using System.Text.Json;
using DysonNetwork.Drive.Storage.Model;
using DysonNetwork.Shared.Proto;
using DysonNetwork.Shared.Stream;
using FFMpegCore;
using Microsoft.EntityFrameworkCore;
using NATS.Client.Core;
using NATS.Client.JetStream;
using NATS.Client.JetStream.Models;
using NATS.Net;
using NetVips;
using NodaTime;
using FileService = DysonNetwork.Drive.Storage.FileService;

namespace DysonNetwork.Drive.Startup;

public class BroadcastEventHandler(
    INatsConnection nats,
    ILogger<BroadcastEventHandler> logger,
    IServiceProvider serviceProvider
) : BackgroundService
{
    private const string TempFileSuffix = "dypart";

    private static readonly string[] AnimatedImageTypes =
        ["image/gif", "image/apng", "image/avif"];

    private static readonly string[] AnimatedImageExtensions =
        [".gif", ".apng", ".avif"];
    
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        var js = nats.CreateJetStreamContext();

        await js.EnsureStreamCreated("account_events", [AccountDeletedEvent.Type]);
        
        var accountEventConsumer = await js.CreateOrUpdateConsumerAsync("account_events",
            new ConsumerConfig("drive_account_deleted_handler"), cancellationToken: stoppingToken);
        
        await js.EnsureStreamCreated("file_events", [FileUploadedEvent.Type]);
        var fileUploadedConsumer = await js.CreateOrUpdateConsumerAsync("file_events",
            new ConsumerConfig("drive_file_uploaded_handler"), cancellationToken: stoppingToken);

        var accountDeletedTask = HandleAccountDeleted(accountEventConsumer, stoppingToken);
        var fileUploadedTask = HandleFileUploaded(fileUploadedConsumer, stoppingToken);

        await Task.WhenAll(accountDeletedTask, fileUploadedTask);
    }

    private async Task HandleFileUploaded(INatsJSConsumer consumer, CancellationToken stoppingToken)
    {
        await foreach (var msg in consumer.ConsumeAsync<byte[]>(cancellationToken: stoppingToken))
        {
            var payload = JsonSerializer.Deserialize<FileUploadedEventPayload>(msg.Data, GrpcTypeHelper.SerializerOptions);
            if (payload == null)
            {
                await msg.AckAsync(cancellationToken: stoppingToken);
                continue;
            }
            
            try
            {
                await ProcessAndUploadInBackgroundAsync(
                    payload.FileId,
                    payload.RemoteId,
                    payload.StorageId,
                    payload.ContentType,
                    payload.ProcessingFilePath,
                    payload.IsTempFile
                );

                await msg.AckAsync(cancellationToken: stoppingToken);
            }
            catch (Exception ex)
            {
                logger.LogError(ex, "Error processing FileUploadedEvent for file {FileId}", payload?.FileId);
                await msg.NakAsync(cancellationToken: stoppingToken);
            }
        }
    }

    private async Task HandleAccountDeleted(INatsJSConsumer consumer, CancellationToken stoppingToken)
    {
        await foreach (var msg in consumer.ConsumeAsync<byte[]>(cancellationToken: stoppingToken))
        {
            try
            {
                var evt = JsonSerializer.Deserialize<AccountDeletedEvent>(msg.Data, GrpcTypeHelper.SerializerOptions);
                if (evt == null)
                {
                    await msg.AckAsync(cancellationToken: stoppingToken);
                    continue;
                }

                logger.LogInformation("Account deleted: {AccountId}", evt.AccountId);

                using var scope = serviceProvider.CreateScope();
                var fs = scope.ServiceProvider.GetRequiredService<FileService>();
                var db = scope.ServiceProvider.GetRequiredService<AppDatabase>();

                await using var transaction = await db.Database.BeginTransactionAsync(cancellationToken: stoppingToken);
                try
                {
                    var files = await db.Files
                        .Where(p => p.AccountId == evt.AccountId)
                        .ToListAsync(cancellationToken: stoppingToken);

                    await fs.DeleteFileDataBatchAsync(files);
                    await db.Files
                        .Where(p => p.AccountId == evt.AccountId)
                        .ExecuteDeleteAsync(cancellationToken: stoppingToken);

                    await transaction.CommitAsync(cancellationToken: stoppingToken);
                }
                catch (Exception)
                {
                    await transaction.RollbackAsync(cancellationToken: stoppingToken);
                    throw;
                }

                await msg.AckAsync(cancellationToken: stoppingToken);
            }
            catch (Exception ex)
            {
                logger.LogError(ex, "Error processing AccountDeleted");
                await msg.NakAsync(cancellationToken: stoppingToken);
            }
        }
    }
    
     private async Task ProcessAndUploadInBackgroundAsync(
        string fileId,
        Guid remoteId,
        string storageId,
        string contentType,
        string processingFilePath,
        bool isTempFile
    )
    {
        using var scope = serviceProvider.CreateScope();
        var fs = scope.ServiceProvider.GetRequiredService<FileService>();
        var scopedDb = scope.ServiceProvider.GetRequiredService<AppDatabase>();
        
        var pool = await fs.GetPoolAsync(remoteId);
        if (pool is null) return;

        var uploads = new List<(string FilePath, string Suffix, string ContentType, bool SelfDestruct)>();
        var newMimeType = contentType;
        var hasCompression = false;
        var hasThumbnail = false;

        try
        {
            logger.LogInformation("Processing file {FileId} in background...", fileId);

            var fileToUpdate = await scopedDb.Files.AsNoTracking().FirstAsync(f => f.Id == fileId);

            if (fileToUpdate.IsEncrypted)
            {
                uploads.Add((processingFilePath, string.Empty, contentType, false));
            }
            else if (!pool.PolicyConfig.NoOptimization)
            {
                var fileExtension = Path.GetExtension(processingFilePath);
                switch (contentType.Split('/')[0])
                {
                    case "image":
                        if (AnimatedImageTypes.Contains(contentType) || AnimatedImageExtensions.Contains(fileExtension))
                        {
                            logger.LogInformation("Skip optimize file {FileId} due to it is animated...", fileId);
                            uploads.Add((processingFilePath, string.Empty, contentType, false));
                            break;
                        }

                        newMimeType = "image/webp";
                        using (var vipsImage = Image.NewFromFile(processingFilePath))
                        {
                            var imageToWrite = vipsImage;

                            if (vipsImage.Interpretation is Enums.Interpretation.Scrgb or Enums.Interpretation.Xyz)
                            {
                                imageToWrite = vipsImage.Colourspace(Enums.Interpretation.Srgb);
                            }

                            var webpPath = Path.Join(Path.GetTempPath(), $"{fileId}.{TempFileSuffix}.webp");
                            imageToWrite.Autorot().WriteToFile(webpPath,
                                new VOption { { "lossless", true }, { "strip", true } });
                            uploads.Add((webpPath, string.Empty, newMimeType, true));

                            if (imageToWrite.Width * imageToWrite.Height >= 1024 * 1024)
                            {
                                var scale = 1024.0 / Math.Max(imageToWrite.Width, imageToWrite.Height);
                                var compressedPath =
                                    Path.Join(Path.GetTempPath(), $"{fileId}.{TempFileSuffix}.compressed.webp");
                                using var compressedImage = imageToWrite.Resize(scale);
                                compressedImage.Autorot().WriteToFile(compressedPath,
                                    new VOption { { "Q", 80 }, { "strip", true } });
                                uploads.Add((compressedPath, ".compressed", newMimeType, true));
                                hasCompression = true;
                            }

                            if (!ReferenceEquals(imageToWrite, vipsImage))
                            {
                                imageToWrite.Dispose();
                            }
                        }

                        break;

                    case "video":
                        uploads.Add((processingFilePath, string.Empty, contentType, false));

                        var thumbnailPath = Path.Join(Path.GetTempPath(), $"{fileId}.{TempFileSuffix}.thumbnail.jpg");
                        try
                        {
                            await FFMpegArguments
                                .FromFileInput(processingFilePath, verifyExists: true)
                                .OutputToFile(thumbnailPath, overwrite: true, options => options
                                    .Seek(TimeSpan.FromSeconds(0))
                                    .WithFrameOutputCount(1)
                                    .WithCustomArgument("-q:v 2")
                                )
                                .NotifyOnOutput(line => logger.LogInformation("[FFmpeg] {Line}", line))
                                .NotifyOnError(line => logger.LogWarning("[FFmpeg] {Line}", line))
                                .ProcessAsynchronously();

                            if (File.Exists(thumbnailPath))
                            {
                                uploads.Add((thumbnailPath, ".thumbnail", "image/jpeg", true));
                                hasThumbnail = true;
                            }
                            else
                            {
                                logger.LogWarning("FFMpeg did not produce thumbnail for video {FileId}", fileId);
                            }
                        }
                        catch (Exception ex)
                        {
                            logger.LogError(ex, "Failed to generate thumbnail for video {FileId}", fileId);
                        }

                        break;

                    default:
                        uploads.Add((processingFilePath, string.Empty, contentType, false));
                        break;
                }
            }
            else uploads.Add((processingFilePath, string.Empty, contentType, false));

            logger.LogInformation("Optimized file {FileId}, now uploading...", fileId);

            if (uploads.Count > 0)
            {
                var destPool = remoteId;
                var uploadTasks = uploads.Select(item =>
                    fs.UploadFileToRemoteAsync(
                        storageId,
                        destPool,
                        item.FilePath,
                        item.Suffix,
                        item.ContentType,
                        item.SelfDestruct
                    )
                ).ToList();

                await Task.WhenAll(uploadTasks);

                logger.LogInformation("Uploaded file {FileId} done!", fileId);

                var now = SystemClock.Instance.GetCurrentInstant();
                await scopedDb.Files.Where(f => f.Id == fileId).ExecuteUpdateAsync(setter => setter
                    .SetProperty(f => f.UploadedAt, now)
                    .SetProperty(f => f.PoolId, destPool)
                    .SetProperty(f => f.MimeType, newMimeType)
                    .SetProperty(f => f.HasCompression, hasCompression)
                    .SetProperty(f => f.HasThumbnail, hasThumbnail)
                );
            }
        }
        catch (Exception err)
        {
            logger.LogError(err, "Failed to process and upload {FileId}", fileId);
        }
        finally
        {
            if (isTempFile)
            {
                File.Delete(processingFilePath);
            }
            await fs._PurgeCacheAsync(fileId);
        }
    }
}