/*
//  Copyright (c) 2015 José Guerreiro. All rights reserved.
//
//  MIT license, see http://www.opensource.org/licenses/mit-license.php
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.
*/

using UnityEngine;
using System.Collections.Generic;
using UnityEngine.Rendering;
//using UnityEngine.VR;

namespace cakeslice
{
	[DisallowMultipleComponent]
	[RequireComponent(typeof(Camera))]
	/* [ExecuteInEditMode] */
	public class OutlineEffect : MonoBehaviour
	{
		/* #if UNITY_EDITOR
				  private void OnValidate()
				  {
						CreateMaterialsIfNeeded();
				  }
		#endif */

		public static OutlineEffect Instance { get; private set; }

		private readonly LinkedSet<Outline> outlines = new LinkedSet<Outline>();

		[Range(1.0f, 6.0f)]
		public float lineThickness = 1.25f;
		[Range(0, 10)]
		public float lineIntensity = .5f;
		[Range(0, 1)]
		public float fillAmount = 0.2f;

		public Color lineColor0 = Color.red;
		public Color lineColor1 = Color.green;
		public Color lineColor2 = Color.blue;

		public bool additiveRendering = false;

		public bool backfaceCulling = true;

		public Color fillColor = Color.blue;
		public bool useFillColor = false;

		[Header("These settings can affect performance!")]
		public bool cornerOutlines = false;
		public bool addLinesBetweenColors = false;

		[Header("Advanced settings")]
		public bool scaleWithScreenSize = true;
		[Range(0.0f, 1.0f)]
		public float alphaCutoff = .5f;
		public bool flipY = false;
		public Camera sourceCamera;
		public bool autoEnableOutlines = false;

		[HideInInspector]
		public Camera outlineCamera;
		Material outline1Material;
		Material outline2Material;
		Material outline3Material;
		Material outlineEraseMaterial;
		Shader outlineShader;
		Shader outlineBufferShader;
		[HideInInspector]
		public Material outlineShaderMaterial;
		[HideInInspector]
		public RenderTexture renderTexture;
		[HideInInspector]
		public RenderTexture extraRenderTexture;

		CommandBuffer commandBuffer;

		Material GetMaterialFromID(int ID)
		{
			if (ID == 0)
				return outline1Material;
			else if (ID == 1)
				return outline2Material;
			else if (ID == 2)
				return outline3Material;
			else
				return outline1Material;
		}
		List<Material> materialBuffer = new List<Material>();
		Material CreateMaterial(Color emissionColor)
		{
			Material m = new Material(outlineBufferShader);
			m.SetColor("_Color", emissionColor);
			m.SetInt("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.SrcAlpha);
			m.SetInt("_DstBlend", (int)UnityEngine.Rendering.BlendMode.OneMinusSrcAlpha);
			m.SetInt("_ZWrite", 0);
			m.DisableKeyword("_ALPHATEST_ON");
			m.EnableKeyword("_ALPHABLEND_ON");
			m.DisableKeyword("_ALPHAPREMULTIPLY_ON");
			m.renderQueue = 3000;
			return m;
		}

		private void Awake()
		{
			if (Instance != null)
			{
				Destroy(this);
				throw new System.Exception("you can only have one outline camera in the scene");
			}

			Instance = this;
		}

		void Start()
		{
			CreateMaterialsIfNeeded();
			UpdateMaterialsPublicProperties();

			if (sourceCamera == null)
			{
				sourceCamera = GetComponent<Camera>();

				if (sourceCamera == null)
					sourceCamera = Camera.main;
			}

			if (outlineCamera == null)
			{
				foreach (Camera c in GetComponentsInChildren<Camera>())
				{
					if (c.name == "Outline Camera")
					{
						outlineCamera = c;
						c.enabled = false;

						break;
					}
				}

				if (outlineCamera == null)
				{
					GameObject cameraGameObject = new GameObject("Outline Camera");
					cameraGameObject.transform.parent = sourceCamera.transform;
					outlineCamera = cameraGameObject.AddComponent<Camera>();
					outlineCamera.enabled = false;
				}
			}

			if (renderTexture != null)
				renderTexture.Release();
			if (extraRenderTexture != null)
				renderTexture.Release();
			renderTexture = new RenderTexture(sourceCamera.pixelWidth, sourceCamera.pixelHeight, 16, RenderTextureFormat.Default);
			extraRenderTexture = new RenderTexture(sourceCamera.pixelWidth, sourceCamera.pixelHeight, 16, RenderTextureFormat.Default);
			UpdateOutlineCameraFromSource();

			commandBuffer = new CommandBuffer();
			outlineCamera.AddCommandBuffer(CameraEvent.BeforeImageEffects, commandBuffer);
		}

		bool RenderTheNextFrame;
		public void OnPreRender()
		{
			if (commandBuffer == null)
				return;

			// The first frame during which there are no outlines, we still need to render 
			// to clear out any outlines that were being rendered on the previous frame
			if (outlines.Count == 0)
			{
				if (!RenderTheNextFrame)
					return;

				RenderTheNextFrame = false;
			}
			else
			{
				RenderTheNextFrame = true;
			}

			CreateMaterialsIfNeeded();

			if (renderTexture == null || renderTexture.width != sourceCamera.pixelWidth || renderTexture.height != sourceCamera.pixelHeight)
			{
				if (renderTexture != null)
					renderTexture.Release();
				if (extraRenderTexture != null)
					renderTexture.Release();
				renderTexture = new RenderTexture(sourceCamera.pixelWidth, sourceCamera.pixelHeight, 16, RenderTextureFormat.Default);
				extraRenderTexture = new RenderTexture(sourceCamera.pixelWidth, sourceCamera.pixelHeight, 16, RenderTextureFormat.Default);
				outlineCamera.targetTexture = renderTexture;
			}
			UpdateMaterialsPublicProperties();
			UpdateOutlineCameraFromSource();
			outlineCamera.targetTexture = renderTexture;
			commandBuffer.SetRenderTarget(renderTexture);

			commandBuffer.Clear();

			foreach (Outline outline in outlines)
			{
				LayerMask l = sourceCamera.cullingMask;

				if (outline != null && l == (l | (1 << outline.gameObject.layer)))
				{
					for (int v = 0; v < outline.SharedMaterials.Length; v++)
					{
						Material m = null;

						if (outline.SharedMaterials[v].HasProperty("_MainTex") && outline.SharedMaterials[v].mainTexture != null && outline.SharedMaterials[v])
						{
							foreach (Material g in materialBuffer)
							{
								if (g.mainTexture == outline.SharedMaterials[v].mainTexture)
								{
									if (outline.eraseRenderer && g.color == outlineEraseMaterial.color)
										m = g;
									else if (!outline.eraseRenderer && g.color == GetMaterialFromID(outline.color).color)
										m = g;
								}
							}

							if (m == null)
							{
								if (outline.eraseRenderer)
									m = new Material(outlineEraseMaterial);
								else
									m = new Material(GetMaterialFromID(outline.color));

								m.mainTexture = outline.SharedMaterials[v].mainTexture;
								materialBuffer.Add(m);
							}
						}
						else
						{
							if (outline.eraseRenderer)
								m = outlineEraseMaterial;
							else
								m = GetMaterialFromID(outline.color);
						}

						if (backfaceCulling)
							m.SetInt("_Culling", (int)UnityEngine.Rendering.CullMode.Back);
						else
							m.SetInt("_Culling", (int)UnityEngine.Rendering.CullMode.Off);

						MeshFilter mL = outline.MeshFilter;
						SkinnedMeshRenderer sMR = outline.SkinnedMeshRenderer;
						SpriteRenderer sR = outline.SpriteRenderer;
						if (mL)
						{
							if (mL.sharedMesh != null)
							{
								if (v < mL.sharedMesh.subMeshCount)
									commandBuffer.DrawRenderer(outline.Renderer, m, v, 0);
							}
						}
						else if (sMR)
						{
							if (sMR.sharedMesh != null)
							{
								if (v < sMR.sharedMesh.subMeshCount)
									commandBuffer.DrawRenderer(outline.Renderer, m, v, 0);
							}
						}
						else if (sR)
						{
							commandBuffer.DrawRenderer(outline.Renderer, m, v, 0);
						}
					}
				}
			}

			outlineCamera.Render();
		}

		private void OnEnable()
		{
			Outline[] o = FindObjectsOfType<Outline>();
			if (autoEnableOutlines)
			{
				foreach (Outline oL in o)
				{
					oL.enabled = false;
					oL.enabled = true;
				}
			}
			else
			{
				foreach (Outline oL in o)
				{
					if (!outlines.Contains(oL))
						outlines.Add(oL);
				}
			}
		}

		void OnDestroy()
		{
			if (renderTexture != null)
				renderTexture.Release();
			if (extraRenderTexture != null)
				extraRenderTexture.Release();
			DestroyMaterials();
		}

		[ImageEffectOpaque]
		void OnRenderImage(RenderTexture source, RenderTexture destination)
		{
			if (outlineShaderMaterial != null)
			{
				outlineShaderMaterial.SetTexture("_OutlineSource", renderTexture);

				if (addLinesBetweenColors)
				{
					Graphics.Blit(source, extraRenderTexture, outlineShaderMaterial, 0);
					outlineShaderMaterial.SetTexture("_OutlineSource", extraRenderTexture);
				}
				Graphics.Blit(source, destination, outlineShaderMaterial, 1);
			}
		}

		private void CreateMaterialsIfNeeded()
		{
			if (outlineShader == null)
				outlineShader = Resources.Load<Shader>("OutlineShader");
			if (outlineBufferShader == null)
			{
				outlineBufferShader = Resources.Load<Shader>("OutlineBufferShader");
			}
			if (outlineShaderMaterial == null)
			{
				outlineShaderMaterial = new Material(outlineShader);
				outlineShaderMaterial.hideFlags = HideFlags.HideAndDontSave;
				UpdateMaterialsPublicProperties();
			}
			if (outlineEraseMaterial == null)
				outlineEraseMaterial = CreateMaterial(new Color(0, 0, 0, 0));
			if (outline1Material == null)
				outline1Material = CreateMaterial(new Color(1, 0, 0, 0));
			if (outline2Material == null)
				outline2Material = CreateMaterial(new Color(0, 1, 0, 0));
			if (outline3Material == null)
				outline3Material = CreateMaterial(new Color(0, 0, 1, 0));
		}

		private void DestroyMaterials()
		{
			foreach (Material m in materialBuffer)
				DestroyImmediate(m);
			materialBuffer.Clear();
			DestroyImmediate(outlineShaderMaterial);
			DestroyImmediate(outlineEraseMaterial);
			DestroyImmediate(outline1Material);
			DestroyImmediate(outline2Material);
			DestroyImmediate(outline3Material);
			outlineShader = null;
			outlineBufferShader = null;
			outlineShaderMaterial = null;
			outlineEraseMaterial = null;
			outline1Material = null;
			outline2Material = null;
			outline3Material = null;
		}

		public void UpdateMaterialsPublicProperties()
		{
			if (outlineShaderMaterial)
			{
				float scalingFactor = 1;
				if (scaleWithScreenSize)
				{
					// If Screen.height gets bigger, outlines gets thicker
					scalingFactor = Screen.height / 360.0f;
				}

				// If scaling is too small (height less than 360 pixels), make sure you still render the outlines, but render them with 1 thickness
				if (scaleWithScreenSize && scalingFactor < 1)
				{
					if (UnityEngine.XR.XRSettings.isDeviceActive && sourceCamera.stereoTargetEye != StereoTargetEyeMask.None)
					{
						outlineShaderMaterial.SetFloat("_LineThicknessX", (1 / 1000.0f) * (1.0f / UnityEngine.XR.XRSettings.eyeTextureWidth) * 1000.0f);
						outlineShaderMaterial.SetFloat("_LineThicknessY", (1 / 1000.0f) * (1.0f / UnityEngine.XR.XRSettings.eyeTextureHeight) * 1000.0f);
					}
					else
					{
						outlineShaderMaterial.SetFloat("_LineThicknessX", (1 / 1000.0f) * (1.0f / Screen.width) * 1000.0f);
						outlineShaderMaterial.SetFloat("_LineThicknessY", (1 / 1000.0f) * (1.0f / Screen.height) * 1000.0f);
					}
				}
				else
				{
					if (UnityEngine.XR.XRSettings.isDeviceActive && sourceCamera.stereoTargetEye != StereoTargetEyeMask.None)
					{
						outlineShaderMaterial.SetFloat("_LineThicknessX", scalingFactor * (lineThickness / 1000.0f) * (1.0f / UnityEngine.XR.XRSettings.eyeTextureWidth) * 1000.0f);
						outlineShaderMaterial.SetFloat("_LineThicknessY", scalingFactor * (lineThickness / 1000.0f) * (1.0f / UnityEngine.XR.XRSettings.eyeTextureHeight) * 1000.0f);
					}
					else
					{
						outlineShaderMaterial.SetFloat("_LineThicknessX", scalingFactor * (lineThickness / 1000.0f) * (1.0f / Screen.width) * 1000.0f);
						outlineShaderMaterial.SetFloat("_LineThicknessY", scalingFactor * (lineThickness / 1000.0f) * (1.0f / Screen.height) * 1000.0f);
					}
				}
				outlineShaderMaterial.SetFloat("_LineIntensity", lineIntensity);
				outlineShaderMaterial.SetFloat("_FillAmount", fillAmount);
				outlineShaderMaterial.SetColor("_FillColor", fillColor);
				outlineShaderMaterial.SetFloat("_UseFillColor", useFillColor ? 1 : 0);
				outlineShaderMaterial.SetColor("_LineColor1", lineColor0 * lineColor0);
				outlineShaderMaterial.SetColor("_LineColor2", lineColor1 * lineColor1);
				outlineShaderMaterial.SetColor("_LineColor3", lineColor2 * lineColor2);
				if (flipY)
					outlineShaderMaterial.SetInt("_FlipY", 1);
				else
					outlineShaderMaterial.SetInt("_FlipY", 0);
				if (!additiveRendering)
					outlineShaderMaterial.SetInt("_Dark", 1);
				else
					outlineShaderMaterial.SetInt("_Dark", 0);
				if (cornerOutlines)
					outlineShaderMaterial.SetInt("_CornerOutlines", 1);
				else
					outlineShaderMaterial.SetInt("_CornerOutlines", 0);

				Shader.SetGlobalFloat("_OutlineAlphaCutoff", alphaCutoff);
			}
		}

		void UpdateOutlineCameraFromSource()
		{
			outlineCamera.CopyFrom(sourceCamera);
			outlineCamera.renderingPath = RenderingPath.Forward;
			outlineCamera.backgroundColor = new Color(0.0f, 0.0f, 0.0f, 0.0f);
			outlineCamera.clearFlags = CameraClearFlags.SolidColor;
			outlineCamera.rect = new Rect(0, 0, 1, 1);
			outlineCamera.cullingMask = 0;
			outlineCamera.targetTexture = renderTexture;
			outlineCamera.enabled = false;
#if UNITY_5_6_OR_NEWER
            outlineCamera.allowHDR = false;
#else
			outlineCamera.hdr = false;
#endif
		}

		public void AddOutline(Outline outline)
			 => outlines.Add(outline);

		public void RemoveOutline(Outline outline)
			 => outlines.Remove(outline);
	}
}