import * as THREE from "../../../../libs/three.js/build/three.module.js";
import { vertexShader, fragmentShader } from './shader.js'
import Tween from './Tween.js'
import Particle from './Particle.js'
import {util} from './Util.js'
import { Shape } from './const.js'


let particleTexture  

const getTexture = ()=>{
    if(!particleTexture){
        particleTexture = new THREE.TextureLoader().load( Potree.resourcePath+'/textures/explode.png')
    }
    return particleTexture
}

const defaults = {
    position: new THREE.Vector3(0, 0 , 4),
     
    positionShape: Shape.SPHERE,
    
    positionRange : new THREE.Vector3(1,1,1),       //cube
    
    positionRadius: 3,     //sphere
    
    velocityShape: Shape.SPHERE,
    
    velocity: new THREE.Vector3(0.3,0.3, 2),   //cube
    velocityRange: new THREE.Vector3(1, 1, 2), 
    speed : 1,            //sphere
    speedRange : 10,
    
    size: 0.4,
    sizeRange: 2,
    //sizeTween: new Tween( [0, 0.05, 0.3, 0.45], [0, 1, 3, 0.1] ),
    sizeTween: new Tween(  ),
    
    
    color : new THREE.Vector3(1.0, 1.0, 1.0),
    colorRange : new THREE.Vector3(0.0, 0.0, 0.0),
    colorTween : new Tween(),
    
    opacity : 1.0,
    opacityRange : 0.0 ,
    opacityTween: new Tween( [0, 0.05, 0.3, 0.45], [1, 1, 0.5, 0] ), 
    blendMode: THREE.AdditiveBlending,
    	 
    acceleration : 0.1,         
    accelerationRange : 0.5,
 
    angle : 0,
    angleRange : 0,
    angleVelocity : 0,
    angleVelocityRange :  0,
    angleAcceleration : 0,
    angleAccelerationRange : 0,
 
    particlesPerSecond: 10,
    particleDeathAge: 1,


	
}



class ExplodeParticle extends THREE.Points{

  constructor(params) {
    super()
    this.particles = []
     
   

    this.age = 0
    this.alive = true
    this.deathAge = 60
    this.loop = true
       
    
    viewer.on('pageVisible', (state)=>{   
        if(state){//重新一个个放出粒子，否则会一股脑儿全部出来，因为同时大于粒子周期了一起重新生成出现。
            setTimeout(()=>{//会先update一次delta为pageUnvisile的时间才触发
                //归零
                console.log('归零')
                this.age = 0;
                
                this.geometry.dispose()
                
                this.createParticles() 
            },1) 
        }  
    }) 
    

    

    this.blendMode = THREE.NormalBlending

    this.setParameters(params)
    this.createParticles()
  }



  setParameters(params) {
    for ( var key in defaults ){
        let value = params[key] != void 0 ? params[key] : defaults[ key ]
        if(key == 'position') this.position.copy(value) 
        else if(value instanceof Array && value[0] instanceof Array  ) this[ key ] = new Tween(...value)
        else this[ key ] = value;	
    }  
    //Object.assign(this, params) 
    

    this.particles = []
    this.age = 0.0
    this.alive = true
    this.particleCount = this.particlesPerSecond * Math.min(this.particleDeathAge, this.deathAge)

    this.geometry = new THREE.BufferGeometry()
    this.material = new THREE.ShaderMaterial({
      uniforms: {
        u_sampler: { value: this.texture ||  getTexture() }
      },
      vertexShader,
      fragmentShader,
      transparent: true,
      alphaTest: 0.5,
      depthTest: false,
      blending: THREE.AdditiveBlending
    })
    

  }








  createParticles() {
    const count = this.particleCount 
    const positionArray = new Float32Array(count * 3)
    const colorArray = new Float32Array(count * 3)

    const sizeArray = new Float32Array(count)
    const angleArray = new Float32Array(count)
    const opacityArray = new Float32Array(count)
    const visibleArray = new Float32Array(count)
    
    for(let i = 0; i < count; i++) {
      const particle = this.createParticle()
      positionArray[i*3] = particle.position.x
      positionArray[i*3+1] = particle.position.y
      positionArray[i*3+2] = particle.position.z
      colorArray[i*3] = particle.color.r
      colorArray[i*3+1] = particle.color.g
      colorArray[i*3+2] = particle.color.b
      sizeArray[i] = particle.size
      angleArray[i] = particle.angel
      opacityArray[i] = particle.opacity
      visibleArray[i] = particle.alive
      this.particles[i] = particle
    }
    this.geometry.setAttribute('position', new THREE.BufferAttribute(positionArray, 3))
    this.geometry.setAttribute('color', new THREE.BufferAttribute(colorArray, 3))
    this.geometry.setAttribute('angle', new THREE.BufferAttribute(angleArray, 1))
    this.geometry.setAttribute('size', new THREE.BufferAttribute(sizeArray, 1))
    this.geometry.setAttribute('visible', new THREE.BufferAttribute(visibleArray, 1))
    this.geometry.setAttribute('opacity', new THREE.BufferAttribute(opacityArray, 1))

    this.material.blending = this.blendMode
    if(this.blendMode != THREE.NormalBlending) {
        this.material.depthTest = false
    }
    
  }





  

  createParticle() {

    const particle = new Particle()
    particle.sizeTween = this.sizeTween
    particle.colorTween = this.colorTween
    particle.opacityTween = this.opacityTween
    particle.deathAge = this.particleDeathAge

    if(this.positionShape == Shape.CUBE) {
      particle.position = util.randomVector3(new THREE.Vector3, this.positionRange)
    }

    if(this.positionShape == Shape.SPHERE) {
      const z = 2 * Math.random() - 1
      const t = Math.PI * 2 * Math.random()
      const r = Math.sqrt(1 - z*z)
      const vec3 = new THREE.Vector3(r * Math.cos(t), r * Math.sin(t), z)
      particle.position = vec3.multiplyScalar(this.positionRadius) 
    }

    if(this.velocityShape == Shape.CUBE) {
        particle.velocity = util.randomVector3(this.velocity, this.velocityRange)
        
    }

    if(this.velocityShape == Shape.SPHERE) {
      const direction = particle.position.clone()
      const speed = util.randomValue(this.speed, this.speedRange)
      particle.velocity = direction.normalize().multiplyScalar(speed)  
    }

    particle.acceleration = util.randomValue(this.acceleration, this.accelerationRange)  
    
    particle.angle = util.randomValue(this.angle, this.angleRange)
    particle.angleVelocity = util.randomValue(this.angleVelocity, this.angleVelocityRange)
    particle.angleAcceleration = util.randomValue(this.angleAcceleration, this.angleAccelerationRange)

    particle.size = util.randomValue(this.size, this.sizeRange)

    const color = util.randomVector3(this.color, this.colorRange)
    particle.color = new THREE.Color().setHSL(color.x, color.y, color.z)

    particle.opacity = util.randomValue(this.opacity, this.opacityRange)
    particle.age = 0

    return particle
  }

  update(dt) {
    dt *= 0.5
    
    const recycleIndices = []
    const positionArray = this.geometry.attributes.position.array
    const opacityArray = this.geometry.attributes.opacity.array
    const visibleArray = this.geometry.attributes.visible.array
    const colorArray = this.geometry.attributes.color.array
    const angleArray = this.geometry.attributes.angle.array
    const sizeArray = this.geometry.attributes.size.array

    for(let i = 0; i < this.particleCount; i++) {
      const particle = this.particles[i]
      if(particle.alive) {
        particle.update(dt)
        if(particle.age > this.particleDeathAge) {
				  particle.alive = 0.0
				  recycleIndices.push(i)
        }
        positionArray[i*3] = particle.position.x
        positionArray[i*3+1] = particle.position.y
        positionArray[i*3+2] = particle.position.z
        colorArray[i*3] = particle.color.r
        colorArray[i*3+1] = particle.color.g
        colorArray[i*3+2] = particle.color.b
        visibleArray[i] = particle.alive
        opacityArray[i] = particle.opacity
        angleArray[i] = particle.angle
        sizeArray[i] = particle.size
      }
    }
    
    this.geometry.attributes.size.needsUpdate = true
    this.geometry.attributes.color.needsUpdate = true
    this.geometry.attributes.angle.needsUpdate = true
    this.geometry.attributes.visible.needsUpdate = true
    this.geometry.attributes.opacity.needsUpdate = true
    this.geometry.attributes.position.needsUpdate = true

    if(!this.alive) return

    if(this.age < this.particleDeathAge) {
      let startIndex = Math.round(this.particlesPerSecond * (this.age + 0))
      let endIndex = Math.round(this.particlesPerSecond * (this.age + dt))
      if(endIndex > this.particleCount) {
        endIndex = this.particleCount
      }
      for(let i = startIndex; i < endIndex; i++) {
        this.particles[i].alive = 1.0
      }
    }

    for(let j = 0;j < recycleIndices.length; j++) {
      let i = recycleIndices[j]
      this.particles[i] = this.createParticle()
      this.particles[i].alive = 1.0
      positionArray[i*3] = this.particles[i].position.x
      positionArray[i*3+1] = this.particles[i].position.y
      positionArray[i*3+2] = this.particles[i].position.z
    }
    this.geometry.attributes.position.needsUpdate = true

    this.age += dt

    if(this.age > this.deathAge && !this.loop) {
      this.alive = false
    }

  }


}

export default ExplodeParticle