using System.ComponentModel.DataAnnotations;
using Microsoft.AspNetCore.Http.HttpResults;
using Microsoft.Extensions.Options;
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddValidation(); builder.Services.AddProblemDetails(); builder.Services.AddOpenApi();
builder.Services.AddOptions<QuoteLimits>().Bind(builder.Configuration.GetSection("Quote")).Validate(x => x.MaximumQuantity is >= 1 and <= 10, "MaximumQuantity must be 1 through 10").ValidateOnStart();
builder.Services.AddSingleton<Catalog>(); builder.Services.AddScoped<QuoteService>();
var app = builder.Build(); app.UseExceptionHandler(); if (app.Environment.IsDevelopment()) app.MapOpenApi();
app.MapPost("/quotes", Results<Ok<Receipt>, NotFound, ProblemHttpResult> (QuoteRequest request, QuoteService service, CancellationToken token) => service.Create(request, token)).ProducesValidationProblem().ProducesProblem(StatusCodes.Status409Conflict).WithName("CreateQuote"); app.Run();
public sealed class QuoteRequest { [Required, MinLength(2)] public string Item { get; set; } = ""; [Range(1, 10)] public int Quantity { get; set; } }
public sealed class QuoteLimits { public int MaximumQuantity { get; set; } }
public sealed record Receipt(string Item, int Quantity, decimal Total);
public sealed class Catalog { public bool TryPrice(string name, out decimal price) { price = 12.5m; return string.Equals(name, "rune", StringComparison.Ordinal); } }
public sealed class QuoteService(Catalog catalog, IOptions<QuoteLimits> options, ILogger<QuoteService> logger) {
    public Results<Ok<Receipt>, NotFound, ProblemHttpResult> Create(QuoteRequest request, CancellationToken token) {
        token.ThrowIfCancellationRequested();
        if (!catalog.TryPrice(request.Item, out decimal price)) return TypedResults.NotFound();
        if (request.Quantity > options.Value.MaximumQuantity) return TypedResults.Problem(statusCode: 409, title: "Configured quantity limit exceeded");
        decimal total = checked(price * request.Quantity); logger.LogInformation("Quoted {Quantity} units of {CatalogItem}", request.Quantity, request.Item);
        return TypedResults.Ok(new Receipt(request.Item, request.Quantity, total));
    }
}