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>();

    // 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>();

    // ============================================
    // 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");

    // 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);
    });

    // ============================================
    // 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<ICommandHandler<CreateLessonCommand, LessonDto>, CreateLessonCommandHandler>();

    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
    if (app.Environment.IsDevelopment())
    {
        await app.SeedDatabaseAsync();
    }

    // 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();
}
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);
}