using UnityEngine;

using System.Collections;

using System.IO;

using System;

using HTTP;

namespace HTTP

{

	public class DiskCacheOperation

	{

		public bool isDone = false;

		public bool fromCache = false;

		public Request request = null;

	}

#if UNITY_WEBPLAYER

	public class DiskCache : MonoBehaviour

	{

		static DiskCache _instance = null;

		public static DiskCache Instance {

			get {

				if (_instance == null) {

					var g = new GameObject ("DiskCache", typeof(DiskCache));

					g.hideFlags = HideFlags.HideAndDontSave;

					_instance = g.GetComponent<DiskCache> ();

				}

				return _instance;

			}

		}

		public DiskCacheOperation Fetch (Request request)

		{

			var handle = new DiskCacheOperation ();

			handle.request = request;

			StartCoroutine (Download (request, handle));

			return handle;

		}

		IEnumerator Download(Request request, DiskCacheOperation handle)

		{

			request.Send ();

			while (!request.isDone)

				yield return new WaitForEndOfFrame ();

			handle.isDone = true;

		}

	}

#else

	public class DiskCache : MonoBehaviour

	{

		string cachePath = null;

		static DiskCache _instance = null;

		public static DiskCache Instance {

			get {

				if (_instance == null) {

					var g = new GameObject ("DiskCache", typeof(DiskCache));

					g.hideFlags = HideFlags.HideAndDontSave;

					_instance = g.GetComponent<DiskCache> ();

				}

				return _instance;

			}

		}

		void Awake ()

		{

			cachePath = System.IO.Path.Combine (Environment.GetFolderPath (Environment.SpecialFolder.LocalApplicationData), "uwcache");

			if (!Directory.Exists (cachePath))

				Directory.CreateDirectory (cachePath);

		}

		public DiskCacheOperation Fetch (Request request)

		{

			var guid = "";

            // MD5 is disposable

            // http://msdn.microsoft.com/en-us/library/system.security.cryptography.md5.aspx#3

            using (System.Security.Cryptography.MD5 md5 = System.Security.Cryptography.MD5.Create ()) {

                foreach (var b in md5.ComputeHash (System.Text.ASCIIEncoding.ASCII.GetBytes (request.uri.ToString ()))) {

                    guid = guid + b.ToString ("X2");

                }

            }

			var filename = System.IO.Path.Combine (cachePath, guid);

			if (File.Exists (filename) && File.Exists (filename + ".etag"))

				request.SetHeader ("If-None-Match", File.ReadAllText (filename + ".etag"));

			var handle = new DiskCacheOperation ();

			handle.request = request;

			StartCoroutine (DownloadAndSave (request, filename, handle));

			return handle;

		}

		IEnumerator DownloadAndSave (Request request, string filename, DiskCacheOperation handle)

		{

			var useCachedVersion = File.Exists(filename);

            Action< HTTP.Request > callback = request.completedCallback;

			request.Send(); // will clear the completedCallback

			while (!request.isDone)

				yield return new WaitForEndOfFrame ();

			if (request.exception == null && request.response != null) {

				if (request.response.status == 200) {

					var etag = request.response.GetHeader ("etag");

					if (etag != "") {

						File.WriteAllBytes (filename, request.response.bytes);

						File.WriteAllText (filename + ".etag", etag);

					}

					useCachedVersion = false;

				}

			}

			if(useCachedVersion) {

				if(request.exception != null) {

					Debug.LogWarning("Using cached version due to exception:" + request.exception);

					request.exception = null;

				}

				request.response.status = 304;

				request.response.bytes = File.ReadAllBytes (filename);

				request.isDone = true;

			}

			handle.isDone = true;

            if ( callback != null )

            {

                callback( request );

            }

		}

	}

#endif

}