using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class InfiniteScrollSnap : MonoBehaviour {
    public ScrollRect scrollRect;
    public RectTransform content;
    public float itemWidth = 200f;
    public float snapSpeed = 10f;
    public List<ZibuPiece> pieces;
    public List<Sprite> zibuSprites;

    private bool isDragging = false;
    private float targetX;
    private int centerIndex = 0;

    void Update() {
        float contentX = content.anchoredPosition.x;

        foreach (var piece in pieces) {
            Vector3 localPos = piece.transform.localPosition;
            if (localPos.x + contentX < -itemWidth * 3) {
                MoveRight(piece);
            } else if (localPos.x + contentX > itemWidth * 3) {
                MoveLeft(piece);
            }
        }

        if (!isDragging) {
            Vector2 pos = content.anchoredPosition;
            float newX = Mathf.Lerp(pos.x, targetX, Time.deltaTime * snapSpeed);
            content.anchoredPosition = new Vector2(newX, pos.y);
        }
    }

    public void OnBeginDrag() {
        isDragging = true;
    }

    public void OnEndDrag() {
        isDragging = false;
        float posX = content.anchoredPosition.x;
        int closestIndex = Mathf.RoundToInt(posX / -itemWidth);
        targetX = -closestIndex * itemWidth;
    }

    void MoveRight(ZibuPiece piece) {
        piece.transform.localPosition += new Vector3(itemWidth * pieces.Count, 0, 0);
        RotateForward(piece);
    }

    void MoveLeft(ZibuPiece piece) {
        piece.transform.localPosition -= new Vector3(itemWidth * pieces.Count, 0, 0);
        RotateBackward(piece);
    }

    void RotateForward(ZibuPiece piece) {
        centerIndex = (centerIndex + 1) % zibuSprites.Count;
        ApplySprite(piece, centerIndex);
    }

    void RotateBackward(ZibuPiece piece) {
        centerIndex = (centerIndex - 1 + zibuSprites.Count) % zibuSprites.Count;
        ApplySprite(piece, centerIndex);
    }

    void ApplySprite(ZibuPiece piece, int index) {
        piece.image.sprite = zibuSprites[index];
        piece.zibuId = $"Zibu_{index}";
    }
}