using HSchool.Content;
using HSchool.People;
using HSchool.Schedule;

namespace HSchool.Simulation.Tests;

/// <summary>
/// The canteen is fed in two sittings so it is not the whole school at once: juniors eat in the
/// break after the third lesson, seniors after the fourth. Before that, everybody crossed the
/// hunger threshold at roughly the same minute and the room could not hold them.
/// </summary>
public class LunchTests
{
    private static readonly DateTime Tuesday6 = new(2012, 4, 3, 6, 0, 0, DateTimeKind.Utc);

    [Fact]
    public void JuniorsEatAtTheFirstSitting_SeniorsAtTheSecond()
    {
        using var school = StaffedSchool();
        var (junior, senior) = Parallels(school);

        // Staff belong to no parallel and may eat at either sitting, so the claim is about pupils:
        // the two halves of the school never meet in the canteen.
        AdvanceTo(school, new DateTime(2012, 4, 3, 11, 15, 0, DateTimeKind.Utc));
        var first = InCafeteria(school);
        Assert.Contains(first, junior.Contains);
        Assert.DoesNotContain(first, senior.Contains);

        AdvanceTo(school, new DateTime(2012, 4, 3, 12, 20, 0, DateTimeKind.Utc));
        var second = InCafeteria(school);
        Assert.Contains(second, senior.Contains);
        Assert.DoesNotContain(second, junior.Contains);
    }

    /// <summary>
    /// Hunger is restored off campus — people eat at home — so a school week does not leave the
    /// roster starving. It used to: nothing refilled hunger except eight chairs, and by the end of
    /// the week a sixth of the school sat at zero.
    /// </summary>
    [Fact]
    public void AfterASchoolDay_NobodyIsLeftStarving()
    {
        using var school = StaffedSchool();
        var pupils = school.Roster!.People.Where(person => person.IsStudent).Select(person => person.Id)
            .ToHashSet(StringComparer.Ordinal);

        AdvanceTo(school, new DateTime(2012, 4, 4, 8, 0, 0, DateTimeKind.Utc));

        var hunger = Hunger(school, pupils);
        Assert.NotEmpty(hunger);
        Assert.All(hunger.Values, value => Assert.True(value > 0.5f, $"somebody came back to school at {value:F2}"));
    }

    private static School StaffedSchool()
    {
        var (catalog, map) = Vanilla();
        var roster = RosterGenerator.Generate(catalog, map, schoolSeed: 1, "Slavic", Tuesday6);
        var pool = ApplicantPool.Create(catalog, roster, schoolSeed: 1, "Slavic", Tuesday6);

        foreach (var subject in catalog.Subjects.Values.Where(def => !def.Abstract).Select(def => def.DefName))
        {
            if (pool.Applicants.Count == 0)
            {
                break;
            }

            var candidate = pool.Applicants[0].Person.Id;
            var hired = Staffing.Hire(catalog, map, roster, pool, candidate, Staffing.TeacherPosition, 1_000_000f);
            if (hired.Error != StaffingError.None)
            {
                break;
            }

            roster = hired.Roster;
            pool = hired.Pool;
            var assigned = Staffing.AssignSubject(catalog, roster, pool, candidate, subject, 1_000_000f);
            if (assigned.Error == StaffingError.None)
            {
                roster = assigned.Roster;
            }
        }

        var school = School.Create(1, "Столовая", Tuesday6, catalog, map);
        school.InstallPeople(roster, seed: 1, "Slavic", pool);
        school.SetTimetable(SchoolTimetables.Build(catalog, map, roster, null, weekDays: 5));
        school.ConfigurePresence(weekDays: 5, maxDecisionsPerTick: 64);
        return school;
    }

    private static (HashSet<string> Junior, HashSet<string> Senior) Parallels(School school)
    {
        var junior = new HashSet<string>(StringComparer.Ordinal);
        var senior = new HashSet<string>(StringComparer.Ordinal);
        foreach (var row in school.Roster!.Classes)
        {
            foreach (var id in row.PupilIds)
            {
                (row.Year <= 5 ? junior : senior).Add(id);
            }
        }

        return (junior, senior);
    }

    private static string[] InCafeteria(School school) =>
        school.CapturePresence()
            .Where(row => row.NodeId == "cafeteria")
            .Select(row => row.PersonId)
            .ToArray();

    private static Dictionary<string, float> Hunger(School school, HashSet<string> pupils)
    {
        var values = new Dictionary<string, float>(StringComparer.Ordinal);
        var query = new Arch.Core.QueryDescription().WithAll<PersonIdentity, PersonNeeds>();
        school.World.Query(in query, (ref PersonIdentity identity, ref PersonNeeds needs) =>
        {
            if (pupils.Contains(identity.Id) && needs.Values.TryGetValue("Hunger", out var value))
            {
                values[identity.Id] = value;
            }
        });
        return values;
    }

    private static void AdvanceTo(School school, DateTime until)
    {
        while (school.Clock.Time < until)
        {
            school.Tick(0.2d, 5d);
        }
    }

    private static (DefCatalog Catalog, MapLayout Map) Vanilla()
    {
        var root = Path.Combine(AppContext.BaseDirectory, "vanilla");
        var documents = PackDocumentsFrom(root);
        var catalog = new CatalogLoader().Load([CatalogLoader.CorePackId], documents);
        var map = CatalogLoader.LastDefaultMap([CatalogLoader.CorePackId], documents);
        Assert.NotNull(map);
        return (catalog, map);
    }

    private static IReadOnlyList<ContentDocument> PackDocumentsFrom(string root)
    {
        var documents = new List<ContentDocument>();
        foreach (var path in Directory.EnumerateFiles(root, "*.*", SearchOption.AllDirectories))
        {
            if (!path.EndsWith(".jsonc", StringComparison.OrdinalIgnoreCase)
                && !path.EndsWith(".json", StringComparison.OrdinalIgnoreCase))
            {
                continue;
            }

            var relative = Path.GetRelativePath(root, path).Replace(Path.DirectorySeparatorChar, (char)47);
            documents.Add(new ContentDocument(CatalogLoader.CorePackId, relative, File.ReadAllText(path)));
        }

        return documents;
    }
}