name: commit-lint

# Enforce Conventional Commits in CI, as a backstop to the local commit-msg hook
# (which a contributor only gets after `git config core.hooksPath tools/git-hooks`).
# Lints every new commit's summary line against tools/git-hooks/lib.sh — the same
# rule the hook uses, so the two can never drift.
on:
  push:
    branches: [main]
  pull_request:
  workflow_dispatch: {}

jobs:
  conventional-commits:
    runs-on: docker
    container: node:20-bookworm
    steps:
      - name: Check out with history
        env:
          REPO_URL: ${{ github.server_url }}/${{ github.repository }}.git
        run: |
          set -eu
          git config --global --add safe.directory '*'
          # Full clone so both endpoints of the range are present.
          git clone "$REPO_URL" .
          git checkout "${GITHUB_SHA}" 2>/dev/null || git checkout "${GITHUB_REF_NAME:-main}"

      - name: Lint the new commits
        env:
          BEFORE: ${{ github.event.before }}
          BASE: ${{ github.base_ref }}
        run: |
          set -eu
          # Pick the range of *new* commits to lint:
          #  - pull_request: base branch .. this commit
          #  - push:         the pushed range (event.before .. this commit)
          #  - new branch / unknown: just the tip commit
          # `event.before` is only usable if it still resolves: a force-push
          # rewrites (and a gc can remove) the commit it names, which made this
          # job fail with "Invalid revision range" on an otherwise clean push.
          # Fall back to the tip commit in that case.
          if [ -n "${BASE:-}" ]; then
            git fetch --quiet origin "${BASE}" 2>/dev/null || true
            RANGE="origin/${BASE}..${GITHUB_SHA}"
          elif [ -n "${BEFORE:-}" ] && ! printf '%s' "$BEFORE" | grep -qE '^0+$' \
               && git cat-file -e "${BEFORE}^{commit}" 2>/dev/null; then
            RANGE="${BEFORE}..${GITHUB_SHA}"
          else
            RANGE="${GITHUB_SHA}~1..${GITHUB_SHA}"
          fi
          echo "linting range: $RANGE"
          sh tools/git-hooks/lint-range.sh "$RANGE"