simplify

#!/usr/bin/env node

const fs = require('fs')
const path = require('path')
const yargs = require('yargs/yargs')
const { JSDOM } = require('jsdom')
const paper = require('paper')
const pluralize = require('pluralize')
const { SVGPathData } = require('svg-pathdata');

const main = async () => {
  const args = (
    yargs(process.argv.slice(2))
    .command(
      '* [files..]',
      'This program uses paper.js to reduce the number of points in an SVG’s <path/>s.',
    )
    .option('tolerance', {
      default: 10,
      alias: 't',
    })
    .demandOption('files')
    .alias('h', 'help')
    .help()
    .showHelpOnFail(true, 'HELP!')
  )
  const argv = await args.argv

  paper.setup(new paper.Canvas(1000, 1000))

  await Promise.all(
    argv.files.map(async (file) => {
      try {
        const out = `${path.basename(file, '.svg')}.simplified.svg`
        try {
          await fs.promises.access(out, fs.F_OK)
          console.error(`Destination ${out} Exists: Skipping`)
        } catch(dne) {
          const dom = (await JSDOM.fromFile(
            file,
            { contentType: 'image/svg+xml' },
          ))
          const { document: doc } = dom.window
          const counts = await Promise.all(
            Array.from(doc.querySelectorAll('path')).map(
              (elem) => {
                const data = elem.getAttribute('d')
                const path = new paper.Path(
                   // paper.js path parsing sometimes fails
                  new SVGPathData(data).encode()
                )
                const preCount = path.segments.length
                path.simplify(argv.tolerance)
                const postCount = path.segments.length
                elem.setAttribute(
                  'd', path.exportSVG().getAttribute('d')
                )
                console.info(
                  `Reduced ${preCount} ${pluralize('segment', preCount)}`
                  + ` to ${postCount}`
                  + ` (-${((preCount - postCount) * 100 / preCount).toFixed(2)}%)`
                )
                return { preCount, postCount }
              }
            )
          )
          console.info(`Writing processed SVG (tolerance: ${argv.tolerance}) to ${out}`)
          await fs.promises.writeFile(out, await dom.serialize())
        }
      } catch(err) {
        console.error(`Couldn’t Load: ${path.basename(file)}`)
        console.error(`  Error: ${err.message}`)
      }
    })
  )
}

main()
.then(() => process.exit(0))
.catch((reason) => console.error(reason))