using System;
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;
using Jellyfin.Plugin.RecentlyAddedGuard.Core;
using MediaBrowser.Controller.Library;

namespace Jellyfin.Plugin.RecentlyAddedGuard.Services;

/// <summary>
/// Writes "date added" through the library manager and remembers which items it is currently saving,
/// so the resulting <c>ItemUpdated</c> events can be ignored.
/// </summary>
public sealed class LibraryItemDateWriter : IItemDateWriter
{
    private readonly ILibraryManager _libraryManager;
    private readonly ConcurrentDictionary<Guid, byte> _inFlight = new();

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

    /// <summary>
    /// Checks whether the item is being saved by this writer right now.
    /// </summary>
    /// <param name="itemId">The item.</param>
    /// <returns><c>true</c> while a correction of the item is in progress.</returns>
    public bool IsWriting(Guid itemId) => _inFlight.ContainsKey(itemId);

    /// <inheritdoc />
    public async Task<bool> TrySetDateCreatedAsync(Guid itemId, DateTime dateCreated, CancellationToken cancellationToken)
    {
        var item = _libraryManager.GetItemById(itemId);
        if (item is null)
        {
            return false;
        }

        _inFlight.TryAdd(itemId, 0);
        try
        {
            item.DateCreated = dateCreated;

            // MetadataEdit also lets the NFO saver (if enabled) write the restored <dateadded>.
            await _libraryManager.UpdateItemAsync(item, item.GetParent(), ItemUpdateType.MetadataEdit, cancellationToken)
                .ConfigureAwait(false);
            return true;
        }
        finally
        {
            _inFlight.TryRemove(itemId, out _);
        }
    }
}