const fs = require('fs')

function usage () {
  console.log(`
Usage: csv2colormap.js <id> <name> <csv_file> <json_file>

Given a CSV file with red, green, and blue values in the range
of 0-255, create a colormap JSON file that goes in the
common/config/palettes-custom.json directory.
  `)
}

if (process.argv.length !== 4 + 2) {
  usage()
  // process.exit(1)
  throw new Error('Incorrect argv length')
}

const [id, name, csvFile, jsonFile] = process.argv.slice(2)
const file = fs.readFileSync(csvFile, 'utf8')
const lines = file.split('\n')
const colors = []
for (const line of lines) {
  if (line.trim().length !== 0) {
    const [r, g, b] = line.split(',')
    const color = `${hex(r)}${hex(g)}${hex(b)}ff`
    colors.push(color)
  }
}

const colormap = {
  [id]: {
    id,
    name,
    colors
  }
}
fs.writeFileSync(jsonFile, JSON.stringify(colormap))

// decimal to hex for bytes, 10 => 0a
function hex (dec) {
  dec = Number.parseInt(dec, 10)
  let h = dec.toString(16)
  if (h.length === 1) {
    h = `0${h}`
  }
  return h
}