namespace ASC.Core.ChunkedUploader;

public class CommonChunkedUploadSessionHolder
{
    public IDataStore DataStore { get; set; }

    public static readonly TimeSpan SlidingExpiration = TimeSpan.FromHours(12);
    private readonly TempPath _tempPath;
    private readonly IOptionsMonitor<ILog> _option;
    private readonly string _domain;
    private readonly long _maxChunkUploadSize;

    private const string StoragePath = "sessions";

    public CommonChunkedUploadSessionHolder(
        TempPath tempPath,
        IOptionsMonitor<ILog> option,
        IDataStore dataStore,
        string domain,
        long maxChunkUploadSize = 10 * 1024 * 1024)
    {
        _tempPath = tempPath;
        _option = option;
        DataStore = dataStore;
        _domain = domain;
        _maxChunkUploadSize = maxChunkUploadSize;
    }

    public async Task DeleteExpiredAsync()
    {
        // clear old sessions
        try
        {
            await DataStore.DeleteExpiredAsync(_domain, StoragePath, SlidingExpiration);
        }
        catch (Exception err)
        {
            _option.CurrentValue.Error(err);
        }
    }

    public async Task StoreAsync(CommonChunkedUploadSession s)
    {
        using var stream = s.Serialize();
        await DataStore.SavePrivateAsync(_domain, GetPathWithId(s.Id), stream, s.Expired);
    }

    public async Task RemoveAsync(CommonChunkedUploadSession s)
    {
        await DataStore.DeleteAsync(_domain, GetPathWithId(s.Id));
    }

    public Task<Stream> GetStreamAsync(string sessionId)
    {
        return DataStore.GetReadStreamAsync(_domain, GetPathWithId(sessionId));
    }

    public Task InitAsync(CommonChunkedUploadSession chunkedUploadSession)
    {
        if (chunkedUploadSession.BytesTotal < _maxChunkUploadSize)
        {
            chunkedUploadSession.UseChunks = false;
            return Task.CompletedTask;
        }

        return internalInitAsync(chunkedUploadSession);
    }

    private async Task internalInitAsync(CommonChunkedUploadSession chunkedUploadSession)
    {
        var tempPath = Guid.NewGuid().ToString();
        var uploadId = await DataStore.InitiateChunkedUploadAsync(_domain, tempPath);

        chunkedUploadSession.TempPath = tempPath;
        chunkedUploadSession.UploadId = uploadId;
    }

    public async Task FinalizeAsync(CommonChunkedUploadSession uploadSession)
    {
        var tempPath = uploadSession.TempPath;
        var uploadId = uploadSession.UploadId;
        var eTags = uploadSession.GetItemOrDefault<List<string>>("ETag")
            .Select((x, i) => new KeyValuePair<int, string>(i + 1, x))
            .ToDictionary(x => x.Key, x => x.Value);

        await DataStore.FinalizeChunkedUploadAsync(_domain, tempPath, uploadId, eTags);
    }

    public async Task MoveAsync(CommonChunkedUploadSession chunkedUploadSession, string newPath, bool quotaCheckFileSize = true)
    {
        await DataStore.MoveAsync(_domain, chunkedUploadSession.TempPath, string.Empty, newPath, quotaCheckFileSize);
    }

    public async Task AbortAsync(CommonChunkedUploadSession uploadSession)
    {
        if (uploadSession.UseChunks)
        {
            var tempPath = uploadSession.TempPath;
            var uploadId = uploadSession.UploadId;

            await DataStore.AbortChunkedUploadAsync(_domain, tempPath, uploadId);
        }
        else if (!string.IsNullOrEmpty(uploadSession.ChunksBuffer))
        {
            File.Delete(uploadSession.ChunksBuffer);
        }
    }

    public async Task UploadChunkAsync(CommonChunkedUploadSession uploadSession, Stream stream, long length)
    {
        var tempPath = uploadSession.TempPath;
        var uploadId = uploadSession.UploadId;
        var chunkNumber = uploadSession.GetItemOrDefault<int>("ChunksUploaded") + 1;

        var eTag = await DataStore.UploadChunkAsync(_domain, tempPath, uploadId, stream, _maxChunkUploadSize, chunkNumber, length);

        uploadSession.Items["ChunksUploaded"] = chunkNumber;
        uploadSession.BytesUploaded += length;

        var eTags = uploadSession.GetItemOrDefault<List<string>>("ETag") ?? new List<string>();
        eTags.Add(eTag);
        uploadSession.Items["ETag"] = eTags;
    }

    public Stream UploadSingleChunk(CommonChunkedUploadSession uploadSession, Stream stream, long chunkLength)
    {
        if (uploadSession.BytesTotal == 0)
            uploadSession.BytesTotal = chunkLength;

        if (uploadSession.BytesTotal >= chunkLength)
        {
            //This is hack fixing strange behaviour of plupload in flash mode.

            if (string.IsNullOrEmpty(uploadSession.ChunksBuffer))
            {
                uploadSession.ChunksBuffer = _tempPath.GetTempFileName();
            }

            using (var bufferStream = new FileStream(uploadSession.ChunksBuffer, FileMode.Append))
            {
                stream.CopyTo(bufferStream);
            }

            uploadSession.BytesUploaded += chunkLength;

            if (uploadSession.BytesTotal == uploadSession.BytesUploaded)
            {
                return new FileStream(uploadSession.ChunksBuffer, FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite,
                    4096, FileOptions.DeleteOnClose);
            }
        }

        return Stream.Null;
    }

    public async Task<Stream> UploadSingleChunkAsync(CommonChunkedUploadSession uploadSession, Stream stream, long chunkLength)
    {
        if (uploadSession.BytesTotal == 0)
            uploadSession.BytesTotal = chunkLength;

        if (uploadSession.BytesTotal >= chunkLength)
        {
            //This is hack fixing strange behaviour of plupload in flash mode.

            if (string.IsNullOrEmpty(uploadSession.ChunksBuffer))
            {
                uploadSession.ChunksBuffer = _tempPath.GetTempFileName();
            }

            using (var bufferStream = new FileStream(uploadSession.ChunksBuffer, FileMode.Append))
            {
                await stream.CopyToAsync(bufferStream);
            }

            uploadSession.BytesUploaded += chunkLength;

            if (uploadSession.BytesTotal == uploadSession.BytesUploaded)
            {
                return new FileStream(uploadSession.ChunksBuffer, FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite,
                    4096, FileOptions.DeleteOnClose);
            }
        }

        return Stream.Null;
    }

    private string GetPathWithId(string id)
    {
        return CrossPlatform.PathCombine(StoragePath, id + ".session");
    }
}