/* 
Copyright (c) 2005 Tim Taylor Consulting <http://tool-man.org/>

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
IN THE SOFTWARE.
 */
ToolMan._dragFactory = {
	createSimpleGroup : function(element, handle) {
		handle = handle ? handle : element
		var group = this.createGroup(element)
		group.setHandle(handle)
		group.transparentDrag()
		group.onTopWhileDragging()
		return group
	},

	createGroup : function(element) {
		var group = new _ToolManDragGroup(this, element)

		var position = ToolMan.css().readStyle(element, 'position')
		if (position == 'static') {
			element.style["position"] = 'relative'
		} else if (position == 'absolute') {
			/* for Safari 1.2 */
			ToolMan.coordinates().topLeftOffset(element).reposition(element)
		}

		// TODO: only if ToolMan.isDebugging()
		group.register('draginit', this._showDragEventStatus)
		group.register('dragmove', this._showDragEventStatus)
		group.register('dragend', this._showDragEventStatus)

		return group
	},

	_showDragEventStatus : function(dragEvent) {
		window.status = dragEvent.toString()
	},

	constraints : function() {
		return this._constraintFactory
	},

	_createEvent : function(type, event, group) {
		return new _ToolManDragEvent(type, event, group)
	}
}

function _ToolManDragGroup(factory, element) {
	this.factory = factory
	this.element = element
	this._handle = null
	this._thresholdDistance = 0
	this._transforms = new Array()
	// TODO: refactor into a helper object, move into events.js
	this._listeners = new Array()
	this._listeners['draginit'] = new Array()
	this._listeners['dragstart'] = new Array()
	this._listeners['dragmove'] = new Array()
	this._listeners['dragend'] = new Array()
}

_ToolManDragGroup.prototype = {

	setHandle : function(handle) {
		var events = ToolMan.events()

		handle.toolManDragGroup = this
		events.register(handle, 'mousedown', this._dragInit)
		handle.onmousedown = function() { return false }

		if (this.element != handle)
			events.unregister(this.element, 'mousedown', this._dragInit)
	},

	register : function(type, func) {
		this._listeners[type].push(func)
	},

	addTransform : function(transformFunc) {
		this._transforms.push(transformFunc)
	},

	verticalOnly : function() {
		this.addTransform(this.factory.constraints().vertical())
	},

	horizontalOnly : function() {
		this.addTransform(this.factory.constraints().horizontal())
	},

	setThreshold : function(thresholdDistance) {
		this._thresholdDistance = thresholdDistance
	},

	transparentDrag : function(opacity) {
		var opacity = typeof(opacity) != "undefined" ? opacity : 0.75;
		var originalOpacity = ToolMan.css().readStyle(this.element, "opacity")

		this.register('dragstart', function(dragEvent) {
			var element = dragEvent.group.element
			element.style.opacity = opacity
			element.style.filter = 'alpha(opacity=' + (opacity * 100) + ')'
		})
		this.register('dragend', function(dragEvent) {
			var element = dragEvent.group.element
			element.style.opacity = originalOpacity
			element.style.filter = 'alpha(opacity=100)'
		})
	},

	onTopWhileDragging : function(zIndex) {
		var zIndex = typeof(zIndex) != "undefined" ? zIndex : 100000;
		var originalZIndex = ToolMan.css().readStyle(this.element, "z-index")

		this.register('dragstart', function(dragEvent) {
			dragEvent.group.element.style.zIndex = zIndex
		})
		this.register('dragend', function(dragEvent) {
			dragEvent.group.element.style.zIndex = originalZIndex
		})
	},

	_dragInit : function(event) {
		event = ToolMan.events().fix(event)
		var group = document.toolManDragGroup = this.toolManDragGroup
		var dragEvent = group.factory._createEvent('draginit', event, group)

		group._isThresholdExceeded = false
		group._initialMouseOffset = dragEvent.mouseOffset
		group._grabOffset = dragEvent.mouseOffset.minus(dragEvent.topLeftOffset)
		ToolMan.events().register(document, 'mousemove', group._drag)
		document.onmousemove = function() { return false }
		ToolMan.events().register(document, 'mouseup', group._dragEnd)

		group._notifyListeners(dragEvent)
	},

	_drag : function(event) {
		event = ToolMan.events().fix(event)
		var coordinates = ToolMan.coordinates()
		var group = this.toolManDragGroup
		if (!group) return
		var dragEvent = group.factory._createEvent('dragmove', event, group)

		var newTopLeftOffset = dragEvent.mouseOffset.minus(group._grabOffset)

		// TODO: replace with DragThreshold object
		if (!group._isThresholdExceeded) {
			var distance = 
					dragEvent.mouseOffset.distance(group._initialMouseOffset)
			if (distance < group._thresholdDistance) return
			group._isThresholdExceeded = true
			group._notifyListeners(
					group.factory._createEvent('dragstart', event, group))
		}

		for (i in group._transforms) {
			var transform = group._transforms[i]
			newTopLeftOffset = transform(newTopLeftOffset, dragEvent)
		}

		var dragDelta = newTopLeftOffset.minus(dragEvent.topLeftOffset)
		var newTopLeftPosition = dragEvent.topLeftPosition.plus(dragDelta)
		newTopLeftPosition.reposition(group.element)
		dragEvent.transformedMouseOffset = newTopLeftOffset.plus(group._grabOffset)

		group._notifyListeners(dragEvent)

		var errorDelta = newTopLeftOffset.minus(coordinates.topLeftOffset(group.element))
		if (errorDelta.x != 0 || errorDelta.y != 0) {
			coordinates.topLeftPosition(group.element).plus(errorDelta).reposition(group.element)
		}
	},

	_dragEnd : function(event) {
		event = ToolMan.events().fix(event)
		var group = this.toolManDragGroup
		var dragEvent = group.factory._createEvent('dragend', event, group)

		group._notifyListeners(dragEvent)

		this.toolManDragGroup = null
		ToolMan.events().unregister(document, 'mousemove', group._drag)
		document.onmousemove = null
		ToolMan.events().unregister(document, 'mouseup', group._dragEnd)
	},

	_notifyListeners : function(dragEvent) {
		var listeners = this._listeners[dragEvent.type]
		for (i in listeners) {
			listeners[i](dragEvent)
		}
	}
}

function _ToolManDragEvent(type, event, group) {
	this.type = type
	this.group = group
	this.mousePosition = ToolMan.coordinates().mousePosition(event)
	this.mouseOffset = ToolMan.coordinates().mouseOffset(event)
	this.transformedMouseOffset = this.mouseOffset
	this.topLeftPosition = ToolMan.coordinates().topLeftPosition(group.element)
	this.topLeftOffset = ToolMan.coordinates().topLeftOffset(group.element)
}

_ToolManDragEvent.prototype = {
	toString : function() {
		return "mouse: " + this.mousePosition + this.mouseOffset + "    " +
				"xmouse: " + this.transformedMouseOffset + "    " +
				"left,top: " + this.topLeftPosition + this.topLeftOffset
	}
}

ToolMan._dragFactory._constraintFactory = {
	vertical : function() {
		return function(coordinate, dragEvent) {
			var x = dragEvent.topLeftOffset.x
			return coordinate.x != x
					? coordinate.factory.create(x, coordinate.y) 
					: coordinate
		}
	},

	horizontal : function() {
		return function(coordinate, dragEvent) {
			var y = dragEvent.topLeftOffset.y
			return coordinate.y != y
					? coordinate.factory.create(coordinate.x, y) 
					: coordinate
		}
	}
}