using System;
using System.Collections;
using System.Threading.Tasks;
using UnityEngine;
using UnityEngine.UI;

/// <summary>
/// Handles auto scrolling helper GUIs that are instanced when an item is hovered
/// </summary>
public class AutoScroller : MonoBehaviour
{
    [Header("Scroll Values")]
    [SerializeField] private AspectHelperUI aspectHelperComponent;
    [SerializeField] private bool isHorizontal                  = false;
    [SerializeField] private bool isVertical                    = true;

    private ScrollRect scrollingRect;
    private bool resetScroll;
    private int effectCount;

    // Start is called before the first frame update
    private async void OnEnable()
    {
        scrollingRect = GetComponent<ScrollRect>();
        
        try
        {
            effectCount = aspectHelperComponent.GetEffectCount();
        }
        catch
        {
            while (effectCount == default)
                await Task.Yield();
        }

        StartCoroutine(Scroll(0f, 1f));
    }

    private void Update()
    {
        if (resetScroll)
        {
            StopAllCoroutines();
            StartCoroutine(Scroll(0f, 1f));
        }
    }

    private IEnumerator Scroll(float startPosition, float endPosition)
    {
        resetScroll = false;
        yield return new WaitForSeconds(1f);
        float currentNormalization = 0.0f;
        while (currentNormalization < 1f) 
        {
            currentNormalization += Time.deltaTime / effectCount;

            // Scrolls in the desired direction
            if (isHorizontal)
                scrollingRect.horizontalNormalizedPosition = Mathf.Lerp(endPosition, startPosition, currentNormalization);
            if (isVertical)
                scrollingRect.verticalNormalizedPosition = Mathf.Lerp(endPosition, startPosition, currentNormalization);
            
            yield return null;
        }
        yield return new WaitForSeconds(1f);

        resetScroll = true;
    }

    public void InjectEffectCount(int count)
        => effectCount = count;
}