using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Reflection;
using System.IO;
using System.IO.Compression;

using Essgee.Emulation.Machines;
using Essgee.Exceptions;
using Essgee.Utilities;

namespace Essgee.Emulation
{
	public static class CartridgeLoader
	{
		static Dictionary<string, Type> fileExtensionSystemDictionary;

		static CartridgeLoader()
		{
			fileExtensionSystemDictionary = new Dictionary<string, Type>();
			foreach (var machineType in Assembly.GetExecutingAssembly().GetTypes().Where(x => typeof(IMachine).IsAssignableFrom(x) && !x.IsInterface).OrderBy(x => x.GetCustomAttribute<MachineIndexAttribute>()?.Index))
			{
				if (machineType == null) continue;

				var instance = (IMachine)Activator.CreateInstance(machineType);
				foreach (var extension in instance.FileFilter.Extension.Split(';'))
					fileExtensionSystemDictionary.Add(extension, machineType);
			}
		}

		public static (Type, byte[]) Load(string fileName, string fileType)
		{
			Type machineType = null;
			byte[] romData = null;

			if (!File.Exists(fileName))
				throw new CartridgeLoaderException($"{fileType} file not found.");

			try
			{
				var fileExtension = Path.GetExtension(fileName);
				if (fileExtension == ".zip")
				{
					using (var zip = ZipFile.Open(fileName, ZipArchiveMode.Read))
					{
						foreach (var entry in zip.Entries)
						{
							var entryExtension = Path.GetExtension(entry.Name);
							if (fileExtensionSystemDictionary.ContainsKey(entryExtension))
							{
								machineType = fileExtensionSystemDictionary[entryExtension];
								using (var stream = entry.Open())
								{
									romData = new byte[entry.Length];
									stream.Read(romData, 0, romData.Length);
								}
								break;
							}
						}
					}
				}
				else if (fileExtensionSystemDictionary.ContainsKey(fileExtension))
				{
					machineType = fileExtensionSystemDictionary[fileExtension];
					romData = File.ReadAllBytes(fileName);
				}
			}
			catch (Exception ex) when (!AppEnvironment.DebugMode)
			{
				throw new CartridgeLoaderException("File load error", ex);
			}

			if (machineType == null)
				throw new CartridgeLoaderException($"File could not be recognized as {fileType}.");

			return (machineType, romData);
		}
	}
}