using UnityEngine;
using UnityEngine.InputSystem;
using System;
using System.Collections.Generic;
using Touch = UnityEngine.InputSystem.EnhancedTouch.Touch;
using TouchPhase = UnityEngine.InputSystem.TouchPhase;

/// <summary>
/// 为节奏游戏设计的输入管理器，处理多点触控并分发三种主要事件。
/// 【重要】此版本内置了编辑器内的鼠标模拟功能，无需手机即可测试。
/// </summary>
public class RhythmInputManager : MonoBehaviour
{
    // =====================================================================
    // 公共事件 (Public Events)
    // =====================================================================
    public static event Action<int, Vector2> OnTap;
    public static event Action<int, Vector2> OnTouch;
    public static event Action<int, Vector2, Vector2> OnSwipe;

    // =====================================================================
    // 可配置参数 (Configurable Parameters)
    // =====================================================================

    [Header("划动设置 (Swipe Settings)")]
    [Tooltip("识别为划动的最小移动距离（像素）")]
    [SerializeField] private float minSwipeDistance = 50.0f;

    // =====================================================================
    // 内部状态 (Internal State)
    // =====================================================================
    private class TouchState
    {
        public int TouchId;
        public Vector2 StartPosition;
        public float StartTime;
        public Vector2 LastSwipeDirection = Vector2.zero;
        public bool IsTapCandidate = true;
    }

    private readonly Dictionary<int, TouchState> _activeTouches = new Dictionary<int, TouchState>();

    // 为鼠标模拟专门设置一个固定的Touch ID
    private const int MOUSE_TOUCH_ID = 999; 

    // =====================================================================
    // MonoBehaviour 生命周期方法 (Lifecycle Methods)
    // =====================================================================

    private void Awake()
    {
        //OnTap += (id, pos)=> Debug.Log($"Tap Detected: Touch ID {id}, Position {pos}");
        //OnTouch += (id, pos) => Debug.Log($"Touch Detected: Touch ID {id}, Position {pos}");
        //OnSwipe += (id, pos, dir) => Debug.Log($"Swipe Detected: Touch ID {id}, Position {pos}, Direction {dir}");
    }

    private void Update()
    {
        // 使用预处理指令区分平台
#if UNITY_EDITOR
        // --- 在Unity编辑器中，使用鼠标模拟触摸 ---
        ProcessMouseInput();
#else
        // --- 在真机设备上，使用真实的触摸输入 ---
        ProcessRealTouchInput();
#endif
    }
    
    // =====================================================================
    // 核心处理逻辑 (Core Processing Logic)
    // =====================================================================

#if UNITY_EDITOR
    /// <summary>
    /// 【仅在编辑器中运行】处理鼠标输入并模拟触摸事件。
    /// </summary>
    private void ProcessMouseInput()
    {
        if (Mouse.current == null) return;

        Vector2 position = Mouse.current.position.ReadValue();

        if (Mouse.current.leftButton.wasPressedThisFrame)
        {
            ProcessInputEvent(MOUSE_TOUCH_ID, TouchPhase.Began, position);
        }
        else if (Mouse.current.leftButton.isPressed)
        {
            // 如果鼠标位置有变化，则为Moved，否则为Stationary
            if (Mouse.current.delta.ReadValue().sqrMagnitude > 0.1f)
            {
                 ProcessInputEvent(MOUSE_TOUCH_ID, TouchPhase.Moved, position);
            }
            else
            {
                 ProcessInputEvent(MOUSE_TOUCH_ID, TouchPhase.Stationary, position);
            }
        }
        else if (Mouse.current.leftButton.wasReleasedThisFrame)
        {
            ProcessInputEvent(MOUSE_TOUCH_ID, TouchPhase.Ended, position);
        }
        
        if (Mouse.current.rightButton.wasPressedThisFrame)
        {
            ProcessInputEvent(MOUSE_TOUCH_ID + 1, TouchPhase.Began, position);
        }
        else if (Mouse.current.rightButton.isPressed)
        {
            // 如果鼠标位置有变化，则为Moved，否则为Stationary
            if (Mouse.current.delta.ReadValue().sqrMagnitude > 0.1f)
            {
                ProcessInputEvent(MOUSE_TOUCH_ID + 1, TouchPhase.Moved, position);
            }
            else
            {
                ProcessInputEvent(MOUSE_TOUCH_ID + 1, TouchPhase.Stationary, position);
            }
        }
        else if (Mouse.current.rightButton.wasReleasedThisFrame)
        {
            ProcessInputEvent(MOUSE_TOUCH_ID + 1, TouchPhase.Ended, position);
        }
    }
#endif

    /// <summary>
    /// 【仅在真机上运行】处理真实的触摸屏输入。
    /// </summary>
    private void ProcessRealTouchInput()
    {
        if (Touchscreen.current == null) return;

        foreach (Touch touch in Touch.activeTouches)
        {
            ProcessInputEvent(
                touch.touchId, 
                touch.phase, 
                touch.screenPosition
            );
        }
    }

    /// <summary>
    /// 所有输入事件的核心处理函数，无论是真实触摸还是鼠标模拟都会调用它。
    /// </summary>
    private void ProcessInputEvent(int touchId, TouchPhase phase, Vector2 position)
    {
        switch (phase)
        {
            case TouchPhase.Began:
                var newState = new TouchState
                {
                    TouchId = touchId,
                    StartPosition = position,
                    StartTime = Time.time,
                };
                _activeTouches[touchId] = newState;
                OnTap?.Invoke(touchId, position);
                OnTouch?.Invoke(touchId, position);
                break;

            case TouchPhase.Moved:
                if (_activeTouches.TryGetValue(touchId, out TouchState movedState))
                {
                    OnTouch?.Invoke(touchId, position);
                    DetectSwipe(movedState, position);
                }

                break;

            case TouchPhase.Stationary:
                if (_activeTouches.TryGetValue(touchId, out TouchState stationaryState))
                {
                    OnTouch?.Invoke(touchId, position);
                }

                break;

            case TouchPhase.Canceled:
                if (_activeTouches.ContainsKey(touchId))
                {
                    _activeTouches.Remove(touchId);
                }

                break;
        }
    }

    /// <summary>
    /// 检测划动逻辑 (无需修改)
    /// </summary>
    private void DetectSwipe(TouchState state, Vector2 currentPosition)
    {
        Vector2 swipeVector = currentPosition - state.StartPosition;
        if (swipeVector.magnitude < minSwipeDistance) return;

        Vector2 direction = swipeVector.normalized;
        
        // 检查是否是新的划动方向
        if (Vector2.Dot(direction, state.LastSwipeDirection) < 0.5f)
        {
            OnSwipe?.Invoke(state.TouchId, state.StartPosition, direction);
            state.LastSwipeDirection = direction;
            state.StartPosition = currentPosition;
            state.StartTime = Time.time;
        }
    }
}