/**
* _Internal Class_, not generally used outside of the engine's internals.
*
* @class Mouse
*/

var Mouse = {};

(function() {

    /**
     * Description
     * @method create
     * @param {HTMLElement} element
     * @return {mouse} A new mouse
     */
    Mouse.create = function(element) {
        var mouse = {};
        
        mouse.element = element || document.body;
        mouse.absolute = { x: 0, y: 0 };
        mouse.position = { x: 0, y: 0 };
        mouse.mousedownPosition = { x: 0, y: 0 };
        mouse.mouseupPosition = { x: 0, y: 0 };
        mouse.offset = { x: 0, y: 0 };
        mouse.scale = { x: 1, y: 1 };
        mouse.wheelDelta = 0;
        mouse.button = -1;

        mouse.sourceEvents = {
            mousemove: null,
            mousedown: null,
            mouseup: null,
            mousewheel: null
        };
        
        mouse.mousemove = function(event) { 
            var position = _getRelativeMousePosition(event, mouse.element),
                touches = event.changedTouches;

            if (touches) {
                mouse.button = 0;
                event.preventDefault();
            }

            mouse.absolute.x = position.x;
            mouse.absolute.y = position.y;
            mouse.position.x = mouse.absolute.x * mouse.scale.x + mouse.offset.x;
            mouse.position.y = mouse.absolute.y * mouse.scale.y + mouse.offset.y;
            mouse.sourceEvents.mousemove = event;
        };
        
        mouse.mousedown = function(event) {
            var position = _getRelativeMousePosition(event, mouse.element),
                touches = event.changedTouches;

            if (touches) {
                mouse.button = 0;
                event.preventDefault();
            } else {
                mouse.button = event.button;
            }

            mouse.absolute.x = position.x;
            mouse.absolute.y = position.y;
            mouse.position.x = mouse.absolute.x * mouse.scale.x + mouse.offset.x;
            mouse.position.y = mouse.absolute.y * mouse.scale.y + mouse.offset.y;
            mouse.mousedownPosition.x = mouse.position.x;
            mouse.mousedownPosition.y = mouse.position.y;
            mouse.sourceEvents.mousedown = event;
        };
        
        mouse.mouseup = function(event) {
            var position = _getRelativeMousePosition(event, mouse.element),
                touches = event.changedTouches;

            if (touches) {
                event.preventDefault();
            }
            
            mouse.button = -1;
            mouse.absolute.x = position.x;
            mouse.absolute.y = position.y;
            mouse.position.x = mouse.absolute.x * mouse.scale.x + mouse.offset.x;
            mouse.position.y = mouse.absolute.y * mouse.scale.y + mouse.offset.y;
            mouse.mouseupPosition.x = mouse.position.x;
            mouse.mouseupPosition.y = mouse.position.y;
            mouse.sourceEvents.mouseup = event;
        };

        mouse.mousewheel = function(event) {
            mouse.wheelDelta = Math.max(-1, Math.min(1, event.wheelDelta || -event.detail));
            event.preventDefault();
        };

        Mouse.setElement(mouse, mouse.element);

        return mouse;
    };

    /**
     * Sets the element the mouse is bound to (and relative to)
     * @method setElement
     * @param {mouse} mouse
     * @param {HTMLElement} element
     */
    Mouse.setElement = function(mouse, element) {
        mouse.element = element;

        element.addEventListener('mousemove', mouse.mousemove);
        element.addEventListener('mousedown', mouse.mousedown);
        element.addEventListener('mouseup', mouse.mouseup);
        
        element.addEventListener("mousewheel", mouse.mousewheel);
        element.addEventListener("DOMMouseScroll", mouse.mousewheel);

        element.addEventListener('touchmove', mouse.mousemove);
        element.addEventListener('touchstart', mouse.mousedown);
        element.addEventListener('touchend', mouse.mouseup);
    };

    /**
     * Clears all captured source events
     * @method clearSourceEvents
     * @param {mouse} mouse
     */
    Mouse.clearSourceEvents = function(mouse) {
        mouse.sourceEvents.mousemove = null;
        mouse.sourceEvents.mousedown = null;
        mouse.sourceEvents.mouseup = null;
        mouse.sourceEvents.mousewheel = null;
        mouse.wheelDelta = 0;
    };

    /**
     * Sets the offset
     * @method setOffset
     * @param {mouse} mouse
     */
    Mouse.setOffset = function(mouse, offset) {
        mouse.offset.x = offset.x;
        mouse.offset.y = offset.y;
        mouse.position.x = mouse.absolute.x * mouse.scale.x + mouse.offset.x;
        mouse.position.y = mouse.absolute.y * mouse.scale.y + mouse.offset.y;
    };

    /**
     * Sets the scale
     * @method setScale
     * @param {mouse} mouse
     */
    Mouse.setScale = function(mouse, scale) {
        mouse.scale.x = scale.x;
        mouse.scale.y = scale.y;
        mouse.position.x = mouse.absolute.x * mouse.scale.x + mouse.offset.x;
        mouse.position.y = mouse.absolute.y * mouse.scale.y + mouse.offset.y;
    };
    
    /**
     * Description
     * @method _getRelativeMousePosition
     * @private
     * @param {} event
     * @param {} element
     * @return ObjectExpression
     */
    var _getRelativeMousePosition = function(event, element) {
        var elementBounds = element.getBoundingClientRect(),
            rootNode = (document.documentElement || document.body.parentNode || document.body),
            scrollX = (window.pageXOffset !== undefined) ? window.pageXOffset : rootNode.scrollLeft,
            scrollY = (window.pageYOffset !== undefined) ? window.pageYOffset : rootNode.scrollTop,
            touches = event.changedTouches,
            x, y;
        
        if (touches) {
            x = touches[0].pageX - elementBounds.left - scrollX;
            y = touches[0].pageY - elementBounds.top - scrollY;
        } else {
            x = event.pageX - elementBounds.left - scrollX;
            y = event.pageY - elementBounds.top - scrollY;
        }
        
        return { 
            x: x / (element.clientWidth / element.width), 
            y: y / (element.clientHeight / element.height)
        };
    };

})();