docs/.github/actions-scripts/content-changes-table-comment.js

#!/usr/bin/env node

import * as github from '@actions/github'
import { setOutput } from '@actions/core'

import { getContents } from '../../script/helpers/git-utils.js'
import parse from '../../lib/read-frontmatter.js'
import getApplicableVersions from '../../lib/get-applicable-versions.js'
import nonEnterpriseDefaultVersion from '../../lib/non-enterprise-default-version.js'
import { allVersionShortnames } from '../../lib/all-versions.js'

const { GITHUB_TOKEN, APP_URL } = process.env
const context = github.context

if (!GITHUB_TOKEN) {
  throw new Error(`GITHUB_TOKEN environment variable not set`)
}

if (!APP_URL) {
  throw new Error(`APP_URL environment variable not set`)
}

// the max size of the comment (in bytes)
// the action we use to post the comment caps out at about 144kb
// see docs-engineering#1849 for more info
const MAX_COMMENT_SIZE = 125000

const PROD_URL = 'https://docs.github.com'
const octokit = github.getOctokit(GITHUB_TOKEN)

// get the list of file changes from the PR
const response = await octokit.rest.repos.compareCommitsWithBasehead({
  owner: context.repo.owner,
  repo: context.payload.repository.name,
  basehead: `${context.payload.pull_request.base.sha}...${context.payload.pull_request.head.sha}`,
})

const { files } = response.data

let markdownTable =
  '| **Source** | **Preview** | **Production** | **What Changed** |\n|:----------- |:----------- |:----------- |:----------- |\n'

const pathPrefix = 'content/'
const articleFiles = files.filter(
  ({ filename }) => filename.startsWith(pathPrefix) && !filename.endsWith('/index.md')
)

const lines = await Promise.all(
  articleFiles.map(async (file) => {
    const sourceUrl = file.blob_url
    const fileName = file.filename.slice(pathPrefix.length)
    const fileUrl = fileName.slice(0, fileName.lastIndexOf('.'))

    // get the file contents and decode them
    // this script is called from the main branch, so we need the API call to get the contents from the branch, instead
    const fileContents = await getContents(
      context.repo.owner,
      context.payload.repository.name,
      // Can't get its content if it no longer exists.
      // Meaning, you'd get a 404 on the `getContents()` utility function.
      // So, to be able to get necessary meta data about what it *was*,
      // if it was removed, fall back to the 'base'.
      file.status === 'removed'
        ? context.payload.pull_request.base.sha
        : context.payload.pull_request.head.sha,
      file.filename
    )

    // parse the frontmatter
    const { data } = parse(fileContents)

    let contentCell = ''
    let previewCell = ''
    let prodCell = ''

    if (file.status === 'added') contentCell = 'New file: '
    else if (file.status === 'removed') contentCell = 'Removed: '
    contentCell += `[\`${fileName}\`](${sourceUrl})`

    try {
      // the try/catch is needed because getApplicableVersions() returns either [] or throws an error when it can't parse the versions frontmatter
      // try/catch can be removed if docs-engineering#1821 is resolved
      // i.e. for feature based versioning, like ghae: 'issue-6337'
      const fileVersions = getApplicableVersions(data.versions)

      for (const plan in allVersionShortnames) {
        // plan is the shortName (i.e., fpt)
        // allVersionShortNames[plan] is the planName (i.e., free-pro-team)

        // walk by the plan names since we generate links differently for most plans
        const versions = fileVersions.filter((fileVersion) =>
          fileVersion.includes(allVersionShortnames[plan])
        )

        if (versions.length === 1) {
          // for fpt, ghec, and ghae

          if (versions.toString() === nonEnterpriseDefaultVersion) {
            // omit version from fpt url

            previewCell += `[${plan}](${APP_URL}/${fileUrl})<br>`
            prodCell += `[${plan}](${PROD_URL}/${fileUrl})<br>`
          } else {
            // for non-versioned releases (ghae, ghec) use full url

            previewCell += `[${plan}](${APP_URL}/${versions}/${fileUrl})<br>`
            prodCell += `[${plan}](${PROD_URL}/${versions}/${fileUrl})<br>`
          }
        } else if (versions.length) {
          // for ghes releases, link each version

          previewCell += `${plan}@ `
          prodCell += `${plan}@ `

          versions.forEach((version) => {
            previewCell += `[${version.split('@')[1]}](${APP_URL}/${version}/${fileUrl}) `
            prodCell += `[${version.split('@')[1]}](${PROD_URL}/${version}/${fileUrl}) `
          })
          previewCell += '<br>'
          prodCell += '<br>'
        }
      }
    } catch (e) {
      console.error(
        `Version information for ${file.filename} couldn't be determined from its frontmatter.`
      )
    }
    let note = ''
    if (file.status === 'removed') {
      note = 'removed'
      // If the file was removed, the `previewCell` no longer makes sense
      // since it was based on looking at the base sha.
      previewCell = 'n/a'
    }

    return `| ${contentCell} | ${previewCell} | ${prodCell} | ${note} |`
  })
)

// this section limits the size of the comment
const cappedLines = []
let underMax = true

lines.reduce((previous, current, index, array) => {
  if (underMax) {
    if (previous + current.length > MAX_COMMENT_SIZE) {
      underMax = false
      cappedLines.push('**Note** There are more changes in this PR than we can show.')
      return previous
    }

    cappedLines.push(array[index])
    return previous + current.length
  }
  return previous
}, markdownTable.length)

markdownTable += cappedLines.join('\n')

setOutput('changesTable', markdownTable)