/**********************************************************************
*
* XXX add copyright and licence info...
*
**********************************************************************/

//var NAVIGATE_RELATIVE_TO_VISIBLE = false
var NAVIGATE_RELATIVE_TO_VISIBLE = true

var USE_PAGE_ALIGN = true

var PAGES_IN_RIBBON = 4



/********************************************************** layout ***/

var togglePageFitMode = createCSSClassToggler(
		'.viewer', 
		'.page-fit-to-viewer', 
		function(action){
			if(action == 'on'){
				console.log('fitting pages to view...')
				var n = getPageNumber()
				var scale = getMagazineScale()
				$('.page:not(.no-resize)').width($('.viewer').width()/scale)
			} else {
				console.log('restoring page sizes...')
				var n = getPageNumber()
				$('.page:not(.no-resize)').width('')
			}
			setCurrentPage(n)
		})


var togglePageView = createCSSClassToggler(
		'.viewer',
		'.full-page-view-mode',
		// XXX make this support transitions...
		function(action){
			var view = $('.viewer')
			var page = $('.page')

			if(action == 'on'){
				var W = view.width()
				var H = view.height()
				var w = page.width()
				var h = page.height()

				// XXX this is not correct...
				// 		...need to fit one rectangel (page) into another (viewer)
				if(W >= H){
					// fit to width...
					var scale = W/w
				} else {
					// fit to height...
					var scale = H/h
				}
				setMagazineScale(scale)
				unanimated($('.magazine, .viewer'), togglePageFitMode)('on')
			} else {
				unanimated($('.magazine, .viewer'), togglePageFitMode)('off')

				var W = view.width()
				var H = view.height()
				var w = page.width()
				var h = page.height()

				scale = W/(w*PAGES_IN_RIBBON)
				setMagazineScale(scale)
			}
			// NOTE: can't disable transitions on this one because ScrollTo
			// 		uses jQuery animation...
			setCurrentPage()
		})



/************************************************** event handlers ***/

function makeScrollHandler(root, callback){

	// local data...
	var scrolling = false
	var touch = false
	var touches = 0
	var start
	var prev_x
	var prev_t
	var shift
	var scale
	var x
	var t
	var dx
	var dt

	function startMoveHandler(evt, callback){
		prev_t = event.timeStamp || Date.now();
		setTransitionDuration($('.magazine'), 0)
		if(event.touches != null){
			touch = true
		}
		scrolling = true
		scroller.state = 'scrolling'
		//root.trigger('userScrollStart')
		//togglePageDragging('on')
		shift = getMagazineShift()
		scale = getMagazineScale()
		// get the user coords...
		prev_x = touch ? event.touches[0].pageX : evt.clientX
		start = prev_x

		return false
	}
	// XXX add limits to this...
	// XXX try and make this adaptive to stay ahead of the lags...
	function moveHandler(evt){
		evt.preventDefault()
		t = event.timeStamp || Date.now();
		// get the user coords...
		x = touch ? event.touches[0].pageX : evt.clientX
		touches = touch ? event.touches.length : 0
		if(scrolling){
			shift += x - prev_x
			setElementTransform($('.magazine'), shift, scale)
		}
		dx = x - prev_x
		dt = t - prev_t
		prev_t = t
		prev_x = x
		//root.trigger('userScroll')

		return false
	}
	function endMoveHandler(evt){
		// XXX get real transition duration...
		setTransitionDuration($('.magazine'), 200)
		x = touch ? event.changedTouches[0].pageX : evt.clientX
		touch = false
		scrolling = false
		scroller.state = 'waiting'
		touches = 0
		//togglePageDragging('off')
		// XXX add speed to this...
		//root.trigger('userScrollEnd')
		callback && callback(dx/dt, start - x)

		return false
	}

	var scroller = {
		start: function(){
			this.state = 'waiting'
			// XXX STUB: this makes starting the scroll a bit sluggish, 
			//		find a faster way...
			//togglePageDragging('on')

			// NOTE: if we bind both touch and mouse events, on touch devices they 
			//		might start interfering with each other...
			if('ontouchmove' in window){
				root
					.on('touchstart', startMoveHandler)
					.on('touchmove', moveHandler) 
					.on('touchend', endMoveHandler)
			} else {
				root
					.on('mousedown', startMoveHandler) 
					.on('mousemove', moveHandler) 
					.on('mouseup', endMoveHandler) 
			}
			return this
		},
		stop: function(){
			this.state = 'stopped'
			if('ontouchmove' in window){
				root
					.off('touchstart', startMoveHandler)
					.off('touchmove', moveHandler) 
					.off('touchend', endMoveHandler)
			} else {
				root
					.off('mousedown', startMoveHandler) 
					.off('mousemove', moveHandler) 
					.off('mouseup', endMoveHandler) 
			}
			return this
		},
		// NOTE: this is updated live but not used by the system in any way...
		state: 'stopped'
	}
	return scroller
}



/********************************************************* helpers ***/

// XXX there is something here that depends on scale that is either not 
// 		compensated, or is over compensated...
function getMagazineOffset(page, scale, align){
	if(page == null){
		page = $('.current.page')
	}
	if(scale == null){
		scale = getMagazineScale()
	}
	if(align == null){
		align = getPageAlign(page)
	}
	var mag = $('.magazine')

	// calculate the align offset...
	if(align == 'left'){
		var offset = 0

	} else if(align == 'right'){
		var offset = $('.viewer').width() - page.width()*scale

	// center (default)
	} else {
		var offset = $('.viewer').width()/2 - (page.width()/2)*scale
	}

	var w = mag.outerWidth(true)
	// XXX this depends on scale...
	var pos = page.position().left//*scale

	return -((w - w*scale)/2 + pos) + offset
}


// XXX make this work for narrow and left/right alligned pages...
function getPageNumber(page){
	// a page is given...
	if(page != null){
		return $('.page').index($(page))
	}

	// get the next page... 
	if(!NAVIGATE_RELATIVE_TO_VISIBLE){
		return $('.page').index($('.current.page'))

	// get the closest page to view... 
	} else {
		// XXX this gets crazy when magazine is scaled...
		//var s = $('.viewer').scrollLeft()
		var o = -$($('.magazine')[0]).offset().left - $('.viewer').offset().left
		var W = $('.viewer').width()
		var scale = getMagazineScale()
		var cur = -1
		var res = $('.page').map(function(i, e){
			e = $(e)
			var l = e.position().left
			var w = e.width()*scale
			return Math.abs((l+(w/2)) - (o+(W/2)))
		}).toArray()
		cur = res.indexOf(Math.min.apply(Math, res))
		return cur
	}
}


function getMagazineScale(){
	return getElementScale($('.magazine'))
}
function setMagazineScale(scale){
	var mag = $('.magazine')
	var cur = $('.current.page')

	var left = getMagazineOffset(cur, scale, 'center')

	setElementTransform(mag, left, scale)
}



/********************************************************* actions ***/

function setCurrentPage(n){
	if(n == null){
		n = getPageNumber()
	}
	var scale = getMagazineScale()
	var l = $('.page').length
	n = n < 0 ? l - n : n
	n = n < -l ? 0 : n
	n = n >= l ? l - 1 : n

	$('.current.page').removeClass('current')
	$($('.page')[n]).addClass('current')

	var cur = $('.current.page')

	var left = getMagazineOffset(cur)

	setElementTransform($('.magazine'), left, scale)

	return cur
}


function nextPage(page){
	setCurrentPage(getPageNumber(page)+1)
}
function prevPage(page){
	var n = getPageNumber(page)-1
	n = n < 0 ? 0 : n
	setCurrentPage(n)
}


function firstPage(){
	setCurrentPage(0)
}
function lastPage(){
	setCurrentPage(-1)
}



/*********************************************************************/
// vim:set ts=4 sw=4 :