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

namespace LehrerApp.Tests;

public class ExamWeekLoadServiceTests
{
    private static Exam MakeExam(DateOnly date, ExamStatus status = ExamStatus.Planned) => new()
    {
        GroupId = Guid.NewGuid(), Title = "Klausur", Status = status, Date = date,
    };

    [Fact]
    public void CountInSameWeek_ZaehltNurKlausurenInDerselbenIsoWoche()
    {
        // KW 12/2026: Montag 16.03. bis Sonntag 22.03.
        var monday = new DateOnly(2026, 3, 16);
        var exams = new List<Exam>
        {
            MakeExam(monday),
            MakeExam(monday.AddDays(4)),   // Freitag derselben Woche
            MakeExam(monday.AddDays(-1)),  // Sonntag der Vorwoche
            MakeExam(monday.AddDays(7)),   // Montag der Folgewoche
        };

        var count = ExamWeekLoadService.CountInSameWeek(exams, monday.AddDays(2));

        Assert.Equal(2, count);
    }

    [Fact]
    public void CountInSameWeek_SchliesstAngegebeneKlausurAus()
    {
        var monday = new DateOnly(2026, 3, 16);
        var editing = MakeExam(monday);
        var exams = new List<Exam> { editing, MakeExam(monday.AddDays(1)) };

        var count = ExamWeekLoadService.CountInSameWeek(exams, monday, editing.Id);

        Assert.Equal(1, count);
    }

    [Fact]
    public void FindOverloadedWeeks_MeldetNurWochenAbDemSchwellenwert()
    {
        var monday = new DateOnly(2026, 3, 16);
        var exams = new List<Exam>
        {
            MakeExam(monday), MakeExam(monday.AddDays(1)),                    // KW 12: 2 -> unauffällig
            MakeExam(monday.AddDays(7)), MakeExam(monday.AddDays(8)), MakeExam(monday.AddDays(9)), // KW 13: 3 -> Meldung
        };

        var overloaded = ExamWeekLoadService.FindOverloadedWeeks(exams);

        var week = Assert.Single(overloaded);
        Assert.Equal(3, week.ExamCount);
        Assert.Equal(monday.AddDays(7), week.WeekStart);
    }

    [Fact]
    public void FindOverloadedWeeks_OhneHaeufung_GibtLeereListeZurueck()
    {
        var monday = new DateOnly(2026, 3, 16);
        var exams = new List<Exam> { MakeExam(monday), MakeExam(monday.AddDays(7)) };

        Assert.Empty(ExamWeekLoadService.FindOverloadedWeeks(exams));
    }

    [Fact]
    public void FindOverloadedWeeks_SortiertChronologisch()
    {
        var laterWeek = new DateOnly(2026, 4, 20);
        var earlierWeek = new DateOnly(2026, 3, 16);
        var exams = new List<Exam>
        {
            MakeExam(laterWeek), MakeExam(laterWeek.AddDays(1)), MakeExam(laterWeek.AddDays(2)),
            MakeExam(earlierWeek), MakeExam(earlierWeek.AddDays(1)), MakeExam(earlierWeek.AddDays(2)),
        };

        var overloaded = ExamWeekLoadService.FindOverloadedWeeks(exams);

        Assert.Equal(2, overloaded.Count);
        Assert.True(overloaded[0].WeekStart < overloaded[1].WeekStart);
    }
}