//以下是抽象类，主要是看着内部只有逻辑的代码出现了Keys这种很具体的类型，不爽。说不定会用作别的。
using System.Collections.Generic;

namespace KeyboardSynchronizer {
    public abstract class FuncQueue<T> {
        public bool Adding { get; private set; }
        private T toggler;
        public int Id { get; private set; }
        public int Index { get; private set; } = -1;
        public List<T> Parameters { get; } = new List<T>();
        protected abstract T Empty { get; }
        /// <summary>
        /// Insert these to stop adding more parameters and reset this instance.
        /// </summary>
        public T[] Restarter { get; set; }

        protected abstract bool IsIndexElement(T t);
        protected abstract int CreateNewIndex(T t);
        protected abstract bool Equals(T a, T b);

        public void Insert(T t) {
            if (Equals(t, Empty)) {
                return;
            }
            if (IsIndexElement(t)) {
                if (Adding) {
                    add(t);
                } else {
                    Index = CreateNewIndex(t);
                }
            } else {
                if (Equals(toggler, Empty)) {
                    toggler = t;
                } else if (Equals(toggler, t)) {
                    if (Adding) {
                        add(t);
                    } else {
                        if (Index == -1) {
                            Id++;
                        } else {
                            Adding = true;
                        }
                    }
                } else {
                    if (Adding) {
                        add(t);
                    } else {
                        toggler = t;
                        Id = 0;
                        Index = -1;
                    }
                }
            }
        }

        private void add(T t) {
            if (Restarter != null && Restarter.Length > 0 && Parameters.Count + 1 >= Restarter.Length && Equals(Restarter[Restarter.Length - 1], t)) {
                var i = Parameters.Count - 1;
                var j = Restarter.Length - 2;
                for (; i >= 0 && j >= 0;) {
                    if (Equals(Parameters[i], Restarter[j])) {
                        i--;
                        j--;
                        continue;
                    }
                    Parameters.Add(t);
                    return;
                }
                Adding = false;
                Id = 0;
                toggler = Empty;
                Index = -1;
                Parameters.Clear();
            } else {
                Parameters.Add(t);
            }
        }
    }
}
//以下是实现类，用于自定义快捷键，先按下一个键X一次或多次，用于区分不同功能，然后按一些数字，指定第一个参数，再次按X，结束指定第一个参数，并开始输入更多参数。

using System.Linq;
using System.Windows.Forms;

namespace KeyboardSynchronizer {
    public class KeysQueue : FuncQueue<Keys> {
        static Keys[] numbers = { Keys.D0, Keys.D1, Keys.D2, Keys.D3, Keys.D4, Keys.D5, Keys.D6, Keys.D7, Keys.D8, Keys.D9 };
　　　　 public KeysQueue(){
　　　　　　Restarter = new[] { Keys.S, Keys.T, Keys.O, Keys.P };
　　　　 }　　
        protected override Keys Empty {
            get { return Keys.None; }
        }

        protected override bool Equals(Keys a, Keys b) {
            return a == b;
        }

        protected override int CreateNewIndex(Keys t) {
            var v = (Index > -1 ? Index.ToString() : string.Empty) + t.ToString()[1];
            try {
                return int.Parse(v);
            } catch {
                return Index;
            }
        }

        protected override bool IsIndexElement(Keys t) {
            return numbers.Contains(t);
        }
    }
}