using MrGameEng.Core;
using Xunit;

namespace MrGameEng.Core.Tests;

public class ClimateTests
{
    private static (GameClock Clock, Climate Climate) Make(ClimateSettings settings)
    {
        var clock = new GameClock();
        var calendar = new Calendar(clock, secondsPerDay: 10f);
        return (clock, new Climate(calendar, settings));
    }

    private static ClimateSettings Seasonal =>
        new()
        {
            DaysPerYear = 60,
            MeanTemperature = 10f,
            SeasonalAmplitude = 20f,
            DailyAmplitude = 0f,
            WarmestDay = 15,
        };

    [Fact]
    public void Constructor_NonPositiveYear_Throws()
    {
        Assert.Throws<ArgumentOutOfRangeException>(() =>
            new Climate(new Calendar(new GameClock(), 10f), Seasonal with { DaysPerYear = 0 })
        );
    }

    [Fact]
    public void Temperature_PeaksOnWarmestDay_AndBottomsHalfYearLater()
    {
        var (clock, climate) = Make(Seasonal);

        clock.Advance(15 * 10f); // day 15 = warmest
        Assert.Equal(30f, climate.Temperature, 2); // mean 10 + amplitude 20

        clock.Advance(30 * 10f); // +30 days = half a 60-day year later
        Assert.Equal(-10f, climate.Temperature, 2); // mean 10 - amplitude 20
    }

    [Fact]
    public void DailySwing_WarmerAtNoonThanMidnight()
    {
        var settings = Seasonal with { SeasonalAmplitude = 0f, DailyAmplitude = 6f };
        var (clock, climate) = Make(settings);

        clock.Advance(5f); // day 0, noon (DayProgress 0.5)
        Assert.Equal(16f, climate.Temperature, 2); // mean 10 + daily 6

        clock.Advance(5f); // day 1, midnight (DayProgress 0)
        Assert.Equal(4f, climate.Temperature, 2); // mean 10 - daily 6
    }

    [Fact]
    public void Season_FollowsTheQuarterOfTheYear()
    {
        var (clock, climate) = Make(Seasonal); // 60-day year → 15 days per season

        Assert.Equal(Season.Spring, climate.Season);
        clock.Advance(20 * 10f);
        Assert.Equal(Season.Summer, climate.Season);
        clock.Advance(15 * 10f);
        Assert.Equal(Season.Autumn, climate.Season);
        clock.Advance(15 * 10f);
        Assert.Equal(Season.Winter, climate.Season);
    }

    [Fact]
    public void YearAndDayOfYear_RollOver()
    {
        var (clock, climate) = Make(Seasonal);

        Assert.Equal(1, climate.Year);
        Assert.Equal(0, climate.DayOfYear);

        clock.Advance(60 * 10f); // exactly one year
        Assert.Equal(2, climate.Year);
        Assert.Equal(0, climate.DayOfYear);
    }
}