using System;
using System.Collections.Generic;
using System.Linq;
using Jellyfin.Data;
using Jellyfin.Database.Implementations.Entities;
using Jellyfin.Database.Implementations.Enums;
using Jellyfin.Plugin.WatchedTogether.Services;
using MediaBrowser.Controller.Entities;
using MediaBrowser.Controller.Library;
using Microsoft.Extensions.Logging.Abstractions;
using Moq;
using Xunit;

namespace Jellyfin.Plugin.WatchedTogether.Tests;

/// <summary>
/// Covers the rule that a shared account sees only what every member can already see.
/// </summary>
public class LibraryAccessTests
{
    private static readonly Guid Movies = Guid.NewGuid();
    private static readonly Guid Shows = Guid.NewGuid();
    private static readonly Guid Kids = Guid.NewGuid();
    private static readonly Guid Adult = Guid.NewGuid();

    private static readonly Guid[] AllLibraries = [Movies, Shows, Kids, Adult];

    /// <summary>
    /// Creates a user with either full access or an explicit library list.
    /// </summary>
    private static User MakeUser(
        string name,
        bool allFolders = false,
        IEnumerable<Guid>? enabled = null,
        IEnumerable<Guid>? blocked = null)
    {
        var user = new User(name, "Prov", "ResetProv");
        user.SetPermission(PermissionKind.EnableAllFolders, allFolders);
        user.SetPreference(PreferenceKind.EnabledFolders, (enabled ?? []).ToArray());
        user.SetPreference(PreferenceKind.BlockedMediaFolders, (blocked ?? []).ToArray());
        return user;
    }

    private static LibraryAccessService MakeService(params User[] users)
    {
        var userManager = new Mock<IUserManager>();
        foreach (var u in users)
        {
            userManager.Setup(m => m.GetUserById(u.Id)).Returns(u);
        }

        // The root folder's children are the server's top-level libraries.
        var children = AllLibraries.Select(id =>
        {
            var folder = new Mock<BaseItem>();
            folder.Object.Id = id;
            return folder.Object;
        }).ToList();

        var root = new Mock<Folder>();
        root.Setup(r => r.Children).Returns(children);

        var libraryManager = new Mock<ILibraryManager>();
        libraryManager.Setup(l => l.GetUserRootFolder()).Returns(root.Object);

        return new LibraryAccessService(
            userManager.Object,
            libraryManager.Object,
            NullLogger<LibraryAccessService>.Instance);
    }

    [Fact]
    public void TwoExplicitLists_IntersectToTheCommonLibraries()
    {
        var alice = MakeUser("alice", enabled: [Movies, Shows, Kids]);
        var bob = MakeUser("bob", enabled: [Shows, Kids, Adult]);
        var service = MakeService(alice, bob);

        var result = service.ComputeIntersection([alice.Id, bob.Id]);

        Assert.Equal([Shows, Kids], result.OrderBy(g => g).ToList().OrderBy(g => g).ToList());
        Assert.DoesNotContain(Movies, result);
        Assert.DoesNotContain(Adult, result);
    }

    [Fact]
    public void AMemberWithAllFolders_DoesNotWidenTheGroup()
    {
        // The restricted member is what bounds the group, not the permissive one.
        var alice = MakeUser("alice", allFolders: true);
        var bob = MakeUser("bob", enabled: [Kids]);
        var service = MakeService(alice, bob);

        var result = service.ComputeIntersection([alice.Id, bob.Id]);

        Assert.Equal([Kids], result);
    }

    [Fact]
    public void AllMembersWithAllFolders_GetEveryLibrary()
    {
        var alice = MakeUser("alice", allFolders: true);
        var bob = MakeUser("bob", allFolders: true);
        var service = MakeService(alice, bob);

        var result = service.ComputeIntersection([alice.Id, bob.Id]);

        Assert.Equal(AllLibraries.OrderBy(g => g), result.OrderBy(g => g));
    }

    [Fact]
    public void ABlockedFolder_IsRemovedEvenWithAllFolders()
    {
        // Blocking is an explicit denial and must survive the "sees everything" permission.
        var alice = MakeUser("alice", allFolders: true, blocked: [Adult]);
        var bob = MakeUser("bob", allFolders: true);
        var service = MakeService(alice, bob);

        var result = service.ComputeIntersection([alice.Id, bob.Id]);

        Assert.DoesNotContain(Adult, result);
        Assert.Contains(Movies, result);
    }

    [Fact]
    public void MembersWithNothingInCommon_GetNoLibraries()
    {
        var alice = MakeUser("alice", enabled: [Movies]);
        var bob = MakeUser("bob", enabled: [Adult]);
        var service = MakeService(alice, bob);

        Assert.Empty(service.ComputeIntersection([alice.Id, bob.Id]));
    }

    [Fact]
    public void AddingAThirdMember_CanOnlyNarrowAccess()
    {
        var alice = MakeUser("alice", enabled: [Movies, Shows, Kids]);
        var bob = MakeUser("bob", enabled: [Shows, Kids]);
        var carol = MakeUser("carol", enabled: [Kids]);
        var service = MakeService(alice, bob, carol);

        var pair = service.ComputeIntersection([alice.Id, bob.Id]);
        var trio = service.ComputeIntersection([alice.Id, bob.Id, carol.Id]);

        Assert.Equal(2, pair.Count);
        Assert.Equal([Kids], trio);
    }

    [Fact]
    public void AnUnresolvableMember_YieldsNoAccess()
    {
        // Failing closed: a member we cannot read must not be treated as unrestricted.
        var alice = MakeUser("alice", allFolders: true);
        var service = MakeService(alice);

        Assert.Empty(service.ComputeIntersection([alice.Id, Guid.NewGuid()]));
    }

    [Fact]
    public void NoMembers_YieldsNoAccess()
    {
        var service = MakeService();

        Assert.Empty(service.ComputeIntersection([]));
    }
}