#!/usr/bin/env node

// [start-readme]
//
// Run this script to fix known frontmatter errors by copying values from english file
// Translatable properties are designated in the frontmatter JSON schema
//
// [end-readme]

const fs = require('fs')
const path = require('path')
const matter = require('gray-matter')
const walk = require('walk-sync')
const readFileAsync = require('../../lib/readfile-async')
const fm = require('../../lib/frontmatter')

// Run!
main()

async function main () {
  const translationDir = path.posix.join(__dirname, '../../translations')
  const translatedMarkdownFiles = walk(translationDir)
    .filter(filename => {
      return filename.includes('/content/') &&
      filename.endsWith('.md') &&
      !filename.endsWith('README.md')
    })
    .map(filename => `translations/${filename}`)

  const extractFrontmatter = async (path) => {
    const fileContents = await readFileAsync(path, 'utf8')
    return fm(fileContents)
  }

  for (const relPath of translatedMarkdownFiles) {
    const localisedAbsPath = path.posix.join(__dirname, '../..', relPath)
    // find the corresponding english file by removing the first 2 path segments: /translations/<language code>
    const engAbsPath = path.posix.join(__dirname, '../..', relPath.split(path.sep).slice(2).join(path.sep))

    if (!fs.existsSync(engAbsPath)) {
      // This happens when an English file has been moved or deleted and translations are not in sync.
      // It does mean this script will not homogenous those translated files, but the docs site does not
      // load translated files that don't correlate to an English file, so those translated files can't break things.
      console.log(`English file does not exist: ${engAbsPath}`)
      continue
    }

    const localisedFrontmatter = await extractFrontmatter(localisedAbsPath)
    if (!localisedFrontmatter) continue

    // Load frontmatter from the source english file
    const englishFrontmatter = await extractFrontmatter(engAbsPath)

    // Look for differences between the english and localised non-translatable properties
    let overwroteSomething = false
    for (const prop in localisedFrontmatter.data) {
      if (!fm.schema.properties[prop].translatable && englishFrontmatter.data[prop] && localisedFrontmatter.data[prop] !== englishFrontmatter.data[prop]) {
        localisedFrontmatter.data[prop] = englishFrontmatter.data[prop]
        overwroteSomething = true
      }
    }

    // rewrite the localised file, if it changed
    if (overwroteSomething) {
      const toWrite = matter.stringify(localisedFrontmatter.content, localisedFrontmatter.data, { lineWidth: 10000, forceQuotes: true })
      fs.writeFileSync(localisedAbsPath, toWrite)

      // if it's fixable, output its path to store in the log file
      console.log(relPath)
    }
  }
}