using FictionArchive.Service.UserService.Models.Database;
using FictionArchive.Service.UserService.Services;
using FictionArchive.Service.UserService.Services.AuthenticationClient;
using FictionArchive.Service.UserService.Services.AuthenticationClient.Authentik;
using FluentAssertions;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging.Abstractions;
using NSubstitute;
using Xunit;

namespace FictionArchive.Service.UserService.Tests;

public class UserManagementServiceTests
{
    #region Helper Methods

    private static UserServiceDbContext CreateDbContext()
    {
        var options = new DbContextOptionsBuilder<UserServiceDbContext>()
            .UseInMemoryDatabase($"UserManagementServiceTests-{Guid.NewGuid()}")
            .Options;

        return new UserServiceDbContext(options, NullLogger<UserServiceDbContext>.Instance);
    }

    private static UserManagementService CreateService(
        UserServiceDbContext dbContext,
        IAuthenticationServiceClient authClient)
    {
        return new UserManagementService(
            dbContext,
            NullLogger<UserManagementService>.Instance,
            authClient);
    }

    private static User CreateTestUser(string username, string email, int availableInvites = 5)
    {
        return new User
        {
            Username = username,
            Email = email,
            OAuthProviderId = Guid.NewGuid().ToString(),
            Disabled = false,
            AvailableInvites = availableInvites
        };
    }

    #endregion

    #region InviteUserAsync Tests

    [Fact]
    public async Task InviteUserAsync_WithValidInviter_CreatesUserAndDecrementsInvites()
    {
        // Arrange
        using var dbContext = CreateDbContext();
        var inviter = CreateTestUser("inviter", "inviter@test.com", availableInvites: 3);
        dbContext.Users.Add(inviter);
        await dbContext.SaveChangesAsync();

        var authClient = Substitute.For<IAuthenticationServiceClient>();
        authClient.CreateUserAsync(Arg.Any<string>(), Arg.Any<string>(), Arg.Any<string>())
            .Returns(new AuthentikUserResponse { Pk = 123, Uid = "authentik-uid-456" });
        authClient.SendRecoveryEmailAsync(Arg.Any<int>()).Returns(true);

        var service = CreateService(dbContext, authClient);

        // Act
        var result = await service.InviteUserAsync(inviter, "new@test.com", "newuser");

        // Assert
        result.Should().NotBeNull();
        result!.Username.Should().Be("newuser");
        result.Email.Should().Be("new@test.com");
        result.InviterId.Should().Be(inviter.Id);
        result.AvailableInvites.Should().Be(0);
        inviter.AvailableInvites.Should().Be(2);

        await authClient.Received(1).CreateUserAsync("newuser", "new@test.com", "newuser");
        await authClient.Received(1).SendRecoveryEmailAsync(123);
    }

    [Fact]
    public async Task InviteUserAsync_WithNoAvailableInvites_ReturnsNull()
    {
        // Arrange
        using var dbContext = CreateDbContext();
        var inviter = CreateTestUser("inviter", "inviter@test.com", availableInvites: 0);
        dbContext.Users.Add(inviter);
        await dbContext.SaveChangesAsync();

        var authClient = Substitute.For<IAuthenticationServiceClient>();
        var service = CreateService(dbContext, authClient);

        // Act
        var result = await service.InviteUserAsync(inviter, "new@test.com", "newuser");

        // Assert
        result.Should().BeNull();
        await authClient.DidNotReceive().CreateUserAsync(Arg.Any<string>(), Arg.Any<string>(), Arg.Any<string>());
    }

    [Fact]
    public async Task InviteUserAsync_WithDuplicateEmail_ReturnsNull()
    {
        // Arrange
        using var dbContext = CreateDbContext();
        var existingUser = CreateTestUser("existing", "existing@test.com");
        var inviter = CreateTestUser("inviter", "inviter@test.com", availableInvites: 3);
        dbContext.Users.AddRange(existingUser, inviter);
        await dbContext.SaveChangesAsync();

        var authClient = Substitute.For<IAuthenticationServiceClient>();
        var service = CreateService(dbContext, authClient);

        // Act
        var result = await service.InviteUserAsync(inviter, "existing@test.com", "newuser");

        // Assert
        result.Should().BeNull();
        await authClient.DidNotReceive().CreateUserAsync(Arg.Any<string>(), Arg.Any<string>(), Arg.Any<string>());
        inviter.AvailableInvites.Should().Be(3); // Not decremented
    }

    [Fact]
    public async Task InviteUserAsync_WithDuplicateUsername_ReturnsNull()
    {
        // Arrange
        using var dbContext = CreateDbContext();
        var existingUser = CreateTestUser("existinguser", "existing@test.com");
        var inviter = CreateTestUser("inviter", "inviter@test.com", availableInvites: 3);
        dbContext.Users.AddRange(existingUser, inviter);
        await dbContext.SaveChangesAsync();

        var authClient = Substitute.For<IAuthenticationServiceClient>();
        var service = CreateService(dbContext, authClient);

        // Act
        var result = await service.InviteUserAsync(inviter, "new@test.com", "existinguser");

        // Assert
        result.Should().BeNull();
        await authClient.DidNotReceive().CreateUserAsync(Arg.Any<string>(), Arg.Any<string>(), Arg.Any<string>());
        inviter.AvailableInvites.Should().Be(3); // Not decremented
    }

    [Fact]
    public async Task InviteUserAsync_WhenAuthentikFails_ReturnsNull()
    {
        // Arrange
        using var dbContext = CreateDbContext();
        var inviter = CreateTestUser("inviter", "inviter@test.com", availableInvites: 3);
        dbContext.Users.Add(inviter);
        await dbContext.SaveChangesAsync();

        var authClient = Substitute.For<IAuthenticationServiceClient>();
        authClient.CreateUserAsync(Arg.Any<string>(), Arg.Any<string>(), Arg.Any<string>())
            .Returns((AuthentikUserResponse?)null);

        var service = CreateService(dbContext, authClient);

        // Act
        var result = await service.InviteUserAsync(inviter, "new@test.com", "newuser");

        // Assert
        result.Should().BeNull();
        await authClient.DidNotReceive().SendRecoveryEmailAsync(Arg.Any<int>());

        // Verify no user was added to the database
        var usersInDb = await dbContext.Users.ToListAsync();
        usersInDb.Should().HaveCount(1); // Only the inviter
        inviter.AvailableInvites.Should().Be(3); // Not decremented
    }

    [Fact]
    public async Task InviteUserAsync_WhenRecoveryEmailFails_StillCreatesUser()
    {
        // Arrange
        using var dbContext = CreateDbContext();
        var inviter = CreateTestUser("inviter", "inviter@test.com", availableInvites: 3);
        dbContext.Users.Add(inviter);
        await dbContext.SaveChangesAsync();

        var authClient = Substitute.For<IAuthenticationServiceClient>();
        authClient.CreateUserAsync(Arg.Any<string>(), Arg.Any<string>(), Arg.Any<string>())
            .Returns(new AuthentikUserResponse { Pk = 123, Uid = "authentik-uid-456" });
        authClient.SendRecoveryEmailAsync(Arg.Any<int>()).Returns(false); // Email fails

        var service = CreateService(dbContext, authClient);

        // Act
        var result = await service.InviteUserAsync(inviter, "new@test.com", "newuser");

        // Assert - User should still be created despite email failure
        result.Should().NotBeNull();
        result!.Username.Should().Be("newuser");
        inviter.AvailableInvites.Should().Be(2);

        // Verify user was added to database
        var usersInDb = await dbContext.Users.ToListAsync();
        usersInDb.Should().HaveCount(2);
    }

    [Fact]
    public async Task InviteUserAsync_SetsCorrectUserProperties()
    {
        // Arrange
        using var dbContext = CreateDbContext();
        var inviter = CreateTestUser("inviter", "inviter@test.com", availableInvites: 5);
        dbContext.Users.Add(inviter);
        await dbContext.SaveChangesAsync();

        var authentikUid = "authentik-uid-789";
        var authClient = Substitute.For<IAuthenticationServiceClient>();
        authClient.CreateUserAsync(Arg.Any<string>(), Arg.Any<string>(), Arg.Any<string>())
            .Returns(new AuthentikUserResponse { Pk = 456, Uid = authentikUid });
        authClient.SendRecoveryEmailAsync(Arg.Any<int>()).Returns(true);

        var service = CreateService(dbContext, authClient);

        // Act
        var result = await service.InviteUserAsync(inviter, "newuser@test.com", "newusername");

        // Assert
        result.Should().NotBeNull();
        result!.Username.Should().Be("newusername");
        result.Email.Should().Be("newuser@test.com");
        result.OAuthProviderId.Should().Be(authentikUid);
        result.InviterId.Should().Be(inviter.Id);
        result.AvailableInvites.Should().Be(0);
        result.Disabled.Should().BeFalse();
        result.Id.Should().NotBeEmpty();
    }

    #endregion

    #region GetUserByOAuthProviderIdAsync Tests

    [Fact]
    public async Task GetUserByOAuthProviderIdAsync_WithExistingUser_ReturnsUser()
    {
        // Arrange
        using var dbContext = CreateDbContext();
        var oAuthProviderId = "oauth-provider-123";
        var user = new User
        {
            Username = "testuser",
            Email = "test@test.com",
            OAuthProviderId = oAuthProviderId,
            Disabled = false,
            AvailableInvites = 5
        };
        dbContext.Users.Add(user);
        await dbContext.SaveChangesAsync();

        var authClient = Substitute.For<IAuthenticationServiceClient>();
        var service = CreateService(dbContext, authClient);

        // Act
        var result = await service.GetUserByOAuthProviderIdAsync(oAuthProviderId);

        // Assert
        result.Should().NotBeNull();
        result!.Id.Should().Be(user.Id);
        result.Username.Should().Be("testuser");
        result.OAuthProviderId.Should().Be(oAuthProviderId);
    }

    [Fact]
    public async Task GetUserByOAuthProviderIdAsync_WithNonExistingUser_ReturnsNull()
    {
        // Arrange
        using var dbContext = CreateDbContext();
        var authClient = Substitute.For<IAuthenticationServiceClient>();
        var service = CreateService(dbContext, authClient);

        // Act
        var result = await service.GetUserByOAuthProviderIdAsync("non-existing-id");

        // Assert
        result.Should().BeNull();
    }

    #endregion

    #region GetUsers Tests

    [Fact]
    public async Task GetUsers_ReturnsAllUsers()
    {
        // Arrange
        using var dbContext = CreateDbContext();
        var user1 = CreateTestUser("user1", "user1@test.com");
        var user2 = CreateTestUser("user2", "user2@test.com");
        var user3 = CreateTestUser("user3", "user3@test.com");
        dbContext.Users.AddRange(user1, user2, user3);
        await dbContext.SaveChangesAsync();

        var authClient = Substitute.For<IAuthenticationServiceClient>();
        var service = CreateService(dbContext, authClient);

        // Act
        var result = await service.GetUsers().ToListAsync();

        // Assert
        result.Should().HaveCount(3);
        result.Select(u => u.Username).Should().BeEquivalentTo(new[] { "user1", "user2", "user3" });
    }

    [Fact]
    public async Task GetUsers_WithEmptyDb_ReturnsEmptyQueryable()
    {
        // Arrange
        using var dbContext = CreateDbContext();
        var authClient = Substitute.For<IAuthenticationServiceClient>();
        var service = CreateService(dbContext, authClient);

        // Act
        var result = await service.GetUsers().ToListAsync();

        // Assert
        result.Should().BeEmpty();
    }

    #endregion
}