using FluentAssertions;
using IBKRTrader.Modules.Accounting.Logic;
using IBKRTrader.Modules.Accounting.Models;

namespace IBKRTrader.Tests.Modules.Accounting;

[Trait("cat", "unit")]
public class FxConverterTests
{
    private static FxRate R(int day, decimal rate) =>
        new() { Date = new DateTime(2026, 5, day), UsdToEur = rate, Source = "ECB" };

    [Fact]
    public void UsesNearestRateOnOrBefore()
    {
        var conv = new FxConverter(new[] { R(1, 0.90m), R(10, 0.92m) });

        conv.UsdToEurOn(new DateTime(2026, 5, 5)).Should().Be(0.90m);   // zwischen 1. und 10. → 0.90
        conv.UsdToEurOn(new DateTime(2026, 5, 10)).Should().Be(0.92m);  // exakt
        conv.UsdToEurOn(new DateTime(2026, 5, 20)).Should().Be(0.92m);  // nach letztem → letzter
    }

    [Fact]
    public void ReturnsNull_WhenNoRateBeforeDate()
    {
        var conv = new FxConverter(new[] { R(10, 0.92m) });

        conv.UsdToEurOn(new DateTime(2026, 5, 1)).Should().BeNull();
        conv.UsdToEur(100m, new DateTime(2026, 5, 1)).Should().BeNull();
    }

    [Fact]
    public void ConvertsAndRounds()
    {
        var conv = new FxConverter(new[] { R(1, 0.9123m) });

        conv.UsdToEur(100m, new DateTime(2026, 5, 2)).Should().Be(91.23m);
    }
}