Program.cs

using ClassroomAPI.Data;
using ClassroomAPI.Models;
using Hangfire;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;
using Microsoft.IdentityModel.Tokens;
using System.Text;
using ClassroomAPI.Services;
using ClassroomAPI.Hubs;
using Microsoft.OpenApi.Models;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddDbContext<ClassroomDbContext>(options =>
    options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection"),
    sqlServerOptions => sqlServerOptions.EnableRetryOnFailure
    (
        maxRetryCount: 5, 
        maxRetryDelay: TimeSpan.FromSeconds(30), 
        errorNumbersToAdd: null
    )));

builder.Services.AddIdentity<ApplicationUser, IdentityRole>()
    .AddEntityFrameworkStores<ClassroomDbContext>()
    .AddDefaultTokenProviders();

// Configure JWT authentication
builder.Services.AddAuthentication(options =>
{
    options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
    options.DefaultChallengeScheme = 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"] ?? "SuperLongJWTSecretKeyForSigningJWTokens"))
        };
    });

// Enable CORS
builder.Services.AddCors(options =>
{
    options.AddPolicy("AllowFrontend",
        builder =>
        {
            builder.WithOrigins("http://localhost:5173", "https://localhost:5173", "http://localhost:4173")
                .AllowAnyMethod()
                .AllowAnyHeader()
                .AllowCredentials();
        });
});

builder.Services.Configure<IdentityOptions>(options =>
{
    options.Password.RequiredLength = 6;
    options.Password.RequireDigit = true;
    options.Password.RequireNonAlphanumeric = false;
    options.Password.RequireUppercase = true;
    options.Password.RequireLowercase = true;
});

// Configure SignalR
builder.Services.AddSignalR().AddHubOptions<ChatHub>(options =>
{
    options.EnableDetailedErrors = true;
});

// Add Hangfire
builder.Services.AddHangfire(x => x.UseSqlServerStorage(builder.Configuration.GetConnectionString("DefaultConnection")));

builder.Services.AddHangfireServer();

builder.Services.AddControllers().AddJsonOptions(options =>
{
    options.JsonSerializerOptions.ReferenceHandler = System.Text.Json.Serialization.ReferenceHandler.Preserve;
    options.JsonSerializerOptions.WriteIndented = true; // Optional: Pretty-print the JSON output
});

builder.Services.AddTransient<FileService>();

builder.Services.AddTransient<NotificationService>();

builder.Services.AddTransient<SchedulingService>();

builder.Services.AddScoped<ReportService>();

builder.Services.AddEndpointsApiExplorer();

builder.Services.AddSwaggerGen(c => {
    c.SwaggerDoc("v1", new OpenApiInfo 
    { 
        Title = "ClassroomAPI", Version = "v1" 
    });
    
    // Define the Security Scheme
    c.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme 
    { 
        In = ParameterLocation.Header, 
        Description = "Please enter JWT with Bearer into field", 
        Name = "Authorization", 
        Type = SecuritySchemeType.ApiKey, 
        Scheme = "Bearer" 
    });

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

builder.Configuration.AddEnvironmentVariables();

var app = builder.Build();

// Seed roles and admin user
using (var scope = app.Services.CreateScope())
{
    var services = scope.ServiceProvider;

    try
    {
        await DataSeeder.SeedRolesAndAdminAsync(services);
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Error occurred during seeding: {ex.Message}");
        throw;
    }
}

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI(c => { c.SwaggerEndpoint("/swagger/v1/swagger.json", "ClassroomAPI v1"); });
}

app.UseRouting();

app.UseCors("AllowFrontend");

app.UseAuthentication();

app.UseAuthorization();

app.UseHangfireDashboard();

app.MapControllers();

app.MapHub<ChatHub>("/chatHub");

app.Run();