using After;
using static BeforeAfter.Tests.TestData.ClientBuilder;
using static BeforeAfter.Tests.TestData.OrderBuilder;

namespace BeforeAfter.Tests;

/// <summary>
/// EXERCISE — the mapping from a <see cref="DiscountedOrder"/> onto an
/// <see cref="Order"/> is NOT one-on-one. (This is the solution participants
/// arrive at from the stub in EXERCISE.md.)
/// </summary>
public class DiscountedOrderMappingTests
{
    [Fact] // EXERCISE STEP 2
    public void A_discounted_order_can_be_correlated_onto_its_order()
    {
        var db = new DbContext();
        var order = ValidOrder().WithDescription("big order").WithTotal(150_00).Build();
        var client = ValidClient().WithName("Acme").WithOrder(order).Build();
        db.Save(client);
        db.Save(order);

        // 10 % for orders above €100:
        var discounted = DiscountCalculator.CalculateDiscount(
            order, discountBarrierCents: 100_00, discountPercentage: 10);

        // Correlate: the discounted result belongs to the order carrying this id.
        Assert.Equal(order.Id, discounted.OrderId);

        // Copy the discounted total onto the order. The discount percentage is
        // deliberately NOT copied — it is derivable from the two totals.
        order.DiscountedTotalInCents = discounted.DiscountedTotalInCents;

        Assert.Equal(135_00, order.DiscountedTotalInCents);
    }

    [Fact] // EXERCISE STEP 3
    public void Saving_a_discounted_order_keeps_the_stored_total_untouched()
    {
        var db = new DbContext();
        var order = ValidOrder().WithDescription("big order").WithTotal(150_00).Build();
        var client = ValidClient().WithName("Acme").WithOrder(order).Build();
        db.Save(client);
        db.Save(order);

        var discounted = DiscountCalculator.CalculateDiscount(
            order, discountBarrierCents: 100_00, discountPercentage: 10);
        Assert.Equal(order.Id, discounted.OrderId);
        order.DiscountedTotalInCents = discounted.DiscountedTotalInCents;

        // Save the updated order: the context refreshes the stored row in place.
        db.Save(order);

        // The persisted record keeps the ORIGINAL total: the database knows
        // nothing about discounts — derived data lives in the domain only.
        var row = db.Find<OrderData>(candidate => candidate.Id == discounted.OrderId)!;
        Assert.Equal(150_00, row.TotalInCents);
    }
}