// -------------------------------------------------------------------------------------------------
// JavaScript Snow Effect - © Copyright 2020 - Jam-Es.com
// Licensed under the MIT License (MIT). See LICENSE in the repo root for license information.
// -------------------------------------------------------------------------------------------------

// Change the following variables to customize the appearance of the particles
let numParticles = window.innerWidth / 50
let maxSpeed = 2.5
let minSpeed = 1
let maxSize = 5
let minSize = 3
let maxOpacity = 1
let minOpacity = 0.2

// If the following is true, the canvas resolution will be set to match the full viewport width and height.
// var fixCanvasResolution = true;

let snow_particles = []

let canvas

window.onload = function() {
  canvas = document.createElement('canvas')
  canvas.style.position = 'fixed'
  canvas.style.top = '0px'
  canvas.style.left = '0px'
  canvas.style.pointerEvents = 'none'
  canvas.style.zIndex = 100
  canvas.width = document.documentElement.clientWidth
  canvas.height = document.documentElement.clientHeight
  document.body.appendChild(canvas)

  // if (fixCanvasResolution) {
  //  // canvas.width = window.innerWidth;
  //  canvas.height = window.innerHeight;
  // }

  InitPoints()

  window.requestAnimationFrame(Redraw, 15)
  window.addEventListener('resize', this.onWindowResize)
}
// function onWindowResize(e) {
//   canvas.width = document.documentElement.clientWidth
//   canvas.height = document.documentElement.clientHeight
// }

function Redraw() {
  let ctx = canvas.getContext('2d')
  ctx.clearRect(0, 0, canvas.width, canvas.height)
  for (let i = 0; i < snow_particles.length; i++) {
    let newYPos = snow_particles[i].yPos + snow_particles[i].speed
    if (newYPos > window.innerHeight) {
      newYPos = getRandomInt(-100, -10)
      snow_particles[i].xPos = getRandomInt(0, window.innerWidth)
      snow_particles[i].speed = Math.random() * (maxSpeed - minSpeed) + minSpeed
      snow_particles[i].opacity = Math.random() * (maxOpacity - minOpacity) + minOpacity
      snow_particles[i].size = Math.random() * (maxSize - minSize) + minSize
    }
    snow_particles[i].yPos = newYPos
    ctx.beginPath()
    ctx.arc(snow_particles[i].xPos, newYPos, snow_particles[i].size, 0, 2 * Math.PI)
    ctx.fillStyle = 'rgba(255, 255, 255, ' + snow_particles[i].opacity + ')'
    ctx.fill()
  }
  window.requestAnimationFrame(Redraw)
}

function InitPoints() {
  for (let i = 0; i < numParticles; i++) {
    let startX = getRandomInt(0, window.innerWidth)
    let startY = getRandomInt(0, window.innerHeight)
    let speed = Math.random() * (maxSpeed - minSpeed) + minSpeed
    let opacity = Math.random() * (maxOpacity - minOpacity) + minOpacity
    let size = Math.random() * (maxSize - minSize) + minSize

    snow_particles.push({
      xPos: startX,
      yPos: startY,
      speed,
      opacity,
      size,
    })
  }
}

function getRandomInt(min, max) {
  min = Math.ceil(min)
  max = Math.floor(max)
  return Math.floor(Math.random() * (max - min)) + min
}