using ChatBot.Data;
using ChatBot.Migrations;
using FluentAssertions;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;

namespace ChatBot.Tests.Data;

public class MigrationsTests : IDisposable
{
    private readonly ServiceProvider _serviceProvider;
    private readonly ChatBotDbContext _dbContext;

    public MigrationsTests()
    {
        var services = new ServiceCollection();

        // Add in-memory database with unique name per test
        services.AddDbContext<ChatBotDbContext>(options =>
            options.UseInMemoryDatabase(Guid.NewGuid().ToString())
        );

        _serviceProvider = services.BuildServiceProvider();
        _dbContext = _serviceProvider.GetRequiredService<ChatBotDbContext>();
    }

    [Fact]
    public void InitialCreateMigration_ShouldHaveCorrectName()
    {
        // Arrange
        var migration = new InitialCreate();

        // Assert
        migration.Should().NotBeNull();
        migration.GetType().Name.Should().Be("InitialCreate");
    }

    [Fact]
    public void InitialCreateMigration_ShouldInheritFromMigration()
    {
        // Arrange
        var migration = new InitialCreate();

        // Assert
        migration.Should().BeAssignableTo<Microsoft.EntityFrameworkCore.Migrations.Migration>();
    }

    [Fact]
    public void InitialCreateMigration_ShouldBeInstantiable()
    {
        // Arrange & Act
        var migration = new InitialCreate();

        // Assert
        migration.Should().NotBeNull();
    }

    [Fact]
    public void InitialCreateMigration_ShouldHaveCorrectConstants()
    {
        // Arrange
        var migration = new InitialCreate();

        // Act & Assert
        // Use reflection to access private constants
        var migrationType = typeof(InitialCreate);

        var chatSessionsTableNameField = migrationType.GetField(
            "ChatSessionsTableName",
            System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static
        );
        chatSessionsTableNameField.Should().NotBeNull();
        chatSessionsTableNameField!.GetValue(null).Should().Be("chat_sessions");

        var chatMessagesTableNameField = migrationType.GetField(
            "ChatMessagesTableName",
            System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static
        );
        chatMessagesTableNameField.Should().NotBeNull();
        chatMessagesTableNameField!.GetValue(null).Should().Be("chat_messages");

        var chatSessionsIdColumnField = migrationType.GetField(
            "ChatSessionsIdColumn",
            System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static
        );
        chatSessionsIdColumnField.Should().NotBeNull();
        chatSessionsIdColumnField!.GetValue(null).Should().Be("id");

        var chatMessagesSessionIdColumnField = migrationType.GetField(
            "ChatMessagesSessionIdColumn",
            System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static
        );
        chatMessagesSessionIdColumnField.Should().NotBeNull();
        chatMessagesSessionIdColumnField!.GetValue(null).Should().Be("session_id");

        var integerTypeField = migrationType.GetField(
            "IntegerType",
            System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static
        );
        integerTypeField.Should().NotBeNull();
        integerTypeField!.GetValue(null).Should().Be("integer");
    }

    [Fact]
    public async Task InitialCreateMigration_ShouldApplySuccessfullyToDatabase()
    {
        // Arrange
        var options = new DbContextOptionsBuilder<ChatBotDbContext>()
            .UseInMemoryDatabase(Guid.NewGuid().ToString())
            .Options;

        using var context = new ChatBotDbContext(options);

        // Act
        await context.Database.EnsureCreatedAsync();

        // Assert
        var canConnect = await context.Database.CanConnectAsync();
        canConnect.Should().BeTrue();

        // Verify tables exist by trying to query them
        var sessions = await context.ChatSessions.ToListAsync();
        var messages = await context.ChatMessages.ToListAsync();

        sessions.Should().NotBeNull();
        messages.Should().NotBeNull();
    }

    [Fact]
    public async Task InitialCreateMigration_ShouldCreateCorrectTableStructure()
    {
        // Arrange
        var options = new DbContextOptionsBuilder<ChatBotDbContext>()
            .UseInMemoryDatabase(Guid.NewGuid().ToString())
            .Options;

        using var context = new ChatBotDbContext(options);

        // Act
        await context.Database.EnsureCreatedAsync();

        // Assert
        var model = context.Model;

        // Check chat_sessions entity
        var chatSessionEntity = model.FindEntityType(
            typeof(ChatBot.Models.Entities.ChatSessionEntity)
        );
        chatSessionEntity.Should().NotBeNull();
        chatSessionEntity!.GetTableName().Should().Be("chat_sessions");

        // Check chat_messages entity
        var chatMessageEntity = model.FindEntityType(
            typeof(ChatBot.Models.Entities.ChatMessageEntity)
        );
        chatMessageEntity.Should().NotBeNull();
        chatMessageEntity!.GetTableName().Should().Be("chat_messages");

        // Check foreign key relationship
        var foreignKeys = chatMessageEntity.GetForeignKeys();
        foreignKeys.Should().HaveCount(1);

        var foreignKey = foreignKeys.First();
        foreignKey.PrincipalEntityType.Should().Be(chatSessionEntity);
        foreignKey.Properties.Should().HaveCount(1);
        foreignKey.Properties.First().Name.Should().Be("SessionId");
        foreignKey.DeleteBehavior.Should().Be(DeleteBehavior.Cascade);
    }

    [Fact]
    public async Task InitialCreateMigration_ShouldCreateIndexes()
    {
        // Arrange
        var options = new DbContextOptionsBuilder<ChatBotDbContext>()
            .UseInMemoryDatabase(Guid.NewGuid().ToString())
            .Options;

        using var context = new ChatBotDbContext(options);

        // Act
        await context.Database.EnsureCreatedAsync();

        // Assert
        var model = context.Model;

        // Check chat_sessions entity indexes
        var chatSessionEntity = model.FindEntityType(
            typeof(ChatBot.Models.Entities.ChatSessionEntity)
        );
        chatSessionEntity.Should().NotBeNull();

        var sessionIndexes = chatSessionEntity!.GetIndexes().ToList();
        sessionIndexes.Should().NotBeEmpty();

        // Check chat_messages entity indexes
        var chatMessageEntity = model.FindEntityType(
            typeof(ChatBot.Models.Entities.ChatMessageEntity)
        );
        chatMessageEntity.Should().NotBeNull();

        var messageIndexes = chatMessageEntity!.GetIndexes().ToList();
        messageIndexes.Should().NotBeEmpty();
    }

    [Fact]
    public async Task InitialCreateMigration_ShouldCreateUniqueConstraintOnSessionId()
    {
        // Arrange
        var options = new DbContextOptionsBuilder<ChatBotDbContext>()
            .UseInMemoryDatabase(Guid.NewGuid().ToString())
            .Options;

        using var context = new ChatBotDbContext(options);

        // Act
        await context.Database.EnsureCreatedAsync();

        // Assert
        var model = context.Model;

        // Check chat_sessions entity has unique index on SessionId
        var chatSessionEntity = model.FindEntityType(
            typeof(ChatBot.Models.Entities.ChatSessionEntity)
        );
        chatSessionEntity.Should().NotBeNull();

        var sessionIdProperty = chatSessionEntity!.FindProperty("SessionId");
        sessionIdProperty.Should().NotBeNull();

        var uniqueIndexes = chatSessionEntity
            .GetIndexes()
            .Where(i => i.IsUnique && i.Properties.Contains(sessionIdProperty))
            .ToList();

        uniqueIndexes.Should().NotBeEmpty();
    }

    [Fact]
    public async Task InitialCreateMigration_ShouldCreateCompositeIndexOnSessionIdAndMessageOrder()
    {
        // Arrange
        var options = new DbContextOptionsBuilder<ChatBotDbContext>()
            .UseInMemoryDatabase(Guid.NewGuid().ToString())
            .Options;

        using var context = new ChatBotDbContext(options);

        // Act
        await context.Database.EnsureCreatedAsync();

        // Assert
        var model = context.Model;

        // Check chat_messages entity has composite index
        var chatMessageEntity = model.FindEntityType(
            typeof(ChatBot.Models.Entities.ChatMessageEntity)
        );
        chatMessageEntity.Should().NotBeNull();

        var sessionIdProperty = chatMessageEntity!.FindProperty("SessionId");
        var messageOrderProperty = chatMessageEntity.FindProperty("MessageOrder");

        sessionIdProperty.Should().NotBeNull();
        messageOrderProperty.Should().NotBeNull();

        var compositeIndexes = chatMessageEntity
            .GetIndexes()
            .Where(i =>
                i.Properties.Count == 2
                && i.Properties.Contains(sessionIdProperty)
                && i.Properties.Contains(messageOrderProperty)
            )
            .ToList();

        compositeIndexes.Should().NotBeEmpty();
    }

    [Fact]
    public async Task InitialCreateMigration_ShouldSupportCascadeDelete()
    {
        // Arrange
        var options = new DbContextOptionsBuilder<ChatBotDbContext>()
            .UseInMemoryDatabase(Guid.NewGuid().ToString())
            .Options;

        using var context = new ChatBotDbContext(options);

        // Act
        await context.Database.EnsureCreatedAsync();

        // Create test data
        var session = new ChatBot.Models.Entities.ChatSessionEntity
        {
            SessionId = "test-session",
            ChatId = 12345L,
            ChatType = "private",
            CreatedAt = DateTime.UtcNow,
            LastUpdatedAt = DateTime.UtcNow,
        };

        context.ChatSessions.Add(session);
        await context.SaveChangesAsync();

        var message = new ChatBot.Models.Entities.ChatMessageEntity
        {
            SessionId = session.Id,
            Content = "Test message",
            Role = "user",
            CreatedAt = DateTime.UtcNow,
            MessageOrder = 1,
        };

        context.ChatMessages.Add(message);
        await context.SaveChangesAsync();

        // Verify data exists
        var messageCount = await context.ChatMessages.CountAsync();
        messageCount.Should().Be(1);

        // Test cascade delete
        context.ChatSessions.Remove(session);
        await context.SaveChangesAsync();

        // Assert - message should be deleted due to cascade
        var remainingMessageCount = await context.ChatMessages.CountAsync();
        remainingMessageCount.Should().Be(0);
    }

    public void Dispose()
    {
        _dbContext?.Dispose();
        _serviceProvider?.Dispose();
    }
}