//

// Use LongPress() to set a function callback for a long-press on a particular DOM element.

//   Parameters:

//      elementId: id string of the element

//      callback: the function to be called when the long-press fires

//      mouseDownCallback: the function to be called on mouse-down

//   Example:

//        <javascript ...> 

//          new LongPress("btnId", function(el) { alert("hello"); });

//        </javascript>

//        ...

//        <img id="btnId" ... />

//

function LongPress(elementId, callback, mouseDownCallback) {

    this.el = document.getElementById(elementId);

    this.callback = callback;

    this.initialX = 0;

    this.initialY = 0;

    this.mouseDownCallback = mouseDownCallback;

	if(!this.el) {

		window.app.debug("LongPress: element " + elementId + " not found");

		return;

	}

    this.onTimerFired = function() {

        window.app.debug("onTimerFired");

        this.callback(this.el);

        this.cancelTimer();

        this.unregisterMouseMove();

    }

    this.startTimer = function() {

        this.cancelTimer();

        this.timer = window.setTimeout(createDelegate(this, this.onTimerFired), 1000);

	}

    this.cancelTimer = function() {

        if(this.timer) {

            window.clearTimeout(this.timer);

            this.timer = null;

        }

    }

    // Stop tracking mouse movements.

    this.unregisterMouseMove= function() {

        this.el.onmousemove = null;

    }

    this.cancel = function() {

        //window.app.debug("cancel");

        this.cancelTimer();

        this.unregisterMouseMove();

    }

    // If the mouse has moved too much it's not considered a long press, so cancel.

    this.onMouseMove = function() {

        //window.app.debug("LongPress::onMouseMove " + this + " event=" + window.event +

        //                    " " + window.event.clientX + "," + window.event.clientY);

        if(Math.abs(this.initialX - window.event.clientX) > 4 ||

           Math.abs(this.initialY - window.event.clientY) > 4) {

            this.cancel();

        }

    }

    // Start tracking the mouse and save the initial mouse coords.

    this.onMouseDown = function() {

        window.app.debug("LongPress::onMouseDown " + this);

        this.isDown = true;

        this.initialX = window.event.clientX;

        this.initialY = window.event.clientY;

        this.el.onmousemove = this.onMouseMove.bind(this);

        this.startTimer();

        if(this.mouseDownCallback != undefined)

            this.mouseDownCallback(this);

    }

	this.el.onmousedown = this.onMouseDown.bind(this);

    // Cancel tracking on mouse up and out events, ie. not a long press.

	this.el.onmouseup = this.cancel.bind(this);

	this.el.onmouseout = this.cancel.bind(this);

}