using UnityEngine;
using System.Collections;

#if UNITY_EDITOR
using UnityEditor;
#endif

public class Fade : MonoBehaviour
{
	float _time;
	float _elapsed;

	Texture2D _fadeTex;
	Material _fadeMat;
	Color _color;
	bool _fadeIn = false;

	void Awake()
	{
		var shader = Shader.Find("Particles/Alpha Blended");
		_fadeMat = new Material(shader);
		_fadeTex = new Texture2D(1, 1);
		_fadeTex.SetPixel(0, 0, new Color(0.5f, 0.5f, 0.5f, 0.5f));
		_fadeTex.Apply();

		_fadeMat.color = Color.black;

		_time = 1.0f;
		_elapsed = 0.0f;
		_color = Color.black;
		enabled = false;
	}

	void Destroy()
	{
#if UNITY_EDITOR
		DestroyImmediate(_fadeTex);
		DestroyImmediate(_fadeMat);
#elif
		Destroy(_fadeTex);
		Destroy(_fadeMat);
#endif
	}

	public void FadeIn(float time)
	{
		enabled = true;
		_time = time;
		_elapsed = 0.0f;
		_fadeIn = true;
	}

	public void FadeOut(float time)
	{
		enabled = true;
		_time = time;
		_elapsed = 0.0f;
		_fadeIn = false;
	}

	void OnPostRender()
	{
		float t = Mathf.Clamp01(_elapsed / _time);
		_color.a = _fadeIn ? 1.0f - t : t;
		_fadeMat.SetColor("_TintColor", _color);
		Graphics.Blit(_fadeTex, _fadeMat);

		if (_time > _elapsed)
		{
			_elapsed += Time.deltaTime;
		}
	}

#if UNITY_EDITOR
	[CustomEditor(typeof(Fade))]
	class FadeInspector : Editor
	{
		public override void OnInspectorGUI()
		{
			if (GUILayout.Button("Fade In"))
			{
				var fade = (Fade)target;
				fade.FadeIn(1.0f);
			}

			if (GUILayout.Button("Fade Out"))
			{
				var fade = (Fade)target;
				fade.FadeOut(1.0f);
			}
		}
	}
#endif
}