/*
Pretty handling of time axes.

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) {
        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 'm': c = leftPad(d.getMonth() + 1); break;
                case 'M': c = leftPad(d.getMinutes()); 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 'u': c = "" + (d.getDay() + 1); 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
        };
        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,
        "year": 365.2425 * 24 * 60 * 60 * 1000
    };

    // the allowed tick sizes, after 1 year we use
    // an integer algorithm
    var spec = [
        [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"], [3, "month"], [6, "month"],
        [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 = [],
                            d = dateGenerator(axis.min, opts),
                            minSize = 0;

                        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));
                        if (unit == "minute")
                            d.setMinutes(floorInBase(d.getMinutes(), tickSize));
                        if (unit == "hour")
                            d.setHours(floorInBase(d.getHours(), tickSize));
                        if (unit == "month")
                            d.setMonth(floorInBase(d.getMonth(), tickSize));
                        if (unit == "year")
                            d.setFullYear(floorInBase(d.getFullYear(), tickSize));
                        
                        // reset smaller components
                        d.setMilliseconds(0);
                        if (step >= timeUnitSize.minute)
                            d.setSeconds(0);
                        if (step >= timeUnitSize.hour)
                            d.setMinutes(0);
                        if (step >= timeUnitSize.day)
                            d.setHours(0);
                        if (step >= timeUnitSize.day * 4)
                            d.setDate(1);
                        if (step >= timeUnitSize.year)
                            d.setMonth(0);


                        var carry = 0, v = Number.NaN, prev;
                        do {
                            prev = v;
                            v = d.getTime();
                            ticks.push(v);
                            if (unit == "month") {
                                if (tickSize < 1) {
                                    // a bit complicated - we'll divide the month
                                    // 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() + 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);
                            }
                            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);
                        
                        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";
                        
                        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 (t < timeUnitSize.year) {
                            if (span < timeUnitSize.year)
                                fmt = "%b";
                            else
                                fmt = "%b %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'
    });
})(jQuery);