/*global global, window*/
/**
 * @author Christian Johansen (christian@cjohansen.no) and contributors
 * @license BSD
 *
 * Copyright (c) 2010-2014 Christian Johansen
 */

(function (global) {
    "use strict";

    // Make properties writable in IE, as per
    // http://www.adequatelygood.com/Replacing-setTimeout-Globally.html
    // JSLint being anal
    var glbl = global;

    global.setTimeout = glbl.setTimeout;
    global.clearTimeout = glbl.clearTimeout;
    global.setInterval = glbl.setInterval;
    global.clearInterval = glbl.clearInterval;
    global.Date = glbl.Date;

    // setImmediate is not a standard function
    // avoid adding the prop to the window object if not present
    if('setImmediate' in global) {
        global.setImmediate = glbl.setImmediate;
        global.clearImmediate = glbl.clearImmediate;
    }

    // node expects setTimeout/setInterval to return a fn object w/ .ref()/.unref()
    // browsers, a number.
    // see https://github.com/cjohansen/Sinon.JS/pull/436

    var NOOP = function () { return undefined; };
    var timeoutResult = setTimeout(NOOP, 0);
    var addTimerReturnsObject = typeof timeoutResult === "object";
    clearTimeout(timeoutResult);

    var NativeDate = Date;
    var uniqueTimerId = 1;

    /**
     * Parse strings like "01:10:00" (meaning 1 hour, 10 minutes, 0 seconds) into
     * number of milliseconds. This is used to support human-readable strings passed
     * to clock.tick()
     */
    function parseTime(str) {
        if (!str) {
            return 0;
        }

        var strings = str.split(":");
        var l = strings.length, i = l;
        var ms = 0, parsed;

        if (l > 3 || !/^(\d\d:){0,2}\d\d?$/.test(str)) {
            throw new Error("tick only understands numbers and 'h:m:s'");
        }

        while (i--) {
            parsed = parseInt(strings[i], 10);

            if (parsed >= 60) {
                throw new Error("Invalid time " + str);
            }

            ms += parsed * Math.pow(60, (l - i - 1));
        }

        return ms * 1000;
    }

    /**
     * Used to grok the `now` parameter to createClock.
     */
    function getEpoch(epoch) {
        if (!epoch) { return 0; }
        if (typeof epoch.getTime === "function") { return epoch.getTime(); }
        if (typeof epoch === "number") { return epoch; }
        throw new TypeError("now should be milliseconds since UNIX epoch");
    }

    function inRange(from, to, timer) {
        return timer && timer.callAt >= from && timer.callAt <= to;
    }

    function mirrorDateProperties(target, source) {
        var prop;
        for (prop in source) {
            if (source.hasOwnProperty(prop)) {
                target[prop] = source[prop];
            }
        }

        // set special now implementation
        if (source.now) {
            target.now = function now() {
                return target.clock.now;
            };
        } else {
            delete target.now;
        }

        // set special toSource implementation
        if (source.toSource) {
            target.toSource = function toSource() {
                return source.toSource();
            };
        } else {
            delete target.toSource;
        }

        // set special toString implementation
        target.toString = function toString() {
            return source.toString();
        };

        target.prototype = source.prototype;
        target.parse = source.parse;
        target.UTC = source.UTC;
        target.prototype.toUTCString = source.prototype.toUTCString;

        return target;
    }

    function createDate() {
        function ClockDate(year, month, date, hour, minute, second, ms) {
            // Defensive and verbose to avoid potential harm in passing
            // explicit undefined when user does not pass argument
            switch (arguments.length) {
            case 0:
                return new NativeDate(ClockDate.clock.now);
            case 1:
                return new NativeDate(year);
            case 2:
                return new NativeDate(year, month);
            case 3:
                return new NativeDate(year, month, date);
            case 4:
                return new NativeDate(year, month, date, hour);
            case 5:
                return new NativeDate(year, month, date, hour, minute);
            case 6:
                return new NativeDate(year, month, date, hour, minute, second);
            default:
                return new NativeDate(year, month, date, hour, minute, second, ms);
            }
        }

        return mirrorDateProperties(ClockDate, NativeDate);
    }

    function addTimer(clock, timer) {
        if (timer.func === undefined) {
            throw new Error("Callback must be provided to timer calls");
        }

        if (!clock.timers) {
            clock.timers = {};
        }

        timer.id = uniqueTimerId++;
        timer.createdAt = clock.now;
        timer.callAt = clock.now + (timer.delay || (clock.duringTick ? 1 : 0));

        clock.timers[timer.id] = timer;

        if (addTimerReturnsObject) {
            return {
                id: timer.id,
                ref: NOOP,
                unref: NOOP
            };
        }

        return timer.id;
    }


    function compareTimers(a, b) {
        // Sort first by absolute timing
        if (a.callAt < b.callAt) {
            return -1;
        }
        if (a.callAt > b.callAt) {
            return 1;
        }

        // Sort next by immediate, immediate timers take precedence
        if (a.immediate && !b.immediate) {
            return -1;
        }
        if (!a.immediate && b.immediate) {
            return 1;
        }

        // Sort next by creation time, earlier-created timers take precedence
        if (a.createdAt < b.createdAt) {
            return -1;
        }
        if (a.createdAt > b.createdAt) {
            return 1;
        }

        // Sort next by id, lower-id timers take precedence
        if (a.id < b.id) {
            return -1;
        }
        if (a.id > b.id) {
            return 1;
        }

        // As timer ids are unique, no fallback `0` is necessary
    }

    function firstTimerInRange(clock, from, to) {
        var timers = clock.timers,
            timer = null,
            id,
            isInRange;

        for (id in timers) {
            if (timers.hasOwnProperty(id)) {
                isInRange = inRange(from, to, timers[id]);

                if (isInRange && (!timer || compareTimers(timer, timers[id]) === 1)) {
                    timer = timers[id];
                }
            }
        }

        return timer;
    }

    function callTimer(clock, timer) {
        var exception;

        if (typeof timer.interval === "number") {
            clock.timers[timer.id].callAt += timer.interval;
        } else {
            delete clock.timers[timer.id];
        }

        try {
            if (typeof timer.func === "function") {
                timer.func.apply(null, timer.args);
            } else {
                eval(timer.func);
            }
        } catch (e) {
            exception = e;
        }

        if (!clock.timers[timer.id]) {
            if (exception) {
                throw exception;
            }
            return;
        }

        if (exception) {
            throw exception;
        }
    }

    function timerType(timer) {
        if (timer.immediate) {
            return "Immediate";
        } else if (typeof timer.interval !== "undefined") {
            return "Interval";
        } else {
            return "Timeout";
        }
    }

    function clearTimer(clock, timerId, ttype) {
        if (!timerId) {
            // null appears to be allowed in most browsers, and appears to be
            // relied upon by some libraries, like Bootstrap carousel
            return;
        }

        if (!clock.timers) {
            clock.timers = [];
        }

        // in Node, timerId is an object with .ref()/.unref(), and
        // its .id field is the actual timer id.
        if (typeof timerId === "object") {
            timerId = timerId.id;
        }

        if (clock.timers.hasOwnProperty(timerId)) {
            // check that the ID matches a timer of the correct type
            var timer = clock.timers[timerId];
            if (timerType(timer) === ttype) {
                delete clock.timers[timerId];
            } else {
				throw new Error("Cannot clear timer: timer created with set" + ttype + "() but cleared with clear" + timerType(timer) + "()");
			}
        }
    }

    function uninstall(clock, target) {
        var method,
            i,
            l;

        for (i = 0, l = clock.methods.length; i < l; i++) {
            method = clock.methods[i];

            if (target[method].hadOwnProperty) {
                target[method] = clock["_" + method];
            } else {
                try {
                    delete target[method];
                } catch (ignore) {}
            }
        }

        // Prevent multiple executions which will completely remove these props
        clock.methods = [];
    }

    function hijackMethod(target, method, clock) {
        var prop;

        clock[method].hadOwnProperty = Object.prototype.hasOwnProperty.call(target, method);
        clock["_" + method] = target[method];

        if (method === "Date") {
            var date = mirrorDateProperties(clock[method], target[method]);
            target[method] = date;
        } else {
            target[method] = function () {
                return clock[method].apply(clock, arguments);
            };

            for (prop in clock[method]) {
                if (clock[method].hasOwnProperty(prop)) {
                    target[method][prop] = clock[method][prop];
                }
            }
        }

        target[method].clock = clock;
    }

    var timers = {
        setTimeout: setTimeout,
        clearTimeout: clearTimeout,
        setImmediate: global.setImmediate,
        clearImmediate: global.clearImmediate,
        setInterval: setInterval,
        clearInterval: clearInterval,
        Date: Date
    };

    var keys = Object.keys || function (obj) {
        var ks = [],
            key;

        for (key in obj) {
            if (obj.hasOwnProperty(key)) {
                ks.push(key);
            }
        }

        return ks;
    };

    exports.timers = timers;

    function createClock(now) {
        var clock = {
            now: getEpoch(now),
            timeouts: {},
            Date: createDate()
        };

        clock.Date.clock = clock;

        clock.setTimeout = function setTimeout(func, timeout) {
            return addTimer(clock, {
                func: func,
                args: Array.prototype.slice.call(arguments, 2),
                delay: timeout
            });
        };

        clock.clearTimeout = function clearTimeout(timerId) {
            return clearTimer(clock, timerId, "Timeout");
        };

        clock.setInterval = function setInterval(func, timeout) {
            return addTimer(clock, {
                func: func,
                args: Array.prototype.slice.call(arguments, 2),
                delay: timeout,
                interval: timeout
            });
        };

        clock.clearInterval = function clearInterval(timerId) {
            return clearTimer(clock, timerId, "Interval");
        };

        clock.setImmediate = function setImmediate(func) {
            return addTimer(clock, {
                func: func,
                args: Array.prototype.slice.call(arguments, 1),
                immediate: true
            });
        };

        clock.clearImmediate = function clearImmediate(timerId) {
            return clearTimer(clock, timerId, "Immediate");
        };

        clock.tick = function tick(ms) {
            ms = typeof ms === "number" ? ms : parseTime(ms);
            var tickFrom = clock.now, tickTo = clock.now + ms, previous = clock.now;
            var timer = firstTimerInRange(clock, tickFrom, tickTo);
            var oldNow;

            clock.duringTick = true;

            var firstException;
            while (timer && tickFrom <= tickTo) {
                if (clock.timers[timer.id]) {
                    tickFrom = clock.now = timer.callAt;
                    try {
                        oldNow = clock.now;
                        callTimer(clock, timer);
                        // compensate for any setSystemTime() call during timer callback
                        if (oldNow !== clock.now) {
                            tickFrom += clock.now - oldNow;
                            tickTo += clock.now - oldNow;
                            previous += clock.now - oldNow;
                        }
                    } catch (e) {
                        firstException = firstException || e;
                    }
                }

                timer = firstTimerInRange(clock, previous, tickTo);
                previous = tickFrom;
            }

            clock.duringTick = false;
            clock.now = tickTo;

            if (firstException) {
                throw firstException;
            }

            return clock.now;
        };

        clock.reset = function reset() {
            clock.timers = {};
        };

        clock.setSystemTime = function setSystemTime(now) {
            // determine time difference
            var newNow = getEpoch(now);
            var difference = newNow - clock.now;

            // update 'system clock'
            clock.now = newNow;

            // update timers and intervals to keep them stable
            for (var id in clock.timers) {
                if (clock.timers.hasOwnProperty(id)) {
                    var timer = clock.timers[id];
                    timer.createdAt += difference;
                    timer.callAt += difference;
                }
            }
        };

        return clock;
    }
    exports.createClock = createClock;

    exports.install = function install(target, now, toFake) {
        var i,
            l;

        if (typeof target === "number") {
            toFake = now;
            now = target;
            target = null;
        }

        if (!target) {
            target = global;
        }

        var clock = createClock(now);

        clock.uninstall = function () {
            uninstall(clock, target);
        };

        clock.methods = toFake || [];

        if (clock.methods.length === 0) {
            clock.methods = keys(timers);
        }

        for (i = 0, l = clock.methods.length; i < l; i++) {
            hijackMethod(target, clock.methods[i], clock);
        }

        return clock;
    };

}(global || this));