using System;
using System.Linq;
using Microsoft.eShopWeb.ApplicationCore.Entities.BasketAggregate;
using Xunit;

namespace Microsoft.eShopWeb.UnitTests.ApplicationCore.Entities.BasketTests;

public class BasketAddItem
{
    private readonly int _testCatalogItemId = 123;
    private readonly decimal _testUnitPrice = 1.23m;
    private readonly int _testQuantity = 2;
    private readonly string _buyerId = "Test buyerId";

    [Fact]
    public void AddsBasketItemIfNotPresent()
    {
        var basket = new Basket(_buyerId);
        basket.AddItem(_testCatalogItemId, _testUnitPrice, _testQuantity);

        var firstItem = basket.Items.Single();
        Assert.Equal(_testCatalogItemId, firstItem.CatalogItemId);
        Assert.Equal(_testUnitPrice, firstItem.UnitPrice);
        Assert.Equal(_testQuantity, firstItem.Quantity);
    }

    [Fact]
    public void IncrementsQuantityOfItemIfPresent()
    {
        var basket = new Basket(_buyerId);
        basket.AddItem(_testCatalogItemId, _testUnitPrice, _testQuantity);
        basket.AddItem(_testCatalogItemId, _testUnitPrice, _testQuantity);

        var firstItem = basket.Items.Single();
        Assert.Equal(_testQuantity * 2, firstItem.Quantity);
    }

    [Fact]
    public void KeepsOriginalUnitPriceIfMoreItemsAdded()
    {
        var basket = new Basket(_buyerId);
        basket.AddItem(_testCatalogItemId, _testUnitPrice, _testQuantity);
        basket.AddItem(_testCatalogItemId, _testUnitPrice * 2, _testQuantity);

        var firstItem = basket.Items.Single();
        Assert.Equal(_testUnitPrice, firstItem.UnitPrice);
    }

    [Fact]
    public void DefaultsToQuantityOfOne()
    {
        var basket = new Basket(_buyerId);
        basket.AddItem(_testCatalogItemId, _testUnitPrice);

        var firstItem = basket.Items.Single();
        Assert.Equal(1, firstItem.Quantity);
    }

    [Fact]
    public void CantAddItemWithNegativeQuantity()
    {
        var basket = new Basket(_buyerId);

        Assert.Throws<ArgumentOutOfRangeException>(() => basket.AddItem(_testCatalogItemId, _testUnitPrice, -1));
    }

    [Fact]
    public void CantModifyQuantityToNegativeNumber()
    {
        var basket = new Basket(_buyerId);
        basket.AddItem(_testCatalogItemId, _testUnitPrice);

        Assert.Throws<ArgumentOutOfRangeException>(() => basket.AddItem(_testCatalogItemId, _testUnitPrice, -2));
    }
}