package {
	import flash.display.*;
	import flash.events.*;
	import flash.errors.*;
	import flash.net.URLRequest;
	public class AssetManager {
		// a class to hold external assets and manage loading
		// assets' references are held in an array
		// *** properties ***
		var assets: Array;
		// *** methods ***
		// the constructor function
		public function AssetManager() {
			// set up the array
			assets = new Array();
		}
		// loads an asset from a given location
		public function addAsset(fileName: String): int {
			// make a loader for the asset
			var loader: Loader = new Loader();
			// set an event listener for loading error events
			loader.contentLoaderInfo.addEventListener(IOErrorEvent.IO_ERROR, ioerrorListener);
			// set an event listener for load progress events
			loader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, progressListener);
			// set an event listener for load complete event
			loader.contentLoaderInfo.addEventListener(Event.COMPLETE, completeListener);
			// try the load
			try {
				loader.load(new URLRequest(fileName));
				// save the loader if load was allowed|
				assets.push(loader);
				return assets.length - 1;
			} catch (e: SecurityError) {
				// trying to load from a forbidden source
				trace("AssetManager: Security Error - Not allowed to load file " + fileName);
			}
			return -1;
		}
		private function ioerrorListener(e: IOErrorEvent): void {
			trace("AsssetManager: Error - could not load a file");
			// find the Loader that couldn't load file and delete it
			for (var i: Number = 0; i < getAssetCount(); i++) {
				var info: LoaderInfo = assets[i].contentLoaderInfo;
				if (info == e.target) {
					assets[i] = null;
				}
			}
		}
		private function progressListener(e: ProgressEvent): void {
			// you could display the progress of the download here
		}
		private function completeListener(e: Event): void {
			trace("AssetManager: Info - load complete for" + e.target.url);
		}
		// tests if all assets have loaded yet
		public function loaded(): Boolean {
			var loadDone: Boolean = true;
			// go through each in turn using a loop
			for (var i: Number = 0; i < getAssetCount(); i++) {
				if (assets[i] != null) {
					var info: LoaderInfo = assets[i].contentLoaderInfo;
					// if the load is not complete, switch variable
					if (info.bytesLoaded != info.bytesTotal) {
						loadDone = false;
					}
				}
			}
			return loadDone;
		}
		// gets an asset based on its number
		public function getAsset(id: Number): * {
			// send back the asset in that position in the array
			if (assets[id] != null) {
				return Loader(assets[id]).content;
			}
			// or null if it didn't load
			return null;
		}
		// returns the number of assets
		public function getAssetCount(): Number {
			// send back the number of assets
			return assets.length;
		}
	}
}