using System;
using System.Collections.Generic;
using System.Threading;
using Jellyfin.Database.Implementations.Entities;
using Jellyfin.Plugin.WatchedTogether.Configuration;
using Jellyfin.Plugin.WatchedTogether.Services;
using MediaBrowser.Controller.Entities;
using MediaBrowser.Controller.Library;
using MediaBrowser.Model.Entities;
using Microsoft.Extensions.Logging.Abstractions;
using Moq;
using Xunit;

namespace Jellyfin.Plugin.WatchedTogether.Tests;

/// <summary>
/// Covers propagation of played state from a shared account to its members.
/// </summary>
public class WatchedStateSyncTests
{
    private static readonly Guid SharedId = Guid.NewGuid();

    private sealed class Harness
    {
        public Mock<IUserDataManager> UserData { get; } = new();

        public Mock<IGroupService> Groups { get; } = new();

        public List<(User Member, bool Played, int PlayCount)> Saves { get; } = new();

        public WatchedStateSyncService Service { get; private set; } = null!;

        public static Harness Create(
            SharedGroup? group,
            IReadOnlyList<User> members,
            bool memberAlreadyPlayed = false,
            int memberPlayCount = 0)
        {
            var h = new Harness();

            h.Groups.Setup(g => g.GetGroupForSharedUser(It.IsAny<Guid>())).Returns(group);
            h.Groups.Setup(g => g.GetEligibleMembers(It.IsAny<SharedGroup>())).Returns(members);

            h.UserData.Setup(m => m.GetUserData(It.IsAny<User>(), It.IsAny<BaseItem>()))
                .Returns(() => new UserItemData
                {
                    Key = "k",
                    Played = memberAlreadyPlayed,
                    PlayCount = memberPlayCount
                });

            h.UserData.Setup(m => m.SaveUserData(
                    It.IsAny<User>(),
                    It.IsAny<BaseItem>(),
                    It.IsAny<UserItemData>(),
                    It.IsAny<UserDataSaveReason>(),
                    It.IsAny<CancellationToken>()))
                .Callback<User, BaseItem, UserItemData, UserDataSaveReason, CancellationToken>(
                    (u, _, d, _, _) => h.Saves.Add((u, d.Played, d.PlayCount)));

            h.Service = new WatchedStateSyncService(
                h.UserData.Object,
                new Mock<IUserManager>().Object,
                h.Groups.Object,
                NullLogger<WatchedStateSyncService>.Instance);

            return h;
        }

        /// <summary>
        /// Raises UserDataSaved as the server would, by starting the service so it subscribes.
        /// </summary>
        public void Raise(Guid userId, bool played, UserDataSaveReason reason)
        {
            Service.StartAsync(CancellationToken.None).GetAwaiter().GetResult();

            UserData.Raise(
                m => m.UserDataSaved += null,
                new UserDataSaveEventArgs
                {
                    UserId = userId,
                    Item = new Folder { Name = "Some Item" },
                    UserData = new UserItemData { Key = "k", Played = played },
                    SaveReason = reason
                });

            Service.StopAsync(CancellationToken.None).GetAwaiter().GetResult();
        }
    }

    private static User MakeUser(string name) => new(name, "Prov", "ResetProv");

    private static SharedGroup MakeGroup(bool syncUnwatched = true, bool syncPlayCount = false)
        => new()
        {
            SharedUserId = SharedId,
            MemberUserIds = [Guid.NewGuid(), Guid.NewGuid()],
            SyncUnwatched = syncUnwatched,
            SyncPlayCount = syncPlayCount
        };

    [Fact]
    public void Played_PropagatesToEveryMember()
    {
        var alice = MakeUser("alice");
        var bob = MakeUser("bob");
        var h = Harness.Create(MakeGroup(), [alice, bob]);

        h.Raise(SharedId, true, UserDataSaveReason.PlaybackFinished);

        Assert.Equal(2, h.Saves.Count);
        Assert.All(h.Saves, s => Assert.True(s.Played));
    }

    [Fact]
    public void WritesFromAMember_AreIgnored()
    {
        // The loop guard: a member's own save must not be treated as a shared-account change.
        // GetGroupForSharedUser returns null for any id that is not a shared account.
        var h = Harness.Create(null, []);

        h.Raise(Guid.NewGuid(), true, UserDataSaveReason.PlaybackFinished);

        Assert.Empty(h.Saves);
    }

    [Theory]
    [InlineData(UserDataSaveReason.PlaybackStart)]
    [InlineData(UserDataSaveReason.PlaybackProgress)]
    [InlineData(UserDataSaveReason.UpdateUserRating)]
    public void IrrelevantSaveReasons_AreIgnored(UserDataSaveReason reason)
    {
        // UserDataSaved fires constantly during playback; only watched-state changes matter.
        var h = Harness.Create(MakeGroup(), [MakeUser("alice")]);

        h.Raise(SharedId, true, reason);

        Assert.Empty(h.Saves);
    }

    [Fact]
    public void Unwatched_PropagatesWhenSyncUnwatchedEnabled()
    {
        var h = Harness.Create(MakeGroup(syncUnwatched: true), [MakeUser("alice")], memberAlreadyPlayed: true);

        h.Raise(SharedId, false, UserDataSaveReason.TogglePlayed);

        Assert.Single(h.Saves);
        Assert.False(h.Saves[0].Played);
    }

    [Fact]
    public void Unwatched_IsSuppressedWhenSyncUnwatchedDisabled()
    {
        var h = Harness.Create(MakeGroup(syncUnwatched: false), [MakeUser("alice")], memberAlreadyPlayed: true);

        h.Raise(SharedId, false, UserDataSaveReason.TogglePlayed);

        Assert.Empty(h.Saves);
    }

    [Fact]
    public void RedundantWrites_AreSuppressed()
    {
        // The member already matches the shared account, so there is nothing to write.
        var h = Harness.Create(MakeGroup(), [MakeUser("alice")], memberAlreadyPlayed: true);

        h.Raise(SharedId, true, UserDataSaveReason.PlaybackFinished);

        Assert.Empty(h.Saves);
    }

    [Fact]
    public void PlayCount_IsRaisedWhenEnabled()
    {
        var h = Harness.Create(MakeGroup(syncPlayCount: true), [MakeUser("alice")]);

        h.Raise(SharedId, true, UserDataSaveReason.PlaybackFinished);

        Assert.Single(h.Saves);
        Assert.Equal(1, h.Saves[0].PlayCount);
    }

    [Fact]
    public void PlayCount_IsNotDecrementedForAlreadyWatchedItems()
    {
        // A member who has watched something five times keeps that count.
        var h = Harness.Create(
            MakeGroup(syncPlayCount: true),
            [MakeUser("alice")],
            memberAlreadyPlayed: false,
            memberPlayCount: 5);

        h.Raise(SharedId, true, UserDataSaveReason.PlaybackFinished);

        Assert.Single(h.Saves);
        Assert.Equal(5, h.Saves[0].PlayCount);
    }

    [Fact]
    public void PlayCount_IsLeftAloneWhenDisabled()
    {
        var h = Harness.Create(MakeGroup(syncPlayCount: false), [MakeUser("alice")]);

        h.Raise(SharedId, true, UserDataSaveReason.PlaybackFinished);

        Assert.Single(h.Saves);
        Assert.Equal(0, h.Saves[0].PlayCount);
    }

    [Fact]
    public void DisabledGroup_DoesNotSync()
    {
        // GetGroupForSharedUser returns null for suspended groups.
        var h = Harness.Create(null, [MakeUser("alice")]);

        h.Raise(SharedId, true, UserDataSaveReason.PlaybackFinished);

        Assert.Empty(h.Saves);
    }
}