using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.IO.IsolatedStorage;
using System.Runtime.Serialization;
using System.Threading.Tasks;
using Xamarin.Forms.Internals;

namespace Xamarin.Forms.Platform.GTK
{
	internal sealed class GtkSerializer : IDeserializer
	{
		const string PropertyStoreFile = "PropertyStore.forms";

		public Task<IDictionary<string, object>> DeserializePropertiesAsync()
		{
			try
			{
				var store = IsolatedStorageFile.GetStore(
					IsolatedStorageScope.User | IsolatedStorageScope.Domain | IsolatedStorageScope.Assembly,
					null, null);

				if (store.FileExists(PropertyStoreFile))
				{
					using (IsolatedStorageFileStream isoStream = new IsolatedStorageFileStream(PropertyStoreFile, System.IO.FileMode.Open, store))
					{
						using (StreamReader reader = new StreamReader(isoStream))
						{
							var content = reader.ReadToEnd();

							if (content.Length == 0)
								return Task.FromResult<IDictionary<string, object>>(new Dictionary<string, object>(4));


							using (Stream stream = new MemoryStream())
							{
								byte[] data = System.Text.Encoding.UTF8.GetBytes(content);
								stream.Write(data, 0, data.Length);
								stream.Position = 0;
								DataContractSerializer deserializer = new DataContractSerializer(typeof(IDictionary<string, object>));
								var result = (IDictionary<string, object>)deserializer.ReadObject(stream);
								return Task.FromResult(result);
							}
						}
					}
				}

				return Task.FromResult<IDictionary<string, object>>(new Dictionary<string, object>(4));
			}
			catch (FileNotFoundException)
			{
				return Task.FromResult<IDictionary<string, object>>(new Dictionary<string, object>(4));
			}
		}

		public Task SerializePropertiesAsync(IDictionary<string, object> properties)
		{
			try
			{
				var store = IsolatedStorageFile.GetStore(
					IsolatedStorageScope.User | IsolatedStorageScope.Domain | IsolatedStorageScope.Assembly,
					null, null);

				var file = store.CreateFile(PropertyStoreFile);

				using (IsolatedStorageFileStream isoStream = file)
				{
					var serializer = new DataContractSerializer(typeof(IDictionary<string, object>));
					serializer.WriteObject(isoStream, properties);
				}

				return Task.FromResult(true);
			}
			catch (Exception e)
			{
				Debug.WriteLine("Could not move new serialized property file over old: " + e.Message);

				return Task.FromResult(false);
			}
		}
	}
}