using UnityEngine;
using UnityEngine.EventSystems;

public class MouseFollowRotation : MonoBehaviour
{
    public Transform target;
    public float xSpeed = 200;
    public float ySpeed = 200;
    public float mSpeed = 10;
    public float moveSpeed = 30f;
    public float dragPanSpeed = 1f;
    public float yMinLimit = -50;
    public float yMaxLimit = 50;
    public float xPosMinLimit = -20;
    public float xPosMaxLimit = 20; 
    public float zPosMinLimit = -20;
    public float zPosMaxLimit = 20;
    public float distance = 2;
    public float minDistance = 2;
    public float maxDistance = 30;

    private bool dragPanMoveActive;
    private Vector2 lastMousePosition;
    public bool OnUI = false;
    public bool OnOffUI = false;
    public bool move = false;

    public bool needDamping = false;
    float damping = 5.0f;

    public float x = 0.0f;
    public float y = 0.0f;

    // Use this for initialization
    void Start()
    {
        Vector3 angles = transform.eulerAngles;
        x = angles.y;
        y = angles.x;


    }

    // Update is called once per frame
    void LateUpdate()
    {

        onoffUI();
/*        if (EventSystem.current.IsPointerOverGameObject())
        {
            OnUI = true;

        }
        else
        {
            OnUI = false;
            if (move == true)
            {
                MovementView();
            }
            Rotate();
        }*/
    }

    void onoffUI()
    {
        if (EventSystem.current.IsPointerOverGameObject() && OnOffUI)
        {
            OnUI = true;

        }
        else
        {
            OnUI = false;
            if (move == true)
            {
                MovementView();
            }
            Rotate();
        }
    }
    void Rotate()
    {
        if (target)
        {
            //use the light button of mouse to rotate the camera
            if (Input.GetMouseButton(1))
            {
                x += Input.GetAxis("Mouse X") * xSpeed * 0.02f;
                y -= Input.GetAxis("Mouse Y") * ySpeed * 0.02f;

                y = ClampAngle(y, yMinLimit, yMaxLimit);
            }
            distance -= Input.GetAxis("Mouse ScrollWheel") * mSpeed;
            distance = Mathf.Clamp(distance, minDistance, maxDistance);
            Quaternion rotation = Quaternion.Euler(y, x, 0.0f);
            Vector3 disVector = new Vector3(0.0f, 0.0f, -distance);
            Vector3 position = rotation * disVector + target.position;
            //adjust the camera
            if (needDamping)
            {
                transform.rotation = Quaternion.Lerp(transform.rotation, rotation, Time.deltaTime * damping);
                transform.position = Vector3.Lerp(transform.position, position, Time.deltaTime * damping);
            }
            else
            {
                transform.rotation = rotation;
                transform.position = position;
                target.rotation = rotation;
            }
        }
    }


    void MovementView()
    {
        Vector3 inputDir = new Vector3(0, 0, 0);

        if (Input.GetMouseButtonDown(0))
        {
            dragPanMoveActive = true;
            lastMousePosition = Input.mousePosition;
        }
        if (Input.GetMouseButtonUp(0))
        {
            dragPanMoveActive = false;
        }

        if (dragPanMoveActive)
        {
            Vector2 mouseMovementDelta = (Vector2)Input.mousePosition - lastMousePosition;

            // float dragPanSpeed = 1f;
            inputDir.x = mouseMovementDelta.x * dragPanSpeed;
            inputDir.z = mouseMovementDelta.y * dragPanSpeed;

            lastMousePosition = Input.mousePosition;
        }

        Vector3 moveDir = target.forward * -inputDir.z + target.right * -inputDir.x;

        target.position += moveDir * moveSpeed * Time.deltaTime;
        target.position = new Vector3(Mathf.Clamp(target.position.x, xPosMinLimit, xPosMaxLimit), 0, Mathf.Clamp(target.position.z, zPosMinLimit, zPosMaxLimit));

    }


    static float ClampAngle(float angle, float min, float max)
    {
        if (angle < -360)
            angle += 360;
        if (angle > 360)
            angle -= 360;
        return Mathf.Clamp(angle, min, max);
    }

}