var svgcanvas = null;

function SvgCanvas(c)
{

// private members
	var canvas = this;
	var container = c;
	var svgns = "http://www.w3.org/2000/svg";

	var idprefix = "svg_";
	var svgdoc  = c.ownerDocument;
	var svgroot = svgdoc.createElementNS(svgns, "svg");
	svgroot.setAttribute("width", 640);
	svgroot.setAttribute("height", 480);
	svgroot.setAttribute("id", "svgroot");
	svgroot.setAttribute("xmlns", svgns);
	container.appendChild(svgroot);

	var d_attr = null;
	var started = false;
	var obj_num = 1;
	var start_x = null;
	var start_y = null;
	var current_mode = "path";
	var current_fill = "none";
	var current_stroke = "black";
	var current_stroke_width = 1;
	var current_stroke_style = "none";
	var current_opacity = 1;
	var current_stroke_opacity = 1;
	var current_fill_opacity = 1;
	var current_font_size = "12pt";
	var current_font_family = "serif";
	var freehand_min_x = null;
	var freehand_max_x = null;
	var freehand_min_y = null;
	var freehand_max_y = null;
	var selected = null;
	var selectedOutline = null;
	var events = {};

// private functions
	var getId = function() {
	    if (events["getid"]) return call("getid",obj_num);
		return idprefix+obj_num;
	}

	var call = function(event, arg) {
		if (events[event]) {
			return events[event](this,arg);
		}
	}

	var assignAttributes = function(node, attrs) {
		for (i in attrs) {
			node.setAttributeNS(null, i, attrs[i]);
		}
	}

	// remove unneeded attributes
	// makes resulting SVG smaller
	var cleanupElement = function(element) {
		if (element.getAttribute('fill-opacity') == '1')
			element.removeAttribute('fill-opacity');
		if (element.getAttribute('opacity') == '1')
			element.removeAttribute('opacity');
		if (element.getAttribute('stroke') == 'none')
			element.removeAttribute('stroke');
		if (element.getAttribute('stroke-dasharray') == 'none')
			element.removeAttribute('stroke-dasharray');
		if (element.getAttribute('stroke-opacity') == '1')
			element.removeAttribute('stroke-opacity');
		if (element.getAttribute('stroke-width') == '1')
			element.removeAttribute('stroke-width');
		if (element.getAttribute('rx') == '0')
			element.removeAttribute('rx')
		if (element.getAttribute('ry') == '0')
			element.removeAttribute('ry')
	}

	var addSvgElementFromJson = function(data) {
		return canvas.updateElementFromJson(data)
	}

	var svgToString = function(elem, indent) {
		var out = "";
		if (elem) {
			var attrs = elem.attributes;
			var attr;
			var i;
			var childs = elem.childNodes;
			for (i=0; i<indent; i++) out += "  ";
			out += "<" + elem.nodeName;
			for (i=attrs.length-1; i>=0; i--) {
				attr = attrs.item(i);
				out += " " + attr.nodeName + "=\"" + attr.nodeValue+ "\"";
			}
			if (elem.hasChildNodes()) {
				out += ">";
				indent++;
				for (i=0; i<childs.length; i++)
				{
					if (childs.item(i).nodeType == 1) { // element node
						out = out + svgToString(childs.item(i), indent);
					} else if (childs.item(i).nodeType == 3) { // text node
						for (j=0; j<indent; j++) out += "  ";
						out += childs.item(i).nodeValue + "";
					}
				}
				indent--;
				for (i=0; i<indent; i++) out += "  ";
				out += "</" + elem.nodeName + ">";
			} else {
				out += " />";
			}
		}
		return out;
	} // end svgToString()

// public events
	// call this function to set the selected element
	// call this function with null to clear the selected element
	var selectElement = function(newSelected) 
	{
		if (selected == newSelected) return;
		
		// remove selected outline from previously selected element
		if (selected != null && selectedOutline != null) {
			// remove from DOM and store reference in JS
			selectedOutline = svgroot.removeChild(selectedOutline);
		}
		
		selected = newSelected;
		
		if (selected != null) {
			// we create this element for the first time here
			if (selectedOutline == null) {
				selectedOutline = addSvgElementFromJson({
					"element": "rect",
					"attr": {
						"id": "selectedBox",
						"fill": "none",
						"stroke": "blue",
						"stroke-width": "1",
						"stroke-dasharray": "5,5",
						"width": 1,
						"height": 1,
						// need to specify this style so that the selectedOutline is not selectable
						"style": "pointer-events:none",
					}
				});
				// TODO: add SMIL animate child on stroke-dashoffset here
				// This only works in Opera, but it appears to cause some
				// problem when more than one selected element is in the canvas?
				/*
				selectedOutline.appendChild( addSvgElementFromJson({
					"element": "animate",
					"attr": {
						"attributeName": "stroke-dashoffset",
						"repeatCount": "indefinite",
						"dur": "500ms",
						"from": "0",
						"to": "10",
					}
				}) );
				*/
			}
			// recalculate size and then re-append to bottom of document
			recalculateSelectedOutline();
			svgroot.appendChild(selectedOutline);
			
			// set all our current styles to the selected styles
			current_fill = selected.getAttribute("fill");
			current_fill_opacity = selected.getAttribute("fill-opacity");
			current_stroke = selected.getAttribute("stroke");
			current_stroke_opacity = selected.getAttribute("stroke-opacity");
			current_stroke_width = selected.getAttribute("stroke-width");
			current_stroke_style = selected.getAttribute("stroke-dasharray");
			if (selected.tagName == "text") {
				current_font_size = selected.getAttribute("font-size");
				current_font_family = selected.getAttribute("font-family");
			}
		}
		
		call("selected", selected);
	}
	
	var recalculateSelectedOutline = function() {
		if (selected != null && selectedOutline != null) {
			var bbox = selected.getBBox();
			var sw = selected.getAttribute("stroke-width");
			var offset = 1;
			if (sw != null && sw != "") {
				offset += parseInt(sw)/2;
			}
			if (selected.tagName == "text") {
				offset += 2;
			}
			selectedOutline.setAttribute("x", bbox.x-offset);
			selectedOutline.setAttribute("y", bbox.y-offset);
			selectedOutline.setAttribute("width", bbox.width+(offset<<1));
			selectedOutline.setAttribute("height", bbox.height+(offset<<1));
		}	
	}

	var mouseDown = function(evt)
	{
		var x = evt.pageX - container.offsetLeft;
		var y = evt.pageY - container.offsetTop;
		switch (current_mode) {
			case "select":
				started = true;
				start_x = x;
				start_y = y;
				var t = evt.target;
				if (t != svgroot) {
					selectElement(t);
				}
				break;
			case "fhellipse":
			case "fhrect":
			case "path":
				started = true;
				start_x = x;
				start_y = y;
				d_attr = "M" + x + "," + y + " ";
				addSvgElementFromJson({
					"element": "path",
					"attr": {
						"d": d_attr,
						"id": getId(),
						"fill": "none",
						"stroke": current_stroke,
						"stroke-width": current_stroke_width,
						"stroke-dasharray": current_stroke_style,
						"stroke-opacity": current_stroke_opacity,
						"opacity": current_opacity / 2
					}
				});
				freehand_min_x = x;
				freehand_max_x = x;
				freehand_min_y = y;
				freehand_max_y = y;
				break;
			case "square":
			case "rect":
				started = true;
				start_x = x;
				start_y = y;
				addSvgElementFromJson({
					"element": "rect",
					"attr": {
						"x": x,
						"y": y,
						"width": 0,
						"height": 0,
						"id": getId(),
						"fill": current_fill,
						"stroke": current_stroke,
						"stroke-width": current_stroke_width,
						"stroke-dasharray": current_stroke_style,
						"stroke-opacity": current_stroke_opacity,
						"fill-opacity": current_fill_opacity,
						"opacity": current_opacity / 2
					}
				});
				break;
			case "line":
				started = true;
				addSvgElementFromJson({
					"element": "line",
					"attr": {
						"x1": x,
						"y1": y,
						"x2": x,
						"y2": y,
						"id": getId(),
						"stroke": current_stroke,
						"stroke-width": current_stroke_width,
						"stroke-dasharray": current_stroke_style,
						"stroke-opacity": current_stroke_opacity,
						"opacity": current_opacity / 2
					}
				});
				break;
			case "circle":
				started = true;
				addSvgElementFromJson({
					"element": "circle",
					"attr": {
						"cx": x,
						"cy": y,
						"r": 0,
						"id": getId(),
						"fill": current_fill,
						"stroke": current_stroke,
						"stroke-width": current_stroke_width,
						"stroke-dasharray": current_stroke_style,
						"stroke-opacity": current_stroke_opacity,
						"fill-opacity": current_fill_opacity,
						"opacity": current_opacity / 2
					}
				});
				break;
			case "ellipse":
				started = true;
				addSvgElementFromJson({
					"element": "ellipse",
					"attr": {
						"cx": x,
						"cy": y,
						"rx": 0,
						"ry": 0,
						"id": getId(),
						"fill": current_fill,
						"stroke": current_stroke,
						"stroke-width": current_stroke_width,
						"stroke-dasharray": current_stroke_style,
						"stroke-opacity": current_stroke_opacity,
						"fill-opacity": current_fill_opacity,
						"opacity": current_opacity / 2
					}
				});
				break;
			case "text":
				started = true;
				var newText = addSvgElementFromJson({
					"element": "text",
					"attr": {
						"x": x,
						"y": y,
						"id": getId(),
						"fill": current_fill,
						"stroke": current_stroke,
						"stroke-width": current_stroke_width,
						"stroke-dasharray": current_stroke_style,
						"stroke-opacity": current_stroke_opacity,
						"fill-opacity": current_fill_opacity,
						// fix for bug where text elements were always 50% opacity
						"opacity": current_opacity,
						"font-size": current_font_size,
						"font-family": current_font_family,
					}
				});
				newText.textContent = "text";
				break;
		}
	}

	var mouseMove = function(evt)
	{
		if (!started) return;
		var x = evt.pageX - container.offsetLeft;
		var y = evt.pageY - container.offsetTop;
		var shape = svgdoc.getElementById(getId());
		switch (current_mode)
		{
			case "select":
				// we temporarily use a translate on the element being dragged
				// this transform is removed upon mouseUp and the element is relocated to the
				// new location
				if (selected != null && selectedOutline != null) {
					var dx = x - start_x;
					var dy = y - start_y;
					selected.setAttributeNS(null, "transform", "translate(" + dx + "," + dy + ")");
					selectedOutline.setAttributeNS(null, "transform", "translate(" + dx + "," + dy + ")");
				}
				break;
			case "text":
				shape.setAttribute("x", x);
				shape.setAttribute("y", y);
				break;
			case "line":
				shape.setAttributeNS(null, "x2", x);
				shape.setAttributeNS(null, "y2", y);
				break;
			case "square":
				var size = Math.max( Math.abs(x - start_x), Math.abs(y - start_y) );
				shape.setAttributeNS(null, "width", size);
				shape.setAttributeNS(null, "height", size);
				shape.setAttributeNS(null, "x", start_x < x ? start_x : start_x - size);
				shape.setAttributeNS(null, "y", start_y < y ? start_y : start_y - size);
				break;
			// case "select":
			case "rect":
				shape.setAttributeNS(null, "x", Math.min(start_x,x));
				shape.setAttributeNS(null, "y", Math.min(start_y,y));
				shape.setAttributeNS(null, "width", Math.abs(x-start_x));
				shape.setAttributeNS(null, "height", Math.abs(y-start_y));
				break;
			case "circle":
				var cx = shape.getAttributeNS(null, "cx");
				var cy = shape.getAttributeNS(null, "cy");
				var rad = Math.sqrt( (x-cx)*(x-cx) + (y-cy)*(y-cy) );
				shape.setAttributeNS(null, "r", rad);
				break;
			case "ellipse":
				var cx = shape.getAttributeNS(null, "cx");
				var cy = shape.getAttributeNS(null, "cy");
				shape.setAttributeNS(null, "rx", Math.abs(x - cx) );
				shape.setAttributeNS(null, "ry", Math.abs(y - cy) );
				break;
			case "fhellipse":
			case "fhrect":
				freehand_min_x = Math.min(x, freehand_min_x);
				freehand_max_x = Math.max(x, freehand_max_x);
				freehand_min_y = Math.min(y, freehand_min_y);
				freehand_max_y = Math.max(y, freehand_max_y);
			// break; missing on purpose
			case "path":
				var dx = x - start_x;
				var dy = y - start_y;
				start_x = x;
				start_y = y;
				d_attr += "l" + dx + "," + dy + " ";
				shape.setAttributeNS(null, "d", d_attr);
				break;
		}
	}

	var mouseUp = function(evt)
	{
		if (!started) return;

		started = false;
		var element = svgdoc.getElementById(getId());
		var keep = false;
		switch (current_mode)
		{
			case "select":
				if (selected != null) {
					var dx = evt.pageX - container.offsetLeft - start_x;
					var dy = evt.pageY - container.offsetTop - start_y;
					selected.removeAttribute("transform");
					selectedOutline.removeAttribute("transform");
					switch (selected.tagName)
					{
						case "path":
							// extract the x,y from the path, adjust it and write back the new path
							var M = selected.pathSegList.getItem(0);
							var newd = "M" + (M.x+dx) + "," + (M.y+dy);
							for (var i = 1; i < selected.pathSegList.numberOfItems; ++i) {
								var l = selected.pathSegList.getItem(i);
								newd += " l" + l.x + "," + l.y;
							}
							selected.setAttributeNS(null, "d", newd);
							break;
						case "line":
							var x1 = parseInt(selected.getAttributeNS(null, "x1"));
							var y1 = parseInt(selected.getAttributeNS(null, "y1"));
							var x2 = parseInt(selected.getAttributeNS(null, "x2"));
							var y2 = parseInt(selected.getAttributeNS(null, "y2"));
							selected.setAttributeNS(null, "x1", x1+dx);
							selected.setAttributeNS(null, "y1", y1+dy);
							selected.setAttributeNS(null, "x2", x2+dx);
							selected.setAttributeNS(null, "y2", y2+dy);
							break;
						case "circle":
						case "ellipse":
							var cx = parseInt(selected.getAttributeNS(null, "cx"));
							var cy = parseInt(selected.getAttributeNS(null, "cy"));
							selected.setAttributeNS(null, "cx", cx+dx);
							selected.setAttributeNS(null, "cy", cy+dy);
							break;
						default: // rect
							var x = parseInt(selected.getAttributeNS(null, "x"));
							var y = parseInt(selected.getAttributeNS(null, "y"));
							selected.setAttributeNS(null, "x", x+dx);
							selected.setAttributeNS(null, "y", y+dy);
							break;
					}
					var sx = parseInt(selectedOutline.getAttributeNS(null, "x"));
					var sy = parseInt(selectedOutline.getAttributeNS(null, "y"));
					selectedOutline.setAttributeNS(null, "x", sx+dx);
					selectedOutline.setAttributeNS(null, "y", sy+dy);
					// we return immediately from select so that the obj_num is not incremented
					return;
				}
				break;
			case "path":
				keep = true;
				break;
			case "line":
				keep = (element.getAttribute('x1') != element.getAttribute('x2') ||
				        element.getAttribute('y1') == element.getAttribute('y2'));
				break;
			case "square":
			case "rect":
				keep = (element.getAttribute('width') != 0 ||
				        element.getAttribute('height') != 0);
				break;
			case "circle":
				keep = (element.getAttribute('r') != 0);
				break;
			case "ellipse":
				keep = (element.getAttribute('rx') != 0 ||
				        element.getAttribute('ry') != 0);
				break;
			case "fhellipse":
				if ((freehand_max_x - freehand_min_x) > 0 &&
				    (freehand_max_y - freehand_min_y) > 0) {
					call("changed",addSvgElementFromJson({
						"element": "ellipse",
						"attr": {
							"cx": (freehand_min_x + freehand_max_x) / 2,
							"cy": (freehand_min_y + freehand_max_y) / 2,
							"rx": (freehand_max_x - freehand_min_x) / 2,
							"ry": (freehand_max_y - freehand_min_y) / 2,
							"id": getId(),
							"fill": current_fill,
							"stroke": current_stroke,
							"stroke-width": current_stroke_width,
							"stroke-dasharray": current_stroke_style,
							"opacity": current_opacity,
							"stroke-opacity": current_stroke_opacity,
							"fill-opacity": current_fill_opacity
						}
					}));
				}
				break;
			case "fhrect":
				if ((freehand_max_x - freehand_min_x) > 0 &&
				    (freehand_max_y - freehand_min_y) > 0) {
					call("changed",addSvgElementFromJson({
						"element": "rect",
						"attr": {
							"x": freehand_min_x,
							"y": freehand_min_y,
							"width": (freehand_max_x - freehand_min_x),
							"height": (freehand_max_y - freehand_min_y),
							"id": getId(),
							"fill": current_fill,
							"stroke": current_stroke,
							"stroke-width": current_stroke_width,
							"stroke-dasharray": current_stroke_style,
							"opacity": current_opacity,
							"stroke-opacity": current_stroke_opacity,
							"fill-opacity": current_fill_opacity
						}
					}));
				}
				break;
			case "text":
				keep = true;
				selectElement(element);
				break;
		}
		d_attr = null;
		obj_num++;
		if (!keep) {
			element.parentNode.removeChild(element);
			element = null;
		} else if (element != null) {
			element.setAttribute("opacity", current_opacity);
			cleanupElement(element);
			call("changed",element);
		}
	}

// public functions

	this.save = function() {
		// remove the selected outline before serializing
		this.selectNone();
		var str = "<?xml version=\"1.0\" standalone=\"no\"?>"
		str += "<!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.1//EN\" \"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd\">";
		str += svgToString(svgroot, 0);
		this.saveHandler(str);
	}

	this.clear = function() {
		var nodes = svgroot.childNodes;
		var len = svgroot.childNodes.length;
		var i = 0;
		this.selectNone();
		for(var rep = 0; rep < len; rep++){
			if (nodes[i].nodeType == 1) { // element node
				nodes[i].parentNode.removeChild(nodes[i]);
			} else {
				i++;
			}
		}
		call("cleared");
	}

	this.getMode = function() {
		return current_mode;
	}

	this.setMode = function(name) {
		current_mode = name;
	}

	this.getStrokeColor = function() {
		return current_stroke;
	}

	this.setStrokeColor = function(color) {
		current_stroke = color;
		if (selected != null) {
			selected.setAttribute("stroke", color);
			call("changed", selected);
		}
	}

	this.getFillColor = function() {
		return current_fill;
	}

	this.setFillColor = function(color) {
		current_fill = color;
		if (selected != null) {
			selected.setAttribute("fill", color);
			call("changed", selected);
		}
	}

	this.getStrokeWidth = function() {
		return current_stroke_width;
	}

	this.setStrokeWidth = function(val) {
		current_stroke_width = val;
		if (selected != null) {
			selected.setAttribute("stroke-width", val);
			recalculateSelectedOutline();
			call("changed", selected);
		}
	}

	this.getStrokeStyle = function() {
		return current_stroke_style;
	}

	this.setStrokeStyle = function(val) {
		current_stroke_style = val;
		if (selected != null) {
			selected.setAttribute("stroke-dasharray", val);
			call("changed", selected);
		}
	}

	this.getOpacity = function() {
		return current_opacity;
	}

	this.setOpacity = function(val) {
		current_opacity = val;
		if (selected != null) {
			selected.setAttribute("opacity", val);
			call("changed", selected);
		}
	}

	this.getFillOpacity = function() {
		return current_fill_opacity;
	}

	this.setFillOpacity = function(val) {
		current_fill_opacity = val;
		if (selected != null) {
			selected.setAttribute("fill-opacity", val);
			call("changed", selected);
		}
	}

	this.getStrokeOpacity = function() {
		return current_stroke_opacity;
	}

	this.setStrokeOpacity = function(val) {
		current_stroke_opacity = val;
		if (selected != null) {
			selected.setAttribute("stroke-opacity", val);
			call("changed", selected);
		}
	}

	this.updateElementFromJson = function(data) {
		var shape = svgdoc.getElementById(data.attr.id);
		var newshape = !shape;
		if (newshape) shape = svgdoc.createElementNS(svgns, data.element);
		assignAttributes(shape, data.attr);
		cleanupElement(shape);
		if (newshape) svgroot.appendChild(shape);
		return shape;
	}

	this.each = function(cb) {
		$(svgroot).children().each(cb);
	}

	this.bind = function(event, f) {
		events[event] = f;
	}

	this.setIdPrefix = function(p) {
		idprefix = p;
	}

	this.getFontFamily = function() {
		return current_font_family;
	}
        
	this.setFontFamily = function(val) {
    	current_font_family = val;
		if (selected != null) {
			selected.setAttribute("font-family", val);
			recalculateSelectedOutline();
			call("changed", selected);
		}
	}

	this.getFontSize = function() {
		return current_font_size;
	}
	
	this.setFontSize = function(val) {
		current_font_size = val;
		if (selected != null) {
			selected.setAttribute("font-size", val);
			recalculateSelectedOutline();
			call("changed", selected);
		}
	}
	
	this.getText = function() {
		if (selected == null) { return ""; }
		return selected.textContent;
	}
	
	this.setTextContent = function(val) {
		if (selected != null) {
			selected.textContent = val;
			recalculateSelectedOutline();
			call("changed", selected);
		}
	}
	
	this.setRectRadius = function(val) {
		if (selected != null && selected.tagName == "rect") {
			selected.setAttribute("rx", val);
			selected.setAttribute("rx", val);
			call("changed", selected);
		}
	}
	
	$(container).mouseup(mouseUp);
	$(container).mousedown(mouseDown);
	$(container).mousemove(mouseMove);

	this.saveHandler = function(svg) {
		//alert(svg);
		window.open("data:image/svg+xml;base64," + Utils.encode64(svg));
	}

	this.selectNone = function() {
		selectElement(null);
	}

	this.deleteSelectedElement = function() {
		if (selected != null) {
			var t = selected;
			// this will unselect the element (and remove the selectedOutline)
			selectElement(null);
			t.parentNode.removeChild(t);
			call("deleted",t);
		}
		else {
			alert("Error!  Nothing selected!");
		}
	}

}

// Static class for various utility functions

var Utils = {

// This code was written by Tyler Akins and has been placed in the
// public domain.  It would be nice if you left this header intact.
// Base64 code from Tyler Akins -- http://rumkin.com

	"_keyStr" : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",

	"encode64" : function(input) {
		var output = "";
		var chr1, chr2, chr3;
		var enc1, enc2, enc3, enc4;
		var i = 0;

		do {
			chr1 = input.charCodeAt(i++);
			chr2 = input.charCodeAt(i++);
			chr3 = input.charCodeAt(i++);

			enc1 = chr1 >> 2;
			enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
			enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
			enc4 = chr3 & 63;

			if (isNaN(chr2)) {
				enc3 = enc4 = 64;
			} else if (isNaN(chr3)) {
				enc4 = 64;
			}

			output = output + this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) +
				this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4);
		} while (i < input.length);

		return output;
	},

	"decode64" : function(input) {
		var output = "";
		var chr1, chr2, chr3;
		var enc1, enc2, enc3, enc4;
		var i = 0;

		// remove all characters that are not A-Z, a-z, 0-9, +, /, or =
		input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

		do {
			enc1 = this._keyStr.indexOf(input.charAt(i++));
			enc2 = this._keyStr.indexOf(input.charAt(i++));
			enc3 = this._keyStr.indexOf(input.charAt(i++));
			enc4 = this._keyStr.indexOf(input.charAt(i++));

			chr1 = (enc1 << 2) | (enc2 >> 4);
			chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
			chr3 = ((enc3 & 3) << 6) | enc4;

			output = output + String.fromCharCode(chr1);

			if (enc3 != 64) {
				output = output + String.fromCharCode(chr2);
			}
			if (enc4 != 64) {
				output = output + String.fromCharCode(chr3);
			}
		} while (i < input.length);

		return output;
	}
}