/*************************************************************************
	This code is from Dynamic Web Coding at dyn-web.com
	Copyright 2001-2008 by Sharon Paine
	See Terms of Use at www.dyn-web.com/business/terms.php
	regarding conditions under which you may use this code.
	This notice must be retained in the code as is!

	for use with dw_scroll.js - provides scrollbar functionality
	version date: Aug 2008
		bug fixed in .setBarSize
*************************************************************************/

function dw_Slidebar(barId, trackId, axis, x, y) {
	var bar = document.getElementById(barId);
	var track = document.getElementById(trackId);
	this.barId = barId; this.trackId = trackId;
	this.axis = axis; this.x = x || 0; this.y = y || 0;
	dw_Slidebar.col[this.barId] = this;
	this.bar = bar;  this.shiftTo(x, y);

	// hold for setBarSize
	this.trkHt = track.offsetHeight;
	this.trkWd = track.offsetWidth;

	if (axis == 'v') {
		this.maxY = this.trkHt - bar.offsetHeight - y;
		this.maxX = x; this.minX = x; this.minY = y;
	} else {
		this.maxX = this.trkWd - bar.offsetWidth - x;
		this.minX = x; this.maxY = y; this.minY = y;
	}

	this.on_drag_start =  this.on_drag =   this.on_drag_end =
	this.on_slide_start = this.on_slide =  this.on_slide_end = function() {}

	bar.onmousedown = dw_Slidebar.prepDrag;
	// pass barId to obtain instance from dw_Slidebar.col
	track.onmousedown = function(e) { dw_Slidebar.prepSlide(barId, e); }
	this.bar = bar = null; track = null;
}

dw_Slidebar.col = {}; // hold instances for global access
dw_Slidebar.current = null; // hold current instance

dw_Slidebar.prototype.slideDur = 100;

// track received onmousedown event
dw_Slidebar.prepSlide = function(barId, e) {
	var _this = dw_Slidebar.col[barId];
	dw_Slidebar.current = _this;
	var bar = _this.bar = document.getElementById(barId);

	if ( _this.timer ) { clearInterval(_this.timer); _this.timer = 0; }
	e = e? e: window.event;

	e.offX = (typeof e.layerX != "undefined")? e.layerX: e.offsetX;
	e.offY = (typeof e.layerY != "undefined")? e.layerY: e.offsetY;
	_this.startX = parseInt(bar.style.left); _this.startY = parseInt(bar.style.top);

	if (_this.axis == "v") {
		_this.destX = _this.startX;
		_this.destY = (e.offY < _this.startY)? e.offY: e.offY - bar.offsetHeight;
		_this.destY = Math.min( Math.max(_this.destY, _this.minY), _this.maxY );
	} else {
		_this.destX = (e.offX < _this.startX)? e.offX: e.offX - bar.offsetWidth;
		_this.destX = Math.min( Math.max(_this.destX, _this.minX), _this.maxX );
		_this.destY = _this.startY;
	}
	_this.distX = _this.destX - _this.startX; _this.distY = _this.destY - _this.startY;
	_this.per = Math.PI/(2 * _this.slideDur);
	_this.slideStartTime = new Date().getTime();
	_this.on_slide_start(_this.startX, _this.startY);
	_this.timer = setInterval("dw_Slidebar.doSlide()", 10);
}

dw_Slidebar.doSlide = function() {
	var _this = dw_Slidebar.current;
	var elapsed = new Date().getTime() - _this.slideStartTime;
	if (elapsed < _this.slideDur) {
		var x = _this.startX + _this.distX * Math.sin(_this.per*elapsed);
		var y = _this.startY + _this.distY * Math.sin(_this.per*elapsed);
		_this.shiftTo(x,y);
		_this.on_slide(x, y);
	} else {	// if time's up
		clearInterval(_this.timer);
		_this.shiftTo(_this.destX,  _this.destY);
		_this.on_slide(_this.destX,  _this.destY);
		_this.on_slide_end(_this.destX, _this.destY);
		dw_Slidebar.current = null;
	}
}

dw_Slidebar.prepDrag = function (e) {
	var bar = this; // bar received onmousedown event
	var barId = this.id; // id of element mousedown event assigned to
	var _this = dw_Slidebar.col[barId]; // Slidebar instance
	dw_Slidebar.current = _this;
	_this.bar = bar;
	e = dw_Event.DOMit(e);
	if ( _this.timer ) { clearInterval(_this.timer); _this.timer = 0; }
	_this.downX = e.clientX; _this.downY = e.clientY;
	_this.startX = parseInt(bar.style.left);
	_this.startY = parseInt(bar.style.top);
	_this.on_drag_start(_this.startX, _this.startY);
	dw_Event.add( document, "mousemove", dw_Slidebar.doDrag, true );
	dw_Event.add( document, "mouseup",   dw_Slidebar.endDrag,  true );
	e.stopPropagation(); e.preventDefault();
}

dw_Slidebar.doDrag = function(e) {
	if ( !dw_Slidebar.current ) return; // avoid errors in ie if inappropriate selections
	var _this = dw_Slidebar.current;
	var bar = _this.bar;
	e = dw_Event.DOMit(e);
	var nx = _this.startX + e.clientX - _this.downX;
	var ny = _this.startY + e.clientY - _this.downY;
	nx = Math.min( Math.max( _this.minX, nx ), _this.maxX);
	ny = Math.min( Math.max( _this.minY, ny ), _this.maxY);
	_this.shiftTo(nx, ny);
	_this.on_drag(nx, ny);
	e.preventDefault(); e.stopPropagation();
}

dw_Slidebar.endDrag = function() {
	if ( !dw_Slidebar.current ) return; // avoid errors in ie if inappropriate selections
	var _this = dw_Slidebar.current;
	var bar = _this.bar;
	dw_Event.remove( document, "mousemove", dw_Slidebar.doDrag, true );
	dw_Event.remove( document, "mouseup",   dw_Slidebar.endDrag,  true );
	_this.on_drag_end( parseInt(bar.style.left), parseInt(bar.style.top) );
	dw_Slidebar.current = null;
}

dw_Slidebar.prototype.shiftTo = function(x, y) {
	if ( this.bar ) {
		this.bar.style.left = x + "px";
		this.bar.style.top = y + "px";
	}
}

/////////////////////////////////////////////////////////////////////
//  connect slidebar with scrollObj
dw_scrollObj.prototype.setUpScrollbar = function(barId, trkId, axis, offx, offy, bSize) {
	var scrollbar = new dw_Slidebar(barId, trkId, axis, offx, offy);
	if (axis == "v") {
		this.vBarId = barId;
	} else {
		this.hBarId = barId;
	}
	scrollbar.wndoId = this.id;
	scrollbar.bSizeDragBar = (bSize == false)? false: true;
	if (scrollbar.bSizeDragBar) {
		dw_Scrollbar_Co.setBarSize(this, scrollbar);
	}
	dw_Scrollbar_Co.setEvents(this, scrollbar);
}

// Coordinates slidebar and scrollObj
dw_Scrollbar_Co = {

	// This function is called for each scrollbar attached to a scroll area (change from previous version)
	setBarSize: function(scrollObj, barObj) {
		var lyr = document.getElementById(scrollObj.lyrId);
		var wn = document.getElementById(scrollObj.id);
		if ( barObj.axis == 'v' ) {
			var bar = document.getElementById(scrollObj.vBarId);
			bar.style.height = (lyr.offsetHeight > wn.offsetHeight)?
				barObj.trkHt / ( lyr.offsetHeight / wn.offsetHeight ) + "px":
				barObj.trkHt - ( 2 * barObj.minY ) + "px";
			barObj.maxY = barObj.trkHt - bar.offsetHeight - barObj.minY;
		} else if ( barObj.axis == 'h' ) {
			var bar = document.getElementById(scrollObj.hBarId);
			bar.style.width = (scrollObj.wd > wn.offsetWidth)?
				barObj.trkWd / ( scrollObj.wd / wn.offsetWidth ) + "px":
				barObj.trkWd - ( 2 * barObj.minX ) + "px";
			barObj.maxX = barObj.trkWd - bar.offsetWidth - barObj.minX;
		}
	},

	// Find bars associated with this scrollObj. if they have bSizeDragBar set true reevaluate size and reset position to top
	resetBars: function(scrollObj) {
		var barObj, bar;
		if (scrollObj.vBarId) {
			barObj = dw_Slidebar.col[scrollObj.vBarId];
			bar = document.getElementById(scrollObj.vBarId);
			bar.style.left = barObj.minX + "px"; bar.style.top = barObj.minY + "px";
			if (barObj.bSizeDragBar) {
				dw_Scrollbar_Co.setBarSize(scrollObj, barObj);
			}
		}
		if (scrollObj.hBarId) {
			barObj = dw_Slidebar.col[scrollObj.hBarId];
			bar = document.getElementById(scrollObj.hBarId);
			bar.style.left = barObj.minX + "px"; bar.style.top = barObj.minY + "px";
			if (barObj.bSizeDragBar) {
				dw_Scrollbar_Co.setBarSize(scrollObj, barObj);
			}
		}
	},

	setEvents: function(scrollObj, barObj) {
		// scrollObj
		this.addEvent(scrollObj, 'on_load', function() { dw_Scrollbar_Co.resetBars(scrollObj); } );
		this.addEvent(scrollObj, 'on_scroll_start', function() { dw_Scrollbar_Co.getBarRefs(scrollObj) } );
		this.addEvent(scrollObj, 'on_glidescroll_start', function() { dw_Scrollbar_Co.getBarRefs(scrollObj) } );
		this.addEvent(scrollObj, 'on_scroll', function(x,y) { dw_Scrollbar_Co.updateScrollbar(scrollObj, x, y) } );
		this.addEvent(scrollObj, 'on_glidescroll', function(x,y) { dw_Scrollbar_Co.updateScrollbar(scrollObj, x, y) } );
		this.addEvent(scrollObj, 'on_scroll_stop', function(x,y) { dw_Scrollbar_Co.updateScrollbar(scrollObj, x, y); } );
		this.addEvent(scrollObj, 'on_glidescroll_stop', function(x,y) { dw_Scrollbar_Co.updateScrollbar(scrollObj, x, y); } );
		this.addEvent(scrollObj, 'on_scroll_end', function(x,y) { dw_Scrollbar_Co.updateScrollbar(scrollObj, x, y); } );
		this.addEvent(scrollObj, 'on_glidescroll_end', function(x,y) { dw_Scrollbar_Co.updateScrollbar(scrollObj, x, y); } );

		// barObj
		this.addEvent(barObj, 'on_slide_start', function() { dw_Scrollbar_Co.getWndoLyrRef(barObj) } );
		this.addEvent(barObj, 'on_drag_start', function() { dw_Scrollbar_Co.getWndoLyrRef(barObj) } );
		this.addEvent(barObj, 'on_slide', function(x,y) { dw_Scrollbar_Co.updateScrollPosition(barObj, x, y) } );
		this.addEvent(barObj, 'on_drag', function(x,y) { dw_Scrollbar_Co.updateScrollPosition(barObj, x, y) } );
		this.addEvent(barObj, 'on_slide_end', function(x,y) { dw_Scrollbar_Co.updateScrollPosition(barObj, x, y); } );
		this.addEvent(barObj, 'on_drag_end', function(x,y) { dw_Scrollbar_Co.updateScrollPosition(barObj, x, y); } );

	},

	// Provide means to add functions to be invoked on pseudo events (on_load, on_scroll, etc)
	// without overwriting any others that may already be set
	// by Mark Wubben (see http://simonwillison.net/2004/May/26/addLoadEvent/)
	addEvent: function(o, ev, fp) {
		var oldEv = o[ev];
		if ( typeof oldEv != 'function' ) {
			//o[ev] = fp;
			// almost all the functions (on_scroll, on_drag, etc.) pass x,y
			o[ev] = function (x,y) { fp(x,y); }
		} else {
			o[ev] = function (x,y) {
				  oldEv(x,y );
				  fp(x,y);
			}
		}
	},

	// Keep position of dragBar in sync with position of layer when scrolled by other means (mouseover, etc.)
	updateScrollbar: function(scrollObj, x, y) { //
		var nx, ny;
		if ( scrollObj.vBar && scrollObj.maxY ) {
			var vBar = scrollObj.vBar;
			ny = -( y * ( (vBar.maxY - vBar.minY) / scrollObj.maxY ) - vBar.minY );
			ny = Math.min( Math.max(ny, vBar.minY), vBar.maxY);
			if (vBar.bar) { // ref to bar el
				nx = parseInt(vBar.bar.style.left);
				vBar.shiftTo(nx, ny);
			}
		}
		if ( scrollObj.hBar && scrollObj.maxX ) {
			var hBar = scrollObj.hBar;
			nx = -( x * ( (hBar.maxX - hBar.minX) / scrollObj.maxX ) - hBar.minX );
			nx = Math.min( Math.max(nx, hBar.minX), hBar.maxX);
			if (hBar.bar) {
				ny = parseInt(hBar.bar.style.top);
				hBar.shiftTo(nx, ny);
			}
		}
	},

	updateScrollPosition: function(barObj, x, y) { // on scrollbar movement
		var nx, ny; var wndo = barObj.wndo;
		if ( !wndo.lyr ) {
			wndo.lyr = document.getElementById(wndo.lyrId);
		}
		if (barObj.axis == "v") {
			nx = wndo.x; // floating point values for loaded layer's position held in shiftTo method
			ny = -(y - barObj.minY) * ( wndo.maxY / (barObj.maxY - barObj.minY) ) || 0;
		} else {
			ny = wndo.y;
			nx = -(x - barObj.minX) * ( wndo.maxX / (barObj.maxX - barObj.minX) ) || 0;
		}
		wndo.shiftTo(nx, ny);
	},

	// Scroll area may have both vertical and horizontal bars
	getBarRefs: function(scrollObj) { // References to Slidebar instance and dom element
		if ( scrollObj.vBarId ) {
			scrollObj.vBar = dw_Slidebar.col[scrollObj.vBarId];
			scrollObj.vBar.bar = document.getElementById(scrollObj.vBarId);
		}
		if ( scrollObj.hBarId ) {
			scrollObj.hBar = dw_Slidebar.col[scrollObj.hBarId];
			scrollObj.hBar.bar = document.getElementById(scrollObj.hBarId);
		}
	},

	getWndoLyrRef: function(barObj) {
		var wndo = barObj.wndo = dw_scrollObj.col[ barObj.wndoId ];
		if ( wndo && !wndo.lyr ) {
			wndo.lyr = document.getElementById(wndo.lyrId);
		}
	}

}