FormatCheckComment.yml

name: "FormatCheckComment"

# Comment phase of the format-check pipeline. Triggered by a `workflow_run`
# event after FormatCheck.yml completes. Runs in the base repo's trusted
# context (with secrets, write-scope `GITHUB_TOKEN`) and never touches
# PR-controlled code: it only downloads the diff artifact produced by the parse
# phase and posts or updates the format-suggestion comment on the PR.
#
# Branch protection should require the FormatCheck check, not this
# one — this workflow's job exists to update the comment, not to gate
# merging.

on:
  workflow_call:
    inputs:
      check-name:
        description: "Name of the parse-phase workflow this comment workflow runs after. Used to filter unrelated workflow_run events."
        default: "FormatCheck"
        required: false
        type: string

jobs:
  format-check-comment:
    name: "FormatCheckComment"
    # Only run when the parse-phase workflow that triggered us is the
    # expected FormatCheck workflow on a pull_request event.
    if: >-
      github.event.workflow_run.name == inputs.check-name
      && github.event.workflow_run.event == 'pull_request'
    runs-on: ubuntu-latest
    permissions:
      pull-requests: write
      actions: read
    steps:
      - name: "Download FormatCheck artifact"
        id: download
        uses: actions/download-artifact@v4
        with:
          name: "format-check"
          run-id: ${{ github.event.workflow_run.id }}
          github-token: ${{ github.token }}
        continue-on-error: true

      - name: "Read metadata"
        if: steps.download.outcome == 'success'
        id: meta
        run: |
          if [ ! -f metadata.txt ]; then
            echo "metadata.txt missing; skipping comment update."
            echo "skip=true" >> "$GITHUB_OUTPUT"
            exit 0
          fi
          PR_NUMBER=$(grep -E '^pr_number=' metadata.txt | cut -d= -f2-)
          EXIT_CODE=$(grep -E '^exit_code=' metadata.txt | cut -d= -f2-)
          if [ -z "$PR_NUMBER" ]; then
            echo "pr_number empty; skipping comment update."
            echo "skip=true" >> "$GITHUB_OUTPUT"
            exit 0
          fi
          echo "pr_number=$PR_NUMBER" >> "$GITHUB_OUTPUT"
          echo "exit_code=$EXIT_CODE" >> "$GITHUB_OUTPUT"
          echo "skip=false" >> "$GITHUB_OUTPUT"

      - name: "Find existing format-check comment"
        if: steps.meta.outputs.skip == 'false'
        uses: peter-evans/find-comment@v3
        id: find-comment
        with:
          token: ${{ secrets.FORMATPULLREQUEST_PAT || github.token }}
          issue-number: ${{ steps.meta.outputs.pr_number }}
          body-includes: "<!-- format-check-summary -->"

      - name: "Compose suggestion-comment body"
        if: steps.meta.outputs.skip == 'false' && steps.meta.outputs.exit_code == '1'
        run: |
          {
            echo "<!-- format-check-summary -->"
            echo
            echo "Your PR requires formatting changes to meet the project's style guidelines."
            echo "Please run the [ITensorFormatter](https://github.com/ITensor/ITensorFormatter.jl) to apply these changes."
            echo
            echo "<details>"
            echo "<summary>Click here to view the suggested changes.</summary>"
            echo
            echo '~~~diff'
            cat diff.patch
            echo
            echo '~~~'
            echo
            echo "</details>"
          } > comment-body.md

      - name: "Post or update suggestion comment"
        if: steps.meta.outputs.skip == 'false' && steps.meta.outputs.exit_code == '1'
        uses: peter-evans/create-or-update-comment@v5
        with:
          token: ${{ secrets.FORMATPULLREQUEST_PAT || github.token }}
          comment-id: ${{ steps.find-comment.outputs.comment-id }}
          issue-number: ${{ steps.meta.outputs.pr_number }}
          body-path: comment-body.md
          edit-mode: replace

      - name: "Clear stale comment when formatting now passes"
        if: steps.meta.outputs.skip == 'false' && steps.meta.outputs.exit_code == '0' && steps.find-comment.outputs.comment-id
        uses: peter-evans/create-or-update-comment@v5
        with:
          token: ${{ secrets.FORMATPULLREQUEST_PAT || github.token }}
          comment-id: ${{ steps.find-comment.outputs.comment-id }}
          issue-number: ${{ steps.meta.outputs.pr_number }}
          body: |
            <!-- format-check-summary -->

            Your PR no longer requires formatting changes. Thank you for your contribution!
          edit-mode: replace