#nullable enable // <-------------------- PORTFOLIO CODE SAMPLE: Miniature SaaS API (BEGIN) --------------------> // Author: [Your Name] // Tech Stack: .NET 6+ Minimal API, C#, In-Memory Data Store // Purpose: Demonstrates a clean, modern, and scalable approach to building a Full-Stack application backend.

// --- 1. USING STATEMENTS & GLOBAL CONFIG --- using Microsoft.AspNetCore.Mvc; using System.Collections.Concurrent;

var builder = WebApplication.CreateBuilder(args); builder.Services.AddEndpointsApiExplorer(); builder.Services.AddSwaggerGen();

// --- 2. DEPENDENCY INJECTION: Simulating Clean Architecture Layers ---

// Data Layer: Stores the application's data (in-memory for this example). builder.Services.AddSingleton<IProductRepository, InMemoryProductRepository>();

// Service Layer (Business Logic): Contains the core application logic. builder.Services.AddScoped();

var app = builder.Build();

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

app.UseHttpsRedirection();

// --- 3. PRESENTATION LAYER: The API Endpoints --- // These are the public-facing endpoints that a Frontend (Vue, React, etc.) would consume.

var api = app.MapGroup("/api/products");

// GET /api/products api.MapGet("/", (ProductService productService) => { return productService.GetAllProducts(); });

// GET /api/products/{id} api.MapGet("/{id:int}", (int id, ProductService productService) => { var product = productService.GetProductById(id); return product is not null ? Results.Ok(product) : Results.NotFound(); });

// GET /api/products/premium api.MapGet("/premium", (ProductService productService) => { // This simulates a feature only available to premium users. return productService.GetPremiumProducts(); });

app.Run();

// --- 4. DOMAIN: The Core Business Models --- // These classes define the essential data structures of the application.

public record Product(int Id, string Name, double Price, bool IsPremium = false);

// --- 5. SERVICE LAYER: Application Business Logic --- // This layer orchestrates data and applies business rules.

public class ProductService { private readonly IProductRepository _repository;

public ProductService(IProductRepository repository)
{
    _repository = repository;
}

public IEnumerable<Product> GetAllProducts() => _repository.GetAll();

public Product? GetProductById(int id) => _repository.GetById(id);

public IEnumerable<Product> GetPremiumProducts()
{
    // Business Rule: Only return products marked as premium.
    return _repository.GetAll().Where(p => p.IsPremium);
}

}

// --- 6. DATA LAYER: Data Access and Persistence --- // This layer is responsible for retrieving and storing data.

public interface IProductRepository { IEnumerable GetAll(); Product? GetById(int id); }

public class InMemoryProductRepository : IProductRepository { // Using a ConcurrentDictionary to be thread-safe. private readonly ConcurrentDictionary<int, Product> _products = new(new[] { KeyValuePair.Create(1, new Product(1, "Standard Widget", 9.99)), KeyValuePair.Create(2, new Product(2, "Advanced Gadget", 29.99)), KeyValuePair.Create(3, new Product(3, "Pro Gear", 99.99, IsPremium: true)), KeyValuePair.Create(4, new Product(4, "Ultimate Gizmo", 199.99, IsPremium: true)), });

public IEnumerable<Product> GetAll() => _products.Values.OrderBy(p => p.Id);

public Product? GetById(int id) => _products.GetValueOrDefault(id);

}

// <-------------------- PORTFOLIO CODE SAMPLE: Miniature SaaS API (END) --------------------># GeminiLightControl