/**
 * This scripts gathers source markdown files of approved and proposed RFCS into the mdbook/src directory.
 */

const fs = require('fs');

// The amount of days that an RFC is considered "new".
// Counted from the creation of a given PR.
const NEW_RFC_PERIOD_DAYS = 7

// The amount of days that an RFC is considered "stale".
// Counted from the last update on a PR.
const STALE_RFC_PERIOD_DAYS = 30

const dateDaysBefore = (daysBefore) => {
  const result = new Date()
  result.setDate(result.getDate() - daysBefore)
  return result
}

[
  "mdbook/src/approved",
  "mdbook/src/new",
  "mdbook/src/stale",
  "mdbook/src/proposed"
].forEach(path => fs.mkdirSync(path, {resursive: true}))

const TOC = "**Table of Contents**\n\n<\!-- toc -->\n"

module.exports = async ({github, context}) => {
  const owner = 'polkadot-fellows'
  const repo = 'RFCs'
  const prs = await github.paginate(github.rest.pulls.list, {owner, repo, state: 'open'})

  /*
    The open PRs are potential proposed RFCs.
    We iterate over them and filter those that include a new RFC markdown file.
  */
  for (const pr of prs) {
    const addedMarkdownFiles = (
      await github.rest.pulls.listFiles({
        owner, repo,
        pull_number: pr.number,
      })
    ).data.filter(
      (file) => file.status === "added" && file.filename.startsWith("text/") && file.filename.includes(".md"),
    );
    if (addedMarkdownFiles.length !== 1) continue;
    const [rfcFile] = addedMarkdownFiles;
    const rawText = await (await fetch(rfcFile.raw_url)).text();

    const isNew = new Date(pr.created_at) > dateDaysBefore(NEW_RFC_PERIOD_DAYS)
    const isStale = new Date(pr.updated_at) < dateDaysBefore(STALE_RFC_PERIOD_DAYS)
    const status = isNew ? 'new' : (isStale ? 'stale' : 'proposed')

    const filename = rfcFile.filename.replace("text/", "")

    fs.writeFileSync(
      `mdbook/src/${status}/${filename}`,
      `[(source)](${pr.html_url})\n\n`
      + TOC
      + rawText
    )
  }

  // Copy the approved (already-merged) RFCs markdown files, first adding a source link at the top and a TOC.
  for (const file of fs.readdirSync("text/")) {
    if (!file.endsWith(".md")) continue;
    const text = `[(source)](https://github.com/polkadot-fellows/RFCs/blob/main/text/${file})\n\n`
      + TOC
      + fs.readFileSync(`text/${file}`)
    fs.writeFileSync(`mdbook/src/approved/${file}`, text)
  }
}