using Grpc.Core;
using ZR.Admin.Grpc;

namespace GrpcService.Services
{
    public class FileTransferService : FileTransfer.FileTransferBase
    {
        private readonly string _storagePath = "Îļþ";
        private readonly IUploadSessionManager _sessionManager;

        public FileTransferService(IUploadSessionManager sessionManager)
        {
            Directory.CreateDirectory(_storagePath);
            _sessionManager = sessionManager;
        }

        public override Task<InitUploadResponse> InitUpload(InitUploadRequest request, ServerCallContext context)
        {
            var sessionId = _sessionManager.CreateSession(request.FileName, request.FileSize, request.FileHash);
            var uploadedBytes = _sessionManager.GetUploadedBytes(sessionId);

            return Task.FromResult(new InitUploadResponse
            {
                SessionId = sessionId,
                UploadedBytes = uploadedBytes
            });
        }

        public override async Task<UploadChunkResponse> UploadChunk(IAsyncStreamReader<UploadChunkRequest> requestStream, ServerCallContext context)
        {
            UploadChunkRequest currentRequest = null;
            var response = new UploadChunkResponse();

            while (await requestStream.MoveNext())
            {
                currentRequest = requestStream.Current;
                var session = _sessionManager.GetSession(currentRequest.SessionId);

                if (session == null)
                {
                    throw new RpcException(new Status(StatusCode.NotFound, "Session not found"));
                }

                using (var fileStream = new FileStream(session.TempFilePath, FileMode.OpenOrCreate, FileAccess.Write))
                {
                    fileStream.Seek(currentRequest.Offset, SeekOrigin.Begin);
                    await fileStream.WriteAsync(currentRequest.ChunkData.ToByteArray(), 0, currentRequest.ChunkData.Length);
                }

                _sessionManager.UpdateSessionProgress(currentRequest.SessionId, currentRequest.Offset + currentRequest.ChunkData.Length);
                response.UploadedBytes = currentRequest.Offset + currentRequest.ChunkData.Length;
            }

            return response;
        }

        public override async Task<CompleteUploadResponse> CompleteUpload(CompleteUploadRequest request, ServerCallContext context)
        {
            var session = _sessionManager.GetSession(request.SessionId);
            if (session == null)
            {
                return await Task.FromResult(new CompleteUploadResponse
                {
                    Success = false,
                    Message = "Session not found"
                });
            }

            // Verify file hash if needed
            if (!string.IsNullOrEmpty(request.FileHash))
            {
                var actualHash = await FileHelper.GetQuickFileIdentity(session.TempFilePath);
                if (actualHash != request.FileHash)
                {
                    return await Task.FromResult(new CompleteUploadResponse
                    {
                        Success = false,
                        Message = "File hash mismatch"
                    });
                }
            }

            // Move temp file to final location
            var finalPath = Path.Combine(_storagePath, session.FileName);
            //var finalPath = FileHelper.GetUniqueFilePath(_storagePath, session.FileName);
            File.Move(session.TempFilePath, finalPath, true);

            _sessionManager.CompleteSession(request.SessionId);

            return await Task.FromResult(new CompleteUploadResponse
            {
                Success = true,
                Message = "File uploaded successfully"
            });
        }

        public override Task<CheckUploadStatusResponse> CheckUploadStatus(CheckUploadStatusRequest request, ServerCallContext context)
        {
            var session = _sessionManager.FindSession(request.FileName, request.FileHash);

            return Task.FromResult(new CheckUploadStatusResponse
            {
                SessionId = session?.SessionId ?? "",
                UploadedBytes = session?.UploadedBytes ?? 0,
                Exists = session != null
            });
        }
    }
}