using UnityEngine;

public class CameraDragMove : MonoBehaviour
{
    public Camera cam;                  // 이동시킬 카메라
    public SpriteRenderer targetSprite; // 영역 기준이 되는 스프라이트
    public GameObject go_btnbg;
    public float dragSpeed = 1f;

    private Vector3 lastTouchPos;
    private Vector3 pressPos;           // 입력 시작 지점
    private bool isDragging = false;

    void Reset()
    {
        cam = Camera.main;
    }

    void Update()
    {
#if UNITY_EDITOR || UNITY_STANDALONE
        HandleMouseInput();   // 에디터/PC
#else
        HandleTouchInput();   // 모바일
#endif
    }

    void HandleMouseInput()
    {
        if (Input.GetMouseButtonDown(0))
        {
            pressPos = Input.mousePosition;
            lastTouchPos = Input.mousePosition;
            isDragging = false;
        }
        else if (Input.GetMouseButton(0))
        {
            Vector3 deltaScreen = Input.mousePosition - pressPos;

            isDragging = true;

            if (isDragging)
            {
                Vector3 deltaWorld = cam.ScreenToWorldPoint(Input.mousePosition) - cam.ScreenToWorldPoint(lastTouchPos);
                deltaWorld.z = 0f;

                cam.transform.position -= deltaWorld * dragSpeed;
                ClampCameraPosition();

                lastTouchPos = Input.mousePosition;
            }
        }
        else if (Input.GetMouseButtonUp(0))
        {
        }
    }

    void HandleTouchInput()
    {
        if (Input.touchCount == 1)
        {
            Touch touch = Input.GetTouch(0);

            switch (touch.phase)
            {
                case TouchPhase.Began:
                    pressPos = touch.position;
                    lastTouchPos = touch.position;
                    isDragging = false;
                    break;

                case TouchPhase.Moved:
                    Vector3 deltaScreen = (Vector3)touch.position - pressPos;

                    isDragging = true;

                    if (isDragging)
                    {
                        Vector3 deltaWorld = cam.ScreenToWorldPoint(touch.position) - cam.ScreenToWorldPoint(lastTouchPos);
                        deltaWorld.z = 0f;

                        cam.transform.position -= deltaWorld * dragSpeed;
                        ClampCameraPosition();

                        lastTouchPos = touch.position;
                    }
                    break;

                case TouchPhase.Ended:
                    break;
            }
        }
    }

    void ClampCameraPosition()
    {
        if (targetSprite == null) return;

        Bounds spriteBounds = targetSprite.bounds;
        float camHeight = cam.orthographicSize * 2f;
        float camWidth = camHeight * cam.aspect;

        float minX = spriteBounds.min.x + camWidth / 2f;
        float maxX = spriteBounds.max.x - camWidth / 2f;
        float minY = spriteBounds.min.y + camHeight / 2f;
        float maxY = spriteBounds.max.y - camHeight / 2f;

        Vector3 pos = cam.transform.position;
        pos.x = Mathf.Clamp(pos.x, minX, maxX);
        pos.y = Mathf.Clamp(pos.y, minY, maxY);
        cam.transform.position = pos;
    }
}