MilkyShots/Lactose/Jobs/ThumbnailJob.cs

using Butter.Settings;
using Lactose.Models;
using Lactose.Repositories;
using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Formats.Jpeg;
using SixLabors.ImageSharp.Processing;

namespace Lactose.Jobs;

public class ThumbnailJob : Job {
    ThumbnailJob?         ParentJob;
    List<ThumbnailJob>?   subJobs;
    Asset?                Asset;
    string?               ThumbnailPath;
    int                   processedAssets = 0;
    int                   totalAssets     = 1; // Avoid division by zero
    int                   ThumbnailSize;
    ILogger<ThumbnailJob> Logger;
    ISettingsRepository   SettingsRepository;
    IAssetRepository      AssetRepository;
    JobManager?           JobManager;

    public override string Name { get; }

    public ThumbnailJob(
        ILogger<ThumbnailJob> logger,
        ISettingsRepository settingsRepository,
        IAssetRepository assetRepository,
        JobManager jobManager
    ) {
        Logger             = logger;
        SettingsRepository = settingsRepository;
        AssetRepository    = assetRepository;
        JobManager         = jobManager;
        Name               = "Thumbnail Generation Job";
    }

    public ThumbnailJob(
        ThumbnailJob parentJob,
        Asset asset,
        int thumbnailSize,
        string thumbnailPath,
        ILogger<ThumbnailJob> logger,
        ISettingsRepository settingsRepository,
        IAssetRepository assetRepository
    ) {
        Logger             = logger;
        SettingsRepository = settingsRepository;
        AssetRepository    = assetRepository;
        Asset              = asset;
        Name               = $"Thumbnail Gen for {Asset?.OriginalPath}";
        ParentJob          = parentJob;
        ThumbnailSize      = thumbnailSize;
        ThumbnailPath      = thumbnailPath;
    }

    protected override async Task TaskJob(CancellationToken token) {
        if (ParentJob == null) MasterJob(token);
        else SlaveJob(token);
    }

    void SlaveJob(CancellationToken token) {
        if (token.IsCancellationRequested) {
            JobStatus.Cancel("Cancellation requested from user.");
            return;
        }

        if (Asset == null) {
            Logger.LogError("Sub-job started without an asset. Canceling job.");
            JobStatus.Fail("Sub-job started without an asset. Canceling job.");
            return;
        }

        JobStatus.Start();

        try {
            if (string.IsNullOrEmpty(Asset.OriginalPath) || !File.Exists(Asset.OriginalPath)) {
                var msg = $"Original file for asset ID {Asset.Id} not found at path {Asset.OriginalPath}";
                Logger.LogWarning(msg);
                JobStatus.Fail(msg);
                return;
            }

            using var image = Image.Load(Asset.OriginalPath);

            image.Mutate(x => x.Resize(
                    new ResizeOptions {
                        Size    = new Size(ThumbnailSize),
                        Mode    = ResizeMode.Max,
                        Sampler = KnownResamplers.CatmullRom
                    }
                )
            );

            if (ThumbnailPath == null) {
                var msg = "Thumbnail path is not set. Cannot save thumbnail.";
                Logger.LogError(msg);
                JobStatus.Fail(msg);
                return;
            }

            var path = PathFromGuid(Asset.Id, ThumbnailPath);

            if (!Directory.Exists(path)) Directory.CreateDirectory(Path.GetDirectoryName(path)!);

            image.SaveAsJpeg(
                path,
                new JpegEncoder() {
                    ColorType    = JpegEncodingColor.Rgb,
                    Quality      = 75,
                    SkipMetadata = true
                }
            );

            Asset.ThumbnailPath = path;
            AssetRepository.Update(Asset);
            AssetRepository.Save();
        } catch (Exception ex) {
            Logger.LogError(ex, $"Failed to generate thumbnail for asset ID {Asset.Id}");
            JobStatus.Fail($"Error: {ex.Message}");
            return;
        }

        Logger.LogInformation($"Thumbnail generated for asset ID {Asset.Id} at {Asset.ThumbnailPath}");
        JobStatus.Complete($"Thumbnail generated for asset ID {Asset.Id} at {Asset.ThumbnailPath}");
    }

    void MasterJob(CancellationToken token) {
        if (JobManager == null) {
            Logger.LogError("JobManager is not available. Cannot create sub-jobs.");
            JobStatus.Fail("JobManager is not available. Cannot create sub-jobs.");
            return;
        }

        JobStatus.Start();
        Logger.LogInformation("Starting master Thumbnail job for all assets.");
        var thumbPath = SettingsRepository.Get(Settings.ThumbnailPath.AsString());
        //TODO: Add thumbnail size setting to the system

        if (thumbPath == null) {
            Logger.LogError("Thumbnail path not found. Cannot proceed with thumbnail generation.");
            JobStatus.Fail("Thumbnail path not found. Cannot proceed with thumbnail generation.");
            return;
        }

        var missingThumbnail = AssetRepository.GetAssetsMissingThumbnail(out totalAssets);
        Logger.LogInformation($"Found {totalAssets} assets missing thumbnails.");

        subJobs = new List<ThumbnailJob>();

        foreach (var asset in missingThumbnail) {
            if (token.IsCancellationRequested) {
                lock (subJobs) subJobs.ForEach(j => j.Cancel());
                JobStatus.Cancel("Cancellation requested from user.");
                return;
            }

            // Create a sub-job for each asset
            var job = JobManager.CreateJob<ThumbnailJob>(this, asset, 256, thumbPath.Value!);

            job.Done += (o, _) => {
                IncrementProcessedAssets();
                lock (subJobs) subJobs.Remove((o as ThumbnailJob)!);
            };

            lock (subJobs) subJobs.Add(job);
            JobManager.EnqueueJob(job);
        }

        JobStatus.Wait();

        // Wait for all sub-jobs to complete
        while (subJobs.Count > 0) {
            if (token.IsCancellationRequested) {
                lock (subJobs) subJobs.ForEach(j => j.Cancel());
                JobStatus.Cancel("User requested cancellation.");
                return;
            }
        }

        JobStatus.Complete("All thumbnails generated successfully.");
    }

    void IncrementProcessedAssets() {
        processedAssets++;
        JobStatus.UpdateProgress((float)processedAssets / totalAssets, $"Waiting for {subJobs.Count} sub-jobs to complete.");
    }

    static string PathFromGuid(Guid id, string root) {
        var s = id.ToString("N"); // 32 chars, no dashes

        return Path.Combine(
            root,
            s[..2], // 3F
            s.Substring(2, 2), // 25
            s.Substring(4, 2), // 04
            $"{s}.jpg"
        );
    }
}