riversong-code-showcase/Source/Riversong/Game/Input/CancelActionSystem.cs

using System;
using System.Collections.Generic;
using UnityEngine.InputSystem;

namespace DanieleMarotta.RiversongCodeShowcase
{
    [Service(typeof(ICancelAction))]
    [GameSystemGroup(typeof(LateGameSystemGroup))]
    public class CancelActionSystem : GameSystem, IUpdatable, ICancelAction
    {
        private readonly List<(int, Func<CancelActionType, bool>)> _handlers = new();

        private Comparison<(int, Func<CancelActionType, bool>)> _handlerComparison;

        public CancelActionSystem(IServiceLocator serviceLocator) : base(serviceLocator)
        {
        }

        public void Update()
        {
            if (!TryGetCancelActionType(out var cancelActionType)) return;

            foreach (var (_, handler) in _handlers)
                if (handler.Invoke(cancelActionType))
                    return;
        }

        public void AddHandler(int priority, Func<CancelActionType, bool> cancelAction)
        {
            _handlerComparison ??= (handler, otherHandler) =>
            {
                var (handlerPriority, _) = handler;
                var (otherHandlerPriority, _) = otherHandler;
                return otherHandlerPriority.CompareTo(handlerPriority);
            };

            _handlers.Add((priority, cancelAction));
            _handlers.Sort(_handlerComparison);
        }

        private static bool TryGetCancelActionType(out CancelActionType cancelActionType)
        {
            if (Keyboard.current.escapeKey.wasPressedThisFrame)
            {
                cancelActionType = CancelActionType.EscapeKey;
                return true;
            }

            if (Mouse.current.rightButton.wasPressedThisFrame)
            {
                cancelActionType = CancelActionType.RightMouseButton;
                return true;
            }

            cancelActionType = CancelActionType.None;
            return false;
        }
    }
}