/* Pretty handling of time axes.

Copyright (c) 2007-2012 IOLA and Ole Laursen.
Licensed under the MIT license.

Set axis.mode to "time" to enable. See the section "Time series data" in
API.txt for details.

*/

(function($) {

	var options = {};

	// round to nearby lower multiple of base

	function floorInBase(n, base) {
		return base * Math.floor(n / base);
	}

	// Returns a string with the date d formatted according to fmt.
	// A subset of the Open Group's strftime format is supported.

	function formatDate(d, fmt, monthNames, dayNames) {

		if (typeof d.strftime == "function") {
			return d.strftime(fmt);
		}

		var leftPad = function(n, pad) {
			n = "" + n;
			pad = "" + (pad == null ? "0" : pad);
			return n.length == 1 ? pad + n : n;
		};

		var r = [];
		var escape = false;
		var hours = d.getHours();
		var isAM = hours < 12;

		if (monthNames == null) {
			monthNames = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];
		}

		if (dayNames == null) {
			dayNames = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
		}

		var hours12;

		if (hours > 12) {
			hours12 = hours - 12;
		} else if (hours == 0) {
			hours12 = 12;
		} else {
			hours12 = hours;
		}

		for (var i = 0; i < fmt.length; ++i) {

			var c = fmt.charAt(i);

			if (escape) {
				switch (c) {
					case 'a': c = "" + dayNames[d.getDay()]; break;
					case 'b': c = "" + monthNames[d.getMonth()]; break;
					case 'd': c = leftPad(d.getDate()); break;
					case 'e': c = leftPad(d.getDate(), " "); break;
					case 'H': c = leftPad(hours); break;
					case 'I': c = leftPad(hours12); break;
					case 'l': c = leftPad(hours12, " "); break;
					case 'm': c = leftPad(d.getMonth() + 1); break;
					case 'M': c = leftPad(d.getMinutes()); break;
					// quarters not in Open Group's strftime specification
					case 'q':
						c = "" + (Math.floor(d.getMonth() / 3) + 1); break;
					case 'S': c = leftPad(d.getSeconds()); break;
					case 'y': c = leftPad(d.getFullYear() % 100); break;
					case 'Y': c = "" + d.getFullYear(); break;
					case 'p': c = (isAM) ? ("" + "am") : ("" + "pm"); break;
					case 'P': c = (isAM) ? ("" + "AM") : ("" + "PM"); break;
					case 'w': c = "" + d.getDay(); break;
				}
				r.push(c);
				escape = false;
			} else {
				if (c == "%") {
					escape = true;
				} else {
					r.push(c);
				}
			}
		}

		return r.join("");
	}

	// To have a consistent view of time-based data independent of which time
	// zone the client happens to be in we need a date-like object independent
	// of time zones.  This is done through a wrapper that only calls the UTC
	// versions of the accessor methods.

	function makeUtcWrapper(d) {

		function addProxyMethod(sourceObj, sourceMethod, targetObj, targetMethod) {
			sourceObj[sourceMethod] = function() {
				return targetObj[targetMethod].apply(targetObj, arguments);
			};
		};

		var utc = {
			date: d
		};

		// support strftime, if found

		if (d.strftime != undefined) {
			addProxyMethod(utc, "strftime", d, "strftime");
		}

		addProxyMethod(utc, "getTime", d, "getTime");
		addProxyMethod(utc, "setTime", d, "setTime");

		var props = ["Date", "Day", "FullYear", "Hours", "Milliseconds", "Minutes", "Month", "Seconds"];

		for (var p = 0; p < props.length; p++) {
			addProxyMethod(utc, "get" + props[p], d, "getUTC" + props[p]);
			addProxyMethod(utc, "set" + props[p], d, "setUTC" + props[p]);
		}

		return utc;
	};

	// select time zone strategy.  This returns a date-like object tied to the
	// desired timezone

	function dateGenerator(ts, opts) {
		if (opts.timezone == "browser") {
			return new Date(ts);
		} else if (!opts.timezone || opts.timezone == "utc") {
			return makeUtcWrapper(new Date(ts));
		} else if (typeof timezoneJS != "undefined" && typeof timezoneJS.Date != "undefined") {
			var d = new timezoneJS.Date();
			// timezone-js is fickle, so be sure to set the time zone before
			// setting the time.
			d.setTimezone(opts.timezone);
			d.setTime(ts);
			return d;
		} else {
			return makeUtcWrapper(new Date(ts));
		}
	}
	
	// map of app. size of time units in milliseconds

	var timeUnitSize = {
		"second": 1000,
		"minute": 60 * 1000,
		"hour": 60 * 60 * 1000,
		"day": 24 * 60 * 60 * 1000,
		"month": 30 * 24 * 60 * 60 * 1000,
		"quarter": 3 * 30 * 24 * 60 * 60 * 1000,
		"year": 365.2425 * 24 * 60 * 60 * 1000
	};

	// the allowed tick sizes, after 1 year we use
	// an integer algorithm

	var baseSpec = [
		[1, "second"], [2, "second"], [5, "second"], [10, "second"],
		[30, "second"], 
		[1, "minute"], [2, "minute"], [5, "minute"], [10, "minute"],
		[30, "minute"], 
		[1, "hour"], [2, "hour"], [4, "hour"],
		[8, "hour"], [12, "hour"],
		[1, "day"], [2, "day"], [3, "day"],
		[0.25, "month"], [0.5, "month"], [1, "month"],
		[2, "month"]
	];

	// we don't know which variant(s) we'll need yet, but generating both is
	// cheap

	var specMonths = baseSpec.concat([[3, "month"], [6, "month"],
		[1, "year"]]);
	var specQuarters = baseSpec.concat([[1, "quarter"], [2, "quarter"],
		[1, "year"]]);

	function init(plot) {
		plot.hooks.processDatapoints.push(function (plot, series, datapoints) {
			$.each(plot.getAxes(), function(axisName, axis) {

				var opts = axis.options;

				if (opts.mode == "time") {
					axis.tickGenerator = function(axis) {

						var ticks = [];
						var d = dateGenerator(axis.min, opts);
						var minSize = 0;

						// make quarter use a possibility if quarters are
						// mentioned in either of these options

						var spec = (opts.tickSize && opts.tickSize[1] ===
							"quarter") ||
							(opts.minTickSize && opts.minTickSize[1] ===
							"quarter") ? specQuarters : specMonths;

						if (opts.minTickSize != null) {
							if (typeof opts.tickSize == "number") {
								minSize = opts.tickSize;
							} else {
								minSize = opts.minTickSize[0] * timeUnitSize[opts.minTickSize[1]];
							}
						}

						for (var i = 0; i < spec.length - 1; ++i) {
							if (axis.delta < (spec[i][0] * timeUnitSize[spec[i][1]]
											  + spec[i + 1][0] * timeUnitSize[spec[i + 1][1]]) / 2
								&& spec[i][0] * timeUnitSize[spec[i][1]] >= minSize) {
								break;
							}
						}

						var size = spec[i][0];
						var unit = spec[i][1];

						// special-case the possibility of several years

						if (unit == "year") {

							// if given a minTickSize in years, just use it,
							// ensuring that it's an integer

							if (opts.minTickSize != null && opts.minTickSize[1] == "year") {
								size = Math.floor(opts.minTickSize[0]);
							} else {

								var magn = Math.pow(10, Math.floor(Math.log(axis.delta / timeUnitSize.year) / Math.LN10));
								var norm = (axis.delta / timeUnitSize.year) / magn;

								if (norm < 1.5) {
									size = 1;
								} else if (norm < 3) {
									size = 2;
								} else if (norm < 7.5) {
									size = 5;
								} else {
									size = 10;
								}

								size *= magn;
							}

							// minimum size for years is 1

							if (size < 1) {
								size = 1;
							}
						}

						axis.tickSize = opts.tickSize || [size, unit];
						var tickSize = axis.tickSize[0];
						unit = axis.tickSize[1];

						var step = tickSize * timeUnitSize[unit];

						if (unit == "second") {
							d.setSeconds(floorInBase(d.getSeconds(), tickSize));
						} else if (unit == "minute") {
							d.setMinutes(floorInBase(d.getMinutes(), tickSize));
						} else if (unit == "hour") {
							d.setHours(floorInBase(d.getHours(), tickSize));
						} else if (unit == "month") {
							d.setMonth(floorInBase(d.getMonth(), tickSize));
						} else if (unit == "quarter") {
							d.setMonth(3 * floorInBase(d.getMonth() / 3,
								tickSize));
						} else if (unit == "year") {
							d.setFullYear(floorInBase(d.getFullYear(), tickSize));
						}

						// reset smaller components

						d.setMilliseconds(0);

						if (step >= timeUnitSize.minute) {
							d.setSeconds(0);
						} else if (step >= timeUnitSize.hour) {
							d.setMinutes(0);
						} else if (step >= timeUnitSize.day) {
							d.setHours(0);
						} else if (step >= timeUnitSize.day * 4) {
							d.setDate(1);
						} else if (step >= timeUnitSize.month * 2) {
							d.setMonth(floorInBase(d.getMonth(), 3));
						} else if (step >= timeUnitSize.quarter * 2) {
							d.setMonth(floorInBase(d.getMonth(), 6));
						} else if (step >= timeUnitSize.year) {
							d.setMonth(0);
						}

						var carry = 0;
						var v = Number.NaN;
						var prev;

						do {

							prev = v;
							v = d.getTime();
							ticks.push(v);

							if (unit == "month" || unit == "quarter") {
								if (tickSize < 1) {

									// a bit complicated - we'll divide the
									// month/quarter up but we need to take
									// care of fractions so we don't end up in
									// the middle of a day

									d.setDate(1);
									var start = d.getTime();
									d.setMonth(d.getMonth() +
										(unit == "quarter" ? 3 : 1));
									var end = d.getTime();
									d.setTime(v + carry * timeUnitSize.hour + (end - start) * tickSize);
									carry = d.getHours();
									d.setHours(0);
								} else {
									d.setMonth(d.getMonth() +
										tickSize * (unit == "quarter" ? 3 : 1));
								}
							} else if (unit == "year") {
								d.setFullYear(d.getFullYear() + tickSize);
							} else {
								d.setTime(v + step);
							}
						} while (v < axis.max && v != prev);

						return ticks;
					};

					axis.tickFormatter = function (v, axis) {

						var d = dateGenerator(v, axis.options);

						// first check global format

						if (opts.timeformat != null) {
							return formatDate(d, opts.timeformat, opts.monthNames, opts.dayNames);
						}

						// possibly use quarters if quarters are mentioned in
						// any of these places

						var useQuarters = (axis.options.tickSize &&
								axis.options.tickSize[1] == "quarter") ||
							(axis.options.minTickSize &&
								axis.options.minTickSize[1] == "quarter");

						var t = axis.tickSize[0] * timeUnitSize[axis.tickSize[1]];
						var span = axis.max - axis.min;
						var suffix = (opts.twelveHourClock) ? " %p" : "";
						var hourCode = (opts.twelveHourClock) ? "%I" : "%H";
						var fmt;

						if (t < timeUnitSize.minute) {
							fmt = hourCode + ":%M:%S" + suffix;
						} else if (t < timeUnitSize.day) {
							if (span < 2 * timeUnitSize.day) {
								fmt = hourCode + ":%M" + suffix;
							} else {
								fmt = "%b %d " + hourCode + ":%M" + suffix;
							}
						} else if (t < timeUnitSize.month) {
							fmt = "%b %d";
						} else if ((useQuarters && t < timeUnitSize.quarter) ||
							(!useQuarters && t < timeUnitSize.year)) {
							if (span < timeUnitSize.year) {
								fmt = "%b";
							} else {
								fmt = "%b %Y";
							}
						} else if (useQuarters && t < timeUnitSize.year) {
							if (span < timeUnitSize.year) {
								fmt = "Q%q";
							} else {
								fmt = "Q%q %Y";
							}
						} else {
							fmt = "%Y";
						}

						var rt = formatDate(d, fmt, opts.monthNames, opts.dayNames);

						return rt;
					};
				}
			});
		});
	}

	$.plot.plugins.push({
		init: init,
		options: options,
		name: 'time',
		version: '1.0'
	});

	// Time-axis support used to be in Flot core, which exposed the
	// formatDate function on the plot object.  Various plugins depend
	// on the function, so we need to re-expose it here.

	$.plot.formatDate = formatDate;

})(jQuery);
