DeutschLernen/GermanApp/Program.cs

using FluentValidation;
using FluentValidation.AspNetCore;
using GermanApp.Application.DTOs;
using GermanApp.Application.Services;
using GermanApp.Application.Interfaces;
using GermanApp.Application.UseCases.Commands;
using GermanApp.Domain.Entities;
using GermanApp.Domain.Interfaces;
using GermanApp.Infrastructure.Data.DbContext;
using GermanApp.Infrastructure.Data.Repositories;
using GermanApp.Infrastructure.Data.SeedData;
using GermanApp.Infrastructure.Services;
using GermanApp.Infrastructure.Configuration;
using GermanApp.Presentation.Controllers;
using GermanApp.Presentation.Validators;
using GermanApp.Presentation.Endpoints;
using GermanApp.Shared.Middleware;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Caching.Memory;
using Microsoft.Extensions.Options;
using Microsoft.IdentityModel.Tokens;
using Serilog;
using System.Text;

// Configure Serilog
Log.Logger = new LoggerConfiguration()
    .MinimumLevel.Debug()
    .WriteTo.Console()
    .CreateBootstrapLogger();

try 
{
    var builder = WebApplication.CreateBuilder(args);

    // Add Serilog to the builder
    builder.Host.UseSerilog((ctx, lc) => lc
        .MinimumLevel.Debug()
        .WriteTo.Console()
        .ReadFrom.Configuration(ctx.Configuration));

    // ============================================
    // PRESENTATION LAYER - API Configuration
    // ============================================

    // Add services to the container.
    builder.Services.AddOpenApi();

    // Add Health Checks
    builder.Services.AddHealthChecks()
        .AddDbContextCheck<AppDbContext>()
        .AddCheck<AiServicesHealthCheck>("ai_services");

    // Add Password Hasher for custom User entity
    builder.Services.AddScoped<IPasswordHasher<User>, PasswordHasher<User>>();

    // Configure JWT Authentication
    var jwtKey = builder.Configuration["Jwt:Key"] ?? "super-secret-key-at-least-32-characters";
    var jwtIssuer = builder.Configuration["Jwt:Issuer"] ?? "DeutschLernen";
    var jwtAudience = builder.Configuration["Jwt:Audience"] ?? "DeutschLernen";
    
    builder.Services.AddAuthentication(options =>
    {
        options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
        options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
        options.DefaultScheme = JwtBearerDefaults.AuthenticationScheme;
    })
    .AddJwtBearer(options =>
    {
        options.TokenValidationParameters = new TokenValidationParameters
        {
            ValidateIssuer = true,
            ValidateAudience = true,
            ValidateLifetime = true,
            ValidateIssuerSigningKey = true,
            ValidIssuer = jwtIssuer,
            ValidAudience = jwtAudience,
            IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(jwtKey)),
            ClockSkew = TimeSpan.Zero
        };
    });

    // Add Authorization
    builder.Services.AddAuthorization();

    // Register AuthService
    builder.Services.AddScoped<IAuthService, AuthService>();

    // Configure CORS
    builder.Services.AddCors(options =>
    {
        options.AddPolicy("AllowAll", builder =>
        {
            builder.AllowAnyOrigin()
                   .AllowAnyMethod()
                   .AllowAnyHeader();
        });
    });

    builder.Services.AddControllers();
    
    // ============================================
    // PRESENTATION LAYER - Validation
    // ============================================
    
    // Add FluentValidation
    builder.Services.AddValidatorsFromAssemblyContaining<CreateLevelValidator>();
    builder.Services.AddFluentValidationAutoValidation();
    
    // Add services for Minimal APIs
    builder.Services.AddEndpointsApiExplorer();
    builder.Services.AddSwaggerGen();

    // ============================================
    // INFRASTRUCTURE LAYER - Database & External Services
    // ============================================

    // Add DbContext with PostgreSQL
    builder.Services.AddDbContext<AppDbContext>(options =>
    {
        // Using PostgreSQL for production and development
        options.UseNpgsql(builder.Configuration.GetConnectionString("DefaultConnection") 
            ?? "Host=localhost;Port=5432;Database=DeutschLernen;Username=postgres;Password=postgres");
        
        // Enable sensitive data logging in development
        if (builder.Environment.IsDevelopment())
        {
            options.EnableSensitiveDataLogging();
            options.EnableDetailedErrors();
        }
    });

    // Register repositories (Infrastructure implementations of Domain interfaces)
    builder.Services.AddScoped<ILevelRepository, LevelRepository>();
    builder.Services.AddScoped<ILessonRepository, LessonRepository>();
    builder.Services.AddScoped<IUserProgressRepository, UserProgressRepository>();
    builder.Services.AddScoped<IQuizRepository, QuizRepository>();
    builder.Services.AddScoped<IQuizQuestionRepository, QuizQuestionRepository>();
    builder.Services.AddScoped<IQuizOptionRepository, QuizOptionRepository>();
    builder.Services.AddScoped<IStoryRepository, StoryRepository>();
    builder.Services.AddScoped<IStoryProgressRepository, StoryProgressRepository>();

    // ============================================
    // INFRASTRUCTURE LAYER - AI Services
    // ============================================

    // Add Memory Cache for caching (used by AI services)
    builder.Services.AddMemoryCache();

    // Add Mistral API configuration
    builder.Services.Configure<MistralConfig>(builder.Configuration.GetSection("Mistral"));

    // Add HttpClient for Mistral API
    builder.Services.AddHttpClient("MistralClient");

    // APPLICATION LAYER - Use Cases & Services
    // ============================================
    // Register Mistral Connector
    builder.Services.AddScoped<IMistralConnector>(provider =>
    {
        var httpClient = provider.GetRequiredService<IHttpClientFactory>().CreateClient("MistralClient");
        var config = provider.GetRequiredService<IOptions<MistralConfig>>().Value;
        var logger = provider.GetRequiredService<ILogger<MistralConnector>>();
        var cache = provider.GetRequiredService<IMemoryCache>();
        
        return new MistralConnector(httpClient, config, logger, cache);
    });

    // Add AI service configurations
    builder.Services.Configure<VoskConfig>(builder.Configuration.GetSection("Vosk"));
    builder.Services.Configure<CoquiConfig>(builder.Configuration.GetSection("Coqui"));

    // Validate AI service configurations
    ValidateAiConfigurations(builder.Configuration);

    // Register AI services (Infrastructure implementations of Domain interfaces)
    builder.Services.AddScoped<IMistralService, MistralService>();
    builder.Services.AddScoped<IVoskService, VoskService>();
    builder.Services.AddScoped<ITtsService, TtsService>();

    // ============================================
    // APPLICATION LAYER - Use Cases & Services
    // ========================================================================================
    // APPLICATION LAYER - Use Cases & Services
    // ============================================

    // Register command handlers

    // Register application services
    builder.Services.AddScoped<LevelService>();
    builder.Services.AddScoped<LessonService>();
    builder.Services.AddScoped<ProgressService>();
    builder.Services.AddScoped<QuizService>();
    builder.Services.AddScoped<QuizQuestionService>();
    builder.Services.AddScoped<LessonUnlockService>();
    builder.Services.AddScoped<LevelCompletionCalculator>();

    // Register AI higher-level services
    builder.Services.AddScoped<StoryGenerationService>();
    builder.Services.AddScoped<WritingFeedbackService>();
    builder.Services.AddScoped<SpeechExerciseService>();
    builder.Services.AddScoped<AudioGenerationService>();
    builder.Services.AddScoped<AiFallbackService>();
    
    // Register Story services
    builder.Services.AddScoped<StoryService>();
    builder.Services.AddScoped<StoryUnlockService>();
    builder.Services.AddScoped<ICommandHandler<CreateLessonCommand, LessonDto>, CreateLessonCommandHandler>();
    
    // Note: QuizQuestionService requires IQuizRepository, ILessonRepository, and ProgressService which are registered above
    
    // Register Quiz command handlers
    builder.Services.AddScoped<ICommandHandler<CreateQuizCommand, QuizDto>, CreateQuizCommandHandler>();
    builder.Services.AddScoped<ICommandHandler<UpdateQuizCommand, QuizDto?>, UpdateQuizCommandHandler>();
    builder.Services.AddScoped<ICommandHandler<DeleteQuizCommand, bool>, DeleteQuizCommandHandler>();
    builder.Services.AddScoped<ICommandHandler<GetQuizWithQuestionsCommand, QuizWithQuestionsDto?>, GetQuizWithQuestionsCommandHandler>();

    var app = builder.Build();

    // Configure the HTTP request pipeline.
    
    // Use exception middleware first (to catch all exceptions)
    app.UseExceptionMiddleware();

    if (app.Environment.IsDevelopment())
    {
        app.MapOpenApi();
        app.UseSwagger();
        app.UseSwaggerUI();
    }

    // Use Authentication & Authorization
    app.UseAuthentication();
    app.UseAuthorization();

    // Use CORS
    app.UseCors("AllowAll");

    // Use Health Checks
    app.MapHealthChecks("/health");
    
    // Map Auth endpoints
    app.MapControllerRoute(
        name: "api",
        pattern: "api/{controller}/{action}/{id?}" );

    // Map Clean Architecture endpoints
    app.MapLessonsEndpoints();

    // Seed database with initial data
    // Run migrations and seed in Development, or just migrations in Production/Docker
    // In Docker, we can control seeding via environment variable
    var shouldSeed = app.Environment.IsDevelopment() || 
                   (app.Configuration.GetValue<bool>("SeedDatabase"));
    
    if (shouldSeed)
    {
        await app.SeedDatabaseAsync();
    }
    else
    {
        // In Production/Docker, ensure migrations are applied with retry logic
        await ApplyMigrationsWithRetry(app, maxRetries: 10, delaySeconds: 5);
    }

    // Keep original WeatherForecast endpoint for reference
    app.MapGet("/weatherforecast", () =>
    {
        var summaries = new[]
        {
            "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
        };
        
        var forecast = Enumerable.Range(1, 5).Select(index =>
            new WeatherForecast
            (
                DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
                Random.Shared.Next(-20, 55),
                summaries[Random.Shared.Next(summaries.Length)]
            ))
            .ToArray();
        return forecast;
    })
    .WithName("GetWeatherForecast");

    app.Run();

// Helper method to validate AI service configurations
static void ValidateAiConfigurations(IConfiguration configuration)
{
    // Validate Mistral configuration
    var mistralConfig = configuration.GetSection("Mistral").Get<MistralConfig>() ?? new MistralConfig();
    mistralConfig.Validate();

    // Validate Vosk configuration
    var voskConfig = configuration.GetSection("Vosk").Get<VoskConfig>() ?? new VoskConfig();
    voskConfig.Validate();

    // Validate Coqui configuration
    var coquiConfig = configuration.GetSection("Coqui").Get<CoquiConfig>() ?? new CoquiConfig();
    coquiConfig.Validate();

    Log.Information("All AI service configurations validated successfully");
}

// Helper method to apply migrations with retry logic for Docker
static async Task ApplyMigrationsWithRetry(WebApplication app, int maxRetries, int delaySeconds)
{
    int retryCount = 0;
    while (retryCount < maxRetries)
    {
        try
        {
            using var scope = app.Services.CreateScope();
            var dbContext = scope.ServiceProvider.GetRequiredService<AppDbContext>();
            dbContext.Database.Migrate();
            Log.Information("Database migrations applied in Production environment");
            return;
        }
        catch (Exception ex)
        {
            retryCount++;
            Log.Warning(ex, "Failed to apply database migrations (attempt {Attempt}/{MaxAttempts}). Retrying in {DelaySeconds} seconds...", 
                        retryCount, maxRetries, delaySeconds);
            if (retryCount >= maxRetries)
            {
                Log.Fatal(ex, "Failed to apply database migrations after {MaxAttempts} attempts", maxRetries);
                throw;
            }
            await Task.Delay(TimeSpan.FromSeconds(delaySeconds));
        }
    }
}

}
catch (Exception ex)
{
    Log.Fatal(ex, "Application terminated unexpectedly");
}
finally
{
    Log.CloseAndFlush();
}

// Existing record for reference
record WeatherForecast(DateOnly Date, int TemperatureC, string? Summary)
{
    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
}