using ChatBot.Data;
using ChatBot.Services;
using ChatBot.Tests.TestUtilities;
using FluentAssertions;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Moq;

namespace ChatBot.Tests.Services;

public class DatabaseInitializationServiceTests : UnitTestBase
{
    [Fact]
    public void DatabaseInitializationService_ShouldCreateInstance()
    {
        // Arrange
        var serviceProviderMock = new Mock<IServiceProvider>();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();

        // Act
        var service = new DatabaseInitializationService(
            serviceProviderMock.Object,
            loggerMock.Object
        );

        // Assert
        Assert.NotNull(service);
    }

    [Fact]
    public async Task DatabaseInitializationService_StopAsync_ShouldComplete()
    {
        // Arrange
        var serviceProviderMock = new Mock<IServiceProvider>();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
        var service = new DatabaseInitializationService(
            serviceProviderMock.Object,
            loggerMock.Object
        );

        // Act & Assert
        await service.StopAsync(CancellationToken.None);

        // If we reach here, the method completed successfully
        Assert.True(true);
    }

    [Fact]
    public async Task StartAsync_ShouldLogCorrectInformation_WhenStopping()
    {
        // Arrange
        var serviceProviderMock = new Mock<IServiceProvider>();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
        var service = new DatabaseInitializationService(
            serviceProviderMock.Object,
            loggerMock.Object
        );

        // Act
        await service.StopAsync(CancellationToken.None);

        // Assert
        loggerMock.Verify(
            x =>
                x.Log(
                    LogLevel.Information,
                    It.IsAny<EventId>(),
                    It.Is<It.IsAnyType>(
                        (v, t) => v.ToString()!.Contains("Database initialization service stopped")
                    ),
                    It.IsAny<Exception>(),
                    It.IsAny<Func<It.IsAnyType, Exception?, string>>()
                ),
            Times.Once
        );
    }

    [Fact]
    public async Task StartAsync_ShouldHandleCancellationToken()
    {
        // Arrange
        var serviceProviderMock = new Mock<IServiceProvider>();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
        var cts = new CancellationTokenSource();
        cts.Cancel(); // Cancel immediately

        // Setup service provider to throw when CreateScope is called
        serviceProviderMock
            .Setup(x => x.GetService(typeof(IServiceScopeFactory)))
            .Returns((IServiceScopeFactory)null!);

        var service = new DatabaseInitializationService(
            serviceProviderMock.Object,
            loggerMock.Object
        );

        // Act & Assert
        var act = async () => await service.StartAsync(cts.Token);
        await act.Should().ThrowAsync<InvalidOperationException>();
    }

    [Fact]
    public async Task StartAsync_ShouldLogStartingMessage()
    {
        // Arrange
        var serviceProviderMock = new Mock<IServiceProvider>();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();

        // Setup service provider to throw when CreateScope is called
        serviceProviderMock
            .Setup(x => x.GetService(typeof(IServiceScopeFactory)))
            .Returns((IServiceScopeFactory)null!);

        var service = new DatabaseInitializationService(
            serviceProviderMock.Object,
            loggerMock.Object
        );

        // Act & Assert
        var act = async () => await service.StartAsync(CancellationToken.None);
        await act.Should().ThrowAsync<InvalidOperationException>();

        loggerMock.Verify(
            x =>
                x.Log(
                    LogLevel.Information,
                    It.IsAny<EventId>(),
                    It.Is<It.IsAnyType>(
                        (v, t) => v.ToString()!.Contains("Starting database initialization...")
                    ),
                    It.IsAny<Exception>(),
                    It.IsAny<Func<It.IsAnyType, Exception?, string>>()
                ),
            Times.Once
        );
    }

    [Fact]
    public async Task StartAsync_ShouldThrowExceptionWhenServiceProviderFails()
    {
        // Arrange
        var serviceProviderMock = new Mock<IServiceProvider>();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();

        // Setup service provider to throw when CreateScope is called
        serviceProviderMock
            .Setup(x => x.GetService(typeof(IServiceScopeFactory)))
            .Returns((IServiceScopeFactory)null!);

        var service = new DatabaseInitializationService(
            serviceProviderMock.Object,
            loggerMock.Object
        );

        // Act & Assert
        var act = async () => await service.StartAsync(CancellationToken.None);
        await act.Should().ThrowAsync<InvalidOperationException>();

        // Verify that starting message was logged
        loggerMock.Verify(
            x =>
                x.Log(
                    LogLevel.Information,
                    It.IsAny<EventId>(),
                    It.Is<It.IsAnyType>(
                        (v, t) => v.ToString()!.Contains("Starting database initialization...")
                    ),
                    It.IsAny<Exception>(),
                    It.IsAny<Func<It.IsAnyType, Exception?, string>>()
                ),
            Times.Once
        );
    }

    [Fact]
    public async Task StartAsync_ShouldHandleOperationCanceledException()
    {
        // Arrange
        var serviceProviderMock = new Mock<IServiceProvider>();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
        var cts = new CancellationTokenSource();
        cts.Cancel(); // Cancel immediately

        // Setup service provider to throw when CreateScope is called
        serviceProviderMock
            .Setup(x => x.GetService(typeof(IServiceScopeFactory)))
            .Returns((IServiceScopeFactory)null!);

        var service = new DatabaseInitializationService(
            serviceProviderMock.Object,
            loggerMock.Object
        );

        // Act & Assert
        var act = async () => await service.StartAsync(cts.Token);
        await act.Should().ThrowAsync<InvalidOperationException>();
    }

    [Fact]
    public async Task StartAsync_ShouldHandleGeneralException()
    {
        // Arrange
        var serviceProviderMock = new Mock<IServiceProvider>();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();

        // Setup service provider to throw when CreateScope is called
        serviceProviderMock
            .Setup(x => x.GetService(typeof(IServiceScopeFactory)))
            .Returns((IServiceScopeFactory)null!);

        var service = new DatabaseInitializationService(
            serviceProviderMock.Object,
            loggerMock.Object
        );

        // Act & Assert
        var act = async () => await service.StartAsync(CancellationToken.None);
        await act.Should().ThrowAsync<InvalidOperationException>();
    }

    [Fact]
    public async Task StartAsync_ShouldThrowExceptionWithServiceProviderError()
    {
        // Arrange
        var serviceProviderMock = new Mock<IServiceProvider>();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();

        // Setup service provider to throw when CreateScope is called
        serviceProviderMock
            .Setup(x => x.GetService(typeof(IServiceScopeFactory)))
            .Returns((IServiceScopeFactory)null!);

        var service = new DatabaseInitializationService(
            serviceProviderMock.Object,
            loggerMock.Object
        );

        // Act & Assert
        var act = async () => await service.StartAsync(CancellationToken.None);
        await act.Should().ThrowAsync<InvalidOperationException>();

        // Verify that starting message was logged
        loggerMock.Verify(
            x =>
                x.Log(
                    LogLevel.Information,
                    It.IsAny<EventId>(),
                    It.Is<It.IsAnyType>(
                        (v, t) => v.ToString()!.Contains("Starting database initialization...")
                    ),
                    It.IsAny<Exception>(),
                    It.IsAny<Func<It.IsAnyType, Exception?, string>>()
                ),
            Times.Once
        );
    }

    [Fact]
    public async Task StartAsync_WhenDatabaseExists_ShouldLogAndMigrate()
    {
        // Arrange
        var dbPath = $"TestDb_{Guid.NewGuid()}.db";
        var services = new ServiceCollection();
        services.AddDbContext<ChatBotDbContext>(options =>
            options.UseSqlite($"Data Source={dbPath}")
                .ConfigureWarnings(w => w.Ignore(Microsoft.EntityFrameworkCore.Diagnostics.RelationalEventId.PendingModelChangesWarning))
        );

        var serviceProvider = services.BuildServiceProvider();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();

        var service = new DatabaseInitializationService(serviceProvider, loggerMock.Object);

        try
        {
            // Act
            await service.StartAsync(CancellationToken.None);

            // Assert
            loggerMock.Verify(
                x =>
                    x.Log(
                        LogLevel.Information,
                        It.IsAny<EventId>(),
                        It.Is<It.IsAnyType>(
                            (v, t) => v.ToString()!.Contains("Starting database initialization")
                        ),
                        It.IsAny<Exception>(),
                        It.IsAny<Func<It.IsAnyType, Exception?, string>>()
                    ),
                Times.Once
            );

            loggerMock.Verify(
                x =>
                    x.Log(
                        LogLevel.Information,
                        It.IsAny<EventId>(),
                        It.Is<It.IsAnyType>(
                            (v, t) =>
                                v.ToString()!
                                    .Contains("Database initialization completed successfully")
                        ),
                        It.IsAny<Exception>(),
                        It.IsAny<Func<It.IsAnyType, Exception?, string>>()
                    ),
                Times.Once
            );
        }
        finally
        {
            // Cleanup
            serviceProvider.Dispose();
            GC.Collect();
            GC.WaitForPendingFinalizers();
            if (File.Exists(dbPath))
            {
                try { File.Delete(dbPath); } catch { /* Ignore cleanup errors */ }
            }
        }
    }

    [Fact]
    public async Task StopAsync_WithCancellationToken_ShouldComplete()
    {
        // Arrange
        var serviceProviderMock = new Mock<IServiceProvider>();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
        var service = new DatabaseInitializationService(
            serviceProviderMock.Object,
            loggerMock.Object
        );
        var cts = new CancellationTokenSource();

        // Act
        await service.StopAsync(cts.Token);

        // Assert
        loggerMock.Verify(
            x =>
                x.Log(
                    LogLevel.Information,
                    It.IsAny<EventId>(),
                    It.Is<It.IsAnyType>(
                        (v, t) => v.ToString()!.Contains("Database initialization service stopped")
                    ),
                    It.IsAny<Exception>(),
                    It.IsAny<Func<It.IsAnyType, Exception?, string>>()
                ),
            Times.Once
        );
    }

    [Fact]
    public async Task StopAsync_WhenCancellationRequested_ShouldStillComplete()
    {
        // Arrange
        var serviceProviderMock = new Mock<IServiceProvider>();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
        var service = new DatabaseInitializationService(
            serviceProviderMock.Object,
            loggerMock.Object
        );
        var cts = new CancellationTokenSource();
        cts.Cancel();

        // Act
        await service.StopAsync(cts.Token);

        // Assert
        loggerMock.Verify(
            x =>
                x.Log(
                    LogLevel.Information,
                    It.IsAny<EventId>(),
                    It.Is<It.IsAnyType>(
                        (v, t) => v.ToString()!.Contains("Database initialization service stopped")
                    ),
                    It.IsAny<Exception>(),
                    It.IsAny<Func<It.IsAnyType, Exception?, string>>()
                ),
            Times.Once
        );
    }

    [Fact]
    public async Task StartAsync_ShouldHandleDatabaseDoesNotExistException()
    {
        // Arrange
        var dbPath = $"TestDb_{Guid.NewGuid()}.db";
        var services = new ServiceCollection();
        services.AddDbContext<ChatBotDbContext>(options =>
            options.UseSqlite($"Data Source={dbPath}")
                .ConfigureWarnings(w => w.Ignore(Microsoft.EntityFrameworkCore.Diagnostics.RelationalEventId.PendingModelChangesWarning))
        );

        var serviceProvider = services.BuildServiceProvider();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();

        var service = new DatabaseInitializationService(serviceProvider, loggerMock.Object);

        try
        {
            // Act
            await service.StartAsync(CancellationToken.None);

            // Assert - service should complete successfully
            loggerMock.Verify(
                x =>
                    x.Log(
                        LogLevel.Information,
                        It.IsAny<EventId>(),
                        It.Is<It.IsAnyType>(
                            (v, t) =>
                                v.ToString()!
                                    .Contains("Database initialization completed successfully")
                        ),
                        It.IsAny<Exception>(),
                        It.IsAny<Func<It.IsAnyType, Exception?, string>>()
                    ),
                Times.Once
            );
        }
        finally
        {
            // Cleanup
            serviceProvider.Dispose();
            GC.Collect();
            GC.WaitForPendingFinalizers();
            if (File.Exists(dbPath))
            {
                try { File.Delete(dbPath); } catch { /* Ignore cleanup errors */ }
            }
        }
    }

    [Fact]
    public async Task StartAsync_WithValidDatabase_ShouldLogDatabaseExists()
    {
        // Arrange
        var dbPath = $"TestDb_{Guid.NewGuid()}.db";
        var services = new ServiceCollection();
        services.AddDbContext<ChatBotDbContext>(options =>
            options.UseSqlite($"Data Source={dbPath}")
                .ConfigureWarnings(w => w.Ignore(Microsoft.EntityFrameworkCore.Diagnostics.RelationalEventId.PendingModelChangesWarning))
        );

        var serviceProvider = services.BuildServiceProvider();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();

        var service = new DatabaseInitializationService(serviceProvider, loggerMock.Object);

        try
        {
            // Act
            await service.StartAsync(CancellationToken.None);

            // Assert
            loggerMock.Verify(
                x =>
                    x.Log(
                        LogLevel.Information,
                        It.IsAny<EventId>(),
                        It.Is<It.IsAnyType>((v, t) => true), // Any log message
                        It.IsAny<Exception>(),
                        It.IsAny<Func<It.IsAnyType, Exception?, string>>()
                    ),
                Times.AtLeastOnce
            );
        }
        finally
        {
            // Cleanup
            serviceProvider.Dispose();
            GC.Collect();
            GC.WaitForPendingFinalizers();
            if (File.Exists(dbPath))
            {
                try { File.Delete(dbPath); } catch { /* Ignore cleanup errors */ }
            }
        }
    }

    [Fact]
    public void DatabaseInitializationService_ShouldImplementIHostedService()
    {
        // Arrange
        var serviceProviderMock = new Mock<IServiceProvider>();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();

        // Act
        var service = new DatabaseInitializationService(
            serviceProviderMock.Object,
            loggerMock.Object
        );

        // Assert
        service.Should().BeAssignableTo<Microsoft.Extensions.Hosting.IHostedService>();
    }

    [Fact]
    public async Task StartAsync_MultipleCallsInSequence_ShouldWork()
    {
        // Arrange
        var dbPath = $"TestDb_{Guid.NewGuid()}.db";
        var services = new ServiceCollection();
        services.AddDbContext<ChatBotDbContext>(options =>
            options.UseSqlite($"Data Source={dbPath}")
                .ConfigureWarnings(w => w.Ignore(Microsoft.EntityFrameworkCore.Diagnostics.RelationalEventId.PendingModelChangesWarning))
        );

        var serviceProvider = services.BuildServiceProvider();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
        var service = new DatabaseInitializationService(serviceProvider, loggerMock.Object);

        try
        {
            // Act
            await service.StartAsync(CancellationToken.None);
            await service.StopAsync(CancellationToken.None);

            // Assert - should complete without exceptions
            loggerMock.Verify(
                x =>
                    x.Log(
                        LogLevel.Information,
                        It.IsAny<EventId>(),
                        It.Is<It.IsAnyType>(
                            (v, t) =>
                                v.ToString()!
                                    .Contains("Database initialization completed successfully")
                        ),
                        It.IsAny<Exception>(),
                        It.IsAny<Func<It.IsAnyType, Exception?, string>>()
                    ),
                Times.Once
            );
        }
        finally
        {
            // Cleanup
            serviceProvider.Dispose();
            GC.Collect();
            GC.WaitForPendingFinalizers();
            if (File.Exists(dbPath))
            {
                try { File.Delete(dbPath); } catch { /* Ignore cleanup errors */ }
            }
        }
    }

    [Fact]
    public async Task StopAsync_WithoutStartAsync_ShouldComplete()
    {
        // Arrange
        var serviceProviderMock = new Mock<IServiceProvider>();
        var loggerMock = new Mock<ILogger<DatabaseInitializationService>>();
        var service = new DatabaseInitializationService(
            serviceProviderMock.Object,
            loggerMock.Object
        );

        // Act
        await service.StopAsync(CancellationToken.None);

        // Assert - should complete without exceptions
        loggerMock.Verify(
            x =>
                x.Log(
                    LogLevel.Information,
                    It.IsAny<EventId>(),
                    It.Is<It.IsAnyType>(
                        (v, t) => v.ToString()!.Contains("Database initialization service stopped")
                    ),
                    It.IsAny<Exception>(),
                    It.IsAny<Func<It.IsAnyType, Exception?, string>>()
                ),
            Times.Once
        );
    }
}