import {
  Color,
  FrontSide,
  LinearFilter,
  MathUtils,
  Matrix4,
  Mesh,
  PerspectiveCamera,
  Plane,
  RGBFormat,
  ShaderMaterial,
  UniformsLib,
  UniformsUtils,
  Vector3,
  Vector4,
  WebGLRenderTarget
} from '../../../build/three.module.js';

/**
 * Work based on :
 * http://slayvin.net : Flat mirror for three.js
 * http://www.adelphi.edu/~stemkoski : An implementation of water shader based on the flat mirror
 * http://29a.ch/ && http://29a.ch/slides/2012/webglwater/ : Water shader explanations in WebGL
 */

class Water extends Mesh {

  constructor(geometry, options = {}) {

    super(geometry);

    const scope = this;

    const textureWidth = options.textureWidth !== undefined ? options.textureWidth : 512;
    const textureHeight = options.textureHeight !== undefined ? options.textureHeight : 512;

    const clipBias = options.clipBias !== undefined ? options.clipBias : 0.0;
    const alpha = options.alpha !== undefined ? options.alpha : 1.0;
    const time = options.time !== undefined ? options.time : 0.0;
    const normalSampler = options.waterNormals !== undefined ? options.waterNormals : null;
    const sunDirection = options.sunDirection !== undefined ? options.sunDirection : new Vector3(0.70707, 0.70707, 0.0);
    const sunColor = new Color(options.sunColor !== undefined ? options.sunColor : 0xffffff);
    const waterColor = new Color(options.waterColor !== undefined ? options.waterColor : 0x7F7F7F);
    const eye = options.eye !== undefined ? options.eye : new Vector3(0, 0, 0);
    const distortionScale = options.distortionScale !== undefined ? options.distortionScale : 20.0;
    const side = options.side !== undefined ? options.side : FrontSide;
    const fog = options.fog !== undefined ? options.fog : false;

    //

    const mirrorPlane = new Plane();
    const normal = new Vector3();
    const mirrorWorldPosition = new Vector3();
    const cameraWorldPosition = new Vector3();
    const rotationMatrix = new Matrix4();
    const lookAtPosition = new Vector3(0, 0, - 1);
    const clipPlane = new Vector4();

    const view = new Vector3();
    const target = new Vector3();
    const q = new Vector4();

    const textureMatrix = new Matrix4();

    const mirrorCamera = new PerspectiveCamera();

    const parameters = {
      minFilter: LinearFilter,
      magFilter: LinearFilter,
      format: RGBFormat
    };

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

    if (!MathUtils.isPowerOfTwo(textureWidth) || !MathUtils.isPowerOfTwo(textureHeight)) {

      renderTarget.texture.generateMipmaps = false;

    }

    const mirrorShader = {

      uniforms: UniformsUtils.merge([
        UniformsLib['fog'],
        UniformsLib['lights'],
        {
          'normalSampler': { value: null },
          'mirrorSampler': { value: null },
          'alpha': { value: 1.0 },
          'time': { value: 0.0 },
          'size': { value: 1.0 },
          'distortionScale': { value: 20.0 },
          'textureMatrix': { value: new Matrix4() },
          'sunColor': { value: new Color(0x7F7F7F) },
          'sunDirection': { value: new Vector3(0.70707, 0.70707, 0) },
          'eye': { value: new Vector3() },
          'waterColor': { value: new Color(0x555555) }
        }
      ]),

      vertexShader: /* glsl */`
				uniform mat4 textureMatrix;
				uniform float time;

				varying vec4 mirrorCoord;
				varying vec4 worldPosition;

				#include <common>
				#include <fog_pars_vertex>
				#include <shadowmap_pars_vertex>
				#include <logdepthbuf_pars_vertex>

				void main() {
					mirrorCoord = modelMatrix * vec4( position, 1.0 );
					worldPosition = mirrorCoord.xyzw;
					mirrorCoord = textureMatrix * mirrorCoord;
					vec4 mvPosition =  modelViewMatrix * vec4( position, 1.0 );
					gl_Position = projectionMatrix * mvPosition;

				#include <beginnormal_vertex>
				#include <defaultnormal_vertex>
				#include <logdepthbuf_vertex>
				#include <fog_vertex>
				#include <shadowmap_vertex>
			}`,

      fragmentShader: /* glsl */`
				uniform sampler2D mirrorSampler;
				uniform float alpha;
				uniform float time;
				uniform float size;
				uniform float distortionScale;
				uniform sampler2D normalSampler;
				uniform vec3 sunColor;
				uniform vec3 sunDirection;
				uniform vec3 eye;
				uniform vec3 waterColor;

				varying vec4 mirrorCoord;
				varying vec4 worldPosition;

				vec4 getNoise( vec2 uv ) {
					vec2 uv0 = ( uv / 103.0 ) + vec2(time / 17.0, time / 29.0);
					vec2 uv1 = uv / 107.0-vec2( time / -19.0, time / 31.0 );
					vec2 uv2 = uv / vec2( 8907.0, 9803.0 ) + vec2( time / 101.0, time / 97.0 );
					vec2 uv3 = uv / vec2( 1091.0, 1027.0 ) - vec2( time / 109.0, time / -113.0 );
					vec4 noise = texture2D( normalSampler, uv0 ) +
						texture2D( normalSampler, uv1 ) +
						texture2D( normalSampler, uv2 ) +
						texture2D( normalSampler, uv3 );
					return noise * 0.5 - 1.0;
				}

				void sunLight( const vec3 surfaceNormal, const vec3 eyeDirection, float shiny, float spec, float diffuse, inout vec3 diffuseColor, inout vec3 specularColor ) {
					vec3 reflection = normalize( reflect( -sunDirection, surfaceNormal ) );
					float direction = max( 0.0, dot( eyeDirection, reflection ) );
					specularColor += pow( direction, shiny ) * sunColor * spec;
					diffuseColor += max( dot( sunDirection, surfaceNormal ), 0.0 ) * sunColor * diffuse;
				}

				#include <common>
				#include <packing>
				#include <bsdfs>
				#include <fog_pars_fragment>
				#include <logdepthbuf_pars_fragment>
				#include <lights_pars_begin>
				#include <shadowmap_pars_fragment>
				#include <shadowmask_pars_fragment>

				void main() {

					#include <logdepthbuf_fragment>
					vec4 noise = getNoise( worldPosition.xz * size );
					vec3 surfaceNormal = normalize( noise.xzy * vec3( 1.5, 1.0, 1.5 ) );

					vec3 diffuseLight = vec3(0.0);
					vec3 specularLight = vec3(0.0);

					vec3 worldToEye = eye-worldPosition.xyz;
					vec3 eyeDirection = normalize( worldToEye );
					sunLight( surfaceNormal, eyeDirection, 100.0, 2.0, 0.5, diffuseLight, specularLight );

					float distance = length(worldToEye);

					vec2 distortion = surfaceNormal.xz * ( 0.001 + 1.0 / distance ) * distortionScale;
					vec3 reflectionSample = vec3( texture2D( mirrorSampler, mirrorCoord.xy / mirrorCoord.w + distortion ) );

					float theta = max( dot( eyeDirection, surfaceNormal ), 0.0 );
					float rf0 = 0.3;
					float reflectance = rf0 + ( 1.0 - rf0 ) * pow( ( 1.0 - theta ), 5.0 );
					vec3 scatter = max( 0.0, dot( surfaceNormal, eyeDirection ) ) * waterColor;
					vec3 albedo = mix( ( sunColor * diffuseLight * 0.3 + scatter ) * getShadowMask(), ( vec3( 0.1 ) + reflectionSample * 0.9 + reflectionSample * specularLight ), reflectance);
					vec3 outgoingLight = albedo;
					gl_FragColor = vec4( outgoingLight, alpha );

					#include <tonemapping_fragment>
					#include <fog_fragment>
				}`

    };

    const material = new ShaderMaterial({
      fragmentShader: mirrorShader.fragmentShader,
      vertexShader: mirrorShader.vertexShader,
      uniforms: UniformsUtils.clone(mirrorShader.uniforms),
      lights: true,
      side: side,
      fog: fog
    });

    material.uniforms['mirrorSampler'].value = renderTarget.texture;
    material.uniforms['textureMatrix'].value = textureMatrix;
    material.uniforms['alpha'].value = alpha;
    material.uniforms['time'].value = time;
    material.uniforms['normalSampler'].value = normalSampler;
    material.uniforms['sunColor'].value = sunColor;
    material.uniforms['waterColor'].value = waterColor;
    material.uniforms['sunDirection'].value = sunDirection;
    material.uniforms['distortionScale'].value = distortionScale;

    material.uniforms['eye'].value = eye;

    scope.material = material;

    scope.onBeforeRender = function (renderer, scene, camera) {

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

      rotationMatrix.extractRotation(scope.matrixWorld);

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

      view.subVectors(mirrorWorldPosition, cameraWorldPosition);

      // Avoid rendering when mirror is facing away

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

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

      rotationMatrix.extractRotation(camera.matrixWorld);

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

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

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

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

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

      // 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(mirrorCamera.projectionMatrix);
      textureMatrix.multiply(mirrorCamera.matrixWorldInverse);

      // Now update projection matrix with new clip plane, implementing code from: http://www.terathon.com/code/oblique.html
      // Paper explaining this technique: http://www.terathon.com/lengyel/Lengyel-Oblique.pdf
      mirrorPlane.setFromNormalAndCoplanarPoint(normal, mirrorWorldPosition);
      mirrorPlane.applyMatrix4(mirrorCamera.matrixWorldInverse);

      clipPlane.set(mirrorPlane.normal.x, mirrorPlane.normal.y, mirrorPlane.normal.z, mirrorPlane.constant);

      const projectionMatrix = mirrorCamera.projectionMatrix;

      q.x = (Math.sign(clipPlane.x) + projectionMatrix.elements[8]) / projectionMatrix.elements[0];
      q.y = (Math.sign(clipPlane.y) + projectionMatrix.elements[9]) / projectionMatrix.elements[5];
      q.z = - 1.0;
      q.w = (1.0 + projectionMatrix.elements[10]) / projectionMatrix.elements[14];

      // Calculate the scaled plane vector
      clipPlane.multiplyScalar(2.0 / clipPlane.dot(q));

      // Replacing the third row of the projection matrix
      projectionMatrix.elements[2] = clipPlane.x;
      projectionMatrix.elements[6] = clipPlane.y;
      projectionMatrix.elements[10] = clipPlane.z + 1.0 - clipBias;
      projectionMatrix.elements[14] = clipPlane.w;

      eye.setFromMatrixPosition(camera.matrixWorld);

      // Render

      const currentRenderTarget = renderer.getRenderTarget();

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

      scope.visible = false;

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

      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, mirrorCamera);

      scope.visible = true;

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

      renderer.setRenderTarget(currentRenderTarget);

      // Restore viewport

      const viewport = camera.viewport;

      if (viewport !== undefined) {

        renderer.state.viewport(viewport);

      }

    };

  }

}

Water.prototype.isWater = true;

export { Water };