// using System.Numerics;
using Godot;

using System.Collections.Generic;
using System;

public class MoveRecords<T> {
    private readonly LinkedList<MoveRecord> records = new LinkedList<MoveRecord>(); // 使用队列替换栈
    private readonly int maxRecords; // 记录上限
    private readonly Action<T, T, Vector2, Vector2> onAddRecordCallback; // 添加记录时的回调
    private readonly Action<T, T, Vector2, Vector2> onUndoRecordCallback; // 撤销记录时的回调
    
    public MoveRecords(
    Action<T, T, Vector2, Vector2> onAddRecordCallback = null,
    Action<T, T, Vector2, Vector2> onUndoRecordCallback = null,
    int maxRecords = 32) {
        this.maxRecords = maxRecords;
        this.onAddRecordCallback = onAddRecordCallback;
        this.onUndoRecordCallback = onUndoRecordCallback;
    }

    public void AddRecord(T newNode, T oldNode, Vector2 newPos, Vector2 oldPos) {
        // 达到记录上限时，移除最远的记录（队首元素）
        if (records.Count >= maxRecords) {
            records.RemoveFirst();
        }
        var record = new MoveRecord(newNode, oldNode, newPos, oldPos);
        // 触发添加记录的回调
        onAddRecordCallback?.Invoke(newNode, oldNode, newPos, oldPos);
        // GD.Print("In func Addrecord: ", record.NewNode, "->", record.OldNode, ":", record.NewPos, "->", record.OldPos);
        records.AddLast(record); // 将新记录加入队尾
    }

    public void Undo() {
        if (records.Count == 0) return;
        MoveRecord record = records.Last.Value; // 移除并获取队首的记录以执行撤销操作
        records.RemoveLast();
        // 触发撤销记录的回调
        onUndoRecordCallback?.Invoke(record.NewNode, record.OldNode, record.NewPos, record.OldPos);
    }

    public void Clear() {
        records.Clear();
    }

    private class MoveRecord {
        public T NewNode { get; }
        public T OldNode { get; }
        public Vector2 NewPos { get; }
        public Vector2 OldPos { get; }

        public MoveRecord(T newNode, T oldNode, Vector2 newPos, Vector2 oldPos) {
            NewNode = newNode;
            OldNode = oldNode;
            OldPos = oldPos;
            NewPos = newPos;
        }
    }
}