/**
 * Classes for using Opera XML Store
 * 
 * @author Jani Hartikainen
 */

if(!CU)
	var CU = {};
	
CU.opera = {};

/**
 * XML Store URL
 */
CU.opera.STORE_URL = 'http://xmlstore.labs.opera.com/';

CU.opera.xmlStore = { };

/**
 * XML Store proxy class
 * @constructor
 * @param {Object} params 
 */
CU.opera.XmlStore = function(params) {
	params = params || { };
	this.storeUrl = params.storeUrl || CU.opera.STORE_URL;
};

CU.opera.XmlStore.prototype = {
	user: null,
	
	/**
	 * Perform a request to the store
	 * @method
	 * @param {String} method GET/PUT/POST/DELETE
	 * @param {String} path
	 * @param {Object|String} data
	 * @param {Function} callback
	 */
	_request: function(method, path, data, callback) {
		if(this.user)
			path = 'user/' + encodeURIComponent(this.user) + '/' + path;
			
		var url = this.storeUrl + path;
		
		var dataStr = '';
		if (typeof(data) == 'string') 
		{
			dataStr = data;
		}
		else 
		{
			var dataArray = [];
			for (var key in data) 
				dataArray.push(key + '=' + encodeURIComponent(data[key]));
			
			dataStr = dataArray.join('&');
		}
		
		if(method == 'GET')
			url += '?' + dataStr;
			
		var xhr = new XMLHttpRequest();
		
		//PUT etc need to use POST
		if(method == 'GET')
			xhr.open('GET', url, true);
		else
			xhr.open('POST', url, true);
		//opera.postError(url);	
		xhr.setRequestHeader('Content-Type', 'text/xml');
		xhr.setRequestHeader('X-Http-Accept-Override', 'text/xml');
		if (method != 'POST' && method != 'GET') 
		{
//			opera.postError('method-override: ' + method);
			xhr.setRequestHeader('X-Http-Method-Override', method);
		}
		
		if (path.indexOf('login') == 0) 
			xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
			
		xhr.onreadystatechange = function() {
			if(this.readyState != 4)
				return;
				
			callback(this.status, this);
		};
		//opera.postError(dataStr);	
		if(method != 'GET')
			xhr.send(dataStr);
		else
			xhr.send('');
	},
	
	/**
	 * Log in to the store
	 * @method
	 * @param {Object} params username, password
	 * @param {Function} callback
	 */
	login: function(params, callback) {		
		this.user = '';
		var store = this;
		
		this._request('POST', 'login', {
			username: params.username,
			password: params.password
		}, function(status, request) {
			if(status != 200) 
			{
				callback(false);
				return;
			}
			
			var xml = request.responseXML;
			var sc = xml.selectSingleNode('//oxs:statuscode').textContent;
			
			if (sc == 401) 
				callback(false);
			else 
			{
				store.user = params.username;
				callback(true);
			}
		});
	},
	
	/**
	 * Creates or updates documents in the store
	 * @method
	 * @param {Object} doc must comply to CU.store.xmlStore.NoteDocument
	 * @param {Function} callback function(created/updated document)
	 */
	save: function(doc, callback) {
		if(doc.id == '')
			this.create(doc, callback);
		else
			this.update(doc, callback);
	},
	
	/**
	 * Creates new documents in the store
	 * @method
	 * @param {Object} doc must comply to CU.store.xmlStore.NoteDocument
	 * @param {Function} callback function(created document)
	 */
	create: function(doc, callback) {
		this._request('POST', doc.model, doc.data, function(status, request) {
			if(status != 200)
				throw new CU.opera.xmlStore.Error('Create failed');

			var xml = request.responseXML;
			doc.id = xml.selectSingleNode('//oxs:id').textContent;
			
			callback(doc);
		});
	},
	
	/**
	 * Update a document
	 * @method
	 * @param {Object} doc must comply to CU.store.xmlStore.NoteDocument
	 * @param {Function} callback function(updated document)
	 */
	update: function(doc, callback) {
		var path = doc.model + '/default/' + doc.id + '/?version=' + doc.version;
		this._request('PUT', path, doc.data, function(status, request) {
			if(status != 200)
				throw new CU.opera.xmlStore.Error('Update failed');

			var xml = request.responseXML;
			var version = xml.selectSingleNode('//oxs:version').textContent;
			if(xml.selectSingleNode('//oxs:statuscode').textContent == 409)
				throw new CU.opera.xmlStore.VersionError(doc.version, version);
			
			doc.version = version;
			
			callback(doc);
		});
	},
	
	/**
	 * Searches the store based on XPath
	 * @method
	 * @param {Function} type constructor for the document type to return
	 * @param {String} xpath XPath query for the store
	 * @param {Function} callback function(found document|null)
	 */
	findOneBy: function(type, xpath, callback) {
		var doc = new type;
		this._request('GET', doc.model, { q: xpath }, function(status, request) {
			var xml = request.responseXML;
			if(xml.selectSingleNode('//oxs:statuscode').textContent != 200)
				throw new CU.opera.xmlStore.Error('Fetch failed');
			
			var results = xml.selectSingleNode('//oxs:results');
			if (results.getAttribute('count') < 1) 
			{
				callback(null);
				return;
			}
			
			doc.setFromXml(xml.selectSingleNode('//oxs:results/*[1]'));
			callback(doc);
		});
	},
	
	/**
	 * Get an item from the store by id
	 * @method
	 * @param {Function} type constructor for the document type to return
	 * @param {String} id document id
	 * @param {Function} callback function(found document|null)
	 */
	get: function(type, id, callback) {
		var doc = new type;
		this._request('GET', doc.model + '/default/' + id, { }, function(status, request) {
			var xml = request.responseXML;
			if(xml.selectSingleNode('//oxs:statuscode').textContent != 200)
				throw new CU.opera.xmlStore.Error('Fetch failed');
			
			var results = xml.selectSingleNode('//oxs:results');
			if (results.getAttribute('count') < 1) 
			{
				callback(null);
				return;
			}
			
			doc.setFromXml(xml.selectSingleNode('//oxs:results/*[1]'));
			callback(doc);
		});
	}
};

/**
 * Generic error class
 * @constructor
 * @param {String} error message
 */
CU.opera.xmlStore.Error = function(error) {
	this.message = error;
};

CU.opera.xmlStore.Error.prototype = Error.prototype;

/**
 * Error thrown when encountering a version mismatch
 * @constructor
 * @param {Number} expectedVersion
 * @param {Number} returnedVersion
 */
CU.opera.xmlStore.VersionError = function(expectedVersion, returnedVersion) {
	this.expectedVersion = expectedVersion;
	this.returnedVersion = returnedVersion;
	this.message = 'Version mismatch: expected ' + this.expectedVersion 
			+ ', got ' + this.returnedVersion;
};

CU.opera.xmlStore.VersionError.prototype = Error.prototype;

/**
 * Document class for the preferences datamodel
 * @constructor
 * @param {Object} params id, data, version
 */
CU.opera.xmlStore.PreferenceDocument = function(params) {
	var params = params || { };
	this.id = params.id || '';
	this.setData(params.data);
	this.version = params.version || 1;
};

CU.opera.xmlStore.PreferenceDocument.prototype = {
	id: '',
	data: '',
	version: 1,
	model: 'preferences',
	entries: {},
	widget: '',
	
	setFromXml: function(xml) {
		var ns = xml.lookupNamespaceURI('md');
		this.id = xml.getAttributeNS(ns, 'id');
		this.version = xml.getAttributeNS(ns, 'version');

		var entryNodes = xml.selectNodes('//p:preferences/p:entry');
		var entries = { };
		for(var i = 0, len = entryNodes.length; i < len; i++)
		{
			var node = entryNodes[i];
			entries[node.selectSingleNode('p:key').textContent] = node.selectSingleNode('p:value').textContent;
		}

		this.setData({
			widget: xml.selectSingleNode('//p:preferences').getAttribute('id'),
			entries: entries
		});
	},
	
	setData: function(data) {
		if(!data)
			return;
			
		this.widget = data.widget;
		this.entries = data.entries;
		
		this.data = [
			'<?xml version="1.0" encoding="UTF-8"?>',
			'<p:preferences xmlns:p="http://oxs.opera.com/ns/preferences" id="',
			data.widget, 
			'">'
		].join('');
		
		for(var key in data.entries)
		{
			this.data += [
				'<p:entry>',
				'<p:key>', key, '</p:key>',
				'<p:value>', data.entries[key], '</p:value>',
				'</p:entry>'
			].join('');
		}

		this.data += '</p:preferences>';
	}
};

/**
 * Document class for the notes datamodel
 * @constructor
 * @param {Object} params id, data, version
 */
CU.opera.xmlStore.NoteDocument = function(params) {
	var params = params || { };
	this.id = params.id || '';
	this.setData(params.data);
	this.version = params.version || 1;
};

CU.opera.xmlStore.NoteDocument.prototype = {
	/**
	 * Document ID
	 * @type {String}
	 */
	id: '',
	
	/**
	 * XML data for the document
	 * @type {String}
	 */
	data: '',
	
	/**
	 * Document version
	 * @type {Number}
	 */
	version: 1,
	
	/**
	 * datamodel name
	 * @type {String}
	 */
	model: 'notes',
	
	/**
	 * Note title
	 * @type {String}
	 */
	title: '',
	
	/**
	 * Note content
	 * @type {String}
	 */
	content: '',
	
	/**
	 * Set object properties from XML
	 * @method
	 * @param {XMLNode} xml
	 */
	setFromXml: function(xml) {
		var ns = xml.lookupNamespaceURI('md');
		this.id = xml.getAttributeNS(ns, 'id');
		this.version = xml.getAttributeNS(ns, 'version');

		this.setData({
			title: xml.selectSingleNode('//n:title').textContent,
			content: xml.selectSingleNode('//n:content').textContent
		});
	},
	
	/**
	 * Set document data
	 * @method
	 * @param {Object} data title, content
	 */
	setData: function(data) {
		if(!data)
			return;
			
		this.title = data.title;
		this.content = data.content;
		
		this.data = [
			'<?xml version="1.0" encoding="UTF-8"?>',
			'<n:note xmlns:n="http://oxs.opera.com/ns/notes">',
			'<n:title>', data.title, '</n:title>',
			'<n:content>', data.content, '</n:content>',
			'</n:note>'
		].join('');
	}
};