module BABYLON {
    /**
     * Effect layer options. This helps customizing the behaviour
     * of the effect layer.
     */
    export interface IEffectLayerOptions {
        /**
         * Multiplication factor apply to the canvas size to compute the render target size
         * used to generated the objects (the smaller the faster).
         */
        mainTextureRatio: number;

        /**
         * Enforces a fixed size texture to ensure effect stability across devices.
         */
        mainTextureFixedSize?: number;

        /**
         * Alpha blending mode used to apply the blur. Default depends of the implementation.
         */
        alphaBlendingMode: number;

        /**
         * The camera attached to the layer.
         */
        camera: Nullable<Camera>;
    }

    /**
     * The effect layer Helps adding post process effect blended with the main pass.
     * 
     * This can be for instance use to generate glow or higlight effects on the scene.
     * 
     * The effect layer class can not be used directly and is intented to inherited from to be 
     * customized per effects.
     */
    export abstract class EffectLayer {

        private _vertexBuffers: { [key: string]: Nullable<VertexBuffer> } = {};
        private _indexBuffer: Nullable<WebGLBuffer>;
        private _cachedDefines: string;
        private _effectLayerMapGenerationEffect: Effect;
        private _effectLayerOptions: IEffectLayerOptions;
        private _mergeEffect: Effect;

        protected _scene: Scene;
        protected _engine: Engine;
        protected _maxSize: number = 0;
        protected _mainTextureDesiredSize: ISize = { width: 0, height: 0 };
        protected _mainTexture: RenderTargetTexture;
        protected _shouldRender = true;
        protected _postProcesses: PostProcess[] = [];
        protected _textures: BaseTexture[] = [];
        protected _emissiveTextureAndColor: { texture: Nullable<BaseTexture>, color: Color4 } = { texture: null, color: new Color4() };

        /**
         * The name of the layer
         */
        @serialize()
        public name: string;

        /**
         * The clear color of the texture used to generate the glow map.
         */
        @serializeAsColor4()
        public neutralColor: Color4 = new Color4();

        /**
         * Specifies wether the highlight layer is enabled or not.
         */
        @serialize()
        public isEnabled: boolean = true;

        /**
         * Gets the camera attached to the layer.
         */
        @serializeAsCameraReference()
        public get camera(): Nullable<Camera> {
            return this._effectLayerOptions.camera;
        }

        /**
         * An event triggered when the effect layer has been disposed.
         */
        public onDisposeObservable = new Observable<EffectLayer>();

        /**
         * An event triggered when the effect layer is about rendering the main texture with the glowy parts.
         */
        public onBeforeRenderMainTextureObservable = new Observable<EffectLayer>();

        /**
         * An event triggered when the generated texture is being merged in the scene.
         */
        public onBeforeComposeObservable = new Observable<EffectLayer>();

        /**
         * An event triggered when the generated texture has been merged in the scene.
         */
        public onAfterComposeObservable = new Observable<EffectLayer>();

        /**
         * An event triggered when the efffect layer changes its size.
         */
        public onSizeChangedObservable = new Observable<EffectLayer>();

        /**
         * Instantiates a new effect Layer and references it in the scene.
         * @param name The name of the layer
         * @param scene The scene to use the layer in
         */
        constructor(
            /** The Friendly of the effect in the scene */
            name: string,
            scene: Scene) {
            this.name = name;

            this._scene = scene || Engine.LastCreatedScene;
            this._engine = scene.getEngine();
            this._maxSize = this._engine.getCaps().maxTextureSize;
            this._scene.effectLayers.push(this);

            // Generate Buffers
            this._generateIndexBuffer();
            this._genrateVertexBuffer();
        }

        /**
         * Get the effect name of the layer.
         * @return The effect name
         */ 
        public abstract getEffectName(): string;

        /**
         * Checks for the readiness of the element composing the layer.
         * @param subMesh the mesh to check for
         * @param useInstances specify wether or not to use instances to render the mesh
         * @return true if ready otherwise, false
         */ 
        public abstract isReady(subMesh: SubMesh, useInstances: boolean): boolean;

        /**
         * Returns wether or nood the layer needs stencil enabled during the mesh rendering.
         * @returns true if the effect requires stencil during the main canvas render pass.
         */
        public abstract needStencil(): boolean;

        /**
         * Create the merge effect. This is the shader use to blit the information back
         * to the main canvas at the end of the scene rendering.
         * @returns The effect containing the shader used to merge the effect on the  main canvas
         */
        protected abstract _createMergeEffect(): Effect;
        
        /**
         * Creates the render target textures and post processes used in the effect layer.
         */
        protected abstract _createTextureAndPostProcesses(): void;
        
        /**
         * Implementation specific of rendering the generating effect on the main canvas.
         * @param effect The effect used to render through
         */
        protected abstract _internalRender(effect: Effect): void;

        /**
         * Sets the required values for both the emissive texture and and the main color.
         */
        protected abstract _setEmissiveTextureAndColor(mesh: Mesh, subMesh: SubMesh, material: Material): void;

        /**
         * Free any resources and references associated to a mesh.
         * Internal use
         * @param mesh The mesh to free.
         */
        public abstract _disposeMesh(mesh: Mesh): void;

        /**
         * Serializes this layer (Glow or Highlight for example)
         * @returns a serialized layer object
         */
        public abstract serialize?(): any;

        /**
         * Initializes the effect layer with the required options.
         * @param options Sets of none mandatory options to use with the layer (see IEffectLayerOptions for more information)
         */
        protected _init(options: Partial<IEffectLayerOptions>): void {
            // Adapt options
            this._effectLayerOptions = {
                mainTextureRatio: 0.5,
                alphaBlendingMode: Engine.ALPHA_COMBINE,
                camera: null,
                ...options,
            };

            this._setMainTextureSize();
            this._createMainTexture();
            this._createTextureAndPostProcesses();
            this._mergeEffect = this._createMergeEffect();
        }

        /**
         * Generates the index buffer of the full screen quad blending to the main canvas.
         */
        private _generateIndexBuffer(): void {
            // Indices
            var indices = [];
            indices.push(0);
            indices.push(1);
            indices.push(2);

            indices.push(0);
            indices.push(2);
            indices.push(3);

            this._indexBuffer = this._engine.createIndexBuffer(indices);
        }

        /**
         * Generates the vertex buffer of the full screen quad blending to the main canvas.
         */
        private _genrateVertexBuffer(): void {
            // VBO
            var vertices = [];
            vertices.push(1, 1);
            vertices.push(-1, 1);
            vertices.push(-1, -1);
            vertices.push(1, -1);

            var vertexBuffer = new VertexBuffer(this._engine, vertices, VertexBuffer.PositionKind, false, false, 2);
            this._vertexBuffers[VertexBuffer.PositionKind] = vertexBuffer;
        }

        /**
         * Sets the main texture desired size which is the closest power of two
         * of the engine canvas size.
         */
        private _setMainTextureSize(): void {
            if (this._effectLayerOptions.mainTextureFixedSize) {
                this._mainTextureDesiredSize.width = this._effectLayerOptions.mainTextureFixedSize;
                this._mainTextureDesiredSize.height = this._effectLayerOptions.mainTextureFixedSize;
            }
            else {
                this._mainTextureDesiredSize.width = this._engine.getRenderWidth() * this._effectLayerOptions.mainTextureRatio;
                this._mainTextureDesiredSize.height = this._engine.getRenderHeight() * this._effectLayerOptions.mainTextureRatio;

                this._mainTextureDesiredSize.width = this._engine.needPOTTextures ? Tools.GetExponentOfTwo(this._mainTextureDesiredSize.width, this._maxSize) : this._mainTextureDesiredSize.width;
                this._mainTextureDesiredSize.height = this._engine.needPOTTextures ? Tools.GetExponentOfTwo(this._mainTextureDesiredSize.height, this._maxSize) : this._mainTextureDesiredSize.height;
            }

            this._mainTextureDesiredSize.width = Math.floor(this._mainTextureDesiredSize.width);
            this._mainTextureDesiredSize.height = Math.floor(this._mainTextureDesiredSize.height);
        }

        /**
         * Creates the main texture for the effect layer.
         */
        protected _createMainTexture(): void {
            this._mainTexture = new RenderTargetTexture("HighlightLayerMainRTT",
                {
                    width: this._mainTextureDesiredSize.width,
                    height: this._mainTextureDesiredSize.height
                },
                this._scene,
                false,
                true,
                Engine.TEXTURETYPE_UNSIGNED_INT);
            this._mainTexture.activeCamera = this._effectLayerOptions.camera;
            this._mainTexture.wrapU = Texture.CLAMP_ADDRESSMODE;
            this._mainTexture.wrapV = Texture.CLAMP_ADDRESSMODE;
            this._mainTexture.anisotropicFilteringLevel = 1;
            this._mainTexture.updateSamplingMode(Texture.BILINEAR_SAMPLINGMODE);
            this._mainTexture.renderParticles = false;
            this._mainTexture.renderList = null;
            this._mainTexture.ignoreCameraViewport = true;

            // Custom render function
            this._mainTexture.customRenderFunction = (opaqueSubMeshes: SmartArray<SubMesh>, alphaTestSubMeshes: SmartArray<SubMesh>, transparentSubMeshes: SmartArray<SubMesh>, depthOnlySubMeshes: SmartArray<SubMesh>): void => {
                this.onBeforeRenderMainTextureObservable.notifyObservers(this);

                var index: number;

                let engine = this._scene.getEngine();

                if (depthOnlySubMeshes.length) {
                    engine.setColorWrite(false);
                    for (index = 0; index < depthOnlySubMeshes.length; index++) {
                        this._renderSubMesh(depthOnlySubMeshes.data[index]);
                    }
                    engine.setColorWrite(true);
                }

                for (index = 0; index < opaqueSubMeshes.length; index++) {
                    this._renderSubMesh(opaqueSubMeshes.data[index]);
                }

                for (index = 0; index < alphaTestSubMeshes.length; index++) {
                    this._renderSubMesh(alphaTestSubMeshes.data[index]);
                }

                for (index = 0; index < transparentSubMeshes.length; index++) {
                    this._renderSubMesh(transparentSubMeshes.data[index]);
                }
            };

            this._mainTexture.onClearObservable.add((engine: Engine) => {
                engine.clear(this.neutralColor, true, true, true);
            });
        }

        /**
         * Checks for the readiness of the element composing the layer.
         * @param subMesh the mesh to check for
         * @param useInstances specify wether or not to use instances to render the mesh
         * @param emissiveTexture the associated emissive texture used to generate the glow
         * @return true if ready otherwise, false
         */
        protected _isReady(subMesh: SubMesh, useInstances: boolean, emissiveTexture: Nullable<BaseTexture>): boolean {
            let material = subMesh.getMaterial();

            if (!material) {
                return false;
            }

            if (!material.isReady(subMesh.getMesh(), useInstances)) {
                return false;
            }

            var defines = [];

            var attribs = [VertexBuffer.PositionKind];

            var mesh = subMesh.getMesh();
            var uv1 = false;
            var uv2 = false;

            // Alpha test
            if (material && material.needAlphaTesting()) {
                var alphaTexture = material.getAlphaTestTexture();
                if (alphaTexture) {
                    defines.push("#define ALPHATEST");
                    if (mesh.isVerticesDataPresent(VertexBuffer.UV2Kind) &&
                        alphaTexture.coordinatesIndex === 1) {
                        defines.push("#define DIFFUSEUV2");
                        uv2 = true;
                    }
                    else if (mesh.isVerticesDataPresent(VertexBuffer.UVKind)) {
                        defines.push("#define DIFFUSEUV1");
                        uv1 = true;
                    }
                }
            }

            // Emissive
            if (emissiveTexture) {
                defines.push("#define EMISSIVE");
                if (mesh.isVerticesDataPresent(VertexBuffer.UV2Kind) &&
                    emissiveTexture.coordinatesIndex === 1) {
                    defines.push("#define EMISSIVEUV2");
                    uv2 = true;
                }
                else if (mesh.isVerticesDataPresent(VertexBuffer.UVKind)) {
                    defines.push("#define EMISSIVEUV1");
                    uv1 = true;
                }
            }

            if (uv1) {
                attribs.push(VertexBuffer.UVKind);
                defines.push("#define UV1");
            }
            if (uv2) {
                attribs.push(VertexBuffer.UV2Kind);
                defines.push("#define UV2");
            }

            // Bones
            if (mesh.useBones && mesh.computeBonesUsingShaders) {
                attribs.push(VertexBuffer.MatricesIndicesKind);
                attribs.push(VertexBuffer.MatricesWeightsKind);
                if (mesh.numBoneInfluencers > 4) {
                    attribs.push(VertexBuffer.MatricesIndicesExtraKind);
                    attribs.push(VertexBuffer.MatricesWeightsExtraKind);
                }
                defines.push("#define NUM_BONE_INFLUENCERS " + mesh.numBoneInfluencers);
                defines.push("#define BonesPerMesh " + (mesh.skeleton ? (mesh.skeleton.bones.length + 1) : 0));
            } else {
                defines.push("#define NUM_BONE_INFLUENCERS 0");
            }

            // Morph targets         
            var manager = (<Mesh>mesh).morphTargetManager;
            let morphInfluencers = 0;
            if (manager) {
                if (manager.numInfluencers > 0) {
                    defines.push("#define MORPHTARGETS");
                    morphInfluencers = manager.numInfluencers;
                    defines.push("#define NUM_MORPH_INFLUENCERS " + morphInfluencers);
                    MaterialHelper.PrepareAttributesForMorphTargets(attribs, mesh, {"NUM_MORPH_INFLUENCERS": morphInfluencers });
                }
            }            

            // Instances
            if (useInstances) {
                defines.push("#define INSTANCES");
                attribs.push("world0");
                attribs.push("world1");
                attribs.push("world2");
                attribs.push("world3");
            }

            // Get correct effect
            var join = defines.join("\n");
            if (this._cachedDefines !== join) {
                this._cachedDefines = join;
                this._effectLayerMapGenerationEffect = this._scene.getEngine().createEffect("glowMapGeneration",
                    attribs,
                    ["world", "mBones", "viewProjection", "diffuseMatrix", "color", "emissiveMatrix", "morphTargetInfluences"],
                    ["diffuseSampler", "emissiveSampler"], join,
                    undefined, undefined, undefined, { maxSimultaneousMorphTargets: morphInfluencers });
            }

            return this._effectLayerMapGenerationEffect.isReady();
        }

        /**
         * Renders the glowing part of the scene by blending the blurred glowing meshes on top of the rendered scene.
         */
        public render(): void {
            var currentEffect = this._mergeEffect;

            // Check
            if (!currentEffect.isReady())
                return;

            for (var i = 0; i < this._postProcesses.length; i++) {
                if (!this._postProcesses[i].isReady()) {
                    return;
                }
            }

            var engine = this._scene.getEngine();

            this.onBeforeComposeObservable.notifyObservers(this);

            // Render
            engine.enableEffect(currentEffect);
            engine.setState(false);
            
            // VBOs
            engine.bindBuffers(this._vertexBuffers, this._indexBuffer, currentEffect);

            // Cache
            var previousAlphaMode = engine.getAlphaMode();

            // Go Blend.
            engine.setAlphaMode(this._effectLayerOptions.alphaBlendingMode);

            // Blends the map on the main canvas.
            this._internalRender(currentEffect);

            // Restore Alpha
            engine.setAlphaMode(previousAlphaMode);

            this.onAfterComposeObservable.notifyObservers(this);

            // Handle size changes.
            var size = this._mainTexture.getSize();
            this._setMainTextureSize();
            if (size.width !== this._mainTextureDesiredSize.width || size.height !== this._mainTextureDesiredSize.height) {
                // Recreate RTT and post processes on size change.
                this.onSizeChangedObservable.notifyObservers(this);
                this._disposeTextureAndPostProcesses();
                this._createMainTexture();
                this._createTextureAndPostProcesses();
            }
        }

        /**
         * Determine if a given mesh will be used in the current effect.
         * @param mesh mesh to test
         * @returns true if the mesh will be used
         */
        public hasMesh(mesh: AbstractMesh): boolean {
            return true;
        }

        /**
         * Returns true if the layer contains information to display, otherwise false.
         * @returns true if the glow layer should be rendered
         */
        public shouldRender(): boolean {
            return this.isEnabled && this._shouldRender;
        }

        /**
         * Returns true if the mesh should render, otherwise false.
         * @param mesh The mesh to render
         * @returns true if it should render otherwise false
         */
        protected _shouldRenderMesh(mesh: Mesh): boolean {
            return true;
        }

        /**
         * Returns true if the mesh should render, otherwise false.
         * @param mesh The mesh to render
         * @returns true if it should render otherwise false
         */
        protected _shouldRenderEmissiveTextureForMesh(mesh: Mesh): boolean {
            return true;
        }

        /**
         * Renders the submesh passed in parameter to the generation map.
         */
        protected _renderSubMesh(subMesh: SubMesh): void {
            if (!this.shouldRender()) {
                return;
            }

            var material = subMesh.getMaterial();
            var mesh = subMesh.getRenderingMesh();
            var scene = this._scene;
            var engine = scene.getEngine();

            if (!material) {
                return;
            }

            // Do not block in blend mode.
            if (material.needAlphaBlendingForMesh(mesh)) {
                return;
            }

            // Culling
            engine.setState(material.backFaceCulling);

            // Managing instances
            var batch = mesh._getInstancesRenderList(subMesh._id);
            if (batch.mustReturn) {
                return;
            }

            // Early Exit per mesh
            if (!this._shouldRenderMesh(mesh)) {
                return;
            }

            var hardwareInstancedRendering = (engine.getCaps().instancedArrays) && (batch.visibleInstances[subMesh._id] !== null) && (batch.visibleInstances[subMesh._id] !== undefined);

            this._setEmissiveTextureAndColor(mesh, subMesh, material);

            if (this._isReady(subMesh, hardwareInstancedRendering, this._emissiveTextureAndColor.texture)) {
                engine.enableEffect(this._effectLayerMapGenerationEffect);
                mesh._bind(subMesh, this._effectLayerMapGenerationEffect, Material.TriangleFillMode);

                this._effectLayerMapGenerationEffect.setMatrix("viewProjection", scene.getTransformMatrix());

                this._effectLayerMapGenerationEffect.setFloat4("color",
                    this._emissiveTextureAndColor.color.r,
                    this._emissiveTextureAndColor.color.g,
                    this._emissiveTextureAndColor.color.b,
                    this._emissiveTextureAndColor.color.a);

                // Alpha test
                if (material && material.needAlphaTesting()) {
                    var alphaTexture = material.getAlphaTestTexture();
                    if (alphaTexture) {
                        this._effectLayerMapGenerationEffect.setTexture("diffuseSampler", alphaTexture);
                        let textureMatrix = alphaTexture.getTextureMatrix();

                        if (textureMatrix) {
                            this._effectLayerMapGenerationEffect.setMatrix("diffuseMatrix", textureMatrix);
                        }
                    }
                }

                // Glow emissive only
                if (this._emissiveTextureAndColor.texture) {
                    this._effectLayerMapGenerationEffect.setTexture("emissiveSampler", this._emissiveTextureAndColor.texture);
                    this._effectLayerMapGenerationEffect.setMatrix("emissiveMatrix", this._emissiveTextureAndColor.texture.getTextureMatrix());
                }

                // Bones
                if (mesh.useBones && mesh.computeBonesUsingShaders && mesh.skeleton) {
                    this._effectLayerMapGenerationEffect.setMatrices("mBones", mesh.skeleton.getTransformMatrices(mesh));
                }

                // Morph targets
                MaterialHelper.BindMorphTargetParameters(mesh, this._effectLayerMapGenerationEffect);

                // Draw
                mesh._processRendering(subMesh, this._effectLayerMapGenerationEffect, Material.TriangleFillMode, batch, hardwareInstancedRendering,
                    (isInstance, world) => this._effectLayerMapGenerationEffect.setMatrix("world", world));
            } else {
                // Need to reset refresh rate of the shadowMap
                this._mainTexture.resetRefreshCounter();
            }
        }

        /**
         * Rebuild the required buffers.
         * @ignore Internal use only.
         */
        public _rebuild(): void {
            let vb = this._vertexBuffers[VertexBuffer.PositionKind];

            if (vb) {
                vb._rebuild();
            }

            this._generateIndexBuffer();
        }

        /**
         * Dispose only the render target textures and post process.
         */
        private _disposeTextureAndPostProcesses(): void {
            this._mainTexture.dispose();

            for (var i = 0; i < this._postProcesses.length; i++) {
                if (this._postProcesses[i]) {
                    this._postProcesses[i].dispose();
                }
            }
            this._postProcesses = [];

            for (var i = 0; i < this._textures.length; i++) {
                if (this._textures[i]) {
                    this._textures[i].dispose();
                }
            }
            this._textures = [];
        }

        /**
         * Dispose the highlight layer and free resources.
         */
        public dispose(): void {
            var vertexBuffer = this._vertexBuffers[VertexBuffer.PositionKind];
            if (vertexBuffer) {
                vertexBuffer.dispose();
                this._vertexBuffers[VertexBuffer.PositionKind] = null;
            }

            if (this._indexBuffer) {
                this._scene.getEngine()._releaseBuffer(this._indexBuffer);
                this._indexBuffer = null;
            }

            // Clean textures and post processes
            this._disposeTextureAndPostProcesses();

            // Remove from scene
            var index = this._scene.effectLayers.indexOf(this, 0);
            if (index > -1) {
                this._scene.effectLayers.splice(index, 1);
            }

            // Callback
            this.onDisposeObservable.notifyObservers(this);

            this.onDisposeObservable.clear();
            this.onBeforeRenderMainTextureObservable.clear();
            this.onBeforeComposeObservable.clear();
            this.onAfterComposeObservable.clear();
            this.onSizeChangedObservable.clear();
        }

        /**
          * Gets the class name of the effect layer
          * @returns the string with the class name of the effect layer
          */
         public getClassName(): string {
            return "EffectLayer";
        }

        /**
         * Creates an effect layer from parsed effect layer data
         * @param parsedEffectLayer defines effect layer data
         * @param scene defines the current scene
         * @param rootUrl defines the root URL containing the effect layer information
         * @returns a parsed effect Layer
         */
        public static Parse(parsedEffectLayer: any, scene: Scene, rootUrl: string): EffectLayer {
            var effectLayerType = Tools.Instantiate(parsedEffectLayer.customType);
            
            return effectLayerType.Parse(parsedEffectLayer, scene, rootUrl);
        }
    }
}