Program.cs

using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.EntityFrameworkCore;
using Microsoft.IdentityModel.Tokens;
using Microsoft.OpenApi.Models;
using System.Text;
using System.Text.Json.Serialization;
using MicroLearningAPI.Data;
using MicroLearningAPI.Services;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddControllers()
    .AddJsonOptions(options =>
    {
        options.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter());
        options.JsonSerializerOptions.PropertyNamingPolicy = null; // Keep original property names
    });

// Database
builder.Services.AddDbContext<AppDbContext>(options =>
    options.UseNpgsql(builder.Configuration.GetConnectionString("DefaultConnection")));

// Authentication
builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
    .AddJwtBearer(options =>
    {
        options.TokenValidationParameters = new TokenValidationParameters
        {
            ValidateIssuer = true,
            ValidateAudience = true,
            ValidateLifetime = true,
            ValidateIssuerSigningKey = true,
            ValidIssuer = builder.Configuration["Jwt:Issuer"],
            ValidAudience = builder.Configuration["Jwt:Audience"],
            IssuerSigningKey = new SymmetricSecurityKey(
                Encoding.UTF8.GetBytes(builder.Configuration["Jwt:Key"]!))
        };
    });

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

// Swagger/OpenAPI
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen(c =>
{
    c.SwaggerDoc("v1", new OpenApiInfo
    {
        Title = "Micro Learning API",
        Version = "v1",
        Description = "API for tracking learning progress with spaced repetition"
    });

    // Add JWT authentication to Swagger
    c.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme
    {
        Description = "JWT Authorization header using the Bearer scheme. Enter 'Bearer' [space] and then your token in the text input below.",
        Name = "Authorization",
        In = ParameterLocation.Header,
        Type = SecuritySchemeType.ApiKey,
        Scheme = "Bearer"
    });

    c.AddSecurityRequirement(new OpenApiSecurityRequirement
    {
        {
            new OpenApiSecurityScheme
            {
                Reference = new OpenApiReference
                {
                    Type = ReferenceType.SecurityScheme,
                    Id = "Bearer"
                }
            },
            new string[] {}
        }
    });

    // Configure enum handling
    c.UseInlineDefinitionsForEnums();

    // Add XML comments if available
    var xmlFile = $"{System.Reflection.Assembly.GetExecutingAssembly().GetName().Name}.xml";
    var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);
    if (File.Exists(xmlPath))
    {
        c.IncludeXmlComments(xmlPath);
    }
});

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

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();
app.UseCors("AllowAll");
app.UseAuthentication();
app.UseAuthorization();
app.MapControllers();

// Apply migrations on startup
using (var scope = app.Services.CreateScope())
{
    var context = scope.ServiceProvider.GetRequiredService<AppDbContext>();
    context.Database.Migrate();
}

app.Run();