InputQueue.cs

using System.Collections.Generic;
using UnityEngine;

public class InputQueue {
    readonly Queue<UserAction> queue = new();
    readonly float lifeTime;
    public InputQueue(float lifeTime) {
        this.lifeTime = lifeTime;
    }

    public void AddAction(ActionType actionType) {
        UserAction action = new(actionType, lifeTime);
        queue.Enqueue(action);
    }

    // This is C# not Go brother
    public (bool empty, UserAction) Peek() {
        while (queue.Count > 0 && queue.Peek().Expired) {
            queue.Dequeue();
        }
        if (queue.Count == 0) {
            return (true, new());
        }
        return (false, queue.Peek());
    }

    public void Pop() {
        if (queue.Count > 0) {
            queue.Dequeue();
        } else {
            Debug.LogError("Trying to pop input queue with no items");
        }
    }
}

public enum ActionType {
    Attack,
    Dodge
}
public struct UserAction {
    public ActionType actionType;
    readonly float lifeTime;
    readonly float inputTime;
    public UserAction(ActionType actionType, float lifeTime) {
        this.actionType = actionType;
        this.lifeTime = lifeTime;
        this.inputTime = Time.time;
    }
    public readonly bool Expired => (Time.time - inputTime) >= lifeTime;
}