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

namespace Jellyfin.Plugin.WatchedTogether.Tests;

/// <summary>
/// Covers shared-account provisioning against a user manager that dispatches password changes the
/// way Jellyfin's real one does.
/// </summary>
[Collection(nameof(PluginTestContext))]
public class ProvisioningTests
{
    private static readonly string AuthProviderId =
        typeof(Auth.SharedAccountAuthenticationProvider).FullName!;

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

    /// <summary>
    /// Builds a user manager that mimics the one behaviour that matters here: ChangePassword is
    /// routed to the provider named by the user's AuthenticationProviderId, so an account already
    /// claimed by us lands in our provider and is refused.
    /// </summary>
    private static Mock<IUserManager> MakeUserManager(List<User> users, List<string> callLog)
    {
        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.CreateUserAsync(It.IsAny<string>()))
            .ReturnsAsync((string name) =>
            {
                var created = MakeUser(name);
                users.Add(created);
                callLog.Add("CreateUser");
                return created;
            });

        userManager.SetupChangePassword(users, (user, password) =>
            {
                callLog.Add($"ChangePassword(provider={user.AuthenticationProviderId})");

                // This is the dispatch that made provisioning fail in 0.0.3: once the account is
                // claimed, the call reaches our provider, which refuses it by design.
                if (string.Equals(user.AuthenticationProviderId, AuthProviderId, StringComparison.Ordinal))
                {
                    return new Auth.SharedAccountAuthenticationProvider(
                        Mock.Of<MediaBrowser.Model.Cryptography.ICryptoProvider>(),
                        new Lazy<IGroupService>(() => Mock.Of<IGroupService>()),
                        new Lazy<IDynamicGroupService>(() => Mock.Of<IDynamicGroupService>()),
                        NullLogger<Auth.SharedAccountAuthenticationProvider>.Instance)
                        .ChangePassword(user, password);
                }

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

        userManager.Setup(m => m.UpdateUserAsync(It.IsAny<User>()))
            .Returns((User user) =>
            {
                callLog.Add($"UpdateUser(provider={user.AuthenticationProviderId})");
                return Task.CompletedTask;
            });

        return userManager;
    }

    private static ProvisioningService MakeService(Mock<IUserManager> userManager)
        => new(
            userManager.Object,
            Mock.Of<ILibraryAccessService>(),
            NullLogger<ProvisioningService>.Instance);

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

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

        var service = MakeService(MakeUserManager(users, callLog));

        // Before the fix this threw NotSupportedException from our own ChangePassword.
        var group = await service.CreateGroupAsync([alice.Id, bob.Id], null);

        Assert.NotEqual(Guid.Empty, group.SharedUserId);

        // The password must be set while the account is still on Jellyfin's default provider.
        var changeIndex = callLog.FindIndex(c => c.StartsWith("ChangePassword", StringComparison.Ordinal));
        var claimIndex = callLog.FindIndex(c => c.Contains(AuthProviderId, StringComparison.Ordinal));

        Assert.True(changeIndex >= 0, "provisioning should set a password on the shared account");
        Assert.True(claimIndex >= 0, "provisioning should claim the account for our provider");
        Assert.True(
            changeIndex < claimIndex,
            $"password must be set before the account is claimed, but call order was: {string.Join(" -> ", callLog)}");
    }

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

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

        var service = MakeService(MakeUserManager(users, callLog));

        var group = await service.CreateGroupAsync([alice.Id, bob.Id], null);

        // Claiming the account is what routes its logins to us; provisioning is useless without it.
        var sharedUser = users.Find(u => u.Id == group.SharedUserId);
        Assert.NotNull(sharedUser);
        Assert.Equal(AuthProviderId, sharedUser!.AuthenticationProviderId);
    }

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

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

        var service = MakeService(MakeUserManager(users, callLog));

        var group = await service.CreateGroupAsync([alice.Id, bob.Id], null);

        // A passwordless shared account would be directly loginable if the provider were ever
        // unassigned, which is the reason provisioning sets one at all.
        var sharedUser = users.Find(u => u.Id == group.SharedUserId);
        Assert.NotNull(sharedUser);
        Assert.False(string.IsNullOrEmpty(sharedUser!.Password));
    }

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

        // Models Jellyfin 12, where the user manager keeps no cache: every lookup returns a
        // detached copy of the stored row, and UpdateUserAsync writes back every column of the
        // instance it is handed. The random password provisioning sets must survive the provider
        // assignment that is saved afterwards through a different instance.
        var stored = new List<User> { MakeUser("alice"), MakeUser("bob") };
        var userManager = new Mock<IUserManager>();

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

        userManager.Setup(m => m.CreateUserAsync(It.IsAny<string>()))
            .ReturnsAsync((string name) =>
            {
                var row = MakeUser(name);
                stored.Add(row);
                return Copy(row)!;
            });

        // On 12 the helper resolves the stored row by id, so this writes the hash there and only
        // there; on 10.11 it writes to the caller's instance, as the real server does.
        userManager.SetupChangePassword(stored, (user, password) =>
        {
            user.Password = password;
            return Task.CompletedTask;
        });

        userManager.Setup(m => m.UpdateUserAsync(It.IsAny<User>()))
            .Returns((User user) =>
            {
                var row = stored.Find(u => u.Id == user.Id)!;
                row.Password = user.Password;
                row.AuthenticationProviderId = user.AuthenticationProviderId;
                return Task.CompletedTask;
            });

        var service = MakeService(userManager);

        var group = await service.CreateGroupAsync([stored[0].Id, stored[1].Id], null);

        var row = stored.Find(u => u.Id == group.SharedUserId);
        Assert.NotNull(row);
        Assert.Equal(AuthProviderId, row!.AuthenticationProviderId);
        Assert.False(
            string.IsNullOrEmpty(row.Password),
            "claiming the account must not overwrite the password provisioning stored");
    }

    /// <summary>
    /// Copies the columns provisioning touches into a fresh instance with the same id, the way a
    /// cache-less user manager hands out rows.
    /// </summary>
    private static User? Copy(User? row)
        => row is null
            ? null
            : new User(row.Username, row.AuthenticationProviderId, row.PasswordResetProviderId)
            {
                Id = row.Id,
                Password = row.Password,
            };
}