const fs = require("fs")

const srcDir = `${__dirname}/../src/shared/`
const translations = require(`${srcDir}i18n/en.json`)

function getJSFileNames(dir, prevFiles = []) {
  const files = fs.readdirSync(dir)

  files.forEach(file => {
    const name = dir + "/" + file
    if (fs.statSync(name).isDirectory()) {
      getJSFileNames(name, prevFiles)
    } else {
      if (name.endsWith(".js")) {
        prevFiles.push(name)
      }
    }
  })
  return prevFiles
}

function findAndReplace(jsFileContent, translations) {
  const oldImport = `import { translate as t } from "lib/i18n"`
  const newImport = `import { fbt } from "fbt-runtime"`

  const translateMatches = [
    ...jsFileContent.matchAll(new RegExp(/t\("\w+\.(\w+|\.)*\w"\)/, "g")),
  ].map(match => match[0])
  const matchToTranslation = translateMatches.map(match => {
    const translateKey = match.match(new RegExp(/\w+\.(\w+|\.)*\w/, "g"))[0]
    const props = translateKey.split(".")
    const translation = getTranslation(translations, props)
    return {
      match,
      translateKey,
      translation,
    }
  })

  const fbtReplaced = matchToTranslation.reduce((result, m2T) => {
    return result.replace(
      m2T.match,
      `fbt("${m2T.translation}", "${m2T.translateKey}")`
    )
  }, jsFileContent)

  const importAndFbtReplaced = fbtReplaced.replace(oldImport, newImport)

  return importAndFbtReplaced
}

function getTranslation(translation, props) {
  if (props.length === 1) {
    return translation[props[0]]
  }
  return getTranslation(translation[props[0]], props.splice(1, props.length))
}

const jsFileNames = getJSFileNames(srcDir)

jsFileNames.forEach(jsFileName => {
  const jsFileContent = fs.readFileSync(jsFileName)
  const newJSFileContent = findAndReplace(
    jsFileContent.toString(),
    translations
  )
  fs.writeFileSync(jsFileName, newJSFileContent)
})