using System.Linq;
using EmbyToolbox.Models;

namespace EmbyToolbox.Services;

/// <summary>Ход пакетного анализа очереди (ffprobe) для IProgress и UI.</summary>
public readonly record struct QueueAnalysisProgress(int Processed, int Total, int ErrorCount);

/// <summary>
/// Асинхронный батч ffprobe: ограниченный параллелизм, отмена по <see cref="CancellationToken"/>,
/// обновление строки через <paramref name="uiInvoke"/> (UI).
/// </summary>
public sealed class QueueAnalysisService
{
    private const int MaxParallel = 2;
    private readonly FfprobeService _ffprobe;
    private readonly LoggingService _logging;
    private readonly SidecarDiscoveryService _sidecar;
    private readonly ConversionPlanService _planService;
    private readonly IProfileSettingsProvider _profile;

    public QueueAnalysisService(
        FfprobeService ffprobe,
        LoggingService logging,
        SidecarDiscoveryService sidecar,
        ConversionPlanService planService,
        IProfileSettingsProvider profile)
    {
        _ffprobe = ffprobe;
        _logging = logging;
        _sidecar = sidecar;
        _planService = planService;
        _profile = profile;
    }

    public async Task<int> RunAsync(
        IReadOnlyList<ConversionQueueItem> items,
        Func<ConversionQueueItem, bool> isStillInQueue,
        bool autoRemoveForeignTracks,
        bool disableSubtitleDefault,
        IProgress<QueueAnalysisProgress>? progress,
        Func<Action, Task> uiInvoke,
        CancellationToken cancellationToken)
    {
        if (items.Count == 0)
        {
            return 0;
        }

        var total = items.Count;
        var lockObj = new object();
        var state = new ProgressState();
        var sem = new SemaphoreSlim(MaxParallel, MaxParallel);
        var tasks = items
            .Select(
                item => ProcessOneAsync(
                    item,
                    isStillInQueue,
                    progress,
                    uiInvoke,
                    autoRemoveForeignTracks,
                    disableSubtitleDefault,
                    sem,
                    lockObj,
                    total,
                    state,
                    cancellationToken))
            .ToArray();

        await Task.WhenAll(tasks).ConfigureAwait(false);
        return state.ErrorCount;
    }

    private async Task ProcessOneAsync(
        ConversionQueueItem item,
        Func<ConversionQueueItem, bool> isStillInQueue,
        IProgress<QueueAnalysisProgress>? progress,
        Func<Action, Task> uiInvoke,
        bool autoRemoveForeignTracks,
        bool disableSubtitleDefault,
        SemaphoreSlim sem,
        object lockObj,
        int total,
        ProgressState state,
        CancellationToken cancellationToken)
    {
        var acquired = false;
        var itemAnalysisFailed = false;
        try
        {
            try
            {
                await sem.WaitAsync(cancellationToken).ConfigureAwait(false);
            }
            catch (OperationCanceledException)
            {
                await MarkCancelledOnUiAsync(item, isStillInQueue, uiInvoke).ConfigureAwait(false);
                return;
            }

            acquired = true;

            if (cancellationToken.IsCancellationRequested)
            {
                await MarkCancelledOnUiAsync(item, isStillInQueue, uiInvoke).ConfigureAwait(false);
                return;
            }

            FfprobeResult result;
            try
            {
                result = await _ffprobe.AnalyzeAsync(item.FullPath, cancellationToken).ConfigureAwait(false);
            }
            catch (OperationCanceledException)
            {
                await MarkCancelledOnUiAsync(item, isStillInQueue, uiInvoke).ConfigureAwait(false);
                return;
            }

            if (cancellationToken.IsCancellationRequested)
            {
                await MarkCancelledOnUiAsync(item, isStillInQueue, uiInvoke).ConfigureAwait(false);
                return;
            }

            SidecarDiscoveryResult discovery;
            try
            {
                discovery = await _sidecar.DiscoverAsync(item.FullPath, _ffprobe, cancellationToken).ConfigureAwait(false);
            }
            catch (OperationCanceledException)
            {
                await MarkCancelledOnUiAsync(item, isStillInQueue, uiInvoke).ConfigureAwait(false);
                return;
            }
            catch (Exception ex)
            {
                _logging.Error($"поиск sidecar: {ex.Message} — {item.FullPath}", "conversion.sidecar", ex);
                discovery = new SidecarDiscoveryResult(Array.Empty<SidecarFile>(), Array.Empty<ExternalAudioFile>());
            }

            var media = result.IsSuccess ? MediaAnalysisParser.TryParse(result.Json) : null;

            var failed = false;
            await uiInvoke(
                    () =>
                    {
                        if (!isStillInQueue(item))
                        {
                            return;
                        }

                        if (item.Status != ConversionQueueStatus.Analyzing)
                        {
                            return;
                        }

                        if (!result.IsSuccess)
                        {
                            failed = true;
                            item.PlanSummary = "Ошибка анализа";
                            item.Status = ConversionQueueStatus.Error;
                            item.Progress = 0;
                            item.ErrorMessage =
                                string.IsNullOrWhiteSpace(result.Error) ? "Ошибка ffprobe." : result.Error.Trim();
                            item.ErrorDetails =
                                string.IsNullOrWhiteSpace(result.StdErr) ? null : result.StdErr.Trim();
                            _logging.Error($"ffprobe: {result.Error} — {item.FullPath}", "conversion.ffprobe");
                            return;
                        }

                        if (media is null)
                        {
                            failed = true;
                            item.PlanSummary = "Ошибка анализа";
                            item.Status = ConversionQueueStatus.Error;
                            item.Progress = 0;
                            item.ErrorMessage = "Не удалось разобрать ответ ffprobe (неверный JSON).";
                            item.ErrorDetails = !string.IsNullOrWhiteSpace(result.StdErr)
                                ? result.StdErr.Trim()
                                : (string.IsNullOrWhiteSpace(result.Json) ? null : result.Json.Trim());
                            _logging.Error($"ffprobe: неверный JSON (media) — {item.FullPath}", "conversion.ffprobe");
                            return;
                        }

                        var audio = FfprobeAudioInfoParser.TryParse(result.Json) ?? new FfprobeAudioInfo(0, null, true);
                        var side = discovery.Sidecars;
                        var profile = _profile.GetProfile(item.Profile) ?? ConversionProfileMapping.EmbyFallback;
                        // При повторном анализе sidecar-набор может измениться (добавили/удалили внешние файлы).
                        // Пересобираем список дорожек, чтобы не держать устаревшие external entries.
                        item.TaskOverride.TrackOverrides.Clear();
                        TrackOverrideSeeder.EnsureDefaults(
                            item.TaskOverride,
                            media,
                            side,
                            profile,
                            autoRemoveForeignTracks,
                            discovery.ExternalAudioFiles,
                            item.FullPath,
                            sidecarTitleResolver: null,
                            logging: _logging,
                            disableSubtitleDefault: disableSubtitleDefault);
                        if (autoRemoveForeignTracks)
                        {
                            var removedForeign = item.TaskOverride.TrackOverrides.Count(t =>
                                t.Source == SourceKind.Embedded
                                && t.StreamKind is MediaStreamKind.Audio or MediaStreamKind.Subtitle
                                && t.Action == TrackActionKind.Remove
                                && IsForeignLanguageForAutoRemove(t.Language));
                            if (removedForeign > 0)
                            {
                                _logging.Info($"автоудаление иностранных дорожек: {removedForeign} ({item.FullPath})", "conversion.queue");
                            }
                        }

                        var plan = _planService.Build(media, side, profile, item.TaskOverride, discovery.ExternalAudioFiles);
                        item.SetSuccessfulMediaAnalysis(
                            media,
                            side,
                            discovery.ExternalAudioFiles,
                            plan,
                            audio.AudioStreamCount,
                            audio.AudioSizeMbTotal,
                            audio.IsPartial);
                        item.Status = ConversionQueueStatus.Pending;
                        item.Progress = 0;
                    })
                .ConfigureAwait(false);

            if (failed)
            {
                itemAnalysisFailed = true;
            }
        }
        catch (Exception ex) when (ex is not OperationCanceledException)
        {
            itemAnalysisFailed = true;
            _logging.Error($"ffprobe очереди: {ex.Message}", "conversion.ffprobe", ex);
            await uiInvoke(
                    () =>
                    {
                        if (!isStillInQueue(item) || item.Status != ConversionQueueStatus.Analyzing)
                        {
                            return;
                        }

                        item.PlanSummary = "Ошибка анализа";
                        item.Status = ConversionQueueStatus.Error;
                        item.Progress = 0;
                        item.ErrorMessage = ex.Message;
                        item.ErrorDetails = null;
                    })
                .ConfigureAwait(false);
        }
        finally
        {
            int p;
            int e;
            lock (lockObj)
            {
                state.ProcessedCount++;
                if (itemAnalysisFailed)
                {
                    state.ErrorCount++;
                }

                p = state.ProcessedCount;
                e = state.ErrorCount;
            }

            progress?.Report(new QueueAnalysisProgress(p, total, e));
            if (acquired)
            {
                sem.Release();
            }
        }
    }

    private static async Task MarkCancelledOnUiAsync(
        ConversionQueueItem item,
        Func<ConversionQueueItem, bool> isStillInQueue,
        Func<Action, Task> uiInvoke)
    {
        await uiInvoke(
                () =>
                {
                    if (!isStillInQueue(item))
                    {
                        return;
                    }

                    if (item.Status != ConversionQueueStatus.Analyzing)
                    {
                        return;
                    }

                    item.PlanSummary = "Анализ отменён";
                    item.Status = ConversionQueueStatus.Cancelled;
                    item.Progress = 0;
                })
            .ConfigureAwait(false);
    }

    private sealed class ProgressState
    {
        public int ProcessedCount;
        public int ErrorCount;
    }

    private static bool IsForeignLanguageForAutoRemove(string? language)
    {
        if (string.IsNullOrWhiteSpace(language))
        {
            return false;
        }

        var lang = language.Trim().ToLowerInvariant();
        if (lang is "und" or "unknown" or "?")
        {
            return false;
        }

        return lang is not ("rus" or "ru");
    }
}