modular-vr/Assets/Engine/Runtime/Requirements/Placement/PlaceOnBottomOrTopRowAlternating.cs

using System.Collections.Generic;
using EscapeRoomEngine.Engine.Runtime.Modules;
using EscapeRoomEngine.Engine.Runtime.Modules.State;
using EscapeRoomEngine.Engine.Runtime.Utilities;
using UnityEngine;

namespace EscapeRoomEngine.Engine.Runtime.Requirements.Placement
{
    /// <summary>
    /// This requirement guarantees that the back side of the module is placed on the bottom row of an even-numbered space or on the top row of an odd-numbered space.
    /// </summary>
    [CreateAssetMenu(menuName = "Requirements/Place On Bottom Or Top Row Alternating")]
    public class PlaceOnBottomOrTopRowAlternating : PlacementRequirement
    {
        protected override List<Utilities.Placement> FilterCandidates(List<Utilities.Placement> candidates, Module module, Space space)
        {
            if (!module.description.HasType(ModuleType.DoorExit))
            {
                throw new WrongTypeException(module.description.types[0], ModuleType.DoorExit);
            }
            
            var number = FindObjectsByType<DoorState>(FindObjectsInactive.Include, FindObjectsSortMode.None).Length;
            
            if (number / 2 % 2 == 0)
            {
                candidates.RemoveAll(candidate =>
                {
                    var (left, right) = candidate.BackCorners;
                    return !(left.z == 0 && right.z == 0);
                });
            }
            else
            {
                var sizeMinusOne = space.rrPlacement.size - Vector2Int.one;
                
                candidates.RemoveAll(candidate =>
                {
                    var (left, right) = candidate.BackCorners;
                    return !(left.z == sizeMinusOne.y && right.z == sizeMinusOne.y);
                });
            }

            return candidates;
        }
    }
}