name: Lint

on:
  push:
    branches:
      - master
  pull_request:

env:
  PRE_COMMIT_HOME: ${{ github.workspace }}/.cache/pre-commit-cache

jobs:
  lint:
    name: Linting check
    runs-on: ubuntu-latest

    steps:
      - name: Checkout repository
        uses: actions/checkout@v2

      # Python is required for pip installation of pre-commit
      - name: Python setup
        id: python
        uses: actions/setup-python@v2
        with:
          python-version: '3.9.5'

      # Install pre-commit with pip
      - name: Install pre-commit
        run: pip install pre-commit

      # Cache pre-commit environment
      # the key consists relevant factors to allow updating, when pre-commit changes
      - name: Pre-commit Environment Caching
        uses: actions/cache@v2
        with:
          path: ${{ env.PRE_COMMIT_HOME }}
          key: "precommit-0-${{ runner.os }}-${{ env.PRE_COMMIT_HOME }}-\
          ${{ steps.python.outputs.python-version }}-\
          ${{ hashFiles('./.pre-commit-config.yaml') }}"

      # Make a user install for pre-commit by using PIP_USER=0
      - name: Run pre-commit hooks
        run: export PIP_USER=0; pre-commit run --all-files

      # Prepare the Pull Request Payload artifact. If this fails, we
      # we fail silently using the `continue-on-error` option. It's
      # nice if this succeeds, but if it fails for any reason, it
      # does not mean that our lint-test checks failed.
      - name: Prepare Pull Request Payload artifact
        id: prepare-artifact
        if: always() && github.event_name == 'pull_request'
        continue-on-error: true
        run: cat $GITHUB_EVENT_PATH | jq '.pull_request' > pull_request_payload.json

      # This only makes sense if the previous step succeeded. To
      # get the original outcome of the previous step before the
      # `continue-on-error` conclusion is applied, we use the
      # `.outcome` value. This step also fails silently.
      - name: Upload a Build Artifact
        if: always() && steps.prepare-artifact.outcome == 'success'
        continue-on-error: true
        uses: actions/upload-artifact@v2
        with:
          name: pull-request-payload
          path: pull_request_payload.json