h-school/src/HSchool.Simulation/NeedDecay.cs

using Arch.Core;
using HSchool.Ai;
using HSchool.Content;

namespace HSchool.Simulation;

/// <summary>
/// Drains needs by <see cref="NeedDef.DecayPerHour"/> × simulated hours while the person is on
/// campus. Off campus, needs do not drain and <see cref="NeedDef.RestoredOffCampus"/> snaps to max
/// — sleep comes back overnight, hunger does not keep falling at home.
/// </summary>
public static class NeedDecay
{
    private static readonly QueryDescription PeopleWithNeeds =
        new QueryDescription().WithAll<PersonNeeds, Presence>();

    public static void Apply(World world, DefCatalog catalog, double gameMinutes)
    {
        if (gameMinutes <= 0 || (!catalog.AnyNeedDecays && !catalog.AnyNeedRestoredOffCampus))
        {
            return;
        }

        var hours = gameMinutes / 60d;
        world.Query(in PeopleWithNeeds, (ref PersonNeeds needs, ref Presence presence) =>
        {
            if (!presence.IsOnCampus)
            {
                foreach (var def in catalog.Needs.Values)
                {
                    if (def.Abstract || !def.RestoredOffCampus || !needs.Values.ContainsKey(def.DefName))
                    {
                        continue;
                    }

                    needs.Values[def.DefName] = def.Max;
                }

                return;
            }

            if (!catalog.AnyNeedDecays)
            {
                return;
            }

            foreach (var def in catalog.Needs.Values)
            {
                if (def.Abstract || def.Environmental || !needs.Values.TryGetValue(def.DefName, out var current))
                {
                    continue;
                }

                var next = current - (float)(def.DecayPerHour * hours);
                needs.Values[def.DefName] = Math.Clamp(next, def.Min, def.Max);
            }
        });
    }
}