/*
 Author : Wai Lam
 Date : 11/2/2025
 Description : Car obstacle
 */
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;

public class CanvasFade : MonoBehaviour
{
    public CanvasGroup fadeCanvasGroup; // Assign in Inspector
    public float fadeDuration = 1f;     // Duration for fade in/out
    public float displayDuration = 5f;  // Time the UI stays fully visible
    public string nextSceneName;        // Name of the scene to load

    private bool hasTriggered = false;  // Prevent multiple triggers

    private void OnTriggerEnter(Collider other)
    {
        // Check if the player entered the trigger
        if (!hasTriggered && other.CompareTag("Player"))
        {
            hasTriggered = true;
            StartCoroutine(FadeInAndLoadScene());
        }
    }

    IEnumerator FadeInAndLoadScene()
    {
        // Fade In
        yield return StartCoroutine(Fade(0f, 1f, fadeDuration));

        // Display UI for 5 seconds
        yield return new WaitForSeconds(displayDuration);

        // Load the next scene
        SceneManager.LoadScene(nextSceneName);
    }

    IEnumerator Fade(float startAlpha, float endAlpha, float duration)
    {
        float elapsed = 0f;
        fadeCanvasGroup.alpha = startAlpha;

        while (elapsed < duration)
        {
            elapsed += Time.deltaTime;
            fadeCanvasGroup.alpha = Mathf.Lerp(startAlpha, endAlpha, elapsed / duration);
            yield return null;
        }

        fadeCanvasGroup.alpha = endAlpha;
    }
}