decode

#!/usr/bin/env node

const fs = require('fs')
const { promisify } = require('util')
const read = promisify(fs.readFile)
const write = promisify(fs.writeFile)
const { arrayBufferToHex, toArrayBuffer } = require('./utils')

main()

async function main() {
  const [
    ,
    ,
    inputFilename,
    outputFilename = `${inputFilename}.encoded`,
  ] = process.argv
  const writeStream = fs.createWriteStream(outputFilename)
  console.log(`${inputFilename} -> ${outputFilename}`)
  console.log(`reading...`)
  const data = await read(inputFilename)
  console.log('decoding...')
  const buf = toArrayBuffer(data)
  const len = (buf.byteLength / 20) >> 0
  const xs = new Uint8Array(buf)
  console.log(`writing...`)
  for (let i = 0; i < len; i++) {
    const a = i * 20
    const b = a + 20
    const addr = arrayBufferToHex(xs.slice(a, b).buffer)
    writeStream.write(addr + '\n')
  }
  console.log('done! ✨')
}