using System.IO;

namespace YooAsset
{
	internal class LoadCacheManifestOperation : AsyncOperationBase
	{
		private enum ESteps
		{
			None,
			QueryCachePackageHash,
			VerifyFileHash,
			LoadCacheManifest,
			CheckDeserializeManifest,
			Done,
		}

		private readonly string _packageName;
		private readonly string _packageVersion;
		private QueryCachePackageHashOperation _queryCachePackageHashOp;
		private DeserializeManifestOperation _deserializer;
		private string _manifestFilePath;
		private ESteps _steps = ESteps.None;

		/// <summary>
		/// 加载的清单实例
		/// </summary>
		public PackageManifest Manifest { private set; get; }


		public LoadCacheManifestOperation(string packageName, string packageVersion)
		{
			_packageName = packageName;
			_packageVersion = packageVersion;
		}
		internal override void Start()
		{
			_steps = ESteps.QueryCachePackageHash;
		}
		internal override void Update()
		{
			if (_steps == ESteps.None || _steps == ESteps.Done)
				return;

			if (_steps == ESteps.QueryCachePackageHash)
			{
				if (_queryCachePackageHashOp == null)
				{
					_queryCachePackageHashOp = new QueryCachePackageHashOperation(_packageName, _packageVersion);
					OperationSystem.StartOperation(_queryCachePackageHashOp);
				}

				if (_queryCachePackageHashOp.IsDone == false)
					return;

				if (_queryCachePackageHashOp.Status == EOperationStatus.Succeed)
				{
					_steps = ESteps.VerifyFileHash;
				}
				else
				{
					_steps = ESteps.Done;
					Status = EOperationStatus.Failed;
					Error = _queryCachePackageHashOp.Error;
					ClearCacheFile();
				}
			}

			if (_steps == ESteps.VerifyFileHash)
			{
				_manifestFilePath = PersistentTools.GetPersistent(_packageName).GetSandboxPackageManifestFilePath(_packageVersion);
				if (File.Exists(_manifestFilePath) == false)
				{
					_steps = ESteps.Done;
					Status = EOperationStatus.Failed;
					Error = $"Not found cache manifest file : {_manifestFilePath}";
					ClearCacheFile();
					return;
				}

				string fileHash = HashUtility.FileMD5(_manifestFilePath);
				if (fileHash != _queryCachePackageHashOp.PackageHash)
				{
					_steps = ESteps.Done;
					Status = EOperationStatus.Failed;
					Error = "Failed to verify cache manifest file hash !";
					ClearCacheFile();
				}
				else
				{
					_steps = ESteps.LoadCacheManifest;
				}
			}

			if (_steps == ESteps.LoadCacheManifest)
			{
				byte[] bytesData = File.ReadAllBytes(_manifestFilePath);
				_deserializer = new DeserializeManifestOperation(bytesData);
				OperationSystem.StartOperation(_deserializer);
				_steps = ESteps.CheckDeserializeManifest;
			}

			if (_steps == ESteps.CheckDeserializeManifest)
			{
				Progress = _deserializer.Progress;
				if (_deserializer.IsDone == false)
					return;

				if (_deserializer.Status == EOperationStatus.Succeed)
				{
					Manifest = _deserializer.Manifest;
					_steps = ESteps.Done;
					Status = EOperationStatus.Succeed;
				}
				else
				{
					_steps = ESteps.Done;
					Status = EOperationStatus.Failed;
					Error = _deserializer.Error;
					ClearCacheFile();
				}
			}
		}

		private void ClearCacheFile()
		{
			// 注意：如果加载沙盒内的清单报错，为了避免流程被卡住，主动把损坏的文件删除。
			if (File.Exists(_manifestFilePath))
			{
				YooLogger.Warning($"Failed to load cache manifest file : {Error}");
				YooLogger.Warning($"Invalid cache manifest file have been removed : {_manifestFilePath}");
				File.Delete(_manifestFilePath);
			}

			string hashFilePath = PersistentTools.GetPersistent(_packageName).GetSandboxPackageHashFilePath(_packageVersion);
			if (File.Exists(hashFilePath))
			{
				File.Delete(hashFilePath);
			}
		}
	}
}