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

public class UIFader : MonoBehaviour
{
    public float fadeSpeed = 1.5f;          // Speed that the screen fades to and from black.
    public bool SwitchToMaskEnabled = false;
    public float SwitchToMaskThreshold = 0.3f;
    public float FadeFromAlpha = 1f;
    public float FadeToAlpha = 0;

    public bool Reverse = false;

    private CanvasGroup canvasGroup;
    void Awake()
    {

        // Set the texture so that it is the the size of the screen and covers it.
        canvasGroup = this.GetComponent<CanvasGroup>();

    }

    void Start()
    {
        canvasGroup.alpha = FadeFromAlpha;
    }
    void Update()
    {
        float newAlpha = canvasGroup.alpha;
        if (!Reverse)
        {
            newAlpha = Mathf.Lerp(canvasGroup.alpha, FadeToAlpha, fadeSpeed * Time.deltaTime);
        }
        else
        {
            newAlpha = Mathf.Lerp(canvasGroup.alpha, FadeFromAlpha, fadeSpeed * Time.deltaTime);
        }
        // Lerp the colour of the texture between itself and transparent.
        canvasGroup.alpha = newAlpha;

        if (SwitchToMaskEnabled && ((!Reverse && canvasGroup.alpha <= SwitchToMaskThreshold)||(Reverse && canvasGroup.alpha >= SwitchToMaskThreshold)))
        {
            canvasGroup.blocksRaycasts = Reverse;
        }
    }
    public void ToggleReverse()
    {
        SetReverse(!Reverse);
    }
    public void SetReverse(bool reverse)
    {
        Reverse = reverse;
    }
}