/*globals $, svgedit*/
/*jslint vars: true, eqeq: true, todo: true*/
/**
 * Package: svgedit.draw
 *
 * Licensed under the MIT License
 *
 * Copyright(c) 2011 Jeff Schiller
 */

// Dependencies:
// 1) jQuery
// 2) browser.js
// 3) svgutils.js

(function() {'use strict';

if (!svgedit.draw) {
	svgedit.draw = {};
}
// alias
var NS = svgedit.NS;
var LAYER_CLASS = svgedit.LAYER_CLASS;
var LAYER_CLASS_REGEX = svgedit.LAYER_CLASS_REGEX;

var visElems = 'a,circle,ellipse,foreignObject,g,image,line,path,polygon,polyline,rect,svg,text,tspan,use'.split(',');

var RandomizeModes = {
	LET_DOCUMENT_DECIDE: 0,
	ALWAYS_RANDOMIZE: 1,
	NEVER_RANDOMIZE: 2
};
var randomize_ids = RandomizeModes.LET_DOCUMENT_DECIDE;

/**
 * Add class 'layer' to the element
 *
 * Parameters:
 * @param {SVGGElement} elem - The SVG element to update
 */
function addLayerClass(elem) {
	var classes = elem.getAttribute('class');
	if (classes === null || classes === undefined || classes.length === 0) {
		elem.setAttribute('class', LAYER_CLASS);
	} else if (! LAYER_CLASS_REGEX.test(classes)) {
		elem.setAttribute('class', classes + ' ' + LAYER_CLASS);
	}
}

function createLayer(name, svgElem) {
	if (!svgElem) {
		return undefined;
	}
	var svgdoc = svgElem.ownerDocument;
	var new_layer = svgdoc.createElementNS(NS.SVG, "g");
	var layer_title = svgdoc.createElementNS(NS.SVG, "title");
	layer_title.textContent = name;
	new_layer.appendChild(layer_title);
	svgElem.appendChild(new_layer);
	return new_layer;
}


	/**
 * This class encapsulates the concept of a layer in the drawing. It can be constructed with
 * an existing group element or, with three parameters, will create a new layer group element.
 * @param {string} name - Layer name
 * @param {SVGGElement} group - SVG group element that constitutes the layer or null if a group should be created and added to the DOM..
 * @param {SVGGElement} svgElem - The SVG DOM element. If defined, use this to add
 * 		a new layer to the document.
 */
var Layer = svgedit.draw.Layer = function(name, group, svgElem) {
	this.name_ = name;
	this.group_ = group || createLayer(name, svgElem);

	addLayerClass(this.group_);
	svgedit.utilities.walkTree(this.group_, function(e){e.setAttribute("style", "pointer-events:inherit");});

	this.group_.setAttribute("style", svgElem ? "pointer-events:all" : "pointer-events:none");
};

/**
 * Get the layer's name.
 * @returns {string} The layer name
 */
Layer.prototype.getName = function() {
	return this.name_;
};

/**
 * Get the group element for this layer.
 * @returns {SVGGElement} The layer SVG group
 */
Layer.prototype.getGroup = function() {
	return this.group_;
};

/**
 * Active this layer so it takes pointer events.
 */
Layer.prototype.activate = function() {
	this.group_.setAttribute("style", "pointer-events:all");
};

/**
 * Deactive this layer so it does NOT take pointer events.
 */
Layer.prototype.deactivate = function() {
	this.group_.setAttribute("style", "pointer-events:none");
};

/**
 * Set this layer visible or hidden based on 'visible' parameter.
 * @param {boolean} visible - If true, make visible; otherwise, hide it.
 */
Layer.prototype.setVisible = function(visible) {
	var expected = visible === undefined || visible ? "inline" : "none";
	var oldDisplay = this.group_.getAttribute("display");
	if (oldDisplay !== expected) {
		this.group_.setAttribute("display", expected);
	}
};

/**
 * Is this layer visible?
 * @returns {boolean} True if visible.
 */
Layer.prototype.isVisible = function() {
	return this.group_.getAttribute('display') !== 'none';
};

/**
 * Get layer opacity.
 * @returns {number} Opacity value.
 */
Layer.prototype.getOpacity = function() {
	var opacity = this.group_.getAttribute('opacity');
	if (opacity === null || opacity === undefined) {
		return 1;
	}
	return parseFloat(opacity);
};

/**
 * Sets the opacity of this layer. If opacity is not a value between 0.0 and 1.0,
 * nothing happens.
 * @param {number} opacity - A float value in the range 0.0-1.0
 */
Layer.prototype.setOpacity = function(opacity) {
	if (typeof opacity === 'number' && opacity >= 0.0 && opacity <= 1.0) {
		this.group_.setAttribute('opacity', opacity);
	}
};

/**
 * Append children to this layer.
 * @param {SVGGElement} children - The children to append to this layer.
 */
Layer.prototype.appendChildren = function(children) {
	for (var i = 0; i < children.length; ++i) {
		this.group_.appendChild(children[i]);
	}
};

/**
 * Remove this layer's group from the DOM. No more functions on group can be called after this.
 * @param {SVGGElement} children - The children to append to this layer.
 * @returns {SVGGElement} The layer SVG group that was just removed.
 */
Layer.prototype.removeGroup = function() {
	var parent = this.group_.parentNode;
	var group = parent.removeChild(this.group_);
	this.group_ = undefined;
	return group;
};



	/**
 * Called to ensure that drawings will or will not have randomized ids.
 * The currentDrawing will have its nonce set if it doesn't already.
 * @param {boolean} enableRandomization - flag indicating if documents should have randomized ids
 * @param {svgedit.draw.Drawing} currentDrawing
 */
svgedit.draw.randomizeIds = function(enableRandomization, currentDrawing) {
	randomize_ids = enableRandomization === false ?
		RandomizeModes.NEVER_RANDOMIZE :
		RandomizeModes.ALWAYS_RANDOMIZE;

	if (randomize_ids == RandomizeModes.ALWAYS_RANDOMIZE && !currentDrawing.getNonce()) {
		currentDrawing.setNonce(Math.floor(Math.random() * 100001));
	} else if (randomize_ids == RandomizeModes.NEVER_RANDOMIZE && currentDrawing.getNonce()) {
		currentDrawing.clearNonce();
	}
};

/**
 * This class encapsulates the concept of a SVG-edit drawing
 * @param {SVGSVGElement} svgElem - The SVG DOM Element that this JS object
 *     encapsulates.  If the svgElem has a se:nonce attribute on it, then
 *     IDs will use the nonce as they are generated.
 * @param {String=svg_} [opt_idPrefix] - The ID prefix to use.
 */
svgedit.draw.Drawing = function(svgElem, opt_idPrefix) {
	if (!svgElem || !svgElem.tagName || !svgElem.namespaceURI ||
		svgElem.tagName != 'svg' || svgElem.namespaceURI != NS.SVG) {
		throw "Error: svgedit.draw.Drawing instance initialized without a <svg> element";
	}

	/**
	 * The SVG DOM Element that represents this drawing.
	 * @type {SVGSVGElement}
	 */
	this.svgElem_ = svgElem;
	
	/**
	 * The latest object number used in this drawing.
	 * @type {number}
	 */
	this.obj_num = 0;
	
	/**
	 * The prefix to prepend to each element id in the drawing.
	 * @type {String}
	 */
	this.idPrefix = opt_idPrefix || "svg_";
	
	/**
	 * An array of released element ids to immediately reuse.
	 * @type {Array.<number>}
	 */
	this.releasedNums = [];

	/**
	 * The z-ordered array of tuples containing layer names and <g> elements.
	 * The first layer is the one at the bottom of the rendering.
	 * @type {Layer[]}
	 */
	this.all_layers = [];

	/**
	 * Map of all_layers by name.
	 * @type {Object.<string,Layer>}
	 */
	this.layer_map = {};

	/**
	 * The current layer being used.
	 * @type {Layer}
	 */
	this.current_layer = null;

	/**
	 * The nonce to use to uniquely identify elements across drawings.
	 * @type {!String}
	 */
	this.nonce_ = '';
	var n = this.svgElem_.getAttributeNS(NS.SE, 'nonce');
	// If already set in the DOM, use the nonce throughout the document
	// else, if randomizeIds(true) has been called, create and set the nonce.
	if (!!n && randomize_ids != RandomizeModes.NEVER_RANDOMIZE) {
		this.nonce_ = n;
	} else if (randomize_ids == RandomizeModes.ALWAYS_RANDOMIZE) {
		this.setNonce(Math.floor(Math.random() * 100001));
	}
};

/**
 * @param {string} id Element ID to retrieve
 * @returns {Element} SVG element within the root SVGSVGElement
*/
svgedit.draw.Drawing.prototype.getElem_ = function (id) {
	if (this.svgElem_.querySelector) {
		// querySelector lookup
		return this.svgElem_.querySelector('#' + id);
	}
	// jQuery lookup: twice as slow as xpath in FF
	return $(this.svgElem_).find('[id=' + id + ']')[0];
};

/**
 * @returns {SVGSVGElement}
 */
svgedit.draw.Drawing.prototype.getSvgElem = function () {
	return this.svgElem_;
};

/**
 * @returns {!string|number} The previously set nonce
 */
svgedit.draw.Drawing.prototype.getNonce = function() {
	return this.nonce_;
};

/**
 * @param {!string|number} n The nonce to set
 */
svgedit.draw.Drawing.prototype.setNonce = function(n) {
	this.svgElem_.setAttributeNS(NS.XMLNS, 'xmlns:se', NS.SE);
	this.svgElem_.setAttributeNS(NS.SE, 'se:nonce', n);
	this.nonce_ = n;
};

/**
 * Clears any previously set nonce
 */
svgedit.draw.Drawing.prototype.clearNonce = function () {
	// We deliberately leave any se:nonce attributes alone,
	// we just don't use it to randomize ids.
	this.nonce_ = '';
};

/**
 * Returns the latest object id as a string.
 * @return {String} The latest object Id.
 */
svgedit.draw.Drawing.prototype.getId = function () {
	return this.nonce_ ?
		this.idPrefix + this.nonce_ + '_' + this.obj_num :
		this.idPrefix + this.obj_num;
};

/**
 * Returns the next object Id as a string.
 * @return {String} The next object Id to use.
 */
svgedit.draw.Drawing.prototype.getNextId = function () {
	var oldObjNum = this.obj_num;
	var restoreOldObjNum = false;

	// If there are any released numbers in the release stack, 
	// use the last one instead of the next obj_num.
	// We need to temporarily use obj_num as that is what getId() depends on.
	if (this.releasedNums.length > 0) {
		this.obj_num = this.releasedNums.pop();
		restoreOldObjNum = true;
	} else {
		// If we are not using a released id, then increment the obj_num.
		this.obj_num++;
	}

	// Ensure the ID does not exist.
	var id = this.getId();
	while (this.getElem_(id)) {
		if (restoreOldObjNum) {
			this.obj_num = oldObjNum;
			restoreOldObjNum = false;
		}
		this.obj_num++;
		id = this.getId();
	}
	// Restore the old object number if required.
	if (restoreOldObjNum) {
		this.obj_num = oldObjNum;
	}
	return id;
};

/**
 * Releases the object Id, letting it be used as the next id in getNextId().
 * This method DOES NOT remove any elements from the DOM, it is expected
 * that client code will do this.
 * @param {string} id - The id to release.
 * @returns {boolean} True if the id was valid to be released, false otherwise.
*/
svgedit.draw.Drawing.prototype.releaseId = function (id) {
	// confirm if this is a valid id for this Document, else return false
	var front = this.idPrefix + (this.nonce_ ? this.nonce_ + '_' : '');
	if (typeof id !== 'string' || id.indexOf(front) !== 0) {
		return false;
	}
	// extract the obj_num of this id
	var num = parseInt(id.substr(front.length), 10);

	// if we didn't get a positive number or we already released this number
	// then return false.
	if (typeof num !== 'number' || num <= 0 || this.releasedNums.indexOf(num) != -1) {
		return false;
	}
	
	// push the released number into the released queue
	this.releasedNums.push(num);

	return true;
};

/**
 * Returns the number of layers in the current drawing.
 * @returns {integer} The number of layers in the current drawing.
*/
svgedit.draw.Drawing.prototype.getNumLayers = function() {
	return this.all_layers.length;
};

/**
 * Check if layer with given name already exists
 * @param {string} name - The layer name to check
*/
svgedit.draw.Drawing.prototype.hasLayer = function (name) {
	return this.layer_map[name] !== undefined;
};


/**
 * Returns the name of the ith layer. If the index is out of range, an empty string is returned.
 * @param {integer} i - The zero-based index of the layer you are querying.
 * @returns {string} The name of the ith layer (or the empty string if none found)
*/
svgedit.draw.Drawing.prototype.getLayerName = function (i) {
	return i >= 0 && i < this.getNumLayers() ? this.all_layers[i].getName() : '';
};

/**
 * @returns {SVGGElement} The SVGGElement representing the current layer.
 */
svgedit.draw.Drawing.prototype.getCurrentLayer = function() {
	return this.current_layer ? this.current_layer.getGroup() : null;
};

/**
 * Returns the name of the currently selected layer. If an error occurs, an empty string 
 * is returned.
 * @returns {string} The name of the currently active layer (or the empty string if none found).
*/
svgedit.draw.Drawing.prototype.getCurrentLayerName = function () {
	return this.current_layer ? this.current_layer.getName() : '';
};

/**
 * Sets the current layer. If the name is not a valid layer name, then this
 * function returns false. Otherwise it returns true. This is not an
 * undo-able action.
 * @param {string} name - The name of the layer you want to switch to.
 * @returns {boolean} true if the current layer was switched, otherwise false
 */
svgedit.draw.Drawing.prototype.setCurrentLayer = function(name) {
	var layer = this.layer_map[name];
	if (layer) {
		if (this.current_layer) {
			this.current_layer.deactivate();
		}
		this.current_layer = layer;
		this.current_layer.activate();
		return true;
	}
	return false;
};


/**
 * Deletes the current layer from the drawing and then clears the selection.
 * This function then calls the 'changed' handler.  This is an undoable action.
 * @returns {SVGGElement} The SVGGElement of the layer removed or null.
 */
svgedit.draw.Drawing.prototype.deleteCurrentLayer = function() {
	if (this.current_layer && this.getNumLayers() > 1) {
		var oldLayerGroup = this.current_layer.removeGroup();
		this.identifyLayers();
		return oldLayerGroup;
	}
	return null;
};

/**
 * Find the layer name in a group element.
 * @param group The group element to search in.
 * @returns {string} The layer name or empty string.
 */
function findLayerNameInGroup(group) {
	var name = $("title", group).text();

	// Hack for Opera 10.60
	if (!name && svgedit.browser.isOpera() && group.querySelectorAll) {
		name = $(group.querySelectorAll('title')).text();
	}
	return name;
}

/**
 * Given a set of names, return a new unique name.
 * @param {string[]} existingLayerNames - Existing layer names.
 * @returns {string} - The new name.
 */
function getNewLayerName(existingLayerNames) {
	var i = 1;
	// TODO(codedread): What about internationalization of "Layer"?
	while (existingLayerNames.indexOf(("Layer " + i)) >= 0) { i++; }
	return "Layer " + i;
}

/**
 * Updates layer system and sets the current layer to the
 * top-most layer (last <g> child of this drawing).
*/
svgedit.draw.Drawing.prototype.identifyLayers = function() {
	this.all_layers = [];
	this.layer_map = {};
	var numchildren = this.svgElem_.childNodes.length;
	// loop through all children of SVG element
	var orphans = [], layernames = [];
	var layer = null;
	var childgroups = false;
	for (var i = 0; i < numchildren; ++i) {
		var child = this.svgElem_.childNodes.item(i);
		// for each g, find its layer name
		if (child && child.nodeType == 1) {
			if (child.tagName == "g") {
				childgroups = true;
				var name = findLayerNameInGroup(child);
				if (name) {
					layernames.push(name);
					layer = new Layer(name, child);
					this.all_layers.push(layer);
					this.layer_map[ name] = layer;
				} else {
					// if group did not have a name, it is an orphan
					orphans.push(child);
				}
			} else if (~visElems.indexOf(child.nodeName)) {
				// Child is "visible" (i.e. not a <title> or <defs> element), so it is an orphan
				orphans.push(child);
			}
		}
	}
	
	// If orphans or no layers found, create a new layer and add all the orphans to it
	if (orphans.length > 0 || !childgroups) {
		layer = new Layer(getNewLayerName(layernames), null, this.svgElem_);
		layer.appendChildren(orphans);
		this.all_layers.push(layer);
		this.layer_map[ name] = layer;
	} else {
		layer.activate();
	}
	this.current_layer = layer;
};

/**
 * Creates a new top-level layer in the drawing with the given name and 
 * sets the current layer to it.
 * @param {string} name - The given name. If the layer name exists, a new name will be generated.
 * @returns {SVGGElement} The SVGGElement of the new layer, which is
 * also the current layer of this drawing.
*/
svgedit.draw.Drawing.prototype.createLayer = function(name) {
	if (this.current_layer) {
		this.current_layer.deactivate();
	}
	// Check for duplicate name.
	if (name === undefined || name === null || name === '' || this.layer_map[name]) {
		name = getNewLayerName(Object.keys(this.layer_map));
	}
	var layer = new Layer(name, null, this.svgElem_);
	this.all_layers.push(layer);
	this.layer_map[ name] = layer;
	this.current_layer = layer;
	return layer.getGroup();
};

/**
 * Returns whether the layer is visible.  If the layer name is not valid,
 * then this function returns false.
 * @param {string} layername - The name of the layer which you want to query.
 * @returns {boolean} The visibility state of the layer, or false if the layer name was invalid.
*/
svgedit.draw.Drawing.prototype.getLayerVisibility = function(layername) {
	var layer = this.layer_map[layername];
	return layer ? layer.isVisible() : false;
};

/**
 * Sets the visibility of the layer. If the layer name is not valid, this
 * function returns false, otherwise it returns true. This is an
 * undo-able action.
 * @param {string} layername - The name of the layer to change the visibility
 * @param {boolean} bVisible - Whether the layer should be visible
 * @returns {?SVGGElement} The SVGGElement representing the layer if the
 *   layername was valid, otherwise null.
*/
svgedit.draw.Drawing.prototype.setLayerVisibility = function(layername, bVisible) {
	if (typeof bVisible !== 'boolean') {
		return null;
	}
	var layer = this.layer_map[layername];
	if (!layer) {return null;}
	layer.setVisible(bVisible);
	return layer.getGroup();
};


/**
 * Returns the opacity of the given layer.  If the input name is not a layer, null is returned.
 * @param {string} layername - name of the layer on which to get the opacity
 * @returns {?number} The opacity value of the given layer.  This will be a value between 0.0 and 1.0, or null
 * if layername is not a valid layer
*/
svgedit.draw.Drawing.prototype.getLayerOpacity = function(layername) {
	var layer = this.layer_map[layername];
	if (!layer) {return null;}
	return layer.getOpacity();
};

/**
 * Sets the opacity of the given layer.  If the input name is not a layer,
 * nothing happens. If opacity is not a value between 0.0 and 1.0, then
 * nothing happens.
 * @param {string} layername - Name of the layer on which to set the opacity
 * @param {number} opacity - A float value in the range 0.0-1.0
*/
svgedit.draw.Drawing.prototype.setLayerOpacity = function(layername, opacity) {
	if (typeof opacity !== 'number' || opacity < 0.0 || opacity > 1.0) {
		return;
	}
	var layer = this.layer_map[layername];
	if (layer) {
		layer.setOpacity(opacity);
	}
};

}());