/**
 * Socket to Me World
 *
 * TODO object collisions
 * DONE grab, throw, freeze
 * TODO balls!!
 * TODO momentum response for object collisions
 * TODO fixed objects
 * TODO atmospherics: air pressure/friction DONE, wind
 * TODO projectiles
 */

jQuery.fn.move = function(params)  {


    var radius = function(obj) {

        if(obj.isSphere == true) {
            return radius = obj.width/2;
        }
        return NaN
    }


    // TODO verify iot works

    var distance = function(a,b) {
    
    	return (a > b) ? a - b : b - a;
    
    }
    
    var hasCollision = function(obj0, obj1) {

	var boolean = false; 
	var position0 = $(obj0).position();
	var position1 = $(obj1).position();


	if ((obj0.isSphere == true) && (obj1.isSphere == true)) {
	    var distX = distance(position0.left,position1.left);	
	    var distY = distance(position0.top,position1.top);	
	    radii = obj0.width + obj1.width/2;
	    boolean = radii > Math.sqrt((distX*distX) + (distY*distY));
	} else {
	
	}
    
	return boolean;
    
    };


    var doPhysics = function(obj) {
    
    	// var number = 0;

    	var objPosition = $(obj).position();
    	    	
    	//hits the side edge of the world

    	if (((objPosition.left <= 0) && (obj.xVelocity < 0)) || 
    	    ((objPosition.left + obj.width >= obj.parent.width) && (obj.xVelocity > 0))) {
		obj.xVelocity = 0 - obj.xVelocity;

	} else {

		/*
	
			$(obj.parent).children().each(function() {

				var collision = hasCollision(this, obj);

				if (collision == true) {

				}

			 //TODO collisions not working

				var position = $(this).position();	

				if (obj == this) {

					//do nothing		

				} else {
				    // if they are in the same space, they could horizontally collide
				    var maxDist = obj.height < this.height ? obj.height : this.height;
				    var actualDist = objPosition.top < position.top ? position.top - objPosition.top: objPosition.top - position.top;
				    if (actualDist < maxDist) {

					    // game one
					    if ((objPosition.left < (position.left + this.width)) && (obj.xVelocity > 0)) {
						obj.xVelocity = 0 - obj.xVelocity;
					    } else if (((objPosition.left + obj.width) > position.left) && (obj.xVelocity < 0)) {
						obj.xVelocity = 0 - obj.xVelocity;
					    }	
				    }
				}

			});   	

		*/
	}

    	//hits the top or bottom edge of the world

    	if (((objPosition.top <= 0)&&(obj.yVelocity < 0)) || ((objPosition.top + obj.height >= obj.parent.height) && (obj.yVelocity > 0))) {
		obj.yVelocity = 0 - obj.yVelocity;
            //number += 2;
	}

	//apply atmospheric slowing force
	obj.yVelocity = ((100 - obj.parent.density) * obj.yVelocity)/100
	obj.xVelocity = ((100 - obj.parent.density) * obj.xVelocity)/100
	
	//apply gravity to velocity
    	obj.yVelocity = obj.yVelocity + (obj.parent.gravity /obj.parent.frameRate);

	// clean up dross for smoother garbage collection, perhaps
	
	
    	// return obj; // see if this is required or not
    };

    /**
     *  STEP FRAMES
     */
    var stepFrame = function(obj) {

	if (obj.isPaused == false) {

	    doPhysics(obj); // handle collisions

            var position = $(obj).position();
            
            obj.style.top = Math.round(position.top+ Math.round(obj.yVelocity)) + "px";

            obj.style.left = Math.round(position.left+Math.round(obj.xVelocity)) + "px";

	    if (obj.parent.debug == true) {
	        $(obj.positionBox).html(obj.style.left + ',' + obj.style.top + '<br> (' + (Math.round(obj.xVelocity*1000)/1000) + ',' + (Math.round(obj.yVelocity*1000)/1000) +')' );
	    }
	}

	setTimeout(function() { stepFrame(obj) },1000/obj.parent.frameRate);
    };

    /**
     * INITIALISE EACH OBJECT ANIMATION
     */
    this.each(function() {
	 stepFrame(this);

    });
}

jQuery.fn.atom = function(params)  {


    //setup;
    this.each(function(i) {
	
	var position = $(this).position();
	this.parent = params.parent;
        this.width = $(this).innerWidth();
        this.height = $(this).innerHeight(); 
	this.isSphere = $(this).hasClass('ball') ? true : false ;

	this.xVelocity = (Math.random()*10.0) -5; //hard coded?
	this.yVelocity = (Math.random()*10.0) -5;

	//keep physical position, but be absolutely positioned
	this.style.top = Math.round(position.top) + "px";
	this.style.left = Math.round(position.left) + "px";

	//maybe random pos
        var topPos = Math.round(Math.random() * (this.parent.height - this.height));
        var leftPos = Math.round(Math.random() * (this.parent.width - this.width));
        this.style.top =  topPos + "px";
        this.style.left = leftPos + "px";

	this.isPaused = false;

	if (this.parent.interactive == true) {

	    //TODO add grab and release actions

	}

	if (this.parent.debug == true) {

		this.positionBox = $('<div>').appendTo(this);
		$(this.positionBox).html(this.style.left + ',' + this.style.top + ' (' + this.xVelocity + ',' + this.yVelocity +')' );
		$(this.positionBox).attr('class', 'positionBox');

	}	
/*
        $(this).mouseover(
            function(e) {
            	if (this.override == null) {
                    this.isPaused = true;
                }
        });
        
        $(this).mouseout(
	    function(e) {

		this.isPaused = false;

	    }
        );
*/


       $(this).bind('mousedown',function(e){
	    if (this.fling == null) {
	        this.fling = {};
	        this.fling.position = $(this).position();
	        this.fling.startDrag = new Date();

            }
	    this.isPaused = true;
        });
        
        $(this).bind('drag',function(e){

	if (this.parent.debug == true) {

            $(this.positionBox).html(this.style.left + ',' + this.style.top + ' (' + this.xVelocity + ',' + this.yVelocity +')' );

	}

		//if we're dragging, then we want to listen for a release
	       $(this).bind('mouseup',function(e){

		    if (this.fling != null) {

			var elapsedTime = new Date() - this.fling.startDrag;

			var flingFactor = this.parent.flingFactor;

			var newPosition = $(this).position();

			var xFactor = newPosition.left - this.fling.position.left ;
			var yFactor = newPosition.top - this.fling.position.top 
			this.xVelocity = xFactor*flingFactor/elapsedTime;
			this.yVelocity = yFactor*flingFactor/elapsedTime;
			this.fling = null;
		    }
		    this.isPaused = false;
		    
		    $(this).unbind('mouseup');

		});


            // listen for drag events that take it out of the world
	    var objPosition = $(this).position();
            if ((objPosition.left <= 0) || (objPosition.left + this.width >= this.parent.width) 
                    || (objPosition.top <= 0) || (objPosition.top + this.height >= this.parent.height)) {
                $(this).trigger('dragend');                    
	    }

	});
	
        
    });

    this.each(
        function(i) {
        this.style.position="absolute";
        this.style.padding = 0;		
        this.style.margin = 0;		
        }
    );
	
}


jQuery.fn.world = function(params) {

    this.start = function() {
	$(this).children().move({parent:this});
    };

    
    // setup params
    this.each(function(i){
    
    

	//set params
     	this.frameRate = 30;			// per sec;
        this.bounce = 0.5;			// gravity of the world.
        this.gravity = 1.0;			// gravity of the world.
        this.density = 0.01;			// friction slows motion down in all directions
        this.interactive = true;		// can you grab em and throw em?
        this.collide = false;			// do worlds collide?
        this.erode = false;			// do worlds hurt each other
        this.width = $(this).outerWidth();	// width of the universe
        this.height = $(this).outerHeight(); 	// height of the universe
	this.flingFactor = 20;
	this.debug = false;			// whether to put diagnostics on the screen

	//override params        
        if (params) {
	    if( params.frameRate) this.frameRate = params.frameRate;
	    if( params.bounce) this.bounce = params.bounce;
	    if( params.gravity) this.gravity = params.gravity;
	    if( params.density) this.density = params.density; 
	    if( params.interactive) this.interactive = params.interactive; 
	    if( params.collide) this.collide = params.collide; 
	    if( params.erode) this.erode = params.erode; 
	    if( params.flingFactor) this.flingFactor = params.flingFactor; 
	    if( params.debug) this.debug = params.debug; 
	}

	$(this).children().atom({parent:this});

        this.width = $(this).outerWidth();
        this.height = $(this).outerHeight();


    });

    return this;

}