/**
 * @author spidersharma / http://eduperiment.com/
 *
 * Inspired from Unreal Engine
 * https://docs.unrealengine.com/latest/INT/Engine/Rendering/PostProcessEffects/Bloom/
 */
THREE.UnrealBloomPass = function ( resolution, strength, radius, threshold ) {

	THREE.Pass.call( this );

	this.strength = ( strength !== undefined ) ? strength : 1;
	this.radius = radius;
	this.threshold = threshold;
	this.resolution = ( resolution !== undefined ) ? new THREE.Vector2( resolution.x, resolution.y ) : new THREE.Vector2( 256, 256 );

	// create color only once here, reuse it later inside the render function
	this.clearColor = new THREE.Color( 0, 0, 0 );

	// render targets
	var pars = { minFilter: THREE.LinearFilter, magFilter: THREE.LinearFilter, format: THREE.RGBAFormat };
	this.renderTargetsHorizontal = [];
	this.renderTargetsVertical = [];
	this.nMips = 5;
	var resx = Math.round( this.resolution.x / 2 );
	var resy = Math.round( this.resolution.y / 2 );

	this.renderTargetBright = new THREE.WebGLRenderTarget( resx, resy, pars );
	this.renderTargetBright.texture.name = "UnrealBloomPass.bright";
	this.renderTargetBright.texture.generateMipmaps = false;

	for ( var i = 0; i < this.nMips; i ++ ) {

		var renderTarget = new THREE.WebGLRenderTarget( resx, resy, pars );

		renderTarget.texture.name = "UnrealBloomPass.h" + i;
		renderTarget.texture.generateMipmaps = false;

		this.renderTargetsHorizontal.push( renderTarget );

		var renderTarget = new THREE.WebGLRenderTarget( resx, resy, pars );

		renderTarget.texture.name = "UnrealBloomPass.v" + i;
		renderTarget.texture.generateMipmaps = false;

		this.renderTargetsVertical.push( renderTarget );

		resx = Math.round( resx / 2 );

		resy = Math.round( resy / 2 );

	}

	// luminosity high pass material

	if ( THREE.LuminosityHighPassShader === undefined )
		console.error( "THREE.UnrealBloomPass relies on THREE.LuminosityHighPassShader" );

	var highPassShader = THREE.LuminosityHighPassShader;
	this.highPassUniforms = THREE.UniformsUtils.clone( highPassShader.uniforms );

	this.highPassUniforms[ "luminosityThreshold" ].value = threshold;
	this.highPassUniforms[ "smoothWidth" ].value = 0.01;

	this.materialHighPassFilter = new THREE.ShaderMaterial( {
		uniforms: this.highPassUniforms,
		vertexShader: highPassShader.vertexShader,
		fragmentShader: highPassShader.fragmentShader,
		defines: {}
	} );

	// Gaussian Blur Materials
	this.separableBlurMaterials = [];
	var kernelSizeArray = [ 3, 5, 7, 9, 11 ];
	var resx = Math.round( this.resolution.x / 2 );
	var resy = Math.round( this.resolution.y / 2 );

	for ( var i = 0; i < this.nMips; i ++ ) {

		this.separableBlurMaterials.push( this.getSeperableBlurMaterial( kernelSizeArray[ i ] ) );

		this.separableBlurMaterials[ i ].uniforms[ "texSize" ].value = new THREE.Vector2( resx, resy );

		resx = Math.round( resx / 2 );

		resy = Math.round( resy / 2 );

	}

	// Composite material
	this.compositeMaterial = this.getCompositeMaterial( this.nMips );
	this.compositeMaterial.uniforms[ "blurTexture1" ].value = this.renderTargetsVertical[ 0 ].texture;
	this.compositeMaterial.uniforms[ "blurTexture2" ].value = this.renderTargetsVertical[ 1 ].texture;
	this.compositeMaterial.uniforms[ "blurTexture3" ].value = this.renderTargetsVertical[ 2 ].texture;
	this.compositeMaterial.uniforms[ "blurTexture4" ].value = this.renderTargetsVertical[ 3 ].texture;
	this.compositeMaterial.uniforms[ "blurTexture5" ].value = this.renderTargetsVertical[ 4 ].texture;
	this.compositeMaterial.uniforms[ "bloomStrength" ].value = strength;
	this.compositeMaterial.uniforms[ "bloomRadius" ].value = 0.1;
	this.compositeMaterial.needsUpdate = true;

	var bloomFactors = [ 1.0, 0.8, 0.6, 0.4, 0.2 ];
	this.compositeMaterial.uniforms[ "bloomFactors" ].value = bloomFactors;
	this.bloomTintColors = [ new THREE.Vector3( 1, 1, 1 ), new THREE.Vector3( 1, 1, 1 ), new THREE.Vector3( 1, 1, 1 ),
							 new THREE.Vector3( 1, 1, 1 ), new THREE.Vector3( 1, 1, 1 ) ];
	this.compositeMaterial.uniforms[ "bloomTintColors" ].value = this.bloomTintColors;

	// copy material
	if ( THREE.CopyShader === undefined ) {

		console.error( "THREE.BloomPass relies on THREE.CopyShader" );

	}

	var copyShader = THREE.CopyShader;

	this.copyUniforms = THREE.UniformsUtils.clone( copyShader.uniforms );
	this.copyUniforms[ "opacity" ].value = 1.0;

	this.materialCopy = new THREE.ShaderMaterial( {
		uniforms: this.copyUniforms,
		vertexShader: copyShader.vertexShader,
		fragmentShader: copyShader.fragmentShader,
		blending: THREE.AdditiveBlending,
		depthTest: false,
		depthWrite: false,
		transparent: true
	} );

	this.enabled = true;
	this.needsSwap = false;

	this.oldClearColor = new THREE.Color();
	this.oldClearAlpha = 1;

	this.camera = new THREE.OrthographicCamera( - 1, 1, 1, - 1, 0, 1 );
	this.scene = new THREE.Scene();

	this.basic = new THREE.MeshBasicMaterial();

	this.quad = new THREE.Mesh( new THREE.PlaneBufferGeometry( 2, 2 ), null );
	this.quad.frustumCulled = false; // Avoid getting clipped
	this.scene.add( this.quad );

};

THREE.UnrealBloomPass.prototype = Object.assign( Object.create( THREE.Pass.prototype ), {

	constructor: THREE.UnrealBloomPass,

	dispose: function () {

		for ( var i = 0; i < this.renderTargetsHorizontal.length; i ++ ) {

			this.renderTargetsHorizontal[ i ].dispose();

		}

		for ( var i = 0; i < this.renderTargetsVertical.length; i ++ ) {

			this.renderTargetsVertical[ i ].dispose();

		}

		this.renderTargetBright.dispose();

	},

	setSize: function ( width, height ) {

		var resx = Math.round( width / 2 );
		var resy = Math.round( height / 2 );

		this.renderTargetBright.setSize( resx, resy );

		for ( var i = 0; i < this.nMips; i ++ ) {

			this.renderTargetsHorizontal[ i ].setSize( resx, resy );
			this.renderTargetsVertical[ i ].setSize( resx, resy );

			this.separableBlurMaterials[ i ].uniforms[ "texSize" ].value = new THREE.Vector2( resx, resy );

			resx = Math.round( resx / 2 );
			resy = Math.round( resy / 2 );

		}

	},

	render: function ( renderer, writeBuffer, readBuffer, delta, maskActive ) {

		this.oldClearColor.copy( renderer.getClearColor() );
		this.oldClearAlpha = renderer.getClearAlpha();
		var oldAutoClear = renderer.autoClear;
		renderer.autoClear = false;

		renderer.setClearColor( this.clearColor, 0 );

		if ( maskActive ) renderer.context.disable( renderer.context.STENCIL_TEST );

		// Render input to screen

		if ( this.renderToScreen ) {

			this.quad.material = this.basic;
			this.basic.map = readBuffer.texture;

			renderer.render( this.scene, this.camera, undefined, true );

		}

		// 1. Extract Bright Areas

		this.highPassUniforms[ "tDiffuse" ].value = readBuffer.texture;
		this.highPassUniforms[ "luminosityThreshold" ].value = this.threshold;
		this.quad.material = this.materialHighPassFilter;

		renderer.render( this.scene, this.camera, this.renderTargetBright, true );

		// 2. Blur All the mips progressively

		var inputRenderTarget = this.renderTargetBright;

		for ( var i = 0; i < this.nMips; i ++ ) {

			this.quad.material = this.separableBlurMaterials[ i ];

			this.separableBlurMaterials[ i ].uniforms[ "colorTexture" ].value = inputRenderTarget.texture;
			this.separableBlurMaterials[ i ].uniforms[ "direction" ].value = THREE.UnrealBloomPass.BlurDirectionX;
			renderer.render( this.scene, this.camera, this.renderTargetsHorizontal[ i ], true );

			this.separableBlurMaterials[ i ].uniforms[ "colorTexture" ].value = this.renderTargetsHorizontal[ i ].texture;
			this.separableBlurMaterials[ i ].uniforms[ "direction" ].value = THREE.UnrealBloomPass.BlurDirectionY;
			renderer.render( this.scene, this.camera, this.renderTargetsVertical[ i ], true );

			inputRenderTarget = this.renderTargetsVertical[ i ];

		}

		// Composite All the mips

		this.quad.material = this.compositeMaterial;
		this.compositeMaterial.uniforms[ "bloomStrength" ].value = this.strength;
		this.compositeMaterial.uniforms[ "bloomRadius" ].value = this.radius;
		this.compositeMaterial.uniforms[ "bloomTintColors" ].value = this.bloomTintColors;

		renderer.render( this.scene, this.camera, this.renderTargetsHorizontal[ 0 ], true );

		// Blend it additively over the input texture

		this.quad.material = this.materialCopy;
		this.copyUniforms[ "tDiffuse" ].value = this.renderTargetsHorizontal[ 0 ].texture;

		if ( maskActive ) renderer.context.enable( renderer.context.STENCIL_TEST );


		if ( this.renderToScreen ) {

			renderer.render( this.scene, this.camera, undefined, false );

		} else {

			renderer.render( this.scene, this.camera, readBuffer, false );

		}

		// Restore renderer settings

		renderer.setClearColor( this.oldClearColor, this.oldClearAlpha );
		renderer.autoClear = oldAutoClear;

	},

	getSeperableBlurMaterial: function ( kernelRadius ) {

		return new THREE.ShaderMaterial( {

			defines: {
				"KERNEL_RADIUS": kernelRadius,
				"SIGMA": kernelRadius
			},

			uniforms: {
				"colorTexture": { value: null },
				"texSize": { value: new THREE.Vector2( 0.5, 0.5 ) },
				"direction": { value: new THREE.Vector2( 0.5, 0.5 ) }
			},

			vertexShader:
				"varying vec2 vUv;\n\
				void main() {\n\
					vUv = uv;\n\
					gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );\n\
				}",

			fragmentShader:
				"#include <common>\
				varying vec2 vUv;\n\
				uniform sampler2D colorTexture;\n\
				uniform vec2 texSize;\
				uniform vec2 direction;\
				\
				float gaussianPdf(in float x, in float sigma) {\
					return 0.39894 * exp( -0.5 * x * x/( sigma * sigma))/sigma;\
				}\
				void main() {\n\
					vec2 invSize = 1.0 / texSize;\
					float fSigma = float(SIGMA);\
					float weightSum = gaussianPdf(0.0, fSigma);\
					vec3 diffuseSum = texture2D( colorTexture, vUv).rgb * weightSum;\
					for( int i = 1; i < KERNEL_RADIUS; i ++ ) {\
						float x = float(i);\
						float w = gaussianPdf(x, fSigma);\
						vec2 uvOffset = direction * invSize * x;\
						vec3 sample1 = texture2D( colorTexture, vUv + uvOffset).rgb;\
						vec3 sample2 = texture2D( colorTexture, vUv - uvOffset).rgb;\
						diffuseSum += (sample1 + sample2) * w;\
						weightSum += 2.0 * w;\
					}\
					gl_FragColor = vec4(diffuseSum/weightSum, 1.0);\n\
				}"
		} );

	},

	getCompositeMaterial: function ( nMips ) {

		return new THREE.ShaderMaterial( {

			defines: {
				"NUM_MIPS": nMips
			},

			uniforms: {
				"blurTexture1": { value: null },
				"blurTexture2": { value: null },
				"blurTexture3": { value: null },
				"blurTexture4": { value: null },
				"blurTexture5": { value: null },
				"dirtTexture": { value: null },
				"bloomStrength": { value: 1.0 },
				"bloomFactors": { value: null },
				"bloomTintColors": { value: null },
				"bloomRadius": { value: 0.0 }
			},

			vertexShader:
				"varying vec2 vUv;\n\
				void main() {\n\
					vUv = uv;\n\
					gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );\n\
				}",

			fragmentShader:
				"varying vec2 vUv;\
				uniform sampler2D blurTexture1;\
				uniform sampler2D blurTexture2;\
				uniform sampler2D blurTexture3;\
				uniform sampler2D blurTexture4;\
				uniform sampler2D blurTexture5;\
				uniform sampler2D dirtTexture;\
				uniform float bloomStrength;\
				uniform float bloomRadius;\
				uniform float bloomFactors[NUM_MIPS];\
				uniform vec3 bloomTintColors[NUM_MIPS];\
				\
				float lerpBloomFactor(const in float factor) { \
					float mirrorFactor = 1.2 - factor;\
					return mix(factor, mirrorFactor, bloomRadius);\
				}\
				\
				void main() {\
					gl_FragColor = bloomStrength * ( lerpBloomFactor(bloomFactors[0]) * vec4(bloomTintColors[0], 1.0) * texture2D(blurTexture1, vUv) + \
													 lerpBloomFactor(bloomFactors[1]) * vec4(bloomTintColors[1], 1.0) * texture2D(blurTexture2, vUv) + \
													 lerpBloomFactor(bloomFactors[2]) * vec4(bloomTintColors[2], 1.0) * texture2D(blurTexture3, vUv) + \
													 lerpBloomFactor(bloomFactors[3]) * vec4(bloomTintColors[3], 1.0) * texture2D(blurTexture4, vUv) + \
													 lerpBloomFactor(bloomFactors[4]) * vec4(bloomTintColors[4], 1.0) * texture2D(blurTexture5, vUv) );\
				}"
		} );

	}

} );

THREE.UnrealBloomPass.BlurDirectionX = new THREE.Vector2( 1.0, 0.0 );
THREE.UnrealBloomPass.BlurDirectionY = new THREE.Vector2( 0.0, 1.0 );
