name: ai-self-review

# Checks the self-review declaration of agent-assisted pull requests, see
# docs/adr/0001-self-declared-sha-bound-review-gate.md and docs/develop/ai.md.
#
# It runs on pull_request, see docs/adr/0002-self-review-check-on-pull-request.md. The workflow
# file therefore comes from the pull request, but the job checks out and runs the check script of
# the base branch; it never checks out or runs other code of the pull request and reads the body
# and the commit messages through the API only. A pull request that changes this workflow can
# weaken its own check, so .github/CODEOWNERS requires a maintainer's review for it.
#
# It runs only for pull requests into main, never on pushes to main or to other branches, and not
# for pull requests into other branches.
#
# On failure it posts one comment that explains the fix, found again by its marker and updated in
# place; once the check passes, the comment is updated to say so. Pull requests from forks get a
# read-only token, so the comment step is skipped for them; the report is in the job summary.

on:
  pull_request:
    types: [opened, edited, synchronize, reopened]
    branches: [main]

permissions:
  contents: read
  pull-requests: write

env:
  # Must equal COMMENT_MARKER in scripts/check_pr_self_review.py (checked by tests/test_ai.py).
  COMMENT_MARKER: "<!-- ai-self-review -->"

concurrency:
  group: ai-self-review-${{ github.event.pull_request.number }}
  cancel-in-progress: true

jobs:
  self-review:
    runs-on: ubuntu-latest
    steps:
    - name: Check out the base branch (not the pull request)
      uses: actions/checkout@v7
      with:
        ref: ${{ github.event.pull_request.base.sha }}
        persist-credentials: false
    - uses: actions/setup-python@v7
      with:
        python-version-file: .python-version
    - name: Fetch the pull request body and commit messages
      env:
        GH_TOKEN: ${{ github.token }}
        PR_BODY: ${{ github.event.pull_request.body }}
        PR_URL: repos/${{ github.repository }}/pulls/${{ github.event.pull_request.number }}
      run: |
        printf '%s' "$PR_BODY" > "$RUNNER_TEMP/body.md"
        gh api --paginate "$PR_URL/commits" --jq '.[].commit.message | @json' \
          > "$RUNNER_TEMP/commits.jsonl"
    - name: Check the self-review declaration
      id: check
      env:
        PR_HEAD_SHA: ${{ github.event.pull_request.head.sha }}
        PR_TITLE: ${{ github.event.pull_request.title }}
        PR_AUTHOR: ${{ github.event.pull_request.user.login }}
      run: |
        set +e
        python scripts/check_pr_self_review.py \
          --body-file "$RUNNER_TEMP/body.md" \
          --commits-file "$RUNNER_TEMP/commits.jsonl" \
          --head-sha "$PR_HEAD_SHA" \
          --title "$PR_TITLE" \
          --author "$PR_AUTHOR" \
          --report-file "$RUNNER_TEMP/report.md"
        status=$?
        if [ ! -s "$RUNNER_TEMP/report.md" ]; then
          # The script failed before it could write its report.
          status=1
          {
            echo "$COMMENT_MARKER"
            echo "### ❌ AI self-review check could not run"
            echo
            echo "The check script failed before it could check the declaration. This is a"
            echo "problem of the check, not necessarily of the pull request; see the log of the"
            echo "workflow run."
          } > "$RUNNER_TEMP/report.md"
        fi
        echo "status=$status" >> "$GITHUB_OUTPUT"
        cat "$RUNNER_TEMP/report.md" >> "$GITHUB_STEP_SUMMARY"
    - name: Comment on the pull request
      # The token of a pull request from a fork is read-only and cannot comment.
      if: github.event.pull_request.head.repo.full_name == github.repository
      # A failing comment must not change the result of the check.
      continue-on-error: true
      env:
        GH_TOKEN: ${{ github.token }}
        STATUS: ${{ steps.check.outputs.status }}
        ISSUE_URL: repos/${{ github.repository }}/issues/${{ github.event.pull_request.number }}
        COMMENTS_URL: repos/${{ github.repository }}/issues/comments
      run: |
        comment_id=$(gh api --paginate "$ISSUE_URL/comments" --jq \
          '.[] | select(.user.login == "github-actions[bot]")
               | select(.body | startswith(env.COMMENT_MARKER)) | .id' | head -n 1)
        if [ -n "$comment_id" ]; then
          gh api --method PATCH "$COMMENTS_URL/$comment_id" -F "body=@$RUNNER_TEMP/report.md" \
            > /dev/null
        elif [ "$STATUS" != "0" ]; then
          gh api --method POST "$ISSUE_URL/comments" -F "body=@$RUNNER_TEMP/report.md" > /dev/null
        fi
    - name: Report the result
      if: always()
      env:
        STATUS: ${{ steps.check.outputs.status }}
        FROM_FORK: ${{ github.event.pull_request.head.repo.full_name != github.repository }}
      run: |
        if [ "${STATUS:-1}" != "0" ]; then
          if [ "$FROM_FORK" = "true" ]; then
            echo "::error::The self-review check failed; see the job summary of this run."
          else
            echo "::error::The self-review check failed; see the job summary or the pull request comment."
          fi
        fi
        exit "${STATUS:-1}"