/*!
 * baguettebox.js
 * @author  feimosi
 * @version 0.7.0
 * @url https://github.com/feimosi/baguettebox.js
 */

var baguettebox = (function() {
    // svg shapes used in buttons
    var leftarrow = '<svg width="40" height="60" xmlns="http://www.w3.org/2000/svg" version="1.1">' +
            '<polyline points="30 10 10 30 30 50" stroke="rgba(255,255,255,0.5)" stroke-width="4"' +
              'stroke-linecap="butt" fill="none" stroke-linejoin="round">&lt;</polyline>' +
            '</svg>',
        rightarrow = '<svg width="40" height="60" xmlns="http://www.w3.org/2000/svg" version="1.1">' +
            '<polyline points="10 10 30 30 10 50" stroke="rgba(255,255,255,0.5)" stroke-width="4"' +
              'stroke-linecap="butt" fill="none" stroke-linejoin="round">&gt;</polyline>' +
            '</svg>',
        closex = '<svg width="30" height="30" xmlns="http://www.w3.org/2000/svg" version="1.1">' +
            '<g stroke="rgb(160, 160, 160)" stroke-width="4">' +
            '<line x1="5" y1="5" x2="25" y2="25"/>' +
            '<line x1="5" y1="25" x2="25" y2="5"/>' +
            'x</g></svg>';
    // main id names
    var overlayid = 'baguettebox-overlay';
    var sliderid = 'baguettebox-slider';
    // global options and their defaults
    var options = {}, defaults = {
        captions: true,
        buttons: 'auto',
        async: false,
        preload: 2,
        animation: 'slidein'
    };
    // dom elements references
    var overlay, slider, previousbutton, nextbutton, closebutton;
    // current image index inside the slider and displayed gallery index
    var currentindex = 0, currentgallery = -1;
    // touch event start position (for slide gesture)
    var touchstartx;
    // if set to true ignore touch events because animation was already fired
    var touchflag = false;
    // array of all used galleries (dom elements)
    var galleries = [];
    // 2d array of galleries and images inside them
    var imagesmap = [];
    // array containing temporary images dom elements
    var imagesarray = [];

    // foreach polyfill for ie8
    if(!array.prototype.foreach) {
        array.prototype.foreach = function(callback, thisarg) {
            var len = this.length;
            for(var i = 0; i < len; i++) {
                callback.call(thisarg, this[i], i, this);
            }
        };
    }

    // script entry point
    function run(selector, useroptions) {
        buildoverlay();
        // for each gallery bind a click event to every image inside it
        galleries = document.queryselectorall(selector);
        [].foreach.call(
            galleries,
            function (galleryelement, galleryindex) {
                var galleryid = imagesmap.length;
                imagesmap.push(galleryelement.getelementsbytagname('a'));
                imagesmap[galleryid].options = useroptions;
                [].foreach.call(
                    imagesmap[galleryid],
                    function (imageelement, imageindex) {
                        bind(imageelement, 'click', function(event) {
                            /*jshint -w030 */
                            event.preventdefault ? event.preventdefault() : event.returnvalue = false;
                            prepareoverlay(galleryid);
                            showoverlay(imageindex);
                        });
                    }
                );
            }
        );
        defaults.transforms = testtransformssupport();
    }

    function buildoverlay() {
        overlay = document.getelementbyid(overlayid);
        // check if the overlay already exists
        if(overlay) {
            slider = document.getelementbyid(sliderid);
            previousbutton = document.getelementbyid('previous-button');
            nextbutton = document.getelementbyid('next-button');
            closebutton = document.getelementbyid('close-button');
            return;
        }
        // create overlay element
        overlay = document.createelement('div');
        overlay.id = overlayid;
        document.getelementsbytagname('body')[0].appendchild(overlay);
        // create gallery slider element
        slider = document.createelement('div');
        slider.id = sliderid;
        overlay.appendchild(slider);
        // create all necessary buttons
        previousbutton = document.createelement('button');
        previousbutton.id = 'previous-button';
        previousbutton.innerhtml = leftarrow;
        overlay.appendchild(previousbutton);

        nextbutton = document.createelement('button');
        nextbutton.id = 'next-button';
        nextbutton.innerhtml = rightarrow;
        overlay.appendchild(nextbutton);

        closebutton = document.createelement('button');
        closebutton.id = 'close-button';
        closebutton.innerhtml = closex;
        overlay.appendchild(closebutton);

        previousbutton.classname = nextbutton.classname = closebutton.classname = 'baguettebox-button';

        bindevents();
    }

    function bindevents() {
        // when clicked on the overlay (outside displayed image) close it
        bind(overlay, 'click', function(event) {
            if(event.target && event.target.nodename !== "img")
                hideoverlay();
        });
        // add event listeners for buttons
        bind(document.getelementbyid('previous-button'), 'click', function(event) {
            /*jshint -w030 */
            event.stoppropagation ? event.stoppropagation() : event.cancelbubble = true;
            showpreviousimage();
        });
        bind(document.getelementbyid('next-button'), 'click', function(event) {
            /*jshint -w030 */
            event.stoppropagation ? event.stoppropagation() : event.cancelbubble = true;
            shownextimage();
        });
        bind(document.getelementbyid('close-button'), 'click', function(event) {
            /*jshint -w030 */
            event.stoppropagation ? event.stoppropagation() : event.cancelbubble = true;
            hideoverlay();
        });
        // add touch events
        bind(overlay, 'touchstart', function(event) {
            // save x axis position
            touchstartx = event.changedtouches[0].pagex;
        });
        bind(overlay, 'touchmove', function(event) {
            if(touchflag)
                return;
            /*jshint -w030 */
            event.preventdefault ? event.preventdefault() : event.returnvalue = false;
            touch = event.touches[0] || event.changedtouches[0];
            if(touch.pagex - touchstartx > 40) {
                touchflag = true;
                showpreviousimage();
            } else if (touch.pagex - touchstartx < -40) {
                touchflag = true;
                shownextimage();
            }
        });
        bind(overlay, 'touchend', function(event) {
            touchflag = false;
        });
        // activate keyboard shortcuts
        bind(document, 'keydown', function(event) {
            switch(event.keycode) {
                case 37: // left arrow
                    showpreviousimage();
                    break;
                case 39: // right arrow
                    shownextimage();
                    break;
                case 27: // esc
                    hideoverlay();
                    break;
            }
        });
    }

    function prepareoverlay(galleryindex) {
        // if the same gallery is being opened prevent from loading it once again
        if(currentgallery === galleryindex)
            return;
        currentgallery = galleryindex;
        // update gallery specific options
        setoptions(imagesmap[galleryindex].options);
        // empty slider of previous contents (more effective than .innerhtml = "")
        while(slider.firstchild)
            slider.removechild(slider.firstchild);
        imagesarray.length = 0;
        // prepare and append images containers
        for(var i = 0; i < imagesmap[galleryindex].length; i++) {
            imagesarray.push(returnimagecontainer());
            slider.appendchild(imagesarray[i]);
        }
    }

    function setoptions(newoptions) {
        if(!newoptions)
            newoptions = {};
        for(var item in defaults) {
            options[item] = defaults[item];
            if(typeof newoptions[item] !== 'undefined')
                options[item] = newoptions[item];
        }
        /* apply new options */
        // change transition for proper animation
        slider.style.transition = slider.style.webkittransition = options.animation === 'fadein' ? 'opacity .4s ease' : '';
        // hide buttons if necessary
        if(options.buttons === 'auto' && ('ontouchstart' in window || imagesmap[currentgallery].length === 1))
            options.buttons = false;
        // set buttons style to hide or display them
        previousbutton.style.display = nextbutton.style.display = options.buttons ? '' : 'none';
    }

    // return dom element for image container <div class="full-image">...</div>
    function returnimagecontainer() {
        var fullimage = document.createelement('div');
        fullimage.classname = 'full-image';
        return fullimage;
    }

    function showoverlay(index) {
        // return if overlay is already visible
        if(overlay.style.display === 'block')
            return;
        // set current index to a new value and show proper image
        currentindex = index;
        loadimage(currentindex, function() {
            preloadnext(currentindex);
            preloadprev(currentindex);
        });
        updateoffset();
        overlay.style.display = 'block';
        // fade in overlay
        settimeout(function() {
            overlay.classname = 'visible';
        }, 50);
    }

    function hideoverlay() {
        // return if overlay is already hidden
        if(overlay.style.display === 'none')
            return;
        // fade out and hide the overlay
        overlay.classname = '';
        settimeout(function() {
            overlay.style.display = 'none';
        }, 500);
    }

    function loadimage(index, callback) {
        var imagecontainer = imagesarray[index];
        // if index is invalid return
        if(typeof imagecontainer === 'undefined')
            return;
        // if image is already loaded run callback and return
        if(imagecontainer.getelementsbytagname('img')[0]) {
            if(callback)
                callback();
            return;
        }
        // get element reference, optional caption and source path
        imageelement = imagesmap[currentgallery][index];
        imagecaption = imageelement.getattribute('data-caption') || imageelement.title;
        imagesrc = getimagesrc(imageelement);
        // prepare image container elements
        var figure = document.createelement('figure');
        var image = document.createelement('img');
        var figcaption = document.createelement('figcaption');
        imagecontainer.appendchild(figure);
        // add loader element
        figure.innerhtml = '<div class="spinner">' +
            '<div class="double-bounce1"></div>' +
            '<div class="double-bounce2"></div>' +
            '</div>';
        // set callback function when image loads
        image.onload = function() {
            // remove loader element
            var spinner = this.parentnode.queryselector('.spinner');
            this.parentnode.removechild(spinner);
            if(!options.async && callback)
                callback();
        };
        image.setattribute('src', imagesrc);
        figure.appendchild(image);
        // insert caption if available
        if(options.captions && imagecaption) {
            figcaption.innerhtml = imagecaption;
            figure.appendchild(figcaption);
        }
        // run callback
        if(options.async && callback)
            callback();
    }

    function getimagesrc(image) {
        // set dafult image path from href
        var result = imageelement.getattribute('href');
        // if dataset is supported find the most suitable image
        if(image.dataset) {
            var srcs = [];
            // get all possible image versions depending on the resolution 
            for(var item in image.dataset) {
                if(item.substring(0, 3) === 'at-' && !isnan(item.substring(3)))
                    srcs[item.replace('at-', '')] = image.dataset[item];
            }
            // sort resolutions ascending
            keys = object.keys(srcs).sort(function(a, b) {
                return parseint(a) < parseint(b) ? -1 : 1;
            });
            // get real screen resolution 
            var width = window.innerwidth * window.devicepixelratio;
            // find first image bigger than or equal to the current width
            for(var i = 0; i < keys.length; i++) {
                if(keys[i] >= width) {
                    result = srcs[keys[i]];    
                    break;
                }
                result = srcs[keys[i]];
            }
        }
        return result;
    }

    function shownextimage() {
        if(currentindex <= imagesarray.length - 2) {
            currentindex++;
            updateoffset();
            preloadnext(currentindex);
        } else {
            slider.classname = 'bounce-from-right';
            settimeout(function() {
                slider.classname = '';
            }, 400);
        }
    }

    function showpreviousimage() {
        if(currentindex >= 1) {
            currentindex--;
            updateoffset();
            preloadprev(currentindex);
        } else {
            slider.classname = 'bounce-from-left';
            settimeout(function() {
                slider.classname = '';
            }, 400);
        }
    }

    function updateoffset() {
        var offset = -currentindex * 100 + '%';
        if(options.animation === 'fadein') {
            slider.style.opacity = 0;
            settimeout(function() {
                /*jshint -w030 */
                options.transforms ?
                    slider.style.transform = slider.style.webkittransform = 'translate3d(' + offset + ',0,0)'
                    : slider.style.left = offset;
                slider.style.opacity = 1;
            }, 400);
        } else {
            /*jshint -w030 */
            options.transforms ?
                slider.style.transform = slider.style.webkittransform = 'translate3d(' + offset + ',0,0)'
                : slider.style.left = offset;
        }
    }

    function testtransformssupport() {
        var div = document.createelement('div'),
            support = false;
        support = typeof div.style.perspective !== 'undefined' || typeof div.style.webkitperspective !== 'undefined';
        return support;
    }

    function preloadnext(index) {
        if(index - currentindex >= options.preload)
            return;
        loadimage(index + 1, function() { preloadnext(index + 1); });
    }

    function preloadprev(index) {
        if(currentindex - index >= options.preload)
            return;
        loadimage(index - 1, function() { preloadprev(index - 1); });
    }

    function bind(element, event, callback) {
        if(element.addeventlistener)
            element.addeventlistener(event, callback, false);
        else
            element.attachevent('on' + event, callback);
    }

    return {
        run: run
    };

})();