Transform mime-db (js) to mime_guess (rust)

index.js

const fs = require('fs')


/**
 * Usage:
 * npm install
 * node index.js > mime_types.rs
 *
 * IANA takes precedence over other sources.
 */
const compare = require('compare')
const types = require('./node_modules/mime-db/db.json')
const extensions = new Map()

// Fill Map "ext" => "mime" and log out duplicates
for (let mime in types) {
  if (!types[mime].extensions) {
    continue;
  }

  types[mime].extensions.forEach((extension) => {
    if (extensions.get(extension)) {
      // because one choice possible iana overrides the previous one
      if (types[mime].source === 'iana') {
        console.error('Source of the mime type is IANA, replacing "%s" with "%s"', extensions.get(extension), mime)
        extensions.set(extension, mime)
        return
      }

      console.error('Extension "%s" already has a mime type ("%s") registered can not add "%s" given by "%s".', extension, extensions.get(extension), mime)
      return
    }

    extensions.set(extension, mime)
  })
}

/**
 * Adding data from existing rust file
 */
const data = fs.readFileSync('./old.rs').toString('utf8')

data.split('\n').forEach((line) => {
  if (!/\("/.test(line)) {
    return
  }

  const matches = line.match(/\("(.*?)", "(.*?)"/)

  if (!extensions.get(matches[1])) {
    extensions.set(matches[1], matches[2])
  }
})


// Create rust code
console.log(`pub static MIME_TYPES: &'static [(&'static str, &'static str)] = &[`)
Array
  .from(extensions)
  .sort((a, b) => {
    // a[0], b[0] is the key of the map
    return compare(a[0], b[0]);
  })
  .forEach(([ext, mime]) => {
    console.log(`    ("${ext}", "${mime}"),`)
  })
console.log('];')

package.json

{
  "name": "mime-db-to-mime_guess",
  "version": "0.0.0",
  "main": "index.js",
  "author": "soyuka",
  "license": "WTFPL",
  "dependencies": {
    "compare": "^2.0.0",
    "mime-db": "^1.34.0"
  }
}