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

namespace Jellyfin.Plugin.WatchedTogether.Tests;

/// <summary>
/// Exercises the whole path a real login takes: a group created on demand by typing "alice+bob",
/// then logged into again afterwards by each member in turn.
/// </summary>
/// <remarks>
/// The other suites mock <see cref="IProvisioningService"/>, which is why an ordering bug inside the
/// real provisioning code reached a release. These tests wire the real services together and only
/// stub the host's user manager and crypto.
/// </remarks>
[Collection(nameof(PluginTestContext))]
public class SharedAccountEndToEndTests
{
    private const string AliceHash = "$PBKDF2-SHA512$iterations=210000$A1A1A1A1$AAAAAAAABBBBBBBB";
    private const string BobHash = "$PBKDF2-SHA512$iterations=210000$B2B2B2B2$CCCCCCCCDDDDDDDD";

    private static readonly string AuthProviderId =
        typeof(SharedAccountAuthenticationProvider).FullName!;

    private sealed record Harness(
        SharedAccountAuthenticationProvider Provider,
        List<User> Users);

    private static User MakeUser(string name, string? password = null)
        => new(name, "Prov", "ResetProv") { Password = password! };

    /// <summary>
    /// Wires the real provisioning, group, dynamic-group and authentication services over a user
    /// manager that behaves like Jellyfin's: password changes dispatch to the user's assigned
    /// provider, and users resolve by both name and id.
    /// </summary>
    private static Harness MakeHarness(List<User> users, params (string Hash, string Password)[] validPairs)
    {
        var crypto = new StubCryptoProvider(validPairs);
        var userManager = new Mock<IUserManager>();

        userManager.Setup(m => m.GetUserById(It.IsAny<Guid>()))
            .Returns((Guid id) => users.Find(u => u.Id == id)!);

        userManager.Setup(m => m.GetUserByName(It.IsAny<string>()))
            .Returns((string n) => users.Find(
                u => string.Equals(u.Username, n, StringComparison.OrdinalIgnoreCase))!);

        userManager.Setup(m => m.CreateUserAsync(It.IsAny<string>()))
            .ReturnsAsync((string name) =>
            {
                var created = MakeUser(name);
                users.Add(created);
                return created;
            });

        userManager.Setup(m => m.UpdateUserAsync(It.IsAny<User>())).Returns(Task.CompletedTask);

        userManager.Setup(m => m.ChangePassword(It.IsAny<User>(), It.IsAny<string>()))
            .Returns((User user, string password) =>
            {
                // Jellyfin routes this to the user's assigned provider; ours refuses by design.
                if (string.Equals(user.AuthenticationProviderId, AuthProviderId, StringComparison.Ordinal))
                {
                    throw new NotSupportedException(
                        "A Watched Together shared account has no password of its own.");
                }

                user.Password = password;
                return Task.CompletedTask;
            });

        var groupService = new GroupService(
            userManager.Object,
            NullLogger<GroupService>.Instance);

        var provisioning = new ProvisioningService(
            userManager.Object,
            Mock.Of<ILibraryAccessService>(),
            NullLogger<ProvisioningService>.Instance);

        var dynamicGroups = new DynamicGroupService(
            userManager.Object,
            provisioning,
            crypto,
            NullLogger<DynamicGroupService>.Instance);

        var provider = new SharedAccountAuthenticationProvider(
            crypto,
            new Lazy<IGroupService>(() => groupService),
            new Lazy<IDynamicGroupService>(() => dynamicGroups),
            NullLogger<SharedAccountAuthenticationProvider>.Instance);

        return new Harness(provider, users);
    }

    [Theory]
    [InlineData("alice-pw")]
    [InlineData("bob-pw")]
    public async Task GroupCreatedOnDemand_ThenUnlockedByEitherMemberPassword(string creatingPassword)
    {
        using var ctx = PluginTestContext.Create();

        var alice = MakeUser("alice", AliceHash);
        var bob = MakeUser("bob", BobHash);
        var users = new List<User> { alice, bob };

        var h = MakeHarness(users, (AliceHash, "alice-pw"), (BobHash, "bob-pw"));

        // Creating the group by typing both names. Whichever member types their own password, the
        // resulting account must behave identically.
        var created = await h.Provider.Authenticate("alice+bob", creatingPassword, null);
        Assert.Equal("alice+bob", created.Username);

        var shared = h.Users.Find(u => u.Username == "alice+bob");
        Assert.NotNull(shared);

        // The account exists now, so Jellyfin resolves it and hands it to us as resolvedUser. Both
        // members must be able to unlock it, regardless of who created it.
        var asAlice = await h.Provider.Authenticate("alice+bob", "alice-pw", shared);
        Assert.Equal("alice+bob", asAlice.Username);

        var asBob = await h.Provider.Authenticate("alice+bob", "bob-pw", shared);
        Assert.Equal("alice+bob", asBob.Username);

        // And an outsider's password still must not.
        await Assert.ThrowsAsync<AuthenticationException>(
            () => h.Provider.Authenticate("alice+bob", "not-a-member-pw", shared!));
    }

    [Fact]
    public async Task GroupCreatedOnDemand_ClaimsTheAccountAndKeepsAPassword()
    {
        using var ctx = PluginTestContext.Create();

        var alice = MakeUser("alice", AliceHash);
        var bob = MakeUser("bob", BobHash);
        var users = new List<User> { alice, bob };

        var h = MakeHarness(users, (AliceHash, "alice-pw"), (BobHash, "bob-pw"));

        await h.Provider.Authenticate("alice+bob", "alice-pw", null);

        var shared = h.Users.Find(u => u.Username == "alice+bob");
        Assert.NotNull(shared);

        // Claimed by us, so future logins route here, and holding a password of its own so it is
        // not directly loginable if the provider is ever unassigned.
        Assert.Equal(AuthProviderId, shared!.AuthenticationProviderId);
        Assert.False(string.IsNullOrEmpty(shared.Password));
    }
}