using FluentAssertions;
using Marathon.Application.UseCases;
using Marathon.Domain.Backtesting;
using Marathon.Domain.ValueObjects;
using Marathon.UI.Services;

namespace Marathon.UI.Tests.Services;

/// <summary>
/// Tests the pure <see cref="StrategyComparisonService.BuildVm"/> projection — per-row hit
/// rate and the single best-by-ROI flag — without the (sealed) use case.
/// </summary>
public sealed class StrategyComparisonServiceTests
{
    private static BacktestResult Result(int bets, int wins, int losses, decimal net, decimal? roi, decimal maxDd = 0m) =>
        new(
            StartingBankroll: 1000m,
            FinalBankroll: 1000m + net,
            NetProfit: net,
            RoiPercent: roi,
            TotalStaked: 0m,
            TotalReturned: 0m,
            MaxDrawdown: maxDd,
            MaxDrawdownPercent: null,
            BetsPlaced: bets,
            Wins: wins,
            Losses: losses,
            Skipped: 0,
            SkippedByThreshold: 0,
            SkippedByDataQuality: 0,
            SkippedByBankroll: 0,
            MaxWinStreak: 0,
            MaxLossStreak: 0,
            Trace: Array.Empty<BacktestTrace>(),
            EventTitles: new Dictionary<EventId, string>());

    private static StrategyComparison Comp(string name, BacktestResult result) =>
        new(Guid.NewGuid(), name, result);

    [Fact]
    public void BuildVm_Empty_When_NoComparisons()
    {
        StrategyComparisonService.BuildVm(Array.Empty<StrategyComparison>())
            .Should().Be(StrategyComparisonVm.Empty);
    }

    [Fact]
    public void BuildVm_MarksHighestRoiBest_AndComputesHitRate()
    {
        var comps = new[]
        {
            Comp("Flat", Result(bets: 10, wins: 6, losses: 4, net: 20m, roi: 5m)),
            Comp("Kelly", Result(bets: 10, wins: 7, losses: 3, net: 50m, roi: 12m)),
            Comp("Percent", Result(bets: 10, wins: 5, losses: 5, net: -10m, roi: -3m)),
        };

        var vm = StrategyComparisonService.BuildVm(comps);

        vm.Rows.Should().HaveCount(3);
        vm.Rows.Count(r => r.IsBest).Should().Be(1);
        vm.Rows.Single(r => r.IsBest).Name.Should().Be("Kelly");
        vm.Rows.Single(r => r.Name == "Flat").HitRatePercent.Should().Be(60m); // 6/10
    }

    [Fact]
    public void BuildVm_NoBetsPreset_NotBest_AndNullHitRate()
    {
        var vm = StrategyComparisonService.BuildVm(new[]
        {
            Comp("Idle", Result(bets: 0, wins: 0, losses: 0, net: 0m, roi: null)),
        });

        vm.Rows.Should().ContainSingle();
        vm.Rows[0].IsBest.Should().BeFalse();
        vm.Rows[0].HitRatePercent.Should().BeNull();
    }

    [Fact]
    public void BuildVm_Ties_ProduceSingleBest()
    {
        var comps = new[]
        {
            Comp("A", Result(10, 6, 4, 20m, 5m)),
            Comp("B", Result(10, 6, 4, 20m, 5m)),
        };

        StrategyComparisonService.BuildVm(comps).Rows.Count(r => r.IsBest).Should().Be(1);
    }
}