using UnityEngine;
using UnityEngine.UI;

namespace UC
{
    [ExecuteInEditMode]
    [RequireComponent(typeof(Camera))]
    [AddComponentMenu("Image Effects/Homography")]
    public class ScreenHomography : MonoBehaviour
    {
        public Color color;
        [Range(0.0f, 1.0f)]
        public float amount = 0f;
        
        [SerializeField]
        private Shader m_Shader;
        public Shader shader
        {
            get
            {
                if (m_Shader == null)
                    m_Shader = Shader.Find("Hidden/ScreenHomography");

                return m_Shader;
            }
        }
#if false
        public Vector2 resolution;
        public Texture cornerTexture;
#endif
        private Material m_Material;
        public Material material
        {
            get
            {
                if (m_Material == null)
                    m_Material = ImageEffectHelper.CheckShaderAndCreateMaterial(shader);

                return m_Material;
            }
        }

        private void OnEnable()
        {
            if (!ImageEffectHelper.IsSupported(shader, true, false, this))
                enabled = false;
            GetComponent<Camera>().depthTextureMode = DepthTextureMode.DepthNormals;
        }

        private void OnDisable()
        {
            if (m_Material != null)
                DestroyImmediate(m_Material);

            m_Material = null;
        }

        private void OnRenderImage(RenderTexture source, RenderTexture destination)
        {
            material.SetColor("blend_color", color);
            material.SetFloat("amount", amount);
            Graphics.Blit(source, destination, material);
        }

#if false
        GameObject obj = null;
        void Awake()
        {
            if (Application.isPlaying)
            {
                var camera = GetComponent<Camera>();
                obj = new GameObject();
                obj.transform.parent = transform;
                obj.name = "Homography";
                obj.AddComponent<RectTransform>();
                var canvas = obj.AddComponent<Canvas>();
                canvas.renderMode = RenderMode.ScreenSpaceOverlay;
                canvas.targetDisplay = camera.targetDisplay;
                obj.AddComponent<GraphicRaycaster>();
                obj.AddComponent<CanvasGroup>();
                var homo = obj.AddComponent<DoHomography>();
                homo.homography = this;
                homo.resolution = resolution;
                homo.cornerTexture = cornerTexture;
                homo.reset = true;
            }
            
        }
        void OnDestroy()
        {
            if (obj != null)
            {
                if (Application.isEditor)
                    Object.DestroyImmediate(obj);
                else
                    Object.Destroy(obj);
            }
        }
#endif
    }
}