bundle-size-comment.yml

name: bundle-size-comment

on:
  workflow_run:
    workflows:
      - bundle-size
    types:
      - completed

permissions:
  actions: read
  contents: read
  pull-requests: write

jobs:
  comment:
    if: github.event.workflow_run.conclusion == 'success' && github.event.workflow_run.event == 'pull_request'

    runs-on: ubuntu-latest

    strategy:
      matrix:
        node: [24]

    steps:
      - name: Resolve report artifact
        id: artifact
        uses: actions/github-script@v9
        with:
          script: |
            const run = context.payload.workflow_run

            const artifacts = await github.paginate(github.rest.actions.listWorkflowRunArtifacts, {
              owner: context.repo.owner,
              repo: context.repo.repo,
              run_id: run.id,
              per_page: 100
            })
            const matches = artifacts.filter(artifact => artifact.name === 'bundle-size-report' && !artifact.expired)

            if (matches.length !== 1 || matches[0].size_in_bytes > 1024 * 1024) {
              core.setFailed('Expected exactly one bundle size report under 1 MB.')
              return
            }

            core.setOutput('id', String(matches[0].id))

      # Everything in this artifact comes from the untrusted pull request and is validated before use
      - name: Download report
        uses: actions/download-artifact@v8
        with:
          artifact-ids: ${{ steps.artifact.outputs.id }}
          path: ${{ runner.temp }}/bundle-size
          github-token: ${{ secrets.GITHUB_TOKEN }}
          run-id: ${{ github.event.workflow_run.id }}

      - name: Resolve pull request
        id: pull
        uses: actions/github-script@v9
        env:
          REPORT_DIR: ${{ runner.temp }}/bundle-size
        with:
          script: |
            const fs = require('node:fs')
            const path = require('node:path')
            const run = context.payload.workflow_run
            const dir = process.env.REPORT_DIR

            core.setOutput('should-comment', 'false')

            const files = fs.readdirSync(dir).sort()
            if (files.join() !== 'base.json,context.json,pr.json' || files.some(file => !fs.lstatSync(path.join(dir, file)).isFile())) {
              core.setFailed('The report artifact contains unexpected files.')
              return
            }

            const { prNumber, ...rest } = JSON.parse(fs.readFileSync(path.join(dir, 'context.json'), 'utf8'))
            if (Object.keys(rest).length || !Number.isSafeInteger(prNumber) || prNumber <= 0) {
              core.setFailed('The report context contains an invalid pull request number.')
              return
            }

            const candidates = run.pull_requests || []
            if (candidates.length > 1 || (candidates.length === 1 && candidates[0].number !== prNumber)) {
              core.setFailed('The report context does not match the workflow payload.')
              return
            }

            const { data: pull } = await github.rest.pulls.get({
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: prNumber
            })

            if (pull.state !== 'open' || pull.head.sha !== run.head_sha) {
              core.info(`Skipping stale or closed PR #${prNumber}.`)
              return
            }

            if (pull.head.repo?.id !== run.head_repository.id) {
              core.setFailed('The pull request head repository does not match the triggering workflow.')
              return
            }

            if (pull.base.repo.id !== context.payload.repository.id) {
              core.setFailed('The pull request does not target this repository.')
              return
            }

            core.setOutput('should-comment', 'true')
            core.setOutput('number', String(prNumber))

      - name: Checkout
        if: steps.pull.outputs.should-comment == 'true'
        uses: actions/checkout@v7
        with:
          persist-credentials: false
          ref: ${{ github.sha }}

      - name: Install node
        if: steps.pull.outputs.should-comment == 'true'
        uses: actions/setup-node@v7
        with:
          node-version: ${{ matrix.node }}

      - name: Render report
        if: steps.pull.outputs.should-comment == 'true'
        id: report
        run: node test/bundle/compare.mjs --base "$RUNNER_TEMP/bundle-size/base.json" --head "$RUNNER_TEMP/bundle-size/pr.json" --output "$RUNNER_TEMP/bundle-size.md"

      - name: Update comment
        if: steps.pull.outputs.should-comment == 'true'
        uses: actions/github-script@v9
        env:
          CHANGED: ${{ steps.report.outputs.changed }}
          PR_NUMBER: ${{ steps.pull.outputs.number }}
        with:
          script: |
            const fs = require('node:fs')
            const marker = '<!-- bundle-size -->'
            const issue_number = Number(process.env.PR_NUMBER)
            const body = `${marker}\n${fs.readFileSync(`${process.env.RUNNER_TEMP}/bundle-size.md`, 'utf8')}`

            const comments = await github.paginate(github.rest.issues.listComments, {
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number,
              per_page: 100
            })
            const previous = comments.find(comment => comment.user?.login === 'github-actions[bot]' && comment.body?.includes(marker))

            if (previous) {
              await github.rest.issues.updateComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: previous.id,
                body
              })
            } else if (process.env.CHANGED === 'true') {
              // Only start commenting once a pull request changes the bundle size
              await github.rest.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number,
                body
              })
            }