'use strict';
/*
 * 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.
 */


// TODO:
// conv to req queue 
// split js/css so css can be done later
// set tag.media = 'only you';
// add media in resouces 
// add userAgant match in resouces
// NOTE: add ordered inject, for now JS in non-cache mode needs to be aggragated server side
// add browser supported

var FFSpaLoader = (function () {
	
	var options = {};
	
	var utilDebug = function (message) {
		if (options.debug !== true) {
			return;
		}
		console.log('FFSpaLoader.'+message);
	};
	
	var utilHttpFetch = function (url, cb) {
		var startTime = new Date().getTime();
		var httpRequest = new XMLHttpRequest();
		httpRequest.onreadystatechange = function() {
			if (httpRequest.readyState == 4) {
				utilDebug('utilHttpFetch url: '+url+' done in '+(new Date().getTime()-startTime)+' ms.');
				cb(httpRequest);
			}
		}
		httpRequest.open('GET', url, true);
		httpRequest.send();
	};
	
	var cacheHasItem = function (resource) {
		if (options.cacheGetFn === undefined || options.cacheSetFn === undefined || options.cacheDelFn === undefined) {
			return false;
		}
		var result = options.cacheGetFn(options.cachePrefix + resource.hash) !== null;
		utilDebug('cacheHasItem resource: '+resource.url+' result: '+result);
		return result;
	}
	
	var cacheGetItem = function (resource) {
		if (options.cacheGetFn === undefined) {
			throw new Error('no caching');
		}
		utilDebug('cacheGetItem resource: '+resource.url);
		return JSON.parse(options.cacheGetFn(options.cachePrefix + resource.hash));
	}
	
	var cachePutRequest = function (resource, httpRequest) {
		if (options.cacheSetFn === undefined) {
			throw new Error('no caching');
		}
		var cacheKey = options.cachePrefix + resource.hash;
		var data = httpRequest.responseText;
		utilDebug('cachePutData url: '+resource.url+' key: '+cacheKey);
		options.cacheSetFn(cacheKey, JSON.stringify({
			resource: resource,
			data: data,
			dataDate: new Date().getTime()
		}));
		
		// Add all cache keys in central list so we can clear the cache item if resources are removed.
		var cacheListKey = options.cachePrefix + 'cache-list';
		var cacheListStr = options.cacheGetFn(cacheListKey);
		if (cacheListStr === null) {
			cacheListStr = '[]';
		}
		var cacheList = JSON.parse(cacheListStr);
		cacheList.push(cacheKey);
		options.cacheSetFn(cacheListKey, JSON.stringify(cacheList));
	}
	
	var cacheCleanup = function (resources) {
		if (options.cacheGetFn === undefined || options.cacheSetFn === undefined || options.cacheDelFn === undefined) {
			return;
		}
		var cacheListKey = options.cachePrefix + 'cache-list';
		var cacheListStr = options.cacheGetFn(cacheListKey);
		if (cacheListStr === null) {
			return;
		}
		var cacheList = JSON.parse(cacheListStr);
		
		utilDebug('cacheCleanup TODO cacheList: '+cacheList.length+' resources: '+resources.length);
		
		// TODO: impl for removes in resource lists
	}
	
	var createResource = function (resource, cb) {
		utilDebug('createResource url: '+JSON.stringify(resource));
		if (cacheHasItem(resource)) {
			if (cacheGetItem(resource).resource.hash === resource.hash) {
				cb();
				return;
			}
			utilDebug('createResource hash mismatch request fetch: '+resource.url);
		} else {
			utilDebug('createResource cache miss request fetch: '+resource.url);
		}
		utilHttpFetch(resource.url, function(httpRequest) {
			if (httpRequest.status == 200) {
				cachePutRequest(resource, httpRequest);
			} else {
				console.warn('error loading '+resource.url);
			}
			cb();
		});
	}
	
	var createResources = function(resources, cb) {
		var startTime = new Date().getTime();
		utilDebug('createResources');
		var resourceStack = resources;
		var resourceLoader = function() {
			resourceStack = resourceStack.slice(1);
			if (resourceStack.length === 0) {
				utilDebug('createResources done in '+(new Date().getTime()-startTime)+' ms.');
				cb();
			} else {
				createResource(resourceStack[0],resourceLoader);
			}
		};
		createResource(resourceStack[0],resourceLoader);
	}

	var injectResources = function(resources, cb) {
		var startTime = new Date().getTime();
		utilDebug('injectResources');
		resources.forEach(function (resource) {
			var item = cacheGetItem(resource);
			var tag = null;
			if (resource.type === 'css') {
				tag = document.createElement('style');
				tag.type = 'text/css';
			} else {
				tag = document.createElement('script');
				tag.type = 'text/javascript';
			}
			utilDebug('injectResources resource: '+JSON.stringify(resource));
			
			tag.appendChild(document.createTextNode(item.data));
			
			//document.getElementsByTagName('head')[0].appendChild(tag);
			var ref = document.getElementsByTagName('script')[0];
			ref.parentNode.insertBefore(tag, ref); // note in reverse order
		});
		utilDebug('injectResources done in '+(new Date().getTime()-startTime)+' ms.');
		cb();
	}
	
	var injectLinkResources = function(resources, cb) {
		var startTime = new Date().getTime();
		utilDebug('injectLinkResources');
		resources.forEach(function (resource) {
		utilDebug('injectLinkResources resource: '+JSON.stringify(resource));
			var tag = null;
			if (resource.type === 'css') {
				tag = document.createElement('link');
				tag.type = 'text/css';
				tag.rel = 'stylesheet';
				tag.href = resource.url;
			}
			if (resource.type === 'js') {
				tag = document.createElement('script');
				tag.type = 'text/javascript';
				tag.src = resource.url;
			}
			if (tag !== null) {
				var startTime2 = new Date().getTime();
				document.getElementsByTagName('head')[0].appendChild(tag);
				utilDebug('inject time in '+(new Date().getTime()-startTime2)+' ms.');
				//var ref = document.getElementsByTagName('script')[0];
				//ref.parentNode.insertBefore(tag, ref); // TODO reverser order
			} else {
				utilDebug('unknow resource type: '+resource.type);
				// TODO add err
			}
		});
		utilDebug('injectLinkResources done in '+(new Date().getTime()-startTime)+' ms.');
		cb();
	}
	
	var startDefaults = function () {
		if (options.url === undefined) {
			throw new Error('No url defined');
		}
		if (options.debug === undefined) {
			options.debug = false;
		}
		if (options.cachePrefix === undefined) {
			options.cachePrefix = 'sync-';
		}
	}
	
	var startDone = function (startTime) {
		utilDebug('start done in '+(new Date().getTime()-startTime)+' ms.');
		if (options.resultFn) {
			options.resultFn();
		}
	}
	
	var start = function (opt) {
		if (opt === undefined) {
			throw new Error('need options');
		}
		var startTime = new Date().getTime();
		options = opt;
		startDefaults();
		var injectAsLink = options.cacheGetFn === undefined || options.cacheSetFn === undefined || options.cacheDelFn === undefined;
		utilDebug('start options: '+JSON.stringify(options)+' injectAsLink: '+injectAsLink);
		
		
		
		var resources = [];
		utilHttpFetch(options.url, function(httpRequest) {
			if (httpRequest.status == 200) {
				JSON.parse(httpRequest.responseText).data.resources.forEach(function (r) {
					resources.push(r);
					utilDebug('build resources add: '+JSON.stringify(r));
				});
				if (injectAsLink) {
					injectLinkResources(resources, function () {
						startDone(startTime);
					});
				} else {
					createResources(resources, function () {
						injectResources(resources, function () {
							cacheCleanup(resources);
							startDone(startTime);
						});
					});
				}
			} else {
				console.log('app err'); // TODO: fix async load error code path
			}
		})
	};
	
	var getOrAskUrl = function (opt) {
		
	};
	// TODO: getOrAskUrl: getOrAskUrl,
	
	return {
		start: start
	};
})();

var autoStartFFSpaLoader = function () {
	var scripts = document.getElementsByTagName('SCRIPT');
	if (scripts && scripts.length>0) {
		for (var i in scripts) {
			if (scripts[i].src && scripts[i].src.match(/.*ffSpaLoaderUrl.*/)) {
				var query = scripts[i].src;
				var queryParameters = {};
				query.split('?').forEach(function(part) {
					var item = part.split("=");
					queryParameters[item[0]] = decodeURIComponent(item[1]);
				});
				// TODO: remove debug here
				FFSpaLoader.start({
					debug: true,
					injectAsLink: true,
					url: queryParameters.ffSpaLoaderUrl
				});
				break;
			}
		}
	}
};

autoStartFFSpaLoader(); // TODO: make private