import {
	Color,
	Matrix4,
	Mesh,
	PerspectiveCamera,
	ShaderMaterial,
	UniformsUtils,
	Vector2,
	Vector3,
	WebGLRenderTarget,
	DepthTexture,
	UnsignedShortType,
	NearestFilter,
	Plane,
	HalfFloatType
} from 'three';

/**
 * A special version of {@link Reflector} for usage with {@link SSRPass}.
 *
 * @augments Mesh
 * @three_import import { ReflectorForSSRPass } from 'three/addons/objects/ReflectorForSSRPass.js';
 */
class ReflectorForSSRPass extends Mesh {

	/**
	 * Constructs a new reflector.
	 *
	 * @param {BufferGeometry} geometry - The reflector's geometry.
	 * @param {ReflectorForSSRPass~Options} [options] - The configuration options.
	 */
	constructor( geometry, options = {} ) {

		super( geometry );

		this.isReflectorForSSRPass = true;

		this.type = 'ReflectorForSSRPass';

		const scope = this;

		const color = ( options.color !== undefined ) ? new Color( options.color ) : new Color( 0x7F7F7F );
		const textureWidth = options.textureWidth || 512;
		const textureHeight = options.textureHeight || 512;
		const clipBias = options.clipBias || 0;
		const shader = options.shader || ReflectorForSSRPass.ReflectorShader;
		const useDepthTexture = options.useDepthTexture === true;
		const yAxis = new Vector3( 0, 1, 0 );
		const vecTemp0 = new Vector3();
		const vecTemp1 = new Vector3();

		//

		scope.needsUpdate = false;
		scope.maxDistance = ReflectorForSSRPass.ReflectorShader.uniforms.maxDistance.value;
		scope.opacity = ReflectorForSSRPass.ReflectorShader.uniforms.opacity.value;
		scope.color = color;
		scope.resolution = options.resolution || new Vector2( window.innerWidth, window.innerHeight );


		scope._distanceAttenuation = ReflectorForSSRPass.ReflectorShader.defines.DISTANCE_ATTENUATION;
		Object.defineProperty( scope, 'distanceAttenuation', {
			get() {

				return scope._distanceAttenuation;

			},
			set( val ) {

				if ( scope._distanceAttenuation === val ) return;
				scope._distanceAttenuation = val;
				scope.material.defines.DISTANCE_ATTENUATION = val;
				scope.material.needsUpdate = true;

			}
		} );

		scope._fresnel = ReflectorForSSRPass.ReflectorShader.defines.FRESNEL;
		Object.defineProperty( scope, 'fresnel', {
			get() {

				return scope._fresnel;

			},
			set( val ) {

				if ( scope._fresnel === val ) return;
				scope._fresnel = val;
				scope.material.defines.FRESNEL = val;
				scope.material.needsUpdate = true;

			}
		} );

		const normal = new Vector3();
		const reflectorWorldPosition = new Vector3();
		const cameraWorldPosition = new Vector3();
		const rotationMatrix = new Matrix4();
		const lookAtPosition = new Vector3( 0, 0, - 1 );

		const view = new Vector3();
		const target = new Vector3();

		const textureMatrix = new Matrix4();
		const virtualCamera = new PerspectiveCamera();

		let depthTexture;

		if ( useDepthTexture ) {

			depthTexture = new DepthTexture();
			depthTexture.type = UnsignedShortType;
			depthTexture.minFilter = NearestFilter;
			depthTexture.magFilter = NearestFilter;

		}

		const parameters = {
			depthTexture: useDepthTexture ? depthTexture : null,
			type: HalfFloatType
		};

		const renderTarget = new WebGLRenderTarget( textureWidth, textureHeight, parameters );

		const material = new ShaderMaterial( {
			name: ( shader.name !== undefined ) ? shader.name : 'unspecified',
			transparent: useDepthTexture,
			defines: Object.assign( {}, ReflectorForSSRPass.ReflectorShader.defines, {
				useDepthTexture
			} ),
			uniforms: UniformsUtils.clone( shader.uniforms ),
			fragmentShader: shader.fragmentShader,
			vertexShader: shader.vertexShader
		} );

		material.uniforms[ 'tDiffuse' ].value = renderTarget.texture;
		material.uniforms[ 'color' ].value = scope.color;
		material.uniforms[ 'textureMatrix' ].value = textureMatrix;
		if ( useDepthTexture ) {

			material.uniforms[ 'tDepth' ].value = renderTarget.depthTexture;

		}

		this.material = material;

		const globalPlane = new Plane( new Vector3( 0, 1, 0 ), clipBias );
		const globalPlanes = [ globalPlane ];

		this.doRender = function ( renderer, scene, camera ) {

			material.uniforms[ 'maxDistance' ].value = scope.maxDistance;
			material.uniforms[ 'color' ].value = scope.color;
			material.uniforms[ 'opacity' ].value = scope.opacity;

			vecTemp0.copy( camera.position ).normalize();
			vecTemp1.copy( vecTemp0 ).reflect( yAxis );
			material.uniforms[ 'fresnelCoe' ].value = ( vecTemp0.dot( vecTemp1 ) + 1. ) / 2.; // TODO: Also need to use glsl viewPosition and viewNormal per pixel.

			reflectorWorldPosition.setFromMatrixPosition( scope.matrixWorld );
			cameraWorldPosition.setFromMatrixPosition( camera.matrixWorld );

			rotationMatrix.extractRotation( scope.matrixWorld );

			normal.set( 0, 0, 1 );
			normal.applyMatrix4( rotationMatrix );

			view.subVectors( reflectorWorldPosition, cameraWorldPosition );

			// Avoid rendering when reflector is facing away

			if ( view.dot( normal ) > 0 ) return;

			view.reflect( normal ).negate();
			view.add( reflectorWorldPosition );

			rotationMatrix.extractRotation( camera.matrixWorld );

			lookAtPosition.set( 0, 0, - 1 );
			lookAtPosition.applyMatrix4( rotationMatrix );
			lookAtPosition.add( cameraWorldPosition );

			target.subVectors( reflectorWorldPosition, lookAtPosition );
			target.reflect( normal ).negate();
			target.add( reflectorWorldPosition );

			virtualCamera.position.copy( view );
			virtualCamera.up.set( 0, 1, 0 );
			virtualCamera.up.applyMatrix4( rotationMatrix );
			virtualCamera.up.reflect( normal );
			virtualCamera.lookAt( target );

			virtualCamera.far = camera.far; // Used in WebGLBackground

			virtualCamera.updateMatrixWorld();
			virtualCamera.projectionMatrix.copy( camera.projectionMatrix );

			material.uniforms[ 'virtualCameraNear' ].value = camera.near;
			material.uniforms[ 'virtualCameraFar' ].value = camera.far;
			material.uniforms[ 'virtualCameraMatrixWorld' ].value = virtualCamera.matrixWorld;
			material.uniforms[ 'virtualCameraProjectionMatrix' ].value = camera.projectionMatrix;
			material.uniforms[ 'virtualCameraProjectionMatrixInverse' ].value = camera.projectionMatrixInverse;
			material.uniforms[ 'resolution' ].value = scope.resolution;

			// Update the texture matrix
			textureMatrix.set(
				0.5, 0.0, 0.0, 0.5,
				0.0, 0.5, 0.0, 0.5,
				0.0, 0.0, 0.5, 0.5,
				0.0, 0.0, 0.0, 1.0
			);
			textureMatrix.multiply( virtualCamera.projectionMatrix );
			textureMatrix.multiply( virtualCamera.matrixWorldInverse );
			textureMatrix.multiply( scope.matrixWorld );

			// scope.visible = false;

			const currentRenderTarget = renderer.getRenderTarget();

			const currentXrEnabled = renderer.xr.enabled;
			const currentShadowAutoUpdate = renderer.shadowMap.autoUpdate;
			const currentClippingPlanes = renderer.clippingPlanes;

			renderer.xr.enabled = false; // Avoid camera modification
			renderer.shadowMap.autoUpdate = false; // Avoid re-computing shadows
			renderer.clippingPlanes = globalPlanes;

			renderer.setRenderTarget( renderTarget );

			renderer.state.buffers.depth.setMask( true ); // make sure the depth buffer is writable so it can be properly cleared, see #18897

			if ( renderer.autoClear === false ) renderer.clear();
			renderer.render( scene, virtualCamera );

			renderer.xr.enabled = currentXrEnabled;
			renderer.shadowMap.autoUpdate = currentShadowAutoUpdate;
			renderer.clippingPlanes = currentClippingPlanes;

			renderer.setRenderTarget( currentRenderTarget );

			// Restore viewport

			const viewport = camera.viewport;

			if ( viewport !== undefined ) {

				renderer.state.viewport( viewport );

			}

			// scope.visible = true;

		};

		/**
		 * Returns the reflector's internal render target.
		 *
		 * @return {WebGLRenderTarget} The internal render target
		 */
		this.getRenderTarget = function () {

			return renderTarget;

		};

		/**
		 * Frees the GPU-related resources allocated by this instance. Call this
		 * method whenever this instance is no longer used in your app.
		 */
		this.dispose = function () {

			renderTarget.dispose();
			scope.material.dispose();

		};

	}

}

ReflectorForSSRPass.ReflectorShader = {

	name: 'ReflectorShader',

	defines: {
		DISTANCE_ATTENUATION: true,
		FRESNEL: true,
	},

	uniforms: {

		color: { value: null },
		tDiffuse: { value: null },
		tDepth: { value: null },
		textureMatrix: { value: new Matrix4() },
		maxDistance: { value: 180 },
		opacity: { value: 0.5 },
		fresnelCoe: { value: null },
		virtualCameraNear: { value: null },
		virtualCameraFar: { value: null },
		virtualCameraProjectionMatrix: { value: new Matrix4() },
		virtualCameraMatrixWorld: { value: new Matrix4() },
		virtualCameraProjectionMatrixInverse: { value: new Matrix4() },
		resolution: { value: new Vector2() },

	},

	vertexShader: /* glsl */`
		uniform mat4 textureMatrix;
		varying vec4 vUv;

		void main() {

			vUv = textureMatrix * vec4( position, 1.0 );

			gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );

		}`,

	fragmentShader: /* glsl */`
		uniform vec3 color;
		uniform sampler2D tDiffuse;
		uniform sampler2D tDepth;
		uniform float maxDistance;
		uniform float opacity;
		uniform float fresnelCoe;
		uniform float virtualCameraNear;
		uniform float virtualCameraFar;
		uniform mat4 virtualCameraProjectionMatrix;
		uniform mat4 virtualCameraProjectionMatrixInverse;
		uniform mat4 virtualCameraMatrixWorld;
		uniform vec2 resolution;
		varying vec4 vUv;
		#include <packing>
		float blendOverlay( float base, float blend ) {
			return( base < 0.5 ? ( 2.0 * base * blend ) : ( 1.0 - 2.0 * ( 1.0 - base ) * ( 1.0 - blend ) ) );
		}
		vec3 blendOverlay( vec3 base, vec3 blend ) {
			return vec3( blendOverlay( base.r, blend.r ), blendOverlay( base.g, blend.g ), blendOverlay( base.b, blend.b ) );
		}
		float getDepth( const in vec2 uv ) {
			return texture2D( tDepth, uv ).x;
		}
		float getViewZ( const in float depth ) {
			return perspectiveDepthToViewZ( depth, virtualCameraNear, virtualCameraFar );
		}
		vec3 getViewPosition( const in vec2 uv, const in float depth/*clip space*/, const in float clipW ) {
			vec4 clipPosition = vec4( ( vec3( uv, depth ) - 0.5 ) * 2.0, 1.0 );//ndc
			clipPosition *= clipW; //clip
			return ( virtualCameraProjectionMatrixInverse * clipPosition ).xyz;//view
		}
		void main() {
			vec4 base = texture2DProj( tDiffuse, vUv );
			#ifdef useDepthTexture
				vec2 uv=(gl_FragCoord.xy-.5)/resolution.xy;
				uv.x=1.-uv.x;
				float depth = texture2DProj( tDepth, vUv ).r;
				float viewZ = getViewZ( depth );
				float clipW = virtualCameraProjectionMatrix[2][3] * viewZ+virtualCameraProjectionMatrix[3][3];
				vec3 viewPosition=getViewPosition( uv, depth, clipW );
				vec3 worldPosition=(virtualCameraMatrixWorld*vec4(viewPosition,1)).xyz;
				if(worldPosition.y>maxDistance) discard;
				float op=opacity;
				#ifdef DISTANCE_ATTENUATION
					float ratio=1.-(worldPosition.y/maxDistance);
					float attenuation=ratio*ratio;
					op=opacity*attenuation;
				#endif
				#ifdef FRESNEL
					op*=fresnelCoe;
				#endif
				gl_FragColor = vec4( blendOverlay( base.rgb, color ), op );
			#else
				gl_FragColor = vec4( blendOverlay( base.rgb, color ), 1.0 );
			#endif
		}
	`,
};

/**
 * Constructor options of `ReflectorForSSRPass`.
 *
 * @typedef {Object} ReflectorForSSRPass~Options
 * @property {number|Color|string} [color=0x7F7F7F] - The reflector's color.
 * @property {number} [textureWidth=512] - The texture width. A higher value results in more clear reflections but is also more expensive.
 * @property {number} [textureHeight=512] - The texture height. A higher value results in more clear reflections but is also more expensive.
 * @property {number} [clipBias=0] - The clip bias.
 * @property {Object} [shader] - Can be used to pass in a custom shader that defines how the reflective view is projected onto the reflector's geometry.
 * @property {boolean} [useDepthTexture=true] - Whether to store depth values in a texture or not.
 **/

export { ReflectorForSSRPass };
