dangerfile.ts

import { readFile } from 'node:fs/promises'
import { join } from 'node:path'
import lint from '@commitlint/lint'
import load from '@commitlint/load'
import {
  LintOptions,
  LintOutcome,
  ParserOptions,
  ParserPreset
} from '@commitlint/types'
import { danger, fail, markdown, warn } from 'danger'
import config from './commitlint.config'

export default async () => {
  // merge queues not supported by danger-js
  if (danger.github.pr == null) return

  const isDependabot = danger.github.pr.user.login === 'renovate[bot]'
  // check lockfile updated when package changes
  const packageChanged = danger.git.modified_files.includes('package.json')
  const lockfileChanged =
    danger.git.modified_files.includes('package-lock.json')
  if (packageChanged && !lockfileChanged) {
    const message =
      'Changes were made to package.json, but not to package-lock.json'
    const idea = 'Perhaps you need to run `npm install`?'
    warn(`${message} - <i>${idea}</i>`)
  }

  // check max changes fall below threshold
  const CHANGE_THRESHOLD = 600
  const changeCount = danger.github.pr.additions + danger.github.pr.deletions
  if (changeCount > CHANGE_THRESHOLD) {
    warn(`:exclamation: Big PR (${changeCount} changes)`)
    markdown(
      `> (change count - ${changeCount}): Pull Request size seems relatively large. If Pull Request contains multiple changes, split each into separate PR will helps faster, easier review.`
    )
  }

  // check PR has well-formed title
  const commitlintReport = await lintPrTitle(
    `${danger.github.pr.title} #(${danger.github.pr.number})`
  )
  if (!commitlintReport.valid) {
    fail('Please ensure your PR title matches commitlint convention.')
    let errors = ''
    commitlintReport.errors.forEach((error) => {
      errors = `${errors}# ${error.message}\n`
    })
    markdown(`> (pr title - ${danger.github.pr.title}): \n${errors}`)
  }
  // check PR has description and is different from template

  const pullRequestTemplate = await readFile(
    join(__dirname, '/.github/pull_request_template.md'),
    'utf8'
  )
  if (
    danger.github.pr.body.length < 10 ||
    danger.github.pr.body.replace(/\r\n/g, '\n') === pullRequestTemplate
  ) {
    fail(
      'This pull request needs a description (that differs from the template).'
    )
  }

  // check PR has assignee
  if (danger.github.pr.assignee === null) {
    fail('Please assign someone to merge this PR.')
  }

  // check PR has type label
  if (
    !danger.github.issue.labels.some((label) => label.name.includes('type:'))
  ) {
    fail('Please add type label to this PR.')
  }

  // check PR has priority label
  if (
    !danger.github.issue.labels.some((label) =>
      label.name.includes('priority:')
    )
  ) {
    fail('Please add priority label to this PR.')
  }

  // check PR has effort label
  if (
    !danger.github.issue.labels.some((label) => label.name.includes('effort:'))
  ) {
    fail('Please add effort label to this PR.')
  }

  // pull PR data from GitHub API
  const currentPR = await danger.github.api.pulls.get({
    ...danger.github.thisPR,
    pull_number: danger.github.thisPR.number
  })

  // check PR has milestone
  // ignore dependabot
  if (currentPR.data.milestone === null && !isDependabot) {
    fail('Please add milestone to this PR.')
  }

  // pull reviews for PR from GitHub API
  const reviews = await danger.github.api.pulls.listReviews({
    ...danger.github.thisPR,
    pull_number: danger.github.thisPR.number
  })

  // check PR has requested reviewers or completed reviews
  if (
    currentPR.data.requested_reviewers != null &&
    currentPR.data.requested_reviewers.length === 0 &&
    reviews.data.length === 0
  ) {
    fail('Please request a reviewer for this PR.')
  }
}

async function lintPrTitle(title: string): Promise<LintOutcome> {
  const loaded = await load(config)
  const parserOpts = selectParserOpts(loaded.parserPreset)
  const opts: LintOptions & { parserOpts: ParserOptions } = {
    parserOpts: parserOpts ?? {},
    plugins: loaded.plugins ?? {},
    ignores: loaded.ignores ?? [],
    defaultIgnores: loaded.defaultIgnores ?? true
  }
  return lint(title, loaded.rules, opts)
}

function selectParserOpts(preset?: ParserPreset): ParserOptions | undefined {
  if (typeof preset !== 'object') return undefined
  if (typeof preset.parserOpts !== 'object') return undefined
  return preset.parserOpts ?? undefined
}