using UnityEngine;
using UnityEngine.Events;
using UnityEngine.EventSystems;

[RequireComponent(typeof(ProcessInput))]
public class ProcessInputModule : MonoBehaviour, IPointerDownHandler, IPointerUpHandler, IDragHandler
{
    // 仅仅追踪两根手指
    private InputPointerData[] _fingers;

    public ProcessInput processInput { get; private set; }
    public ProcessCamera processCamera { get; private set; }

    // 当前是操作摄像机还是角色运动
    public bool isCameraMode { get; private set; }
    private bool _clickOnPointerUp;

    public event UnityAction<bool> onCameraModeChange; 

    private void Awake()
    {
        processInput = GetComponent<ProcessInput>();
        processCamera = new ProcessCamera();
        _fingers = new InputPointerData[2];
        for (var i = 0; i < _fingers.Length; i++)
            _fingers[i] = new InputPointerData();
        SetCameraModel(true);
    }

#if UNITY_EDITOR || UNITY_STANDALONE
    private void Update()
    {
        var mouseWheel = Input.GetAxis("Mouse ScrollWheel");
        if (mouseWheel != 0f)
            processCamera.ScaleCamera(mouseWheel * 800f);
    #if UNITY_EDITOR
        if (Input.GetKeyDown(KeyCode.Space))
            SetCameraModel(!isCameraMode);
    #endif
    }
#endif    
    public void SetCameraModel(bool cameraMode)
    {
        if (isCameraMode != cameraMode)
        {
            _clickOnPointerUp = false;
            isCameraMode = cameraMode;
            if (isCameraMode)
                processInput.EndTouchPos();
            if (onCameraModeChange != null)
                onCameraModeChange(isCameraMode);
        }
    }

    #region interface

    private void CleanFingers()
    {
        _clickOnPointerUp = false;
        for (var i = 0; i < _fingers.Length; i++)
            _fingers[i].pointerId = null;
        if (isCameraMode)
        {
            // 不需要处理
        }
        else
            processInput.EndTouchPos();
    }
    
    private void OnApplicationFocus(bool hasFocus)
    {
        // App失去焦点时，释放当前输入状态
        if (!hasFocus)
            CleanFingers();
    }
    
    // 注：任意被追踪的手指抬起，清除全部手指信息而不是回滚到单手指
    public void OnPointerUp(PointerEventData eventData)
    {
        // 检查是否触发抬起点击
        if (isCameraMode && _clickOnPointerUp)
        {
            if (_fingers[0].pointerId == eventData.pointerId)
                processInput.StartOneFrameTouch(eventData.position);
        }
        _clickOnPointerUp = false;
        var remove = false;
        for (var i = 0; i < _fingers.Length; i++)
            if (_fingers[i].pointerId == eventData.pointerId)
            {
                remove = true;
                break;
            }

        if (remove)
            CleanFingers();
    }

    public void OnPointerDown(PointerEventData eventData)
    {
        if (_fingers[0].pointerId == null)
        {
            _fingers[0].pointerId = eventData.pointerId;
            _fingers[0].lastPos = eventData.position;
            // 常规Touch开始
            if (isCameraMode)
                _clickOnPointerUp = true;
            else
                processInput.StartTouchPos(eventData.position);
            if (FunctionExLogic.Instance() != null)
                FunctionExLogic.Instance().ShowDetail(false);
        }
        else if (_fingers[1].pointerId == null)
        {
            _clickOnPointerUp = false;
            _fingers[1].pointerId = eventData.pointerId;
            _fingers[1].lastPos = eventData.position;
            // 进入摄像机缩放模式
            if (isCameraMode)
            {
            }
            else
                processInput.EndTouchPos();
        }
    }

    public void OnDrag(PointerEventData eventData)
    {
        _clickOnPointerUp = false;
        // 单手指模式
        if (_fingers[1].pointerId == null)
        {
            if (_fingers[0].pointerId == eventData.pointerId)
            {
                if (isCameraMode)
                    processCamera.MoveCamera(eventData.delta);
                else
                    processInput.MoveTouchPos(eventData.position);
            }
        }
        // 双手指模式
        else
        {
            InputPointerData current = null;
            InputPointerData other = null;
            if (_fingers[0].pointerId == eventData.pointerId)
            {
                current = _fingers[0];
                other = _fingers[1];
            }
            else if (_fingers[1].pointerId == eventData.pointerId)
            {
                current = _fingers[1];
                other = _fingers[0];
            }

            if (current != null)
            {
                current.lastPos = eventData.position;
                var line = eventData.position - other.lastPos;
                if (line != Vector2.zero)
                {
                    line = line.normalized;
                    var scale = Vector2.Dot(line, eventData.delta);
                    processCamera.ScaleCamera(scale);
                }
            }
        }
    }

    #endregion
    
    public class InputPointerData
    {
        public int? pointerId;
        public Vector2 lastPos;
    }
}