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

public class PhotoScroll_bt : MonoBehaviour, IBeginDragHandler, IEndDragHandler
{
    public ScrollRect scrollRect;
    private Vector2 startDragPos;
    
    [SerializeField] TextMeshProUGUI 相片總數_tb, 相片目前_tb, 報告書號_tb, 文件號_tb;
    [SerializeField] GameObject 前一張_bt, 後一張_bt;
    
    private float currentPage = 0;
    public float swipeThreshold = 200f;
    public static bool currentPageChange;

    void Start()
    {
        // 綁定按鈕事件
        前一張_bt.GetComponent<Button>().onClick.AddListener(ShowPreviousPage);
        後一張_bt.GetComponent<Button>().onClick.AddListener(ShowNextPage);
    }

    void Update()
    {
        if (currentPageChange)
        {
            currentPageChange = false;
            currentPage = 0;
            UpdatePageIndicator();
            UpdateButtonState();
        }
    }

    public void OnBeginDrag(PointerEventData eventData)
    {
        startDragPos = eventData.position;
    }

    public void OnEndDrag(PointerEventData eventData)
    {
        float dragDistance = Mathf.Abs(eventData.position.x - startDragPos.x);
        if (dragDistance > swipeThreshold)
        {
            if (eventData.position.x > startDragPos.x)
            {
                ShowPreviousPage();
            }
            else
            {
                ShowNextPage();
            }
        }
        else
        {
            SnapToNearestPage();
        }
    }

    private void ShowPreviousPage()
    {
        if (currentPage > 0)
        {
            currentPage--;
            UpdatePageScroll();
        }
    }

    private void ShowNextPage()
    {
        if (相片總數_tb.text != "-")
        {
            if (currentPage < float.Parse(相片總數_tb.text) - 1)
            {
                currentPage++;
                UpdatePageScroll();
            }
        }
    }

    private void UpdatePageScroll()
    {
        float normalizedPosition = (float)currentPage / (float)(float.Parse(相片總數_tb.text) - 1);
        StartCoroutine(SmoothScrollTo(normalizedPosition));
        UpdatePageIndicator();
        UpdateButtonState();
    }

    private IEnumerator SmoothScrollTo(float targetNormalizedPosition)
    {
        while (Mathf.Abs(scrollRect.horizontalNormalizedPosition - targetNormalizedPosition) > 0.01f)
        {
            scrollRect.horizontalNormalizedPosition = Mathf.Lerp(scrollRect.horizontalNormalizedPosition, targetNormalizedPosition, 10f * Time.deltaTime);
            yield return null;
        }
        scrollRect.horizontalNormalizedPosition = targetNormalizedPosition;
    }

    private void SnapToNearestPage()
    {
        float targetNormalizedPosition = currentPage / (float)(float.Parse(相片總數_tb.text) - 1);
        StartCoroutine(SmoothScrollTo(targetNormalizedPosition));
    }

    public void UpdatePageIndicator()
    {
        相片目前_tb.text = (currentPage + 1).ToString();
        string 文件號;
        if(相片總數_tb.name.Contains("相關文件")){
            文件號 =  Main.Global.報告書相關文件_table.Rows[int.Parse(currentPage.ToString())][0].ToString();
        }else{
            文件號 =  Main.Global.報告書施作圖片_table.Rows[int.Parse(currentPage.ToString())][0].ToString();
        }
        

        文件號_tb.text = 文件號;
    }

    private void UpdateButtonState()
    {
        // 當是第一張時，禁用「上一張」
        前一張_bt.GetComponent<Button>().interactable = currentPage > 0;
        // 當是最後一張時，禁用「下一張」
        後一張_bt.GetComponent<Button>().interactable = currentPage < float.Parse(相片總數_tb.text) - 1;
    }

    public static void 清除currentPage()
    {
        currentPageChange = true;
    }
}