/*
 * Copyright (c) 2015-2016, Willem Cazander
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided
 * that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice, this list of conditions and the
 *   following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and
 *   the following disclaimer in the documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/* jslint browser: true */
/* global angular,define,sqlitePlugin */

/**
 * FFSpaLoader is an assets loader for single page applications.
 * Its build around the concept the there is only a single static index.html which
 * synces all its assets to local cache for offline and or fast page loads. 
 *
 * @module FFSpaLoader
 */
(function (root, factory) {
    if ( typeof define === 'function' && define.amd ) {
        define('FFSpaLoader', factory(root));
    } else if ( typeof exports === 'object' ) {
        module.exports = factory(root);
    } else {
        root.FFSpaLoader = factory(root);
    }
})(this || window, /** @lends module:FFSpaLoader */ function (rootWindow) {
	'use strict';
	
	/**
     * The options to customize the loader.
     */
	var options = {
		debug: {
			enable:  false,
			handler: null, // auto filled
			prefix:  'FFSpaLoader.'
		},
		error: {
			handler: null, // auto filled
			title:   'Loader ',
			style:   'body {color: #EFF0F1;background: #484948;} .ffError { margin: 3em;border-left: 0.3em solid #B55858;border-radius: 1em;padding: 0em 1em 0.3em 1em;}'
		},
		boot: {
			cordova: {
				enable:  true,
				timeout: -1,  
				flag:    'FFCordovaDevice'
			},
			angular: {
				enable:  true,
				modules: []
			},	
		},
		server: {
			url:         null,
			assets:      null,
			timeout:     4096,
			flag:        'FFServerUrl',
			header: {
				request: {
					'X-FFSpaLoader': 'sync'
				},
				response: { // TODO: add header check support
				}
			}
		},
		question: {
			transport: 'http://',
			title:     'Question',
			submit:    'Start',
			size:      32,
			text:      'Please provide the server name', 
			style:     'body {color: #EFF0F1;background: #484948;} .ffQuestion { margin: 3em;border-left: 0.3em solid #3F68AD;border-radius: 1em;padding: 0em 1em 0.3em 1em;} .ffQuestion > div > input {margin: 0.4em;padding: 0.4em; line-height: 2em;background-color: #454442;color: #EFF0F1;border: none;border-radius: 0.4em;outline: none;min-width: 5em;} .ffQuestion > div > input:focus {border: none;} .ffQuestionError{color: #B55858;} .ffQuestionLoad {transition: all 0.5s ease;color: #484948;} .ffQuestionLoad > div > input {background-color: #484948;color: #484948;}',
			validate: {
				min: {
					value: 3,
					message: 'Server name is to short.'
				},
				max: {
					value: 255,
					message: 'Server name is to long.'
				},
				regex: {
					value: '^([a-zA-Z0-9\.\:])*$',
					message: 'Server name is invalid.'
				}
			}
		},
		cache: {
			meta:    null,
			js:      null,
			css:     null,
			cssData: null
		}
	};
	
	/**
     * Use single instance for websql
     * @private
     */
	var cacheDB = null;
	
	/**
     * The factory which contains detection helpers and cache backend builders.
     */
	var factory = {
		detect: {
			localStorage: function() {
			    try {
			    	var testData = 'localStorageDetect';
			    	rootWindow.localStorage.setItem(testData, testData); // throws err in private browsing mode
			    	rootWindow.localStorage.removeItem(testData);
			        return true;
			    } catch(e) {
			        return false;
			    }
			},
			openDatabase: function() {
				return 'openDatabase' in rootWindow;
			},
			sqlitePlugin: function() {
				return 'sqlitePlugin' in rootWindow;
			},
			cordova: function() {
				return 'cordova' in rootWindow;
			},
			cordovaDevice: function() {
				return options.boot.cordova.flag in rootWindow;
			}
		},
		cache: {
			localStorage: function() {
				return {
					cacheGetValue: function(key, cb) {
						try {
							var dataRaw = rootWindow.localStorage.getItem(key);
							var data = JSON.parse(dataRaw); 
							cb(null, data);
						} catch(e) {
							cb(e);
						}
					},
					cacheSetValue: function(key, value, cb) {
						try {
							rootWindow.localStorage.setItem(key,JSON.stringify(value));
							cb(null);
						} catch(e) {
							cb(e);
						}
					},
					cacheDeleteValue: function(key, cb) {
						try {
							rootWindow.localStorage.removeItem(key);
							cb(null);
						} catch(e) {
							cb(e);
						}
					}
				};
			},
			websql: function(opt) {
				if (opt === undefined)          { opt = {}; }
				if (opt.name === undefined)     { opt.name = 'FFSpaLoader'; }
				if (opt.size === undefined)     { opt.size = 4 * 1024 * 1024; } // reg 4MB let user do higher
				if (opt.version === undefined)  { opt.version = '1.0'; }
				if (opt.table === undefined)    { opt.table = 'cache_store'; }
				if (opt.open === undefined) {
					opt.open = function(dbOpt) {
						return rootWindow.openDatabase(dbOpt.name, dbOpt.version, dbOpt.name, dbOpt.size);
					};
				}
				
				var nullDataHandler = function(cb) {
					return function () {
						cb(null);
					};
				};
				var executeSql = function(tx, query, values, resultHandler, errorHandler) {
					utilDebug('websql.executeSql '+query);
					tx.executeSql(query, values, resultHandler, function(tx,err) {
						errorHandler(new Error('Code: '+err.code+' '+err.message+' by query: '+query));
					});
				};
				var cacheDBInit = function(cb) {
					cacheDB.transaction(function(tx) {
						var query = 'CREATE TABLE '+opt.table+'(id INTEGER PRIMARY KEY AUTOINCREMENT, key TEXT NOT NULL, value TEXT NOT NULL)';
						executeSql(tx, query, [], function(tx) {
							executeSql(tx, 'CREATE UNIQUE INDEX '+opt.table+'__key__udx ON '+opt.table+' (key)', [], nullDataHandler(cb), cb);
						}, cb);
					});
				};
				return {
					cacheOpen: function(cb) {
						if (cacheDB !== null) {
							return cb(null); // open once.
						}
						utilDebug('websql.cacheOpen '+JSON.stringify(opt));
						try {
							cacheDB = opt.open(opt);
						} catch(e) {
							return cb(e);
						}
						cacheDB.transaction(function(tx) {
							executeSql(tx,'SELECT value FROM '+opt.table+' WHERE key = \"if-err-init\"', [], function() {
								cb(null);
							}, function() {
								cacheDBInit(cb);
							});
						});
					},
					cacheGetValue: function(key, cb) {
						cacheDB.transaction(function(tx) {
							executeSql(tx, 'SELECT value FROM '+opt.table+' WHERE key = ?',[key], function(tx, res) {
								if (res.rows.length === 0) {
									cb(null, null);
								} else {
									var value = res.rows.item(0).value;
									cb(null, JSON.parse(value));
								}
							}, cb);
						});
					},
					cacheSetValue: function(key, value, cb) {
						cacheDB.transaction(function(tx) {
							executeSql(tx, 'SELECT value FROM '+opt.table+' WHERE key = ?',[key], function(tx, res) {
								if (res.rows.length === 0) {
									var queryInsert = 'INSERT INTO '+opt.table+' (key,value) VALUES (?,?)';
									executeSql(tx, queryInsert, [key,JSON.stringify(value)], nullDataHandler(cb), cb);		
								} else {
									var queryUpdate = 'UPDATE '+opt.table+' SET value = ? WHERE key = ?';
									executeSql(tx, queryUpdate, [JSON.stringify(value),key], nullDataHandler(cb), cb);
								}
							}, cb);
						});
					},
					cacheDeleteValue: function(key, cb) {
						cacheDB.transaction(function(tx) {
							executeSql(tx, 'DELETE FROM '+opt.table+' WHERE key = ?', [key], nullDataHandler(cb), cb);
						});
					}
				};
			},
		}
	};
	
	/**
     * Prints the debug message with prefix to the options.debug.handler if options.debug.enable is true.
     * @param {String} message	The message to log.
     * @private
     */
	var utilDebug = function (message) {
		if (options.debug.enable !== true) {
			return;
		}
		options.debug.handler(options.debug.prefix+message);
	};
	
	/**
     * The default error handler which renders the error in the browser.
     * @param {Error|String} err	The error object or message.
     * @private
     */
	var utilErrorHandler = function(err) {
		if (!(err instanceof Error)) {
			err = new Error(err);
		}
		utilDebug('utilErrorHandler error '+err.name+' '+err.message);
		
		var rootTag = document.createElement('div');
		rootTag.setAttribute('class','ffError');
		document.getElementsByTagName('body')[0].appendChild(rootTag);
		
		var cssTag = document.createElement('style');
		cssTag.type = 'text/css';
		cssTag.innerHTML = options.error.style;
		rootTag.appendChild(cssTag);

		var titleTag = document.createElement('h1');
		titleTag.appendChild(document.createTextNode(options.error.title+err.name));
		rootTag.appendChild(titleTag);
		
		var questionTag = document.createElement('p');
		questionTag.appendChild(document.createTextNode(err.message));
		rootTag.appendChild(questionTag);

		try {
			var stack = err.stack || '';
			stack = stack.split('\n').map(function (line) { return line.trim()+'\n'; });
			var stackText = stack.splice(stack[0] === 'Error' ? 2 : 1);
			
			var traceTag = document.createElement('pre');
			traceTag.appendChild(document.createTextNode(stackText));
			rootTag.appendChild(traceTag);
		} catch (stackError) {
			utilDebug('No stack: '+stackError);
		}
	};
	
	/**
     * Fetches an url resource with a XMLHttpRequest.
     * @param {String} url	The url to fetch.
     * @param {function} cb	Error first callback when done.
     * @private
     */
	var utilHttpFetch = function (url, cb) {
		var startTime = new Date().getTime();
		var httpRequest = new XMLHttpRequest();
		httpRequest.onreadystatechange = function() {
			if (httpRequest.readyState === 4 && httpRequest.status === 200) {
				utilDebug('utilHttpFetch url \"'+url+'\" done in '+(new Date().getTime()-startTime)+' ms.');
				cb(null, httpRequest);
			} else if (httpRequest.readyState === 4) {
				cb('Wrong status '+httpRequest.status);
			}
		};
		httpRequest.open('GET', url, true);
		httpRequest.timeout = options.server.timeout; // ieX: after open()
		httpRequest.ontimeout = function() {
			cb('timeout after '+options.server.timeout+' of url '+url);
		};
		var headerKeys = Object.keys(options.server.header.request);
		for (var headerKeyIdx in headerKeys) {
			var headerKey = headerKeys[headerKeyIdx];
			var headerValue = options.server.header.request[headerKey];
			httpRequest.setRequestHeader(headerKey,headerValue);
		}
		httpRequest.send();
	};
	
	/**
     * Async helper to run each step from the stack.
     * @param {String} runType	The runType used for debug logging.
     * @param {Array} stack	The stack to run all steps on.
     * @param {function} step	Stack Item + Error first callback when done function callback.
     * @param {function} cb	Error first callback when done.
     * @private
     */
	var utilRunStack = function(runType, stack, step, cb) {
		if (stack.length === 0) {
			return cb(null);
		}
		utilDebug(runType+' start');
		var startTime = new Date().getTime();
		var runStack = stack;
		var runStackStep = function(err) {
			if (err !== null) { return cb(err); }
			runStack = runStack.slice(1);
			if (runStack.length === 0) {
				utilDebug(runType+' done '+stack.length+' in '+(new Date().getTime()-startTime)+' ms.');
				cb(null);
			} else {
				step(runStack[0],runStackStep);
			}
		};
		step(runStack[0],runStackStep);
	};

	var cacheGetService = function (type) {
		if (options.cache[type]) {
			return options.cache[type];
		}
		return null;
	};
	
	var cacheHasService = function (type) {
		return cacheGetService(type) !== null;
	};

	var cacheCheckType = function (type, cb, action) {
		cacheHasService(type)?action():cb(new Error('No caching for '+type));
	};
	
	/**
     * Retreive a cached value.
     * @param {String} type	The cache type to use.
     * @param {String} key	The key to get the value for.
     * @param {function} cb	Error first callback + value callback.
     * @private
     */
	var cacheGetValue = function(type, key , cb) {
		cacheCheckType(type, cb, function() {
			var cacheKey = type+'_'+key;
			utilDebug('cacheGetValue key '+cacheKey);
			cacheGetService(type).cacheGetValue(cacheKey,cb);	
		});
	};
	
	/**
     * Store a value in cache.
     * @param {String} type	The cache type to use.
     * @param {String} key	The key to store the value for.
     * @param {String} value	The value to store.
     * @param {function} cb	Error first callback.
     * @private
     */
	var cacheSetValue = function(type, key, value, cb) {
		cacheCheckType(type, cb, function() {
			var cacheKey = type+'_'+key;
			utilDebug('cacheSetValue key '+cacheKey);
			cacheGetService(type).cacheSetValue(cacheKey,value,cb);	
		});
	};
	
	/**
     * Deletes an cache value.
     * @param {String} type	The cache type to use.
     * @param {String} key	The key to delete the value.
     * @param {function} cb	Error first callback.
     * @private
     */
	var cacheDeleteValue = function(type, key, cb) {
		cacheCheckType(type, cb, function() {
			var cacheKey = type+'_'+key;
			utilDebug('cacheDeleteValue key '+cacheKey);
			cacheGetService(type).cacheDeleteValue(cacheKey,cb);	
		});
	};
	
	var cleanupCache = function (resources, deleteAll, cb) {
		var typedKeys = {};
		resources.forEach(function (r) {
			var typeKey = typedKeys[r.type];
			if (typeKey === undefined) {
				typeKey = [];
				typedKeys[r.type] = typeKey;
			}
			typeKey.push(r.hash);
		});
		var steps = [];
		var keys = Object.keys(typedKeys);
		for (var keyIdx in keys) {
			var type = keys[keyIdx];
			if (!cacheHasService(type)) {
				continue;
			}
			steps.push({keys: typedKeys[type], type: type});
		}
		utilRunStack('cleanupCacheKeys',steps, function(typeKey, cb) {
			cacheGetValue(typeKey.type,'keys',function (err,value) {
				if (err !== null) {
					return cb(err);
				}
				if (value === null) {
					return cb(null); // meta has no keys
				}
				var diff = [];
				for (var i=0;i<value.length;i++) {
					if (deleteAll || typeKey.keys.indexOf(value[i]) === -1) {
						diff.push(value[i]);
					}
				}
				var valueNew = value;
				for (var i2=0;i2<diff.length;i2++) {
					var keyIdx = valueNew.indexOf(diff[i2]);
					if (keyIdx !== -1) {
						valueNew.splice(keyIdx,1);
					}
				} 
				//utilDebug('cleanupCache value1: '+JSON.stringify(value));
				//utilDebug('cleanupCache value2: '+JSON.stringify(valueNew));
				
				utilRunStack('cleanupCacheItems',diff, function(key, cb) {
					cacheDeleteValue(typeKey.type,key,cb);
				}, function(err) {
					if (err !== null) {
						return cb(err);
					}
					if (diff.length === 0) {
						cb(null);
					} else {
						cacheSetValue(typeKey.type,'keys',valueNew ,cb);
					}
				});
			});				
		}, cb);
	};
	
	var injectResourceData = function(resource, data, cb) {
		utilDebug('injectResourceData resource '+JSON.stringify(resource)+' data '+data.length);
		var tag = null;
		if (resource.type === 'css' || resource.type === 'cssData') {
			tag = document.createElement('style');
			tag.type = 'text/css';
		}
		if (resource.type === 'js') {
			tag = document.createElement('script');
			tag.type = 'text/javascript';
		}
		tag.appendChild(document.createTextNode(data));
		
		document.getElementsByTagName('head')[0].appendChild(tag);
		//var ref = document.getElementsByTagName('script')[0];
		//ref.parentNode.insertBefore(tag, ref); // note in reverse order	
		cb(null);
	};
	
	/**
     * Add all cache keys in central list so we can clear the cache item if resources are removed.
     * @param {Object} resource	The resource object with the type and hash.
     * @param {function} cb	Error first callback when done.
     * @private
     */
	var storeResourceKey = function (resource, cb) {
		var cacheKey = 'keys';
		cacheGetValue(resource.type,cacheKey,function (err,value) {
			if (err !== null) {
				return cb(err);
			}
			if (value === null) {
				value = [];
			}
			value.push(resource.hash);
			cacheSetValue(resource.type,cacheKey,value, cb);
		});
	};
	
	var storeResource = function (resource, httpRequest, cb) {
		utilDebug('storeResource url '+resource.url+' hash '+resource.hash);
		var item = {
			resource: resource,
			data: httpRequest.responseText
		};
		cacheSetValue(resource.type, resource.hash, item , function(err) {
			if (err !== null) {
				cb(err);
			} else {
				storeResourceKey(resource,cb);
			}
		});
	};
	
	var loadResource = function (resource, cb) {
		var resourceUrl = resource.url;
		if (resourceUrl.indexOf('http') === -1) {
			resourceUrl = options.server.url + resourceUrl;
		}
		utilDebug('loadResource '+JSON.stringify(resource));
		if (cacheHasService(resource.type)) {
			cacheGetValue(resource.type,resource.hash,function(err, value) {
				if (err !== null) { return cb(err); }
				if (value === null) {
					utilDebug('loadResource cache miss'); // + hash mismatch as its the key
				} else if (value.resource === undefined) {
					utilDebug('loadResource cache wrong obj');
				} else {
					utilDebug('loadResource cache hit');
					injectResourceData(value.resource,value.data,cb);
					return;
				}
				utilHttpFetch(resourceUrl, function(err, httpRequest) {
					if (err !== null) { return cb(err); }
					storeResource(resource, httpRequest, function (err) {
						if (err !== null) { return cb(err); }
						injectResourceData(resource,httpRequest.responseText,cb);
					});
				});
			});
		} else {
			// note: was links but now download + inject so order stays sequenced
			utilHttpFetch(resourceUrl, function(err, httpRequest) {
				if (err !== null) { return cb(err); }
				injectResourceData(resource,httpRequest.responseText,cb);
			});
		}
	};
	
	/**
     * Starts loader by downloading resource list or using cache version to 
     * load/refresh/inject the resources.
     * 
     * @param {function} cb	Error first callback when done.
     * @private
     */
	var startLoader = function (cb) {
		if (options.server.url === null) {
			cb(new Error('No url'));
			return;
		}
		if (options.server.assets === null) {
			cb(new Error('No assets'));
			return;
		}
		rootWindow[options.server.flag] = options.server.url; 
		
		var resourcesUrl = options.server.url + options.server.assets;
		utilDebug('startLoader assets \"'+resourcesUrl+'\"');
		utilHttpFetch(resourcesUrl, function(err, httpRequest) {
			if (err !== null) {
				utilDebug('startLoader fetch error '+err);
				if (cacheHasService('meta')) {
					cacheGetValue('meta','server_resources',function(err, value) {
						if (err !== null) {
							cb(err);
						} else if (value === null) {
							cb(new Error('Have no cache of server resouces from '+options.server.url));
						} else {
							utilRunStack('injectResources', value, function(resource, cb) {
								cacheGetValue(resource.type,resource.hash,function(err,item) {
									injectResourceData(resource,item.data,cb);
								});
							} , cb);
						}
					});
				} else {
					cb(new Error('Could not fetch server resouces from '+options.server.url));
				}
				return;
			}
			var resources = JSON.parse(httpRequest.responseText).data.resources;
			utilDebug('startLoader resources '+resources.length);
			if (cacheHasService('meta')) {
				cacheSetValue('meta','server_resources',resources, function (err) {
					if (err !== null) { return cb(err); }
					utilRunStack('loadResources', resources, loadResource , function (err) {
						if (err !== null) { return cb(err); }
						cleanupCache(resources,false,cb); // only clean when fetched + cached
					});
				});
			} else {
				utilRunStack('loadResources', resources, loadResource , cb);
			}
		});
	};
	
	/**
     * Validates the user input url by downloading it.
     * 
     * @param {HTMLElement} deleteTag The dom element to remove from the body tag after success.
     * @param {function} cb	Error first callback when done.
     * @private
     */
	var askUrlValidate = function (deleteTag, cb) {
		var inputTag = document.getElementById('serverInput');
		var inputErrorTag = document.getElementById('serverInputError');
		var inputValueRaw = inputTag.value;
		
		while (inputErrorTag.firstChild) {
			inputErrorTag.removeChild(inputErrorTag.firstChild);
		}
		
		var inputValueHost = null;
		if (inputValueRaw.indexOf("://") >= 0) {
			inputValueHost = inputValueRaw.split('/')[2];
	    } else {
	    	inputValueHost = inputValueRaw.split('/')[0];
	    }
		
		if (options.question.validate.min.value !== false && inputValueHost.length < options.question.validate.min.value) {
			inputErrorTag.appendChild(document.createTextNode(options.question.validate.min.message));
			return;
		}
		if (options.question.validate.max.value !== false && inputValueHost.length > options.question.validate.max.value) {
			inputErrorTag.appendChild(document.createTextNode(options.question.validate.max.message));
			return;
		}
		if (options.question.validate.regex.value !== false && options.question.validate.regex.value.length !== 0) {
			var regex = new RegExp(options.question.validate.regex.value);
			if (inputValueHost.match(regex) === null) {
				inputErrorTag.appendChild(document.createTextNode(options.question.validate.regex.message));
				return;
			}
		}
		
		if (inputValueRaw.indexOf('https') === 0) {
			options.server.url = 'https://' + inputValueHost; // allow user to upgrade to https but not to downgrade to http
		} else {
			options.server.url = options.question.transport + inputValueHost;
		}
		
		var resourcesUrl = options.server.url + options.server.assets;  
		utilDebug('askUrlStart check assets '+resourcesUrl);
		
		// TODO: check headers
		utilHttpFetch(resourcesUrl,function(err, httpRequest) {
			if (err !== null) {
				inputErrorTag.appendChild(document.createTextNode('Error could not get data.'));
				return;
			}
			if (httpRequest.responseText.length === 0) {
				inputErrorTag.appendChild(document.createTextNode('Error Got empty data.'));
				return;
			}
			
			deleteTag.setAttribute('class','ffQuestion ffQuestionLoad');
			var clearUi = function(err) {
				document.getElementsByTagName('body')[0].removeChild(deleteTag); // also delete on error
				cb(err);
			};
			if (cacheHasService('meta')) {
				cacheSetValue('meta','server_url',options.server.url, function(err) {
					if (err !== null) { return cb(err); }
					startLoader(clearUi);
				});
			} else {
				startLoader(clearUi);
			}
		});
	};
	
	/**
     * Creates the ask url ui.
     * 
     * @param {function} cb Callback gets called when loader is done.
     * @private
     */
	var askUrl = function (cb) {
		utilDebug('askUrl create ui');
		
		var rootTag = document.createElement('div');
		rootTag.setAttribute('class','ffQuestion');
		
		var cssTag = document.createElement('style');
		cssTag.type = 'text/css';
		cssTag.innerHTML = options.question.style;
		rootTag.appendChild(cssTag);
		
		var titleTag = document.createElement('h1');
		titleTag.appendChild(document.createTextNode(options.question.title));
		rootTag.appendChild(titleTag);
		
		var questionTag = document.createElement('p');
		questionTag.appendChild(document.createTextNode(options.question.text));
		rootTag.appendChild(questionTag);
		
		var formTag = document.createElement('div');
		rootTag.appendChild(formTag);
		
		var inputTag = document.createElement('input');
		inputTag.type = 'text';
		inputTag.id = 'serverInput';
		inputTag.setAttribute('autofocus','');
		inputTag.setAttribute('onkeydown','if (event.keyCode == 13) {document.getElementById(\'serverSubmit\').click()}');
		inputTag.setAttribute('size',options.question.size);
		formTag.appendChild(inputTag);
		
		var submitTag = document.createElement('input');
		submitTag.id = 'serverSubmit';
		submitTag.type = 'submit';
		submitTag.value = options.question.submit;
		submitTag.onclick = function() {askUrlValidate(rootTag,cb);};
		formTag.appendChild(submitTag);
		
		var serverErrorTag = document.createElement('div');
		serverErrorTag.id = 'serverInputError';
		serverErrorTag.setAttribute('class','ffQuestionError');
		formTag.appendChild(serverErrorTag);
		
		document.getElementsByTagName('body')[0].appendChild(rootTag);
	};
	
	/**
     * Starts an cache type by auto selecting if needed and opening it if needed.
     * 
     * @param {String} type The cache type to start.
     * @param {function} cb Callback gets called when loader is done.
     * @private
     */
	var startCacheType = function (type,cb) {
		if (options.cache[type] !== null && options.cache[type] === false) {
			utilDebug('startCacheType '+type+' disabled');
			options.cache[type] = null;
			return cb(null);
		}
		if (options.cache[type] === null) {
			if (factory.detect.cordovaDevice() && factory.detect.sqlitePlugin()) {
				utilDebug('startCacheType auto sqlitePlugin for '+type);
				options.cache[type] = factory.cache.websql({open: function(dbOpt) { return sqlitePlugin.openDatabase(dbOpt.name, dbOpt.version, dbOpt.name, dbOpt.size);}});
			} else if (factory.detect.openDatabase()) {
				utilDebug('startCacheType auto openDatabase for '+type);
				options.cache[type] = factory.cache.websql();
			} else if (factory.detect.localStorage()) {
				utilDebug('startCacheType auto localStorage for '+type);
				options.cache[type] = factory.cache.localStorage();
			} else {
				utilDebug('startCacheType '+type+' none');
			}
		}
		if (options.cache[type] !== null && typeof options.cache[type].cacheOpen === 'function') {
			options.cache[type].cacheOpen(cb);
		} else {
			cb(null);
		}
	};
	
	/**
     * Starts all cache types.
     * 
     * @param {function} cb Callback gets called when loader is done.
     * @private
     */
	var startCache = function (cb) {
		// FIXME: use dynamic loop for user defined types.
		startCacheType('meta', function(err) {
			if (err !== null) { return cb(err); }
			startCacheType('js', function(err) {
				if (err !== null) { return cb(err); }
				startCacheType('css', function(err) {
					if (err !== null) { return cb(err); }
					startCacheType('cssData', cb);
				});
			});
		});
	};
	
	/**
     * Starts the loader.
     * 
     * @param {function} cb Optional callback gets called when loader is done.
     */
	var start = function (cbArgu) {
		var startTime = new Date().getTime();
		var cb = function(err) {
			if (err !== null) {
				options.error.handler(err);
			} else {
				utilDebug('start done in '+(new Date().getTime()-startTime)+' ms.'); // last debug line TODO: move bootAngular to onjsloaded 
				bootAngular(function(err) {
					if (err !== null) { return options.error.handler(err); }
					if (typeof cbArgu === 'function') {
						cbArgu();
					}
				});
			}
		};
		utilDebug('start spa loader'); // first debug line TODO: Add version
		if (options.debug.enable === true) {
			var optionsKeys = Object.keys(options);
			for (var keyId in optionsKeys) {
				var key = optionsKeys[keyId];
				utilDebug('start config '+key+' '+JSON.stringify(options[key]));
			}
		}
		bootCordova(function(err) {
			if (err !== null) { return cb(err); }
			startCache(function(err) {
				if (err !== null) { return cb(err); }
				if (options.server.url !== null) {
					startLoader(cb);
					return;
				}
				if (cacheHasService('meta')) {
					cacheGetValue('meta','server_url',function(err, value) {
						if (err !== null) {
							cb(err);
						} else if (value === undefined || value === null || value === '') {
							askUrl(cb);
						} else {
							options.server.url = value;
							startLoader(cb);
						}
					});
				} else {
					askUrl(cb);
				}
			});
		});
	};
	
	/**
     * Clears the server url.
     * 
     * @param {function} cb Optional Error first callback gets called when value is deleted.
     */
	var clearServerUrl = function(cb) {
		if (cb === undefined) {
			cb = function() {};
		}
		if (cacheHasService('meta')) {
			cacheDeleteValue('meta','server_url',function(err) {
				if (err !== null) { return cb(err); }
				setTimeout(function() {cb(null);}); // return next tick so (websql) transaction is flushed before location.reload
			});
		} else {
			cb(null);
		}
	};
	
	/**
     * Clears the cache.
     * 
     * @param {function} cb Optional Error first callback gets called when cache is cleared.
     */
	var clearCache = function(cb2) {
		if (cb2 === undefined) {
			cb2 = function() {};
		}
		var cb = function(err) {
			setTimeout(function() {cb2(err);}); // next tick to flush transactions.
		};
		if (cacheHasService('meta')) {
			cacheGetValue('meta','server_resources',function(err, value) {
				if (err !== null) {
					return cb(err);
				}
				if (value === null) {
					return cb(new Error('No cache value')); // TODO: check this or cb(null) or do fetch ? 
				}
				cleanupCache(value,true,cb);
			});

		} else {
			utilHttpFetch(options.server.url + options.server.assets,function(err, httpRequest) {
				if (err !== null) {
					return cb(err);
				}
				var resources = JSON.parse(httpRequest.responseText).data.resources;
				cleanupCache(resources,false,cb);
			});
		}
	};
	
	/**
     * Boots angular modules if enabled.
     * 
     * @param {function} cb Error first callback gets called done.
     * @private
     */
	var bootAngular = function(cb) {
		if (options.boot.angular.enable !== true) {
			utilDebug('bootAngular disabled by options');
			return cb(null);
		}
		if (options.boot.angular.modules.length === 0) {
			utilDebug('bootAngular disabled by no modules');
			return cb(null);
		}
		utilDebug('bootAngular start '+options.boot.angular.modules);
		angular.bootstrap(document, options.boot.angular.modules);
		cb(null);
	};
	
	/**
     * Boots cordova applications which want to use the sqllite plugin as cache.
     * Note: On none cordova page it will callback directly.
     * Note: On none cordova device page is will timeout if option is set. 
     * 
     * @param {function} cb Error first callback gets called device is ready.
     * @private
     */
	var bootCordova = function(cb) {
		if (options.boot.cordova.enable !== true) {
			utilDebug('bootCordova disabled by options');
			return cb(null);
		}
		if (factory.detect.cordova() !== true) {
			utilDebug('bootCordova disabled by detect');
			return cb(null);
		}
		var startTime = new Date().getTime();
		var bootOnce = function() {
			var callback = cb;
			cb = null;
			utilDebug('bootCordova done in '+(new Date().getTime()-startTime)+' ms.');
			callback(null);
		};
		if (options.boot.cordova.timeout > 0) {
			utilDebug('bootCordova timeout '+options.boot.cordova.timeout);
			setTimeout ( function () {
				utilDebug('bootCordova timeout');
				bootOnce();
			}, options.boot.cordova.timeout);
		}
		document.addEventListener('deviceready', function () {
			rootWindow[options.boot.cordova.flag] = true;
			utilDebug('bootCordova '+options.boot.cordova.flag);
			bootOnce();
	    }, false);
	};
	
	// Auto fill handlers and return public object.
	options.debug.handler = function(msg) {console.log(msg);};
	options.error.handler = utilErrorHandler;
	return {
		options: options,
		factory: factory,
		start: start,
		clearServerUrl: clearServerUrl,
		clearCache: clearCache
	};
});