/*!
 * pure-swipe.js - v@version@
 * Pure JavaScript swipe events
 * https://github.com/john-doherty/pure-swipe
 * @inspiration https://stackoverflow.com/questions/16348031/disable-scrolling-when-touch-moving-certain-element
 * @author John Doherty <www.johndoherty.info>
 * @license MIT
 */
(function (window, document) {

    'use strict';

    // patch CustomEvent to allow constructor creation (IE/Chrome) - resolved once initCustomEvent no longer exists
    if ('initCustomEvent' in document.createEvent('CustomEvent')) {

        window.CustomEvent = function (event, params) {

            params = params || { bubbles: false, cancelable: false, detail: undefined };

            var evt = document.createEvent('CustomEvent');
            evt.initCustomEvent(event, params.bubbles, params.cancelable, params.detail);
            return evt;
        };

        window.CustomEvent.prototype = window.Event.prototype;
    }

    document.addEventListener('touchstart', handleTouchStart, false);
    document.addEventListener('touchmove', handleTouchMove, false);
    document.addEventListener('touchend', handleTouchEnd, false);

    var xDown = null;
    var yDown = null;
    var xDiff = null;
    var yDiff = null;
    var timeDown = null;
    var startEl = null;

    function handleTouchEnd(e) {

        // if the user released on a different target, cancel!
        if (startEl !== e.target) return;

        var swipeThreshold = parseInt(startEl.getAttribute('data-swipe-threshold') || '20', 10);    // default 10px
        var swipeTimeout = parseInt(startEl.getAttribute('data-swipe-timeout') || '500', 10);      // default 1000ms
        var timeDiff = Date.now() - timeDown;
        var eventType = '';

        if (Math.abs(xDiff) > Math.abs(yDiff)) { // most significant
            if (Math.abs(xDiff) > swipeThreshold && timeDiff < swipeTimeout) {
                if (xDiff > 0) {
                    eventType = 'swiped-left';
                }
                else {
                    eventType = 'swiped-right';
                }
            }
        }
        else {
            if (Math.abs(yDiff) > swipeThreshold && timeDiff < swipeTimeout) {
                if (yDiff > 0) {
                    eventType = 'swiped-up';
                }
                else {
                    eventType = 'swiped-down';
                }
            }
        }

        if (eventType !== '') {

            // fire event on the element that started the swipe
            startEl.dispatchEvent(new CustomEvent(eventType, { bubbles: true, cancelable: true }));

            // if (console && console.log) console.log(eventType + ' fired on ' + startEl.tagName);
        }

        // reset values
        xDown = null;
        yDown = null;
        timeDown = null;
    }

    function handleTouchStart(e) {

        // if the element has data-swipe-ignore="true" we stop listening for swipe events
        if (e.target.getAttribute('data-swipe-ignore') === 'true') return;

        startEl = e.target;

        timeDown = Date.now();
        xDown = e.touches[0].clientX;
        yDown = e.touches[0].clientY;
        xDiff = 0;
        yDiff = 0;
    }

    function handleTouchMove(e) {

        if (!xDown || !yDown) return;

        var xUp = e.touches[0].clientX;
        var yUp = e.touches[0].clientY;

        xDiff = xDown - xUp;
        yDiff = yDown - yUp;
    }

}(window, document));