const canvas = require('canvas')
const cnv = canvas.createCanvas(426.6, 240)
const ctx = cnv.getContext('2d')

const colorsys = require('colorsys')

async function convertImage (src, callback) {
  const img = await canvas.loadImage(src).catch(callback)
  if (!img) return
  ctx.drawImage(img, 0, 0, cnv.width, cnv.height)
  const rgba = ctx.getImageData(0, 0, cnv.width, cnv.height).data
  const lines = []
  let line = []
  for (let i = 0; i < rgba.length; i += 4) {
    const r = rgba[i]
    const g = rgba[i + 1]
    const b = rgba[i + 2]
    // const a = rgba[i + 3];
    const hex = colorsys.rgbToHex(r, g, b)
    if (line.length >= 1 && line[line.length - 1].color === hex) { line[line.length - 1].text += '.' } else { line.push({ text: '.', color: hex }) }

    if (((i / 4) % cnv.width) === 0) {
      lines.push(JSON.stringify(line))
      line = []
    }
  }
  callback(undefined, lines)
}

module.exports = convertImage