superlint/.github/workflows/lint-commit.yaml

---
name: Lint commit

on:
  push:
  pull_request:
  merge_group:

# Don't grant any access by default
permissions: {}

jobs:
  commitlint:
    runs-on: ubuntu-latest
    permissions:
        contents: read
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Check if the pull request contains a single commit
        if: github.event_name == 'pull_request'
        run: |
          commit_count=${{ github.event.pull_request.commits }}

          if [ -z ${commit_count} ]; then
            echo "[ERROR] commit_count is empty"
            exit 1
          fi

          if [[ ${commit_count} -ne 1 ]]; then
            echo "[ERROR] This pull request contains ${commit_count} commits. Squash these commits into a single commit."
            exit 1
          else
            echo "This pull request contains ${commit_count} commit."
          fi          

      - name: Set commit metadata
        run: |
          SET_INTERVAL_VALUES="true"
          if [[ ${{ github.event_name }} == 'push' ]] || [[ ${{ github.event_name }} == 'merge_group' ]]; then
            echo "Using default commit metadata"
            SET_INTERVAL_VALUES="false"
          elif [[ ${{ github.event_name }} == 'pull_request' ]]; then
            FROM_INTERVAL_COMMITLINT=${{ github.event.pull_request.head.sha }}~${{ github.event.pull_request.commits }}
            TO_INTERVAL_COMMITLINT=${{ github.event.pull_request.head.sha }}
          else
            echo "[ERROR] Event not supported when setting commit metadata"
            exit 1
          fi

          if [ "${SET_INTERVAL_VALUES}" == "true" ]; then
            if [ -z "${FROM_INTERVAL_COMMITLINT}" ]; then
              echo "[ERROR] FROM_INTERVAL_COMMITLINT is empty"
              exit 1
            fi

            if [ -z "${TO_INTERVAL_COMMITLINT}" ]; then
              echo "[ERROR] TO_INTERVAL_COMMITLINT is empty"
              exit 1
            fi

            {
              echo "FROM_INTERVAL_COMMITLINT=${FROM_INTERVAL_COMMITLINT}"
              echo "TO_INTERVAL_COMMITLINT=${TO_INTERVAL_COMMITLINT}"
            } >> "${GITHUB_ENV}"
          else
            echo "Skip updating GITHUB_ENV. SET_INTERVAL_VALUES: ${SET_INTERVAL_VALUES}"
          fi          

      - name: Validate commits
        run: |
          make lint-commits          
...