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

namespace HSchool.Simulation;

/// <summary>
/// Picks and applies outfits from worn, bag, locker and home. Used at home instantly and after
/// <c>ChangeClothes</c> in a locker room.
/// </summary>
public static class ApparelDresser
{
    private static readonly string[] LayerOrder =
    [
        ApparelLayers.Underwear,
        ApparelLayers.UpperUnderwear,
        ApparelLayers.Socks,
        ApparelLayers.Bottom,
        ApparelLayers.Top,
        ApparelLayers.OverTop,
        ApparelLayers.Outer,
        ApparelLayers.Shoes,
        ApparelLayers.Head,
        ApparelLayers.Accessory,
    ];

    public static bool RedressPerson(
        School school,
        Person person,
        ApparelMode mode,
        bool includeHome,
        IReadOnlyList<string>? todaySubjects = null,
        bool logChanges = true)
    {
        if (school.Catalog is null || school.Roster is null)
        {
            return false;
        }

        var catalog = school.Catalog;
        var rules = RuleFor(school, person);
        var age = person.AgeOn(school.Clock.Time);
        var context = new ApparelContext(
            person.Female,
            age,
            person.IsStudent,
            rules,
            mode,
            school.Weather.TemperatureC,
            catalog.BehaviorRules);

        var pool = Pool(person, includeHome);
        var target = SelectOutfit(catalog, context, pool, mode);
        if (target.Count == 0)
        {
            return false;
        }

        var changed = ApplyOutfit(school, person, pool, target, todaySubjects, logChanges);
        if (changed)
        {
            var updated = school.Roster!.People.First(row => row.Id.Equals(person.Id, StringComparison.Ordinal));
            SyncInsulation(school, updated);
        }

        return changed;
    }

    public static ApparelIssue CurrentIssues(School school, Person person, ApparelMode mode)
    {
        if (school.Catalog is null)
        {
            return ApparelIssue.None;
        }

        var catalog = school.Catalog;
        var rules = RuleFor(school, person);
        var context = new ApparelContext(
            person.Female,
            person.AgeOn(school.Clock.Time),
            person.IsStudent,
            rules,
            mode,
            school.Weather.TemperatureC,
            catalog.BehaviorRules);
        var worn = WornEntries(catalog, person);
        return Appropriateness.Issues(catalog, context, worn);
    }

    public static ApparelMode ModeForLesson(string? subject) =>
        subject is not null && subject.Equals("PhysicalEducation", StringComparison.Ordinal)
            ? ApparelMode.Pe
            : ApparelMode.Everyday;

    public static string ChangeActionId(bool female) => ApparelActions.For(female);

    public static string? ChangingRoomDef(bool female) =>
        female ? "FemaleChangingRoom" : "MaleChangingRoom";

    internal static DressRulePair RuleFor(School school, Person person) =>
        person.IsStudent ? school.DressRules.Students : school.DressRules.Staff;

    private static List<(InventoryItem Item, int Index)> Pool(Person person, bool includeHome)
    {
        var pool = new List<(InventoryItem, int)>();
        for (var i = 0; i < person.Items.Count; i++)
        {
            var item = person.Items[i];
            if (item.Location.Equals(ItemLocations.Worn, StringComparison.Ordinal)
                || item.Location.Equals(ItemLocations.Bag, StringComparison.Ordinal)
                || item.Location.Equals(ItemLocations.Locker, StringComparison.Ordinal)
                || (includeHome && item.Location.Equals(ItemLocations.Home, StringComparison.Ordinal)))
            {
                pool.Add((item, i));
            }
        }

        return pool;
    }

    private static List<InventoryItem> SelectOutfit(
        DefCatalog catalog,
        ApparelContext context,
        List<(InventoryItem Item, int Index)> pool,
        ApparelMode mode)
    {
        var chosen = new List<InventoryItem>();
        var occupied = new HashSet<string>(StringComparer.Ordinal);
        var candidates = pool
            .Where(entry => catalog.Things.TryGetValue(entry.Item.Def, out var def)
                && !def.Abstract
                && def.Layers.Count > 0)
            .Select(entry => (Item: entry.Item, Def: catalog.Things[entry.Item.Def]))
            .Where(entry => SexFits(entry.Def, context.Female) && AgeFits(entry.Def, context.Age))
            .ToList();

        foreach (var layer in LayerOrder)
        {
            if (occupied.Contains(layer))
            {
                continue;
            }

            var pick = PickLayer(catalog, context, candidates, layer, mode, occupied);
            if (pick is null)
            {
                continue;
            }

            chosen.Add(pick.Value.Item);
            foreach (var taken in pick.Value.Def.Layers)
            {
                occupied.Add(taken);
            }
        }

        return chosen;
    }

    private static (InventoryItem Item, ThingDef Def)? PickLayer(
        DefCatalog catalog,
        ApparelContext context,
        List<(InventoryItem Item, ThingDef Def)> candidates,
        string layer,
        ApparelMode mode,
        HashSet<string> occupied)
    {
        (InventoryItem Item, ThingDef Def)? best = null;
        foreach (var entry in candidates)
        {
            if (!entry.Def.Layers.Any(candidate => candidate.Equals(layer, StringComparison.Ordinal))
                || !entry.Def.Layers.All(candidate => !occupied.Contains(candidate)))
            {
                continue;
            }

            if (mode == ApparelMode.Pe && !entry.Def.Pe)
            {
                continue;
            }

            if (mode == ApparelMode.Everyday && entry.Def.Pe)
            {
                continue;
            }

            if (!LayerAllowed(catalog, context, entry.Def, entry.Item.Color, mode))
            {
                continue;
            }

            if (best is null || Score(entry.Def) > Score(best.Value.Def))
            {
                best = entry;
            }
        }

        return best;
    }

    private static bool LayerAllowed(
        DefCatalog catalog,
        ApparelContext context,
        ThingDef def,
        string? color,
        ApparelMode mode)
    {
        if (mode == ApparelMode.Pe)
        {
            return def.Pe;
        }

        if (def.Layers.Any(layer => layer.Equals(ApparelLayers.Outer, StringComparison.Ordinal)))
        {
            var outerBelow = context.Behavior?.OuterBelowC ?? 10f;
            var heavyAbove = context.Behavior?.HeavyOuterAboveC ?? 15f;
            if (context.OutdoorTemperatureC >= outerBelow)
            {
                return false;
            }

            if (context.OutdoorTemperatureC > heavyAbove
                && def.DefName.Equals("FurCoat", StringComparison.Ordinal))
            {
                return false;
            }
        }

        return Appropriateness.FormalityFits(context, def)
            && Appropriateness.SkirtLengthFits(context, def)
            && Appropriateness.ColorAllowed(catalog, context.Rules, def, color);
    }

    private static int Score(ThingDef def)
    {
        var score = def.Formality;
        if (def.Layers.Any(layer => layer.Equals(ApparelLayers.Outer, StringComparison.Ordinal)))
        {
            score += (int)def.Insulation;
        }

        return score;
    }

    private static bool ApplyOutfit(
        School school,
        Person person,
        List<(InventoryItem Item, int Index)> pool,
        List<InventoryItem> target,
        IReadOnlyList<string>? todaySubjects,
        bool logChanges)
    {
        var targetKeys = target
            .Select(item => Key(item))
            .ToHashSet(StringComparer.Ordinal);
        var hasLocker = person.LockerRoomId is not null;
        var changed = false;
        var items = person.Items.ToList();

        for (var i = 0; i < items.Count; i++)
        {
            var item = items[i];
            if (!item.Location.Equals(ItemLocations.Worn, StringComparison.Ordinal))
            {
                continue;
            }

            if (targetKeys.Contains(Key(item)))
            {
                continue;
            }

            items[i] = item with { Location = StashLocation(hasLocker) };
            if (logChanges)
            {
                school.AppendDayLog(new PersonLogEvent(
                    person.Id,
                    school.Clock.Time,
                    PersonLogTypes.ApparelChanged,
                    item.Def));
            }
            changed = true;
        }

        foreach (var want in target)
        {
            var index = items.FindIndex(candidate =>
                Key(candidate).Equals(Key(want), StringComparison.Ordinal));
            if (index < 0)
            {
                continue;
            }

            if (items[index].Location.Equals(ItemLocations.Worn, StringComparison.Ordinal))
            {
                continue;
            }

            items[index] = items[index] with { Location = ItemLocations.Worn };
            if (logChanges)
            {
                school.AppendDayLog(new PersonLogEvent(
                    person.Id,
                    school.Clock.Time,
                    PersonLogTypes.ApparelChanged,
                    want.Def));
            }
            changed = true;
        }

        if (todaySubjects is not null && school.Catalog is { } catalog)
        {
            changed |= RepackBag(school, person, items, todaySubjects);
            changed |= StagePeKit(catalog, person, items, todaySubjects);
        }

        if (changed)
        {
            ReplacePerson(person, items);
        }

        return changed;
    }

    private static bool StagePeKit(
        DefCatalog catalog,
        Person person,
        List<InventoryItem> items,
        IReadOnlyList<string> todaySubjects)
    {
        if (!todaySubjects.Contains("PhysicalEducation", StringComparer.Ordinal))
        {
            return false;
        }

        var hasLocker = person.LockerRoomId is not null;
        var changed = false;
        for (var i = 0; i < items.Count; i++)
        {
            var item = items[i];
            if (!item.Location.Equals(ItemLocations.Home, StringComparison.Ordinal)
                || !catalog.Things.TryGetValue(item.Def, out var def)
                || !def.Pe)
            {
                continue;
            }

            items[i] = item with { Location = StashLocation(hasLocker) };
            changed = true;
        }

        return changed;
    }

    private static bool RepackBag(
        School school,
        Person person,
        List<InventoryItem> items,
        IReadOnlyList<string> todaySubjects)
    {
        if (school.Catalog is null)
        {
            return false;
        }

        var catalog = school.Catalog;
        var haveLocker = person.LockerRoomId is not null;
        var changed = false;
        var want = todaySubjects.ToHashSet(StringComparer.Ordinal);
        var capacity = CarryMass.Capacity(catalog, person.Skills);
        var held = 0f;

        foreach (var item in items.Where(row => row.Location.Equals(ItemLocations.Bag, StringComparison.Ordinal)))
        {
            if (catalog.Things.TryGetValue(item.Def, out var def))
            {
                held += def.Mass;
            }
        }

        for (var i = 0; i < items.Count; i++)
        {
            var item = items[i];
            if (item.Subject is null)
            {
                continue;
            }

            if (want.Contains(item.Subject))
            {
                if (!item.Location.Equals(ItemLocations.Bag, StringComparison.Ordinal)
                    && catalog.Things.TryGetValue(item.Def, out var def)
                    && held + def.Mass <= capacity)
                {
                    items[i] = item with { Location = ItemLocations.Bag };
                    held += def.Mass;
                    changed = true;
                }

                continue;
            }

            if (item.Location.Equals(ItemLocations.Bag, StringComparison.Ordinal))
            {
                items[i] = item with { Location = StashLocation(haveLocker) };
                if (catalog.Things.TryGetValue(item.Def, out var def))
                {
                    held = Math.Max(0, held - def.Mass);
                }

                changed = true;
            }
        }

        return changed;
    }

    private static string StashLocation(bool hasLocker) =>
        hasLocker ? ItemLocations.Locker : ItemLocations.Bag;

    private static string Key(InventoryItem item) =>
        item.Subject is null ? item.Def : $"{item.Def}:{item.Subject}";

    private static IEnumerable<(ThingDef Def, string? Color)> WornEntries(DefCatalog catalog, Person person)
    {
        foreach (var item in person.Items)
        {
            if (!item.Location.Equals(ItemLocations.Worn, StringComparison.Ordinal))
            {
                continue;
            }

            if (catalog.Things.TryGetValue(item.Def, out var def))
            {
                yield return (def, item.Color);
            }
        }
    }

    private static void SyncInsulation(School school, Person person)
    {
        var insulation = PersonInsulation.FromPerson(person, school.Catalog);
        var world = school.World;
        var query = new Arch.Core.QueryDescription().WithAll<PersonIdentity, PersonInsulation>();
        world.Query(in query, (ref PersonIdentity identity, ref PersonInsulation worn) =>
        {
            if (identity.Id.Equals(person.Id, StringComparison.Ordinal))
            {
                worn = insulation;
            }
        });
    }

    private static void ReplacePerson(Person person, List<InventoryItem> items)
    {
        if (person.Items is IList<InventoryItem> list && !list.IsReadOnly)
        {
            list.Clear();
            foreach (var item in items)
            {
                list.Add(item);
            }

            return;
        }

        throw new InvalidOperationException($"Cannot mutate items for {person.Id}.");
    }

    private static bool SexFits(ThingDef def, bool female)
    {
        if (def.Sex is null)
        {
            return true;
        }

        var want = female ? "female" : "male";
        return def.Sex.Equals(want, StringComparison.OrdinalIgnoreCase);
    }

    private static bool AgeFits(ThingDef def, int age) =>
        def.Age is not { } range || (age >= range.Min && age <= range.Max);

    /// <summary>Subjects this pupil needs in the bag today.</summary>
    public static IReadOnlyList<string> TodaySubjects(
        School school,
        Person person,
        SchoolClass? schoolClass)
    {
        if (school.Catalog is null || school.Timetable is null || !person.IsStudent)
        {
            return [];
        }

        var day = SchoolDay.WeekdayIndex(school.Clock.Time);
        return Duty.LessonsToday(person, schoolClass, school.Timetable, day)
            .Select(lesson => lesson.Subject)
            .Distinct(StringComparer.Ordinal)
            .ToArray();
    }
}