				'0316a2193bff': '0316a2193bff_x',
				'0316a21383ff': '0316a21383ff_x'
			},
			names: {
				'0316a2193bff': 'Wassertemperatur in 4 m Tiefe',
				'0316a21383ff': 'Wassertemperatur in 5 m Tiefe'
			},
			xFormat: '%Y-%m-%d %H:%M:%S',
			colors: {
				'0316a2193bff': 'lightblue',
				'0316a21383ff': 'darkblue'
			}
		},
		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(days);
				}
			}
		},
		tooltip: {
			format: {
				name: function (name, ratio, id, index) {
					var re = /\d m/;
					var res = re.exec(name);
					return res;
				},
				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(days) {
	chart.load({
		url: api_base_url_sensors + beginend(days),
		mimeType: 'json'
	});
}

function beginend(days) {
	var now = Date.now();
	var end = new Date(now).toISOString().substr(0, 19); // 2018-06-13T16:52:30.995Z
	var begin = new Date(now - days * 60*60*24 * 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 %d');