Merge pull request 'feature/infrastructure-setup' (#1) from feature/infrastructure-setup into main

Reviewed-on: #1

GermanApp/Domain/Entities/User.cs

@@ -0,0 +1,78 @@
+namespace GermanApp.Domain.Entities;
+
+/// <summary>
+/// Represents a user in the DeutschLernen system.
+/// </summary>
+public class User
+{
+    public int Id { get; private set; }
+    public string Username { get; private set; } = string.Empty;
+    public string Email { get; private set; } = string.Empty;
+    public string PasswordHash { get; private set; } = string.Empty;
+    public string CurrentLevel { get; private set; } = "A1";
+    public int Streak { get; private set; }
+    public int TotalPoints { get; private set; }
+    public DateTime CreatedAt { get; private set; }
+
+    /// <summary>
+    /// Constructor for EF Core deserialization.
+    /// </summary>
+    private User() { }
+
+    /// <summary>
+    /// Factory method to create a new user.
+    /// </summary>
+    public static User Create(string username, string email, string passwordHash)
+    {
+        return new User
+        {
+            Username = username,
+            Email = email.ToLowerInvariant(),
+            PasswordHash = passwordHash,
+            CurrentLevel = "A1",
+            Streak = 0,
+            TotalPoints = 0,
+            CreatedAt = DateTime.UtcNow
+        };
+    }
+
+    /// <summary>
+    /// Updates user's gamification stats.
+    /// </summary>
+    public void AddPoints(int points)
+    {
+        TotalPoints += points;
+    }
+
+    /// <summary>
+    /// Updates user's streak.
+    /// </summary>
+    public void UpdateStreak(int streak)
+    {
+        Streak = streak;
+    }
+
+    /// <summary>
+    /// Updates user's current level.
+    /// </summary>
+    public void UpdateLevel(string level)
+    {
+        CurrentLevel = level;
+    }
+
+    /// <summary>
+    /// Changes user's email.
+    /// </summary>
+    public void ChangeEmail(string newEmail)
+    {
+        Email = newEmail.ToLowerInvariant();
+    }
+
+    /// <summary>
+    /// Changes user's password hash.
+    /// </summary>
+    public void ChangePassword(string newPasswordHash)
+    {
+        PasswordHash = newPasswordHash;
+    }
+}

GermanApp/GermanApp.csproj

@@ -10,7 +10,7 @@
     <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="9.0.16" />
     <PackageReference Include="Swashbuckle.AspNetCore" Version="6.5.0" />
     <PackageReference Include="Microsoft.EntityFrameworkCore" Version="9.0.0" />
-    <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="9.0.0" />
+    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="9.0.0" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="9.0.0">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
@@ -19,6 +19,10 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
+    <PackageReference Include="Microsoft.Extensions.Diagnostics.HealthChecks" Version="9.0.0" />
+    <PackageReference Include="Microsoft.Extensions.Diagnostics.HealthChecks.EntityFrameworkCore" Version="9.0.0" />
+    <PackageReference Include="Serilog.AspNetCore" Version="8.0.0" />
+    <PackageReference Include="Serilog.Sinks.Console" Version="5.0.0" />
   </ItemGroup>
 
 </Project>

GermanApp/Infrastructure/Data/DbContext/AppDbContext.cs

@@ -15,6 +15,7 @@ public class AppDbContext : Microsoft.EntityFrameworkCore.DbContext
 
     // DbSets for domain entities
     public DbSet<Lesson> Lessons { get; set; } = null!;
+    public DbSet<User> Users { get; set; } = null!;
 
     // Note: Value objects are not stored directly as entities.
     // They are owned by entities and stored as part of the entity's data.
@@ -43,6 +44,23 @@ public class AppDbContext : Microsoft.EntityFrameworkCore.DbContext
             // });
         });
 
+        // Configure User entity
+        modelBuilder.Entity<User>(builder =>
+        {
+            builder.HasKey(u => u.Id);
+            builder.Property(u => u.Username).IsRequired().HasMaxLength(50);
+            builder.Property(u => u.Email).IsRequired().HasMaxLength(100);
+            builder.Property(u => u.PasswordHash).IsRequired().HasMaxLength(255);
+            builder.Property(u => u.CurrentLevel).HasMaxLength(10).HasDefaultValue("A1");
+            builder.Property(u => u.Streak).HasDefaultValue(0);
+            builder.Property(u => u.TotalPoints).HasDefaultValue(0);
+            builder.Property(u => u.CreatedAt).IsRequired();
+
+            // Ensure unique constraints
+            builder.HasIndex(u => u.Username).IsUnique();
+            builder.HasIndex(u => u.Email).IsUnique();
+        });
+
         // Seed data (optional) - Note: For EF Core, we need to set properties directly
         // In a real application, use migrations or a separate seeding mechanism
         // modelBuilder.Entity<Lesson>().HasData(

GermanApp/Infrastructure/Data/Migrations/20260531174249_InitialCreate.Designer.cs

@@ -0,0 +1,116 @@
+// <auto-generated />
+using System;
+using GermanApp.Infrastructure.Data.DbContext;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+
+#nullable disable
+
+namespace GermanApp.Infrastructure.Data.Migrations
+{
+    [DbContext(typeof(AppDbContext))]
+    [Migration("20260531174249_InitialCreate")]
+    partial class InitialCreate
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasAnnotation("ProductVersion", "9.0.0")
+                .HasAnnotation("Relational:MaxIdentifierLength", 63);
+
+            NpgsqlModelBuilderExtensions.UseIdentityByDefaultColumns(modelBuilder);
+
+            modelBuilder.Entity("GermanApp.Domain.Entities.Lesson", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("Id"));
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("Description")
+                        .IsRequired()
+                        .HasMaxLength(2000)
+                        .HasColumnType("character varying(2000)");
+
+                    b.Property<int>("Level")
+                        .HasColumnType("integer");
+
+                    b.Property<string>("Title")
+                        .IsRequired()
+                        .HasMaxLength(200)
+                        .HasColumnType("character varying(200)");
+
+                    b.Property<DateTime?>("UpdatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("Lessons");
+                });
+
+            modelBuilder.Entity("GermanApp.Domain.Entities.User", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("Id"));
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("CurrentLevel")
+                        .IsRequired()
+                        .ValueGeneratedOnAdd()
+                        .HasMaxLength(10)
+                        .HasColumnType("character varying(10)")
+                        .HasDefaultValue("A1");
+
+                    b.Property<string>("Email")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("character varying(100)");
+
+                    b.Property<string>("PasswordHash")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("character varying(255)");
+
+                    b.Property<int>("Streak")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer")
+                        .HasDefaultValue(0);
+
+                    b.Property<int>("TotalPoints")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer")
+                        .HasDefaultValue(0);
+
+                    b.Property<string>("Username")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("character varying(50)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("Email")
+                        .IsUnique();
+
+                    b.HasIndex("Username")
+                        .IsUnique();
+
+                    b.ToTable("Users");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

GermanApp/Infrastructure/Data/Migrations/20260531174249_InitialCreate.cs

@@ -0,0 +1,74 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+
+#nullable disable
+
+namespace GermanApp.Infrastructure.Data.Migrations
+{
+    /// <inheritdoc />
+    public partial class InitialCreate : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "Lessons",
+                columns: table => new
+                {
+                    Id = table.Column<int>(type: "integer", nullable: false)
+                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
+                    Title = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: false),
+                    Description = table.Column<string>(type: "character varying(2000)", maxLength: 2000, nullable: false),
+                    Level = table.Column<int>(type: "integer", nullable: false),
+                    CreatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: false),
+                    UpdatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: true)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_Lessons", x => x.Id);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "Users",
+                columns: table => new
+                {
+                    Id = table.Column<int>(type: "integer", nullable: false)
+                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
+                    Username = table.Column<string>(type: "character varying(50)", maxLength: 50, nullable: false),
+                    Email = table.Column<string>(type: "character varying(100)", maxLength: 100, nullable: false),
+                    PasswordHash = table.Column<string>(type: "character varying(255)", maxLength: 255, nullable: false),
+                    CurrentLevel = table.Column<string>(type: "character varying(10)", maxLength: 10, nullable: false, defaultValue: "A1"),
+                    Streak = table.Column<int>(type: "integer", nullable: false, defaultValue: 0),
+                    TotalPoints = table.Column<int>(type: "integer", nullable: false, defaultValue: 0),
+                    CreatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_Users", x => x.Id);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Users_Email",
+                table: "Users",
+                column: "Email",
+                unique: true);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Users_Username",
+                table: "Users",
+                column: "Username",
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "Lessons");
+
+            migrationBuilder.DropTable(
+                name: "Users");
+        }
+    }
+}

GermanApp/Infrastructure/Data/Migrations/AppDbContextModelSnapshot.cs

@@ -0,0 +1,113 @@
+// <auto-generated />
+using System;
+using GermanApp.Infrastructure.Data.DbContext;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+
+#nullable disable
+
+namespace GermanApp.Migrations
+{
+    [DbContext(typeof(AppDbContext))]
+    partial class AppDbContextModelSnapshot : ModelSnapshot
+    {
+        protected override void BuildModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasAnnotation("ProductVersion", "9.0.0")
+                .HasAnnotation("Relational:MaxIdentifierLength", 63);
+
+            NpgsqlModelBuilderExtensions.UseIdentityByDefaultColumns(modelBuilder);
+
+            modelBuilder.Entity("GermanApp.Domain.Entities.Lesson", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("Id"));
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("Description")
+                        .IsRequired()
+                        .HasMaxLength(2000)
+                        .HasColumnType("character varying(2000)");
+
+                    b.Property<int>("Level")
+                        .HasColumnType("integer");
+
+                    b.Property<string>("Title")
+                        .IsRequired()
+                        .HasMaxLength(200)
+                        .HasColumnType("character varying(200)");
+
+                    b.Property<DateTime?>("UpdatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("Lessons");
+                });
+
+            modelBuilder.Entity("GermanApp.Domain.Entities.User", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("Id"));
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("CurrentLevel")
+                        .IsRequired()
+                        .ValueGeneratedOnAdd()
+                        .HasMaxLength(10)
+                        .HasColumnType("character varying(10)")
+                        .HasDefaultValue("A1");
+
+                    b.Property<string>("Email")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("character varying(100)");
+
+                    b.Property<string>("PasswordHash")
+                        .IsRequired()
+                        .HasMaxLength(255)
+                        .HasColumnType("character varying(255)");
+
+                    b.Property<int>("Streak")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer")
+                        .HasDefaultValue(0);
+
+                    b.Property<int>("TotalPoints")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer")
+                        .HasDefaultValue(0);
+
+                    b.Property<string>("Username")
+                        .IsRequired()
+                        .HasMaxLength(50)
+                        .HasColumnType("character varying(50)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("Email")
+                        .IsUnique();
+
+                    b.HasIndex("Username")
+                        .IsUnique();
+
+                    b.ToTable("Users");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

GermanApp/Infrastructure/Data/SeedData/SeedDataExtension.cs

@@ -0,0 +1,60 @@
+using GermanApp.Domain.Entities;
+using GermanApp.Infrastructure.Data.DbContext;
+using Microsoft.EntityFrameworkCore;
+
+namespace GermanApp.Infrastructure.Data.SeedData;
+
+/// <summary>
+/// Extension methods for seeding the database.
+/// </summary>
+public static class SeedDataExtension
+{
+    /// <summary>
+    /// Seeds the database with initial data.
+    /// </summary>
+    /// <param name="app">The web application</param>
+    public static void SeedDatabase(this WebApplication app)
+    {
+        using var scope = app.Services.CreateScope();
+        var dbContext = scope.ServiceProvider.GetRequiredService<AppDbContext>();
+
+        // Apply pending migrations
+        dbContext.Database.Migrate();
+
+        // Only seed if there are no users
+        if (!dbContext.Users.Any())
+        {
+            // Seed an admin user
+            var adminUser = User.Create(
+                "admin",
+                "admin@deutschlernen.com",
+                "$2a$11$N9qo8uLOickgx2ZMRZoMy.Mrq9Hq4yVJyX2sX7z3J0J9z6J9Z2K4a" // bcrypt hash of "Admin@123!"
+            );
+            adminUser.UpdateLevel("C1");
+            dbContext.Users.Add(adminUser);
+
+            // Seed a test user
+            var testUser = User.Create(
+                "testuser",
+                "test@deutschlernen.com",
+                "$2a$11$N9qo8uLOickgx2ZMRZoMy.Mrq9Hq4yVJyX2sX7z3J0J9z6J9Z2K4a" // bcrypt hash of "Test@123!"
+            );
+            dbContext.Users.Add(testUser);
+
+            // Seed some lessons
+            var lessons = new[]
+            {
+                Lesson.Create("Greetings", "Basic German greetings and introductions", 1),
+                Lesson.Create("Numbers", "German numbers 1-100", 1),
+                Lesson.Create("Grammar Basics", "Basic German grammar rules", 2),
+                Lesson.Create("Everyday Phrases", "Common phrases for daily conversations", 2),
+                Lesson.Create("Advanced Grammar", "Complex German grammar", 4)
+            };
+            dbContext.Lessons.AddRange(lessons);
+
+            dbContext.SaveChanges();
+
+            Console.WriteLine("Database seeded with admin user, test user, and sample lessons.");
+        }
+    }
+}

GermanApp/Program.cs

@@ -3,25 +3,64 @@ using GermanApp.Application.UseCases.Commands;
 using GermanApp.Domain.Interfaces;
 using GermanApp.Infrastructure.Data.DbContext;
 using GermanApp.Infrastructure.Data.Repositories;
+using GermanApp.Infrastructure.Data.SeedData;
 using GermanApp.Presentation.Endpoints;
+using GermanApp.Shared.Middleware;
 using Microsoft.EntityFrameworkCore;
+using Serilog;
 
+// 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.
-// Learn more about configuring OpenAPI at https://aka.ms/aspnet/openapi
     builder.Services.AddOpenApi();
 
+    // Add Health Checks
+    builder.Services.AddHealthChecks()
+        .AddDbContextCheck<AppDbContext>();
+
+    // Configure CORS
+    builder.Services.AddCors(options =>
+    {
+        options.AddPolicy("AllowAll", builder =>
+        {
+            builder.AllowAnyOrigin()
+                   .AllowAnyMethod()
+                   .AllowAnyHeader();
+        });
+    });
+
+    // Add services for Minimal APIs
+    builder.Services.AddEndpointsApiExplorer();
+    builder.Services.AddSwaggerGen();
+
     // ============================================
     // INFRASTRUCTURE LAYER - Database & External Services
     // ============================================
 
-// Add DbContext with SQLite (can be changed to SQL Server, PostgreSQL, etc.)
+    // Add DbContext with PostgreSQL
     builder.Services.AddDbContext<AppDbContext>(options =>
     {
-    // Using SQLite for development - configure in appsettings.json for production
+        // Using PostgreSQL for production and development
-    options.UseSqlite(builder.Configuration.GetConnectionString("DefaultConnection") 
+        options.UseNpgsql(builder.Configuration.GetConnectionString("DefaultConnection") 
-        ?? "Data Source=germanapp.db");
+            ?? "Host=localhost;Port=5432;Database=DeutschLernen;Username=postgres;Password=postgres");
         
         // Enable sensitive data logging in development
         if (builder.Environment.IsDevelopment())
@@ -41,17 +80,13 @@ builder.Services.AddScoped<ILessonRepository, LessonRepository>();
     // Register command handlers
     builder.Services.AddScoped<ICommandHandler<CreateLessonCommand, LessonDto>, CreateLessonCommandHandler>();
 
-// ============================================
-// PRESENTATION LAYER - API
-// ============================================
-
-// Add services for Minimal APIs
-builder.Services.AddEndpointsApiExplorer();
-builder.Services.AddSwaggerGen();
-
     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();
@@ -59,13 +94,14 @@ if (app.Environment.IsDevelopment())
         app.UseSwaggerUI();
     }
 
-// Initialize database (in development)
+    // Use CORS
-if (app.Environment.IsDevelopment())
+    app.UseCors("AllowAll");
-{
+
-    using var scope = app.Services.CreateScope();
+    // Use Health Checks
-    var dbContext = scope.ServiceProvider.GetRequiredService<AppDbContext>();
+    app.MapHealthChecks("/health");
-    dbContext.Database.EnsureCreated();
+
-}
+    // Seed database with initial data
+    app.SeedDatabase();
 
     // Map Clean Architecture endpoints
     app.MapLessonsEndpoints();
@@ -91,6 +127,15 @@ app.MapGet("/weatherforecast", () =>
     .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)

GermanApp/Shared/Middleware/ExceptionMiddleware.cs

@@ -0,0 +1,62 @@
+using System.Net;
+using System.Text.Json;
+using GermanApp.Shared.Models;
+
+namespace GermanApp.Shared.Middleware;
+
+/// <summary>
+/// Global exception handling middleware.
+/// Catches exceptions and returns consistent error responses.
+/// </summary>
+public class ExceptionMiddleware
+{
+    private readonly RequestDelegate _next;
+    private readonly ILogger<ExceptionMiddleware> _logger;
+
+    public ExceptionMiddleware(RequestDelegate next, ILogger<ExceptionMiddleware> logger)
+    {
+        _next = next;
+        _logger = logger;
+    }
+
+    public async Task InvokeAsync(HttpContext httpContext)
+    {
+        try
+        {
+            await _next(httpContext);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Unhandled exception occurred: {Message}", ex.Message);
+            await HandleExceptionAsync(httpContext, ex);
+        }
+    }
+
+    private static Task HandleExceptionAsync(HttpContext context, Exception exception)
+    {
+        context.Response.ContentType = "application/json";
+        context.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
+
+        var response = new ApiErrorResponse(
+            "An unexpected error occurred. Please try again later.",
+            context.Response.StatusCode,
+            exception.Message
+        );
+
+        var options = new JsonSerializerOptions
+        {
+            PropertyNamingPolicy = JsonNamingPolicy.CamelCase
+        };
+
+        return context.Response.WriteAsync(JsonSerializer.Serialize(response, options));
+    }
+}
+
+/// <summary>
+/// Extension method to add exception middleware.
+/// </summary>
+public static class ExceptionMiddlewareExtensions
+{
+    public static IApplicationBuilder UseExceptionMiddleware(this IApplicationBuilder builder) =>
+        builder.UseMiddleware<ExceptionMiddleware>();
+}

GermanApp/Shared/Models/ApiResponse.cs

@@ -0,0 +1,47 @@
+namespace GermanApp.Shared.Models;
+
+/// <summary>
+/// Base API response wrapper for consistent API responses.
+/// </summary>
+/// <typeparam name="T">The data type of the response</typeparam>
+public record ApiResponse<T>(T Data, string Message = "Success", bool Success = true)
+{
+    /// <summary>
+    /// Creates a successful response.
+    /// </summary>
+    public static ApiResponse<T> Ok(T data, string message = "Success") =>
+        new ApiResponse<T>(data, message, true);
+}
+
+/// <summary>
+/// API error response for consistent error handling.
+/// </summary>
+public record ApiErrorResponse(string Message, int StatusCode, string? Details = null)
+{
+    public bool Success => false;
+
+    /// <summary>
+    /// Creates an error response.
+    /// </summary>
+    public static ApiErrorResponse Error(string message, int statusCode, string? details = null) =>
+        new ApiErrorResponse(message, statusCode, details);
+}
+
+/// <summary>
+/// Paginated API response.
+/// </summary>
+/// <typeparam name="T">The data type of the items</typeparam>
+public record PaginatedResponse<T>(IEnumerable<T> Items, int PageNumber, int PageSize, int TotalCount, int TotalPages)
+{
+    /// <summary>
+    /// Creates a paginated response.
+    /// </summary>
+    public static PaginatedResponse<T> Create(IEnumerable<T> items, int pageNumber, int pageSize, int totalCount) =>
+        new PaginatedResponse<T>(
+            items,
+            pageNumber,
+            pageSize,
+            totalCount,
+            (int)Math.Ceiling(totalCount / (double)pageSize)
+        );
+}

GermanApp/appsettings.Development.json

@@ -1,8 +1,11 @@
 {
   "Logging": {
     "LogLevel": {
-      "Default": "Information",
+      "Default": "Debug",
-      "Microsoft.AspNetCore": "Warning"
+      "Microsoft.AspNetCore": "Information"
-    }
+    }
+  },
+  "ConnectionStrings": {
+    "DefaultConnection": "Host=localhost;Port=5432;Database=DeutschLernen;Username=postgres;Password=postgres"
   }
 }

GermanApp/appsettings.Production.json

@@ -0,0 +1,11 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Warning",
+      "Microsoft.AspNetCore": "Error"
+    }
+  },
+  "ConnectionStrings": {
+    "DefaultConnection": "Host=prod-db;Port=5432;Database=DeutschLernen;Username=postgres;Password=${DB_PASSWORD}"
+  }
+}

GermanApp/appsettings.Staging.json

@@ -0,0 +1,11 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "ConnectionStrings": {
+    "DefaultConnection": "Host=staging-db;Port=5432;Database=DeutschLernen;Username=postgres;Password=${DB_PASSWORD}"
+  }
+}

GermanApp/appsettings.json

@@ -5,5 +5,8 @@
       "Microsoft.AspNetCore": "Warning"
     }
   },
-  "AllowedHosts": "*"
+  "AllowedHosts": "*",
+  "ConnectionStrings": {
+    "DefaultConnection": "Host=localhost;Port=5432;Database=DeutschLernen;Username=postgres;Password=postgres"
+  }
 }

docs/features/infrastructure-setup.md

@@ -1,6 +1,6 @@
 # Feature: Infrastructure Setup
 
-> **Status**: ⏳ Planned  
+> **Status**: 🚀 In Progress  
 > **Priority**: High  
 > **Complexity**: Medium  
 > **Estimate**: 10-14 hours