using LehrerApp.Core.Models;
using LehrerApp.Core.Services;
using Xunit;

namespace LehrerApp.Tests;

public sealed class PublicHolidayServiceTests
{
    private readonly PublicHolidayService _service = new();

    [Theory]
    [InlineData(2023, "2023-04-09")]
    [InlineData(2024, "2024-03-31")]
    [InlineData(2025, "2025-04-20")]
    [InlineData(2026, "2026-04-05")]
    [InlineData(2027, "2027-03-28")]
    public void GetHolidays_Ostermontag_LiegtEinenTagNachDemBekanntenOstersonntag(int year, string easterSundayIso)
    {
        var easterSunday = DateOnly.Parse(easterSundayIso);
        var holidays = _service.GetHolidays(year, GermanState.NW);

        Assert.Contains(holidays, h => h.Name == "Ostermontag" && h.Date == easterSunday.AddDays(1));
        Assert.Contains(holidays, h => h.Name == "Karfreitag" && h.Date == easterSunday.AddDays(-2));
    }

    [Fact]
    public void GetHolidays_AlleBundeslaender_EnthaltenDieBundesweitenFeiertage()
    {
        foreach (var state in Enum.GetValues<GermanState>())
        {
            var holidays = _service.GetHolidays(2026, state);
            Assert.Contains(holidays, h => h.Date == new DateOnly(2026, 1, 1));   // Neujahr
            Assert.Contains(holidays, h => h.Date == new DateOnly(2026, 5, 1));   // Tag der Arbeit
            Assert.Contains(holidays, h => h.Date == new DateOnly(2026, 10, 3));  // Tag der Deutschen Einheit
            Assert.Contains(holidays, h => h.Date == new DateOnly(2026, 12, 25));
            Assert.Contains(holidays, h => h.Date == new DateOnly(2026, 12, 26));
        }
    }

    [Fact]
    public void GetHolidays_Fronleichnam_NurInDenZustaendigenBundeslaendern()
    {
        var nrw = _service.GetHolidays(2026, GermanState.NW);
        var berlin = _service.GetHolidays(2026, GermanState.BE);

        Assert.Contains(nrw, h => h.Name == "Fronleichnam");
        Assert.DoesNotContain(berlin, h => h.Name == "Fronleichnam");
    }

    [Fact]
    public void GetHolidays_Reformationstag_NurInDenZustaendigenBundeslaendern()
    {
        var sachsen = _service.GetHolidays(2026, GermanState.SN);
        var bayern = _service.GetHolidays(2026, GermanState.BY);

        Assert.Contains(sachsen, h => h.Name == "Reformationstag");
        Assert.DoesNotContain(bayern, h => h.Name == "Reformationstag");
    }

    [Fact]
    public void GetHolidays_SindNachDatumSortiert()
    {
        var holidays = _service.GetHolidays(2026, GermanState.BY);

        Assert.Equal(holidays.OrderBy(h => h.Date).Select(h => h.Date), holidays.Select(h => h.Date));
    }
}