using System.Collections.Immutable;
using System.Globalization;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Domain.Filler;
using ErsatzTV.Core.Domain.Scheduling;
using ErsatzTV.Core.Extensions;
using ErsatzTV.Core.Interfaces.Scheduling;
using ErsatzTV.Core.Scheduling.YamlScheduling.Models;
using Microsoft.Extensions.Logging;

namespace ErsatzTV.Core.Scheduling.YamlScheduling.Handlers;

public abstract class YamlPlayoutContentHandler(EnumeratorCache enumeratorCache) : IYamlPlayoutHandler
{
    public bool Reset => false;

    public abstract Task<bool> Handle(
        YamlPlayoutContext context,
        YamlPlayoutInstruction instruction,
        PlayoutBuildMode mode,
        ILogger<YamlPlayoutBuilder> logger,
        CancellationToken cancellationToken);

    protected async Task<Option<IMediaCollectionEnumerator>> GetContentEnumerator(
        YamlPlayoutContext context,
        string contentKey,
        ILogger<YamlPlayoutBuilder> logger,
        CancellationToken cancellationToken)
    {
        if (string.IsNullOrWhiteSpace(contentKey))
        {
            return Option<IMediaCollectionEnumerator>.None;
        }

        Option<IMediaCollectionEnumerator> maybeEnumerator = await enumeratorCache.GetCachedEnumeratorForContent(
            context,
            contentKey,
            cancellationToken);

        if (maybeEnumerator.IsNone)
        {
            if (!enumeratorCache.MissingContentKeys.Contains(contentKey))
            {
                logger.LogWarning("Unable to locate content with key {Key}", contentKey);
                enumeratorCache.MissingContentKeys.Add(contentKey);
            }
        }

        return maybeEnumerator;
    }

    protected static List<PlayoutHistory> GetHistoryForItem(
        YamlPlayoutContext context,
        string contentKey,
        IMediaCollectionEnumerator enumerator,
        PlayoutItem playoutItem,
        MediaItem mediaItem,
        ILogger<YamlPlayoutBuilder> logger)
    {
        int index = context.Definition.Content.FindIndex(c => c.Key == contentKey);
        if (index < 0)
        {
            logger.LogDebug("Unable to find history for content matching key {ContentKey}", contentKey);
            return [];
        }

        YamlPlayoutContentItem contentItem = context.Definition.Content[index];
        if (!Enum.TryParse(contentItem.Order, true, out PlaybackOrder playbackOrder))
        {
            logger.LogDebug("Unable to find history for content matching playback order {PlaybackOrder}", contentItem.Order);
            return [];
        }

        var result = new List<PlayoutHistory>();

        string historyKey = HistoryDetails.KeyForYamlContent(contentItem);

        if (contentItem is YamlPlayoutContentMarathonItem && enumerator is PlaylistEnumerator playlistEnumerator)
        {
            // create a playout history record
            var nextHistory = new PlayoutHistory
            {
                PlayoutId = context.Playout.Id,
                PlaybackOrder = playbackOrder,
                Index = playlistEnumerator.EnumeratorIndex,
                When = playoutItem.StartOffset.UtcDateTime,
                Finish = playoutItem.FinishOffset.UtcDateTime,
                Key = historyKey,
                Details = HistoryDetails.ForMediaItem(mediaItem)
            };

            result.Add(nextHistory);

            for (var i = 0; i < playlistEnumerator.ChildEnumerators.Count; i++)
            {
                (IMediaCollectionEnumerator childEnumerator, CollectionKey collectionKey) = playlistEnumerator.ChildEnumerators[i];
                bool isCurrentChild = i == playlistEnumerator.EnumeratorIndex;
                foreach (MediaItem currentMediaItem in childEnumerator.Current)
                {
                    // create a playout history record
                    var childHistory = new PlayoutHistory
                    {
                        PlayoutId = context.Playout.Id,
                        PlaybackOrder = playbackOrder,
                        Index = childEnumerator.State.Index,
                        When = playoutItem.StartOffset.UtcDateTime,
                        Finish = playoutItem.FinishOffset.UtcDateTime,
                        Key = historyKey,
                        ChildKey = HistoryDetails.KeyForCollectionKey(collectionKey),
                        IsCurrentChild = isCurrentChild,
                        Details = HistoryDetails.ForMediaItem(currentMediaItem)
                    };

                    result.Add(childHistory);
                }
            }
        }
        else
        {
            // create a playout history record
            var nextHistory = new PlayoutHistory
            {
                PlayoutId = context.Playout.Id,
                PlaybackOrder = playbackOrder,
                Index = enumerator.State.Index,
                When = playoutItem.StartOffset.UtcDateTime,
                Finish = playoutItem.FinishOffset.UtcDateTime,
                Key = historyKey,
                Details = HistoryDetails.ForMediaItem(mediaItem)
            };

            result.Add(nextHistory);
        }

        return result;
    }

    protected static TimeSpan DurationForMediaItem(MediaItem mediaItem)
    {
        if (mediaItem is Image image)
        {
            return TimeSpan.FromSeconds(image.ImageMetadata.Head().DurationSeconds ?? Image.DefaultSeconds);
        }

        MediaVersion version = mediaItem.GetHeadVersion();
        return version.Duration;
    }

    protected static FillerKind GetFillerKind(YamlPlayoutInstruction instruction)
    {
        if (string.IsNullOrWhiteSpace(instruction.FillerKind))
        {
            return FillerKind.None;
        }

        return Enum.TryParse(instruction.FillerKind, ignoreCase: true, out FillerKind result)
            ? result
            : FillerKind.None;
    }
}