(function(win, doc) {

    'use strict';

    // Our export
    var Namespace = 'Snap';

    // Our main toolbelt
    var utils = {

        /**
         * Deeply extends two objects
         * @param  {Object} destination The destination object
         * @param  {Object} source      The custom options to extend destination by
         * @return {Object}             The desination object
         */
        extend: function(destination, source) {
            var property;
            for (property in source) {
                if (source[property] && source[property].constructor && source[property].constructor === Object) {
                    destination[property] = destination[property] || {};
                    utils.extend(destination[property], source[property]);
                } else {
                    destination[property] = source[property];
                }
            }
            return destination;
        }
    };

    /**
     * Our Snap global that initializes our instance
     * @param {Object} opts The custom Snap.js options
     */
    var Core = function( opts ) {

        var self = this;

        /**
         * Our default settings for a Snap instance
         * @type {Object}
         */
        var settings = self.settings = {
            element: null,
            dragger: null,
            disable: 'none',
            addBodyClasses: true,
            hyperextensible: true,
            resistance: 0.5,
            flickThreshold: 50,
            transitionSpeed: 0.3,
            easing: 'ease',
            maxPosition: 266,
            minPosition: -266,
            tapToClose: true,
            touchToDrag: true,
            clickToDrag: true,
            slideIntent: 40, // degrees
            minDragDistance: 5
        };

        /**
         * Stores internally global data
         * @type {Object}
         */
        var cache = self.cache = {
            isDragging: false,
            simpleStates: {
                opening: null,
                towards: null,
                hyperExtending: null,
                halfway: null,
                flick: null,
                translation: {
                    absolute: 0,
                    relative: 0,
                    sinceDirectionChange: 0,
                    percentage: 0
                }
            }
        };

        var eventList = self.eventList = {};

        utils.extend(utils, {

            /**
             * Determines if we are interacting with a touch device
             * @type {Boolean}
             */
            hasTouch: ('ontouchstart' in doc.documentElement || win.navigator.msPointerEnabled),

            /**
             * Returns the appropriate event type based on whether we are a touch device or not
             * @param  {String} action The "action" event you're looking for: up, down, move, out
             * @return {String}        The browsers supported event name
             */
            eventType: function(action) {
                var eventTypes = {
                    down: (utils.hasTouch ? 'touchstart' : settings.clickToDrag ? 'mousedown' : ''),
                    move: (utils.hasTouch ? 'touchmove' : settings.clickToDrag ? 'mousemove' : ''),
                    up: (utils.hasTouch ? 'touchend' : settings.clickToDrag ? 'mouseup': ''),
                    out: (utils.hasTouch ? 'touchcancel' : settings.clickToDrag ? 'mouseout' : '')
                };
                return eventTypes[action];
            },

            /**
             * Returns the correct "cursor" position on both browser and mobile
             * @param  {String} t The coordinate to retrieve, either "X" or "Y"
             * @param  {Object} e The event object being triggered
             * @return {Number}   The desired coordiante for the events interaction
             */
            page: function(t, e){
                return (utils.hasTouch && e.touches.length && e.touches[0]) ? e.touches[0]['page'+t] : e['page'+t];
            },


            klass: {

                /**
                 * Checks if an element has a class name
                 * @param  {Object}  el   The element to check
                 * @param  {String}  name The class name to search for
                 * @return {Boolean}      Returns true if the class exists
                 */
                has: function(el, name){
                    return (el.className).indexOf(name) !== -1;
                },

                /**
                 * Adds a class name to an element
                 * @param  {Object}  el   The element to add to
                 * @param  {String}  name The class name to add
                 */
                add: function(el, name){
                    if(!utils.klass.has(el, name) && settings.addBodyClasses){
                        el.className += " "+name;
                    }
                },

                /**
                 * Removes a class name
                 * @param  {Object} el   The element to remove from
                 * @param  {String} name The class name to remove
                 */
                remove: function(el, name){
                    if(utils.klass.has(el, name) && settings.addBodyClasses){
                        el.className = (el.className).replace(name, "").replace(/^\s+|\s+$/g, '');
                    }
                }
            },

            /**
             * Dispatch a custom Snap.js event
             * @param  {String} type The event name
             */
            dispatchEvent: function(type) {
                if( typeof eventList[type] === 'function') {
                    return eventList[type].apply();
                }
            },

            /**
             * Determines the browsers vendor prefix for CSS3
             * @return {String} The browsers vendor prefix
             */
            vendor: function(){
                var tmp = doc.createElement("div"),
                    prefixes = 'webkit Moz O ms'.split(' '),
                    i;
                for (i in prefixes) {
                    if (typeof tmp.style[prefixes[i] + 'Transition'] !== 'undefined') {
                        return prefixes[i];
                    }
                }
            },

            /**
             * Determines the browsers vendor prefix for transition callback events
             * @return {String} The event name
             */
            transitionCallback: function(){
                return (cache.vendor==='Moz' || cache.vendor==='ms') ? 'transitionend' : cache.vendor+'TransitionEnd';
            },

            /**
             * Determines if the users browser supports CSS3 transformations
             * @return {[type]} [description]
             */
            canTransform: function(){
                return typeof settings.element.style[cache.vendor+'Transform'] !== 'undefined';
            },

            /**
             * Determines an angle between two points
             * @param  {Number} x The X coordinate
             * @param  {Number} y The Y coordinate
             * @return {Number}   The number of degrees between the two points
             */
            angleOfDrag: function(x, y) {
                var degrees, theta;
                // Calc Theta
                theta = Math.atan2(-(cache.startDragY - y), (cache.startDragX - x));
                if (theta < 0) {
                    theta += 2 * Math.PI;
                }
                // Calc Degrees
                degrees = Math.floor(theta * (180 / Math.PI) - 180);
                if (degrees < 0 && degrees > -180) {
                    degrees = 360 - Math.abs(degrees);
                }
                return Math.abs(degrees);
            },


            events: {

                /**
                 * Adds an event to an element
                 * @param {Object} element   Element to add event to
                 * @param {String} eventName The event name
                 * @param {Function} func      Callback function
                 */
                addEvent: function addEvent(element, eventName, func) {
                    if (element.addEventListener) {
                        return element.addEventListener(eventName, func, false);
                    } else if (element.attachEvent) {
                        return element.attachEvent("on" + eventName, func);
                    }
                },

                /**
                 * Removes an event to an element
                 * @param {Object} element   Element to remove event from
                 * @param {String} eventName The event name
                 * @param {Function} func      Callback function
                 */
                removeEvent: function addEvent(element, eventName, func) {
                    if (element.addEventListener) {
                        return element.removeEventListener(eventName, func, false);
                    } else if (element.attachEvent) {
                        return element.detachEvent("on" + eventName, func);
                    }
                },

                /**
                 * Prevents the default event
                 * @param  {Object} e The event object
                 */
                prevent: function(e) {
                    if (e.preventDefault) {
                        e.preventDefault();
                    } else {
                        e.returnValue = false;
                    }
                }
            },

            /**
             * Searches the parent element until a specified attribute has been matched
             * @param  {Object} el   The element to search from
             * @param  {String} attr The attribute to search for
             * @return {Object|null}      Returns a matched element if it exists, else, null
             */
            parentUntil: function(el, attr) {
                var isStr = typeof attr === 'string';
                while (el.parentNode) {
                    if (isStr && el.getAttribute && el.getAttribute(attr)){
                        return el;
                    } else if(!isStr && el === attr){
                        return el;
                    }
                    el = el.parentNode;
                }
                return null;
            }
        });


        var action = self.action = {

            /**
             * Handles translating the elements position
             * @type {Object}
             */
            translate: {
                get: {

                    /**
                     * Returns the amount an element is translated
                     * @param  {Number} index The index desired from the CSS3 values of translate3d
                     * @return {Number}       The amount of pixels an element is translated
                     */
                    matrix: function(index) {

                        if( !cache.canTransform ){
                            return parseInt(settings.element.style.left, 10);
                        } else {
                            var matrix = win.getComputedStyle(settings.element)[cache.vendor+'Transform'].match(/\((.*)\)/),
                                ieOffset = 8;
                            if (matrix) {
                                matrix = matrix[1].split(',');

                                // Internet Explorer likes to give us 16 fucking values
                                if(matrix.length===16){
                                    index+=ieOffset;
                                }
                                return parseInt(matrix[index], 10);
                            }
                            return 0;
                        }
                    }
                },

                /**
                 * Called when the element has finished transitioning
                 */
                easeCallback: function(fn){
                    settings.element.style[cache.vendor+'Transition'] = '';
                    cache.translation = action.translate.get.matrix(4);
                    cache.easing = false;

                    if(cache.easingTo===0){
                        utils.klass.remove(doc.body, 'snapjs-right');
                        utils.klass.remove(doc.body, 'snapjs-left');
                    }

                    if( cache.once ){
                        cache.once.call(self, self.state());
                        delete cache.once;
                    }

                    utils.dispatchEvent('animated');
                    utils.events.removeEvent(settings.element, utils.transitionCallback(), action.translate.easeCallback);

                },

                /**
                 * Animates the pane by the specified amount of pixels
                 * @param  {Number} n The amount of pixels to move the pane
                 */
                easeTo: function(n, cb) {

                    if( !cache.canTransform ){
                        cache.translation = n;
                        action.translate.x(n);
                    } else {
                        cache.easing = true;
                        cache.easingTo = n;

                        settings.element.style[cache.vendor+'Transition'] = 'all ' + settings.transitionSpeed + 's ' + settings.easing;

                        cache.once = cb;

                        utils.events.addEvent(settings.element, utils.transitionCallback(), action.translate.easeCallback);
                        action.translate.x(n);
                    }
                    if(n===0){
                        settings.element.style[cache.vendor+'Transform'] = '';
                    }
                },

                /**
                 * Immediately translates the element on its X axis
                 * @param  {Number} n Amount of pixels to translate
                 */
                x: function(n) {
                    if( (settings.disable==='left' && n>0) ||
                        (settings.disable==='right' && n<0)
                    ){ return; }

                    if( !settings.hyperextensible ){
                        if( n===settings.maxPosition || n>settings.maxPosition ){
                            n=settings.maxPosition;
                        } else if( n===settings.minPosition || n<settings.minPosition ){
                            n=settings.minPosition;
                        }
                    }

                    n = parseInt(n, 10);
                    if(isNaN(n)){
                        n = 0;
                    }

                    if( cache.canTransform ){
                        var theTranslate = 'translate3d(' + n + 'px, 0,0)';
                        settings.element.style[cache.vendor+'Transform'] = theTranslate;
                    } else {
                        settings.element.style.width = (win.innerWidth || doc.documentElement.clientWidth)+'px';

                        settings.element.style.left = n+'px';
                        settings.element.style.right = '';
                    }
                }
            },

            /**
             * Handles all the events that interface with dragging
             * @type {Object}
             */
            drag: {

                /**
                 * Begins listening for drag events on our element
                 */
                listen: function() {
                    cache.translation = 0;
                    cache.easing = false;
                    utils.events.addEvent(self.settings.element, utils.eventType('down'), action.drag.startDrag);
                    utils.events.addEvent(self.settings.element, utils.eventType('move'), action.drag.dragging);
                    utils.events.addEvent(self.settings.element, utils.eventType('up'), action.drag.endDrag);
                },

                /**
                 * Stops listening for drag events on our element
                 */
                stopListening: function() {
                    utils.events.removeEvent(settings.element, utils.eventType('down'), action.drag.startDrag);
                    utils.events.removeEvent(settings.element, utils.eventType('move'), action.drag.dragging);
                    utils.events.removeEvent(settings.element, utils.eventType('up'), action.drag.endDrag);
                },

                /**
                 * Fired immediately when the user begins to drag the content pane
                 * @param  {Object} e Event object
                 */
                startDrag: function(e) {
                    // No drag on ignored elements
                    var target = e.target ? e.target : e.srcElement,
                        ignoreParent = utils.parentUntil(target, 'data-snap-ignore');

                    if (ignoreParent) {
                        utils.dispatchEvent('ignore');
                        return;
                    }


                    if(settings.dragger){
                        var dragParent = utils.parentUntil(target, settings.dragger);

                        // Only use dragger if we're in a closed state
                        if( !dragParent &&
                            (cache.translation !== settings.minPosition &&
                            cache.translation !== settings.maxPosition
                        )){
                            return;
                        }
                    }

                    utils.dispatchEvent('start');
                    settings.element.style[cache.vendor+'Transition'] = '';
                    cache.isDragging = true;

                    cache.intentChecked = false;
                    cache.startDragX = utils.page('X', e);
                    cache.startDragY = utils.page('Y', e);
                    cache.dragWatchers = {
                        current: 0,
                        last: 0,
                        hold: 0,
                        state: ''
                    };
                    cache.simpleStates = {
                        opening: null,
                        towards: null,
                        hyperExtending: null,
                        halfway: null,
                        flick: null,
                        translation: {
                            absolute: 0,
                            relative: 0,
                            sinceDirectionChange: 0,
                            percentage: 0
                        }
                    };
                },

                /**
                 * Fired while the user is moving the content pane
                 * @param  {Object} e Event object
                 */
                dragging: function(e) {

                    if (cache.isDragging && settings.touchToDrag) {

                        var thePageX = utils.page('X', e),
                            thePageY = utils.page('Y', e),
                            translated = cache.translation,
                            absoluteTranslation = action.translate.get.matrix(4),
                            whileDragX = thePageX - cache.startDragX,
                            openingLeft = absoluteTranslation > 0,
                            translateTo = whileDragX,
                            diff;

                        // Shown no intent already
                        if((cache.intentChecked && !cache.hasIntent)){
                            return;
                        }

                        if(settings.addBodyClasses){
                            if((absoluteTranslation)>0){
                                utils.klass.add(doc.body, 'snapjs-left');
                                utils.klass.remove(doc.body, 'snapjs-right');
                            } else if((absoluteTranslation)<0){
                                utils.klass.add(doc.body, 'snapjs-right');
                                utils.klass.remove(doc.body, 'snapjs-left');
                            }
                        }

                        if (cache.hasIntent === false || cache.hasIntent === null) {

                            var deg = utils.angleOfDrag(thePageX, thePageY),
                                inRightRange = (deg >= 0 && deg <= settings.slideIntent) || (deg <= 360 && deg > (360 - settings.slideIntent)),
                                inLeftRange = (deg >= 180 && deg <= (180 + settings.slideIntent)) || (deg <= 180 && deg >= (180 - settings.slideIntent));
                            if (!inLeftRange && !inRightRange) {
                                cache.hasIntent = false;
                            } else {
                                cache.hasIntent = true;
                            }
                            cache.intentChecked = true;
                        }

                        if (
                            (settings.minDragDistance>=Math.abs(thePageX-cache.startDragX)) || // Has user met minimum drag distance?
                            (cache.hasIntent === false)
                        ) {
                            return;
                        }

                        utils.events.prevent(e);
                        utils.dispatchEvent('drag');

                        cache.dragWatchers.current = thePageX;

                        // Determine which direction we are going
                        if (cache.dragWatchers.last > thePageX) {
                            if (cache.dragWatchers.state !== 'left') {
                                cache.dragWatchers.state = 'left';
                                cache.dragWatchers.hold = thePageX;
                            }
                            cache.dragWatchers.last = thePageX;
                        } else if (cache.dragWatchers.last < thePageX) {
                            if (cache.dragWatchers.state !== 'right') {
                                cache.dragWatchers.state = 'right';
                                cache.dragWatchers.hold = thePageX;
                            }
                            cache.dragWatchers.last = thePageX;
                        }
                        if (openingLeft) {
                            // Pulling too far to the right
                            if (settings.maxPosition < absoluteTranslation) {
                                diff = (absoluteTranslation - settings.maxPosition) * settings.resistance;
                                translateTo = whileDragX - diff;
                            }
                            cache.simpleStates = {
                                opening: 'left',
                                towards: cache.dragWatchers.state,
                                hyperExtending: settings.maxPosition < absoluteTranslation,
                                halfway: absoluteTranslation > (settings.maxPosition / 2),
                                flick: Math.abs(cache.dragWatchers.current - cache.dragWatchers.hold) > settings.flickThreshold,
                                translation: {
                                    absolute: absoluteTranslation,
                                    relative: whileDragX,
                                    sinceDirectionChange: (cache.dragWatchers.current - cache.dragWatchers.hold),
                                    percentage: (absoluteTranslation/settings.maxPosition)*100
                                }
                            };
                        } else {
                            // Pulling too far to the left
                            if (settings.minPosition > absoluteTranslation) {
                                diff = (absoluteTranslation - settings.minPosition) * settings.resistance;
                                translateTo = whileDragX - diff;
                            }
                            cache.simpleStates = {
                                opening: 'right',
                                towards: cache.dragWatchers.state,
                                hyperExtending: settings.minPosition > absoluteTranslation,
                                halfway: absoluteTranslation < (settings.minPosition / 2),
                                flick: Math.abs(cache.dragWatchers.current - cache.dragWatchers.hold) > settings.flickThreshold,
                                translation: {
                                    absolute: absoluteTranslation,
                                    relative: whileDragX,
                                    sinceDirectionChange: (cache.dragWatchers.current - cache.dragWatchers.hold),
                                    percentage: (absoluteTranslation/settings.minPosition)*100
                                }
                            };
                        }
                        action.translate.x(translateTo + translated);
                    }
                },

                /**
                 * Fired when the user releases the content pane
                 * @param  {Object} e Event object
                 */
                endDrag: function(e) {
                    if (cache.isDragging) {
                        utils.dispatchEvent('end');
                        var translated = action.translate.get.matrix(4);

                        // Tap Close
                        if (cache.dragWatchers.current === 0 && translated !== 0 && settings.tapToClose) {
                            utils.dispatchEvent('close');
                            utils.events.prevent(e);
                            action.translate.easeTo(0);
                            cache.isDragging = false;
                            cache.startDragX = 0;
                            return;
                        }

                        // Revealing Left
                        if (cache.simpleStates.opening === 'left') {
                            // Halfway, Flicking, or Too Far Out
                            if ((cache.simpleStates.halfway || cache.simpleStates.hyperExtending || cache.simpleStates.flick)) {
                                if (cache.simpleStates.flick && cache.simpleStates.towards === 'left') { // Flicking Closed
                                    action.translate.easeTo(0);
                                } else if (
                                    (cache.simpleStates.flick && cache.simpleStates.towards === 'right') || // Flicking Open OR
                                    (cache.simpleStates.halfway || cache.simpleStates.hyperExtending) // At least halfway open OR hyperextending
                                ) {
                                    action.translate.easeTo(settings.maxPosition); // Open Left
                                }
                            } else {
                                action.translate.easeTo(0); // Close Left
                            }
                            // Revealing Right
                        } else if (cache.simpleStates.opening === 'right') {
                            // Halfway, Flicking, or Too Far Out
                            if ((cache.simpleStates.halfway || cache.simpleStates.hyperExtending || cache.simpleStates.flick)) {
                                if (cache.simpleStates.flick && cache.simpleStates.towards === 'right') { // Flicking Closed
                                    action.translate.easeTo(0);
                                } else if (
                                    (cache.simpleStates.flick && cache.simpleStates.towards === 'left') || // Flicking Open OR
                                    (cache.simpleStates.halfway || cache.simpleStates.hyperExtending) // At least halfway open OR hyperextending
                                ) {
                                    action.translate.easeTo(settings.minPosition); // Open Right
                                }
                            } else {
                                action.translate.easeTo(0); // Close Right
                            }
                        }
                        cache.isDragging = false;
                        cache.startDragX = utils.page('X', e);
                    }
                }
            }
        };


        // Initialize
        if (opts.element) {
            utils.extend(settings, opts);
            cache.vendor = utils.vendor();
            cache.canTransform = utils.canTransform();
            action.drag.listen();
        }
    };


    utils.extend(Core.prototype, {

        /**
         * Opens the specified side menu
         * @param  {String} side Must be "left" or "right"
         */
        open: function(side, cb) {
            utils.dispatchEvent('open');
            utils.klass.remove(doc.body, 'snapjs-expand-left');
            utils.klass.remove(doc.body, 'snapjs-expand-right');

            if (side === 'left') {
                this.cache.simpleStates.opening = 'left';
                this.cache.simpleStates.towards = 'right';
                utils.klass.add(doc.body, 'snapjs-left');
                utils.klass.remove(doc.body, 'snapjs-right');
                this.action.translate.easeTo(this.settings.maxPosition, cb);
            } else if (side === 'right') {
                this.cache.simpleStates.opening = 'right';
                this.cache.simpleStates.towards = 'left';
                utils.klass.remove(doc.body, 'snapjs-left');
                utils.klass.add(doc.body, 'snapjs-right');
                this.action.translate.easeTo(this.settings.minPosition, cb);
            }
        },

        /**
         * Closes the pane
         */
        close: function(cb) {
            utils.dispatchEvent('close');
            this.action.translate.easeTo(0, cb);
        },

        /**
         * Hides the content pane completely allowing for full menu visibility
         * @param  {String} side Must be "left" or "right"
         */
        expand: function(side){
            var to = win.innerWidth || doc.documentElement.clientWidth;

            if(side==='left'){
                utils.dispatchEvent('expandLeft');
                utils.klass.add(doc.body, 'snapjs-expand-left');
                utils.klass.remove(doc.body, 'snapjs-expand-right');
            } else {
                utils.dispatchEvent('expandRight');
                utils.klass.add(doc.body, 'snapjs-expand-right');
                utils.klass.remove(doc.body, 'snapjs-expand-left');
                to *= -1;
            }
            this.action.translate.easeTo(to);
        },

        /**
         * Listen in to custom Snap events
         * @param  {String}   evt The snap event name
         * @param  {Function} fn  Callback function
         * @return {Object}       Snap instance
         */
        on: function(evt, fn) {
            this.eventList[evt] = fn;
            return this;
        },

        /**
         * Stops listening to custom Snap events
         * @param  {String} evt The snap event name
         */
        off: function(evt) {
            if (this.eventList[evt]) {
                this.eventList[evt] = false;
            }
        },

        /**
         * Enables Snap.js events
         */
        enable: function() {
            utils.dispatchEvent('enable');
            this.action.drag.listen();
        },

        /**
         * Disables Snap.js events
         */
        disable: function() {
            utils.dispatchEvent('disable');
            this.action.drag.stopListening();
        },

        /**
         * Updates the instances settings
         * @param  {Object} opts The Snap options to set
         */
        settings: function(opts){
            utils.extend(this.settings, opts);
        },

        /**
         * Returns information about the state of the content pane
         * @return {Object} Information regarding the state of the pane
         */
        state: function() {
            var state,
                fromLeft = this.action.translate.get.matrix(4);
            if (fromLeft === this.settings.maxPosition) {
                state = 'left';
            } else if (fromLeft === this.settings.minPosition) {
                state = 'right';
            } else {
                state = 'closed';
            }
            return {
                state: state,
                info: this.cache.simpleStates
            };
        }
    });

    // Assign to the global namespace
    this[Namespace] = Core;

}).call(this, window, document);
