using System.Text;
using Data.Data.Repositories;
using Data.Managers;
using DeepDrftAPI.Services;
using DeepDrftContent;
using DeepDrftContent.Constants;
using DeepDrftContent.FileDatabase.Models;
using DeepDrftContent.Processors;
using DeepDrftContent.Processors.Opus;
using DeepDrftData;
using DeepDrftData.Data;
using DeepDrftData.Repositories;
using DeepDrftModels.DTOs;
using DeepDrftModels.Entities;
using DeepDrftModels.Enums;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using FileDb = DeepDrftContent.FileDatabase.Services.FileDatabase;

namespace DeepDrftTests;

/// <summary>
/// Tests for the Phase 18.5 Backfill-Opus scheduling contract
/// (<see cref="UnifiedTrackService.BackfillOpusAsync"/> and <see cref="UnifiedTrackService.EnqueueOpusAsync"/>).
/// These assert the enqueue decision — which tracks get a background derive scheduled — over a real
/// <see cref="FileDb"/>, a real <see cref="TrackFormatResolver"/>, and an in-memory SQL store, with a
/// recording <see cref="NoOpOpusTranscodeQueue"/> standing in for the background worker (the actual transcode
/// is not exercised here — it needs ffmpeg and is out of scope for the scheduling contract).
///
/// The decision under test: a track is enqueued iff it lacks a COMPLETE Opus artifact (both the Opus audio
/// bytes and the seek/setup sidecar). A track with both is skipped; a half-derived track (audio without
/// sidecar) is treated as incomplete and re-enqueued so a backfill heals it.
/// </summary>
[TestFixture]
public class OpusBackfillTests
{
    private string _testDir = string.Empty;
    private DeepDrftContext _context = null!;

    [SetUp]
    public void SetUp()
    {
        _testDir = Path.Combine(Path.GetTempPath(), "OpusBackfillTests", Guid.NewGuid().ToString());
        Directory.CreateDirectory(_testDir);

        var options = new DbContextOptionsBuilder<DeepDrftContext>()
            .UseInMemoryDatabase(databaseName: Guid.NewGuid().ToString())
            .Options;
        _context = new DeepDrftContext(options);
    }

    [TearDown]
    public void TearDown()
    {
        _context.Dispose();
        try { Directory.Delete(_testDir, recursive: true); }
        catch { /* Best-effort cleanup — ignore failures */ }
    }

    private TrackManager CreateManager()
    {
        var repository = new TrackRepository(
            _context, NullLogger<Repository<DeepDrftContext, TrackEntity>>.Instance);
        return new TrackManager(
            repository, NullLogger<Manager<TrackEntity, TrackDto, TrackRepository, TrackConverter>>.Instance);
    }

    private sealed record Harness(
        UnifiedTrackService Service,
        NoOpOpusTranscodeQueue Queue,
        TrackContentService Content,
        FileDb FileDatabase,
        ITrackService Sql);

    private async Task<Harness> BuildAsync()
    {
        var fileDatabase = await FileDb.FromAsync(_testDir);
        Assert.That(fileDatabase, Is.Not.Null);

        var content = new TrackContentService(
            fileDatabase!, new AudioProcessorRouter(
                new AudioProcessor(), new Mp3AudioProcessor(), new FlacAudioProcessor()));
        var waveforms = new WaveformProfileService(
            fileDatabase!, new AudioProcessor(), new RmsLoudnessAlgorithm(),
            Options.Create(new WaveformProfileOptions()), NullLogger<WaveformProfileService>.Instance);
        var resolver = new TrackFormatResolver(
            fileDatabase!, content, NullLogger<TrackFormatResolver>.Instance);
        var queue = new NoOpOpusTranscodeQueue();
        var sql = CreateManager();

        var service = new UnifiedTrackService(
            content, sql, fileDatabase!, waveforms, queue, resolver,
            NullLogger<UnifiedTrackService>.Instance);

        await fileDatabase!.CreateVaultAsync(VaultConstants.TrackOpus, MediaVaultType.Audio);

        return new Harness(service, queue, content, fileDatabase!, sql);
    }

    // Seeds a track: stores a real source WAV in the tracks vault and a SQL row pointing at the same EntryKey.
    // Returns the EntryKey so the test can selectively add Opus artifacts to a subset.
    private async Task<string> SeedTrackAsync(Harness h, string title)
    {
        var wavPath = Path.Combine(_testDir, Guid.NewGuid().ToString("N") + ".wav");
        await File.WriteAllBytesAsync(wavPath, BuildMinimalPcmWav(2.0));
        var unpersisted = await h.Content.AddTrackAsync(wavPath, title, "Artist");
        Assert.That(unpersisted, Is.Not.Null);

        var dto = new TrackDto { EntryKey = unpersisted!.EntryKey, TrackName = title };
        var created = await h.Sql.Create(dto);
        Assert.That(created.Success, Is.True, created.Messages.FirstOrDefault()?.Message);

        return unpersisted.EntryKey;
    }

    private async Task StoreOpusAudioAsync(Harness h, string entryKey)
    {
        var opus = new AudioBinary(new AudioBinaryParams("opus"u8.ToArray(), 4, ".opus", 2.0, 320));
        Assert.That(
            await h.FileDatabase.RegisterResourceAsync(
                VaultConstants.TrackOpus, OpusTranscodeService.OpusAudioKey(entryKey), opus),
            Is.True);
    }

    private async Task StoreSidecarAsync(Harness h, string entryKey)
    {
        var sidecar = new MediaBinary(new MediaBinaryParams("idx"u8.ToArray(), 3, ".opusidx"));
        Assert.That(
            await h.FileDatabase.RegisterResourceAsync(
                VaultConstants.TrackOpus, OpusTranscodeService.OpusSidecarKey(entryKey), sidecar),
            Is.True);
    }

    [Test]
    public async Task BackfillOpus_EnqueuesOnlyTracksWithoutCompleteOpus()
    {
        var h = await BuildAsync();

        // Three tracks: one fully derived (audio + sidecar), one bare (no Opus), one half-derived (audio only).
        var complete = await SeedTrackAsync(h, "Complete");
        await StoreOpusAudioAsync(h, complete);
        await StoreSidecarAsync(h, complete);

        var bare = await SeedTrackAsync(h, "Bare");

        var halfDerived = await SeedTrackAsync(h, "HalfDerived");
        await StoreOpusAudioAsync(h, halfDerived); // audio but no sidecar → unseekable → treated as incomplete

        var result = await h.Service.BackfillOpusAsync(CancellationToken.None);

        Assert.That(result.Success, Is.True, result.Messages.FirstOrDefault()?.Message);
        Assert.Multiple(() =>
        {
            Assert.That(result.Value.Enqueued, Is.EqualTo(2), "the bare and half-derived tracks must be enqueued");
            Assert.That(result.Value.Skipped, Is.EqualTo(1), "the fully-derived track must be skipped");
            Assert.That(h.Queue.Enqueued, Does.Contain(bare));
            Assert.That(h.Queue.Enqueued, Does.Contain(halfDerived));
            Assert.That(h.Queue.Enqueued, Does.Not.Contain(complete), "a complete Opus artifact is not re-enqueued");
        });
    }

    [Test]
    public async Task BackfillOpus_WhenAllTracksHaveOpus_EnqueuesNothing()
    {
        var h = await BuildAsync();

        var a = await SeedTrackAsync(h, "A");
        await StoreOpusAudioAsync(h, a);
        await StoreSidecarAsync(h, a);

        var result = await h.Service.BackfillOpusAsync(CancellationToken.None);

        Assert.That(result.Success, Is.True);
        Assert.Multiple(() =>
        {
            Assert.That(result.Value.Enqueued, Is.Zero);
            Assert.That(result.Value.Skipped, Is.EqualTo(1));
            Assert.That(h.Queue.Enqueued, Is.Empty, "an all-derived catalogue schedules no transcodes");
        });
    }

    [Test]
    public async Task EnqueueOpus_KnownTrack_Enqueues()
    {
        var h = await BuildAsync();
        var entryKey = await SeedTrackAsync(h, "Solo");

        var result = await h.Service.EnqueueOpusAsync(entryKey, CancellationToken.None);

        Assert.That(result.Success, Is.True);
        Assert.That(h.Queue.Enqueued, Does.Contain(entryKey));
    }

    [Test]
    public async Task EnqueueOpus_UnknownTrack_FailsWithNotFound_AndEnqueuesNothing()
    {
        var h = await BuildAsync();

        var result = await h.Service.EnqueueOpusAsync("no-such-track", CancellationToken.None);

        Assert.Multiple(() =>
        {
            Assert.That(result.Success, Is.False);
            Assert.That(result.Messages.FirstOrDefault()?.Message, Is.EqualTo(UnifiedTrackService.TrackNotFoundMessage));
            Assert.That(h.Queue.Enqueued, Is.Empty, "an unknown track must not schedule a transcode");
        });
    }

    // Standard-PCM mono 16-bit 44.1 kHz WAV, full-scale square wave. Same layout as the other suites.
    private static byte[] BuildMinimalPcmWav(double durationSeconds)
    {
        const int sampleRate = 44100;
        const ushort channels = 1;
        const ushort bitsPerSample = 16;
        const ushort blockAlign = channels * (bitsPerSample / 8);
        const uint byteRate = sampleRate * blockAlign;

        var frames = (int)(sampleRate * durationSeconds);
        var data = new byte[frames * blockAlign];
        for (var i = 0; i < frames; i++)
        {
            var sample = (i % 2 == 0) ? short.MaxValue : short.MinValue;
            data[i * 2] = (byte)(sample & 0xFF);
            data[i * 2 + 1] = (byte)((sample >> 8) & 0xFF);
        }

        using var ms = new MemoryStream();
        using var w = new BinaryWriter(ms, Encoding.ASCII, leaveOpen: true);

        w.Write(Encoding.ASCII.GetBytes("RIFF"));
        w.Write((uint)(36 + data.Length));
        w.Write(Encoding.ASCII.GetBytes("WAVE"));

        w.Write(Encoding.ASCII.GetBytes("fmt "));
        w.Write(16u);
        w.Write((ushort)1); // PCM
        w.Write(channels);
        w.Write((uint)sampleRate);
        w.Write(byteRate);
        w.Write(blockAlign);
        w.Write(bitsPerSample);

        w.Write(Encoding.ASCII.GetBytes("data"));
        w.Write((uint)data.Length);
        w.Write(data);

        w.Flush();
        return ms.ToArray();
    }
}