var Object = require('./object');

/**
 * Creates a object from a XML specification.
 */
module.exports = new Class({
	 Extends: Object
	,_addedMap: {}
	,_contexts: null
	
	,add: function(id, object) {
		this._addedMap[id] = object;
	}
	
	,setParent: function(parentResult) {
		this._parentResult = parentResult;
		
		if (parentResult && !this.signalData)
			this.signalData = parentResult.builder.signalData;
	}
	
	,getMain: function(result) {
		return result.objects[this._mainContext];
	}
	
	,getById: function(result, objectId) {
		var index = this._contextMap[objectId];
		
		if (index !== undefined)
			return result.objects[index];

		var object = this._addedMap[objectId];

		if (object !== undefined)
			return object;

		if (this._parentResult)
			return this._parentResult.getById(objectId);

		return null;
	}
	
	,getByTagName: function(result, tagName) {	
		var tags = this._tags[tagName];
	
		if (tags) {
			var arr = new Array(tags.length);
			
			for (var i = 0; i < tags.length; i++)
				arr[i] = result.objects[tags[i]];

			return arr;
		}
		
		return [];
	}

	/**
	 * Compiles an XML file.
	 *
	 * @path String The XML path
	 * @dstDocument Document The document used to create the nodes
	 * @return %true on success, %false othersise
	 */
	,loadXml: function(path, dstDocument) {
		this._path = path;
		return this.loadFromXmlDoc(Vn.getXml(path), dstDocument);
	}
	
	,loadFromString: function(xmlString, dstDocument) {
		var parser = new DOMParser();
		var xmlDoc = parser.parseFromString(xmlString, 'text/xml');
		return this.loadFromXmlDoc(xmlDoc, dstDocument);
	}
	
	,loadFromXmlDoc: function(xmlDoc, dstDocument, scope) {	
		if (!xmlDoc)
			return false;

		this._compileInit(dstDocument, scope);

		var docElement = xmlDoc.documentElement;
		
		if (docElement.tagName !== 'vn') {
			this._showError('Malformed XML');
			this._contexts = null;
			return false;
		}

		var childs = docElement.childNodes;

		if (childs)
		for (var i = 0; i < childs.length; i++)
			this._compileNode(childs[i]);

		this._compileEnd();
		return true;
	}
	
	/**
	 * Compiles a single DOM node.
	 *
	 * @path Node The DOM node
	 * @dstDocument Document The document used to create the nodes
	 * @return %true on success, %false othersise
	 */
	,loadXmlFromNode: function(node, dstDocument, scope) {
		this._compileInit(dstDocument, scope);
		this._mainContext = this._compileNode(node).id;
		this._compileEnd();
		return true;
	}
	
	,load: function() {
		if (this._contexts === null)
			return null;
	
		var contexts = this._contexts;
		var len = contexts.length;
		var objects = new Array(len);
	
		for (var i = 0; i < len; i++) {
			var context = contexts[i];
			
			if (context.tagName)
				objects[i] = this.elementInstantiate(context);
			else if (context.klass)
				objects[i] = this.objectInstantiate(context);
			else
				objects[i] = this.textInstantiate(context);
		}
		
		return new BuilderResult(this, objects);
	}
	
	,link: function(result, self, scope) {
		var objects = result.objects;
	
		for (var i = this._links.length - 1; i >= 0; i--) {
			var l = this._links[i];
			var addedObject = this._addedMap[l.objectId];

			if (addedObject) {
				if (l.prop)
					objects[l.context.id][l.prop] = addedObject;
				else
					objects[l.context.id].appendChild(addedObject);
			} else
				this._showError('Referenced unexistent object with id \'%s\'',
					l.objectId);
		}

		this.linkExpr(result, self, scope);

		var contexts = this._contexts;
		for (var i = 0; i < contexts.length; i++) {
			var context = contexts[i];
			var object = objects[i];

			if (context.tagName)
				this.elementLink(context, object, objects, result);
			else if (context.klass)
				this.objectLink(context, object, objects, result);
		}
	}

	,fnExpr(expr) {
		return new Function(this._scopeArgs,
			'"use strict"; return ' + expr + ';'
		);
	}
	
	,matchExpr(value) {
		const match = /^{{(.*)}}$/.exec(value);
		if (!match) return null;
		return this.fnExpr(match[1]);
	}

	,linkExpr(result, self, scope) {
		const contexts = this._contexts;
		const objects = result.objects;
		let args = [_]

		if (scope) args = args.concat(scope);

		for (let i = 0; i < contexts.length; i++) {
			const context = contexts[i];
			const object = objects[i];

			if (context.exprs) {
				const values = [];
				for (expr of context.exprs) {
					let value = undefined;
					try {
						value = expr.apply(self, args);
					} catch (e) {
						console.warn('Expression error:', e.message);
						continue;
					}
					values.push(value);
				}

				let k = 0;
				const text = context.text.replace(/{{\d+}}/g, function() {
					return values[k++];
				});
				object.textContent = text;
			} else {
				const dynProps = context.dynProps;

				for (const prop in dynProps) {
					let value = undefined;
					try {
						value = dynProps[prop].apply(self, args);
					} catch (e) {
						console.warn('Expression error:', e.message);
						continue;
					}

					if (context.tagName)
						object.setAttribute(prop, value);
					else
						object[prop] = value;
				}
			}
		}
	}

	,_compileInit: function(dstDocument, scope) {
		this._path = null;
		this._tags = {};
		this._contexts = [];
		this._contextMap = {};
		this._links = [];
		this._mainContext = null;
		this._doc = dstDocument ? dstDocument : document;
		
		this._scope = ['_'];
		if (scope)
			this._scope = this._scope.concat(scope);
		this._scopeArgs = this._scope.join(',');
	}
	
	,_compileEnd: function() {
		for (var i = this._links.length - 1; i >= 0; i--) {
			var l = this._links[i];
			var contextId = this._contextMap[l.objectId];
			
			if (contextId != undefined) {
				if (l.prop)
					l.context.objectProps[l.prop] = contextId;
				else
					l.context.childs.push(contextId);
				
				this._links.splice(i, 1);
			} else {
				var object = this._addedMap[l.objectId];
				
				if (!object && this._parentResult)
					object = this._parentResult.getById(l.objectId);
			
				if (object) {
					l.context.props[l.prop] = object;
					this._links.splice(i, 1);
				}
			}
		}
	}

	,_compileNode: function(node) {
		var context = null;
		var tagName = null;

		if (node.nodeType === Node.ELEMENT_NODE)
			tagName = node.tagName.toLowerCase();
		else if (node.nodeType !== Node.TEXT_NODE
		|| /^[\n\r\t]*$/.test(node.textContent))
			return null;
			
		var context = 
			   this.textCompile(node, tagName)
			|| this.objectCompile(node, tagName)
			|| this.elementCompile(node, tagName);

		context.id = this._contexts.length;

		if (tagName) {
			var nodeId = node.getAttribute('id');
	
			if (nodeId)
				this._contextMap[nodeId] = context.id;

			var tags = this._tags[tagName];
		
			if (!tags)
				this._tags[tagName] = tags = [];
			
			tags.push(context.id);
		}

		this._contexts.push(context);
		return context;
	}

	/**
	 * Creates a text node context.
	 */
	,textCompile: function(node, tagName) {
		if (!tagName) {
			let text = node.textContent;

			if (/{{.*}}/.test(text)) {
				let i = 0;
				const self = this;
				const exprs = [];
				text = text.replace(/{{((?:(?!}}).)*)}}/g, function(match, capture) {
					exprs.push(self.fnExpr(capture));
					return `{{${i++}}}`;
				});

				return {text, exprs};
			} else
				return {text};
		} else if (tagName === 't')
			return {text: _(node.firstChild.textContent)}; 
		else
			return null;
	}
	
	,textInstantiate: function(context) {
		return this._doc.createTextNode(context.exprs ? '' : context.text);
	}
	
	/**
	 * Creates a object context.
	 */
	,objectCompile: function(node, tagName) {
		var klass = vnCustomTags[tagName];
		
		if (!klass)
			return null;

		var props = {};
		var dynProps = {};
		var objectProps = {};
		var childs = [];
		var events = {};
			
		var context = {
			klass: klass,
			props: props,
			dynProps: dynProps,
			objectProps: objectProps,
			childs: childs,
			events: events,
			custom: null
		};

		var a = node.attributes;

		for (var i = 0; i < a.length; i++) {
			var attribute = a[i].nodeName;
			var value = a[i].nodeValue;

			if (this._isEvent(attribute)) {
				var handler = this._getMethod(value)
				
				if (handler)
					events[attribute.substr(3)] = handler;
			} else if (!/^(id|property)$/.test(attribute)) {
				this.propCompile(context, klass, props, dynProps,
					node, attribute, value);
			}
		}
		
		var childNodes = node.childNodes;

		if (childNodes)
		for (var i = 0; i < childNodes.length; i++) {
			var child = childNodes[i];
			var isElement = child.nodeType === Node.ELEMENT_NODE;
			var childTagName = isElement ? child.tagName.toLowerCase() : null;
			var childContext;
			
			if (childTagName === 'pointer') {
				this._addLink(context, null, child.getAttribute('object'));
			} else if (childTagName === 'custom') {
				context.custom = child;
			} else if (childContext = this._compileNode(child)) {
				var prop = isElement ? child.getAttribute('property') : null;
	
				if (prop) {
					prop = prop.replace(/-./g, this._replaceFunc); 
					objectProps[prop] = childContext.id;
				} else
					childs.push(childContext.id);
			}
		}

		return context;
	}

	,propCompile: function(context, klass, props, dynProps, node, attribute, value) {
		var isLink = false;
		var newValue = null;
		var propName = attribute.replace(/-./g, this._replaceFunc);
		var propInfo = klass.Properties[propName];

		if (!propInfo) {
			this._showError('Attribute \'%s\' not valid for tag \'%s\'',
				attribute, node.tagName);
			return;
		}
		if (!value) {
			this._showError('Attribute \'%s\' empty on tag \'%s\'',
				attribute, node.tagName);
			return;
		}

		const expr = this.matchExpr(value);

		if (expr) {
			dynProps[propName] = expr;
		} else {
			switch (propInfo.type) {
			case Boolean:
				newValue = (/^(true|1)$/i).test(value);
				break;
			case Number:
				newValue = 0 + new Number(value);
				break;
			case String:
				newValue = this._translateValue(value);
				break;
			case Function:
				var method = this._getMethod(value);
				newValue = method ? method.bind(this.signalData) : null;
				break;
			default:
			if (propInfo.enumType)
				newValue = propInfo.enumType[value];
			else if (propInfo.type instanceof Function)
				isLink = true;
			}
			
			if (isLink)
				this._addLink(context, propName, value);
			else if (newValue !== null && newValue !== undefined)
				props[propName] = newValue;
			else
				this._showError('Attribute \'%s\' invalid for tag \'%s\'',
					attribute, node.tagName);
		}
	}
	
	,objectInstantiate: function(context) {
		return new context.klass();
	}
	
	,objectLink: function(context, object, objects, res) {
		object.setProperties(context.props);
	
		var objectProps = context.objectProps;
		for (var prop in objectProps)
			object[prop] = objects[objectProps[prop]];

		var childs = context.childs;
		for (var i = 0; i < childs.length; i++)
			object.appendChild(objects[childs[i]]);
		
		var events = context.events;
		for (var event in events)
			object.on(event, events[event], this.signalData);

		if (context.custom)
			object.loadXml(res, context.custom);
	}
	
	/**
	 * Creates a HTML node context.
	 */
	,elementCompile: function(node, tagName) {
		var attributes = {};
		var dynProps = {};
		var childs = [];
		var events = {};
		var handler;

		var a = node.attributes;

		for (var i = 0; i < a.length; i++) {
			var attribute = a[i].nodeName;
			var value = a[i].nodeValue;
			const expr = this.matchExpr(value);
	
			if (expr) {
				dynProps[attribute] = expr;
			} else if (this._isEvent(attribute)) {
				var handler = this._getMethod(value);
				
				if (handler)
					events[attribute.substr(3)] = handler;
			} else if (attribute !== 'id')
				attributes[attribute] = this._translateValue(value);
		}

		var childContext;
		var childNodes = node.childNodes;

		if (childNodes)
		for (var i = 0; i < childNodes.length; i++)
		if (childContext = this._compileNode(childNodes[i]))
				childs.push(childContext.id);

		return {
			tagName,
			attributes,
			dynProps,
			childs,
			events
		};
	}
	
	,elementInstantiate: function(context) {
		return this._doc.createElement(context.tagName);
	}
	
	,elementLink: function(context, object, objects) {
		var attributes = context.attributes;
		for (var attribute in attributes)
			object.setAttribute(attribute, attributes[attribute]);

		var childs = context.childs;
		for (var i = 0; i < childs.length; i++) {
			var child = objects[childs[i]];
		
			if (child instanceof Htk.Widget)
				child = child.node;
			if (child instanceof Node)
				object.appendChild(child);
		}
		
		var events = context.events;
		for (var event in events)
			object.addEventListener(event,
				events[event].bind(this.signalData));
	}
	
	,_showError: function(error) {
		var path = this._path ? this._path : 'Node';		
		var logArgs = ['Vn.Builder: %s: '+ error, path];

		for (var i = 1; i < arguments.length; i++)
			logArgs.push(arguments[i]);
	
		console.warn.apply(null, logArgs);
	}
	
	,_addLink: function(context, prop, objectId) {
		this._links.push({
			 context: context
			,prop: prop
			,objectId: objectId
		});
	}

	,_translateValue: function(value) {
		var chr = value.charAt(0);

		if (chr === '_')
			return _(value.substr(1));
		else if (chr === '\\' && value.charAt(1) === '_')
			return value.substr(1);
			
		return value;		
	}
	
	,_getMethod: function(value) {	
		if (this.signalData)
			var method = this.signalData[value];
		else
			var method = window[value];

		if (method === undefined)
			this._showError('Function \'%s\' not found', value);

		return method;
	}
	
	,_isEvent: function(attribute) {
		return /^on-\w+/.test(attribute);
	}
	
	,_replaceFunc: function(token) {
		return token.charAt(1).toUpperCase();
	}
});

var BuilderResult = new Class({
	Extends: Object

	,initialize: function(builder, objects) {
		this.builder = builder;
		this.objects = objects;
	}

	,getMain: function() {
		return this.builder.getMain(this);
	}
	
	,$: function(objectId) {
		return this.builder.getById(this, objectId);
	}
	
	,getById: function(objectId) {
		return this.builder.getById(this, objectId);
	}
	
	,getByTagName: function(tagName) {
		return this.builder.getByTagName(this, tagName);
	}
	
	,link: function(self, scope) {
		this.builder.link(this, self, scope);
	}
	
	,_destroy: function() {
		var objects = this.objects;
	
		for (var i = 0; i < objects.length; i++)
		if (objects[i] instanceof Object)
			objects[i].unref();

		this.parent();
	}
});