name: pre-commit

on:
  # pull_request_target instead of pull_request: the workflow definition and
  # the hook config are always taken from the BASE branch, so fork /
  # first-time-contributor PRs run immediately without a maintainer clicking
  # "Approve and run". The PR head is checked out as data only.
  pull_request_target:
    branches: [main]
  workflow_call:
    inputs:
      ref:
        description: 'Git ref to checkout (defaults to github.ref)'
        required: false
        type: string

permissions:
  contents: read

jobs:
  pre-commit:
    if: github.event.pull_request.draft != true
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v4
      with:
        ref: ${{ inputs.ref || '' }}
    # For PR events, lint the PR head — but keep the hook definitions from
    # the base branch so an untrusted PR cannot alter what gets executed.
    # The gate scripts are saved too: the self-test step below executes them,
    # so it must run the base-branch copies, not the PR head's.
    - name: Save trusted hook config and gate scripts
      if: github.event_name == 'pull_request_target'
      run: |
        cp .pre-commit-config.yaml "$RUNNER_TEMP/trusted-pre-commit-config.yaml"
        cp -a .github/scripts "$RUNNER_TEMP/trusted-scripts"
        echo "GATE_SCRIPTS_DIR=$RUNNER_TEMP/trusted-scripts" >> "$GITHUB_ENV"
    # allow-unsafe-pr-checkout acknowledges checkout's pull_request_target
    # guard: the head is data for the trusted hooks to lint; nothing from it
    # is executed (config and gate scripts are pinned to the base branch
    # above) and credentials are not persisted. SHA-pinned to v4.4.0 because
    # actionlint's action schema does not know the new input yet.
    - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
      if: github.event_name == 'pull_request_target'
      with:
        ref: ${{ github.event.pull_request.head.sha }}
        persist-credentials: false
        allow-unsafe-pr-checkout: true
    - name: Restore trusted hook config
      if: github.event_name == 'pull_request_target'
      run: cp "$RUNNER_TEMP/trusted-pre-commit-config.yaml" .pre-commit-config.yaml
    - uses: actions/setup-python@v5
      with:
        python-version: "3.12"
    - run: echo "::add-matcher::.github/workflows/matchers/actionlint.json"
    - run: echo "::add-matcher::.github/workflows/matchers/mypy.json"
    - run: echo "::add-matcher::.github/workflows/matchers/ruff.json"
    - uses: pre-commit/action@v3.0.1
      with:
        extra_args: --all-files --hook-stage manual
    # After pre-commit so a self-test failure cannot mask lint failures.
    # GATE_SCRIPTS_DIR points at the base-branch copy on fork PRs (set above);
    # push / workflow_call runs use the checked-out tree directly.
    - name: Full-suite gate self-test
      run: bash "${GATE_SCRIPTS_DIR:-.github/scripts}/test_gate_full_suite.sh"