using System;
using System.Collections.Generic;
using System.Globalization;
using MediaBrowser.Controller.Entities;
using MediaBrowser.Controller.Entities.Movies;
using MediaBrowser.Controller.Entities.TV;
using MediaBrowser.Controller.Library;
using MediaBrowser.Model.Entities;
using Microsoft.Extensions.Logging;

namespace Jellyfin.Plugin.RecentlyAddedGuard.Core;

/// <summary>
/// Maps Jellyfin items to <see cref="MediaIdentity"/> snapshots for the core logic.
/// </summary>
public sealed class IdentityResolver
{
    private readonly ILibraryManager _libraryManager;
    private readonly ILogger<IdentityResolver> _logger;

    /// <summary>
    /// Initializes a new instance of the <see cref="IdentityResolver"/> class.
    /// </summary>
    /// <param name="libraryManager">The library manager.</param>
    /// <param name="logger">The logger.</param>
    public IdentityResolver(ILibraryManager libraryManager, ILogger<IdentityResolver> logger)
    {
        _libraryManager = libraryManager;
        _logger = logger;
    }

    /// <summary>
    /// Checks whether the item is a real movie or episode: no missing (virtual) episode, no extra.
    /// </summary>
    /// <param name="item">The item.</param>
    /// <returns><c>true</c> if the plugin tracks items of this kind.</returns>
    public static bool IsTracked(BaseItem item)
        => item is Movie or Episode && !item.IsVirtualItem && item.ExtraType is null;

    /// <summary>
    /// Resolves the identity of a tracked item.
    /// </summary>
    /// <param name="item">The item.</param>
    /// <param name="seriesLookup">Optional cached series lookup (used by the synchronization).</param>
    /// <returns>The identity (its keys may be empty if provider ids are still missing),
    /// or <c>null</c> if the item is not tracked or its kind is disabled.</returns>
    public MediaIdentity? Resolve(BaseItem item, Func<Guid, Series?>? seriesLookup = null)
    {
        ArgumentNullException.ThrowIfNull(item);

        if (!IsTracked(item))
        {
            return null;
        }

        var configuration = Plugin.CurrentConfiguration;
        switch (item)
        {
            case Movie movie when configuration.EnableMovies:
                return new MediaIdentity(movie.Id, MediaKind.Movie, movie.DateCreated, MovieKeys(movie), MovieName(movie));
            case Episode episode when configuration.EnableEpisodes:
                var seriesId = FindSeriesId(episode);
                var series = FindSeries(seriesId, seriesLookup);
                return new MediaIdentity(
                    episode.Id,
                    MediaKind.Episode,
                    episode.DateCreated,
                    EpisodeKeys(episode, seriesId, series),
                    EpisodeName(episode, series));
            default:
                return null;
        }
    }

    /// <summary>
    /// Resolves the keys of a removed item. The provider ids are still attached to the object,
    /// but the series may already be gone, so every lookup is defensive.
    /// </summary>
    /// <param name="item">The removed item.</param>
    /// <returns>The keys; empty if they cannot be determined.</returns>
    public IReadOnlyList<string> ResolveKeysForRemoval(BaseItem item)
    {
        ArgumentNullException.ThrowIfNull(item);

        switch (item)
        {
            case Movie movie:
                return MovieKeys(movie);
            case Episode episode:
                var seriesId = FindSeriesId(episode);
                return EpisodeKeys(episode, seriesId, FindSeries(seriesId, null));
            default:
                return [];
        }
    }

    private static IReadOnlyList<string> MovieKeys(Movie movie)
        => MediaKeys.ForMovie(
            movie.GetProviderId(MetadataProvider.Tmdb),
            movie.GetProviderId(MetadataProvider.Imdb),
            movie.GetProviderId(MetadataProvider.Tvdb));

    private static IReadOnlyList<string> EpisodeKeys(Episode episode, Guid seriesId, Series? series)
    {
        var part = MediaKeys.EpisodePart(episode.ParentIndexNumber, episode.IndexNumber, episode.IndexNumberEnd);
        if (part is null)
        {
            return [];
        }

        return MediaKeys.ForEpisode(
            part,
            series?.GetProviderId(MetadataProvider.Tvdb),
            series?.GetProviderId(MetadataProvider.Tmdb),
            series?.GetProviderId(MetadataProvider.Imdb),
            seriesId);
    }

    private static string MovieName(Movie movie)
    {
        var name = string.IsNullOrWhiteSpace(movie.Name) ? movie.Id.ToString("N", CultureInfo.InvariantCulture) : movie.Name;
        return movie.ProductionYear is { } year
            ? string.Create(CultureInfo.InvariantCulture, $"{name} ({year})")
            : name;
    }

    private static string EpisodeName(Episode episode, Series? series)
    {
        var seriesName = episode.SeriesName ?? series?.Name ?? "?";
        var number = string.Create(CultureInfo.InvariantCulture, $"S{episode.ParentIndexNumber ?? 0:00}E{episode.IndexNumber ?? 0:00}");
        if (episode.IndexNumberEnd is { } end && end > (episode.IndexNumber ?? 0))
        {
            number += string.Create(CultureInfo.InvariantCulture, $"-E{end:00}");
        }

        return string.IsNullOrWhiteSpace(episode.Name)
            ? $"{seriesName} {number}"
            : $"{seriesName} {number} – {episode.Name}";
    }

#pragma warning disable CA1031 // Lookups on half-deleted items may fail in many ways; a missing key is acceptable.
    private Guid FindSeriesId(Episode episode)
    {
        if (episode.SeriesId != Guid.Empty)
        {
            return episode.SeriesId;
        }

        try
        {
            return episode.FindSeriesId();
        }
        catch (Exception ex)
        {
            _logger.LogDebug(ex, "Serie von Episode {ItemId} nicht ermittelbar", episode.Id);
            return Guid.Empty;
        }
    }

    private Series? FindSeries(Guid seriesId, Func<Guid, Series?>? seriesLookup)
    {
        if (seriesId == Guid.Empty)
        {
            return null;
        }

        try
        {
            return seriesLookup is not null ? seriesLookup(seriesId) : _libraryManager.GetItemById(seriesId) as Series;
        }
        catch (Exception ex)
        {
            _logger.LogDebug(ex, "Serie {SeriesId} nicht auffindbar", seriesId);
            return null;
        }
    }
#pragma warning restore CA1031
}