var scrollr = scrollr || {};

scrollr.scrollers = [];

scrollr.doInit = function() {
	var elements = scrollr.getElementsByClass(document.body, 'div', 'scrollr');
	for (element in elements) {
		//var new_scroller = new scrollr.Scrollbar(elements[element]);
		//scrollr.scrollers.push(new_scroller);
	}
}

scrollr.Scrollbar = function(element) {
	this.element = element;

	this.element.style.overflow = "hidden";
	this.element.style.whiteSpace = "nowrap";

	//this.element.className = 'scrollr_js';
	this.container = document.createElement('div');
	this.container.className = 'scrollr_container';
	this.element.parentNode.insertBefore(this.container, this.element);
	this.container.appendChild(this.element);
	var divs = this.element.getElementsByTagName('div');
	for (div in divs) {
		divs[div].className = 'scrollr_item';
	}
	this.location = new scrollr.Vector(0, 0, 0);
	this.velocity = new scrollr.Vector(0, 0, 0);
	this.acceleration = new scrollr.Vector(0, 0, 0);
	this.last_x = 0;
	
	this.createScrollbar();
	this.createScroller();
	this.timer = new scrollr.Loop(25,
		(function(context) {
			return function(e) {
				context.doScroll(e);
			}
		})(this)
	);
}
scrollr.Scrollbar.prototype.createScrollbar = function() {
	this.scrollbar = document.createElement('div');
	this.scrollbar.className = 'scrollr_scrollbar';
	this.container.appendChild(this.scrollbar);
	this.container.style.paddingBottom = (this.scrollbar.offsetHeight + (parseInt(this.container.style.paddingBottom) || 0))+"px";

	this.attached_mouse = false;
	this.mouse_event =  (function(context) {
		return function(e) {
			context.onMouseMove(e);
		}
	})(this);


	scrollr.addEvent(this.scrollbar, 'mousedown',
		(function(context) {
			return function(e) {
				context.onClick(e);
				e.preventDefault();
				return false;
			}
		})(this)
	);
	scrollr.addEvent(this.scrollbar, 'mouseup',
		(function(context) {
			return function(e) {
				context.onRelease(e);
			}
		})(this)
	);

}
scrollr.Scrollbar.prototype.createScroller = function() {
	this.scroller_box = document.createElement('div');
	this.scroller_box.className = 'scrollr_scroller_box';
	this.scrollbar.appendChild(this.scroller_box);
//	this.scroller_box.style.width = ( this.scroller_box.offsetWidth * this.getMultiplier() )+"px";

	this.scroller = document.createElement('div');
	this.scroller.className = 'scrollr_scroller';
	this.scroller_box.appendChild(this.scroller);
	this.scroller.style.width = ( this.scroller.offsetWidth * this.getMultiplier() )+"px";
}
scrollr.Scrollbar.prototype.getInnerWidth = function() {
	return (this.element.scrollWidth);
}
scrollr.Scrollbar.prototype.getMultiplier = function() {
	return ( this.element.offsetWidth / this.element.scrollWidth );
}
scrollr.Scrollbar.prototype.onClick = function(event) {
	var e = window.event || event;
	var offset_left = e.clientX-(this.container.offsetLeft);
	this.target_x = offset_left;
	if (offset_left > this.scroller.offsetLeft && offset_left < this.scroller.offsetLeft+this.scroller.offsetWidth) {
		if (!this.attached_mouse) {
			this.attached_mouse = true;
			scrollr.addEvent(window, 'mousemove', this.mouse_event);
		}
	}
/*	if (offset_left < this.location.x) {
		var move = (offset_left - this.location.x)*this.getMultiplier();
		this.applyForce(new scrollr.Vector(move, 0, 0));
	} else if (offset_left > this.location.x+this.scroller.offsetWidth) {
		var move = 4 * (( offset_left - (this.location.x+this.scroller.offsetWidth) ));
		this.applyForce(new scrollr.Vector(move, 0, 0));
	}*/
	this.timer.Start();
	return false;
}
scrollr.Scrollbar.prototype.onRelease = function(event) {
	if (this.attached_mouse) {
		this.attached_mouse = false;
		scrollr.removeEvent(window, 'mousemove', this.mouse_event);
	}
}
scrollr.Scrollbar.prototype.onMouseMove = function(event) {
	var e = window.event || event;
	var offset_left = e.clientX-(this.container.offsetLeft);
	//this.target_x = offset_left;
	if (offset_left < this.previous_x) {
		this.target_x = this.location.x - (this.previous_x-offset_left);
	} else if (offset_left > this.previous_x) {
		this.target_x = this.scroller.offsetWidth+this.location.x+(offset_left-this.previous_x);
	}
	this.previous_x = offset_left;
	this.timer.Start();
}
scrollr.Scrollbar.prototype.doScroll = function(delta) {
	if (this.target_x < this.location.x) {
		var move = (this.target_x - this.location.x)*this.getMultiplier();
		this.applyForce(new scrollr.Vector(move, 0, 0));
	} else if (this.target_x > this.location.x+this.scroller.offsetWidth) {
		var move = (( this.target_x - (this.location.x+this.scroller.offsetWidth) ))*this.getMultiplier();
		this.applyForce(new scrollr.Vector(move, 0, 0));
	}

	if (this.location.x <= 8) {
//		this.velocity.multiply(0);
		this.applyForce(new scrollr.Vector(-this.location.x, 0, 0));
	//this.container.style.paddingBottom = (this.scrollbar.offsetHeight + (parseInt(this.container.style.paddingBottom) || 0))+"px";
	} else if ((this.location.x + this.scroller.offsetWidth) > this.element.offsetWidth-8) {
//		this.velocity.multiply(0);
		this.applyForce(new scrollr.Vector(this.element.offsetWidth-(this.location.x+this.scroller.offsetWidth), 0, 0));
	}

	var friction = this.velocity.copyVector();
	friction.multiply(-1);
	friction.normalize();
	friction.multiply(2.5);
	this.applyForce(friction);

	this.velocity.add(this.acceleration);
	this.location.add(this.velocity);
	this.acceleration.multiply(0);
	this.scroller.style.marginLeft = this.location.x+'px';
	this.element.scrollLeft = this.location.x/this.getMultiplier();
	if (this.location.x == this.last_x) {
		this.timer.Stop();
	}
	this.last_x = this.location.x;
};
scrollr.Scrollbar.prototype.applyForce = function(force) {
	var new_force = force.copyVector();
	new_force.divide(15.0);
	this.acceleration.add(new_force);
}

scrollr.addEvent = function(target, event_type, callback, bubble) {
	bubble = (typeof bubble !== 'undefined' ? bubble : false);
	if (typeof target.attachEvent !== 'undefined') {
		target.attachEvent('on'+event_type, callback);
	} else if (typeof target.addEventListener !== 'undefined') {
		target.addEventListener(event_type, callback, bubble);
	}
}

scrollr.removeEvent = function(target, event_type, callback, bubble) {
	bubble = (typeof bubble !== 'undefined' ? bubble : false);
	if (typeof target.detachEvent !== 'undefined') {
		target.detachEvent('on'+event_type, callback);
	} else if (typeof target.removeEventListener !== 'undefined') {
		target.removeEventListener(event_type, callback, bubble);
	}
}
scrollr.getAbsoluteElementOffset = function(element) {
	var offset_top = 0;
	var offset_left = 0;
	var obj = element;
	do {
		offset_top += obj.offsetTop;
		offset_left += obj.offsetLeft;
	} while (obj = obj.offsetParent);
	return { x: offset_left, y: offset_top };
}
scrollr.getElementsByClass = function(search_element, element_name, class_name) {
	var elements = search_element.getElementsByTagName(element_name);
	var return_elements = [];
	for (element in elements) {
		if (elements[element].className == class_name) {
			return_elements.push(elements[element]);
		}
	}
	return return_elements;
}

scrollr.Loop = function(loop_time, target_callback) {
	this.start_time = new Date().getTime();
	this.current_time = this.start_time;
	this.previous_time = this.start_time;
	this.elapsed_time = 0;
	this.delta_time = 0;
	this.loop_time = loop_time;
	this.is_running = false;

	this.Tick = function() {
		this.current_time = new Date().getTime();

		this.delta_time = (this.current_time - this.previous_time);	
		this.elapsed_time += this.delta_time;

		target_callback(this.delta_time);
		this.previous_time = this.current_time;
		if (this.is_running) {
			(function(_this) { setTimeout(function() { _this.Tick(); }, _this.loop_time-_this.delta_time)})(this);
		}
	};
	this.Start = function() {
		if (!this.is_running) {
			this.start_time = new Date().getTime();
			this.current_time = this.start_time;
			this.previous_time = this.start_time;
			this.elapsed_time = 0;
			this.delta_time = 0;
			this.is_running = true;
			this.Tick();
		}
	};
	this.Stop = function() {
		this.is_running = false;
	};
};

scrollr.Vector = function(x, y, z) {
	this.x = x;
	this.y = y;
	this.z = z;
	this.add = function(vector) {
		this.x += vector.x;
		this.y += vector.y;
		this.z += vector.z;
	};
	this.subtract = function(vector) {
		this.x -= vector.x;
		this.y -= vector.y;
		this.z -= vector.z;
	};
	this.multiply = function(multiplier) {
		this.x = this.x * multiplier;
		this.y = this.y * multiplier;
		this.z = this.z * multiplier;
	};
	this.divide = function(divisor) {
		this.x = this.x / divisor;
		this.y = this.y / divisor;
		this.z = this.z / divisor;
	};
	this.getMagnitude = function() {
		return Math.sqrt(this.x*this.y + this.y*this.y);
	};
	this.copyVector = function() {
		return new scrollr.Vector(this.x, this.y, this.z);
	};
	this.normalize = function() {
		var magnitude = this.getMagnitude();
		(magnitude != 0 ? this.divide(magnitude) : '');
	};
};

scrollr.addEvent(window, 'load', scrollr.doInit);