name: Check for bad links in documentation

on:
  pull_request:
    paths:
    # Only run on changes to .md files -- this check is too flakey to run on every PR
    - '**.md'
  workflow_dispatch: # Manual
  schedule:
  - cron: '0 6 * * *' # Nightly 6AM UTC

# This allows a subsequently queued workflow run to interrupt previous runs
concurrency:
  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id}}
  cancel-in-progress: true

defaults:
  run:
    # fail-fast using bash -eo pipefail. See https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#exit-codes-and-error-action-preference
    shell: bash

permissions:
  contents: read

jobs:
  markdown-link-check:
    permissions:
      contents: read # to read files to check dead links
    runs-on: ubuntu-latest
    steps:
    - name: Harden Runner
      uses: step-security/harden-runner@63c24ba6bd7ba022e95695ff85de572c04a18142 # v2.7.0
      with:
        egress-policy: audit

    - name: Checkout Code
      uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3

    - name: Verify Markdown documentation is free of "here" and "click here" link anchors
      run: |
        if [[ $(grep -Eir --exclude-dir=node_modules --include=\*.md '\[(click )?here\]' .) ]]; then
          echo '❌ fail: links found with "here" or "click here" anchors in Markdown files'
          grep -Eir --exclude-dir=node_modules --include=\*.md '\[(click )?here\]' .
          exit 1
        fi

    - name: Check links
      uses: gaurav-nelson/github-action-markdown-link-check@d53a906aa6b22b8979d33bc86170567e619495ec # v1.0.15
      with:
        use-quiet-mode: 'yes'
        config-file: .github/workflows/config/markdown-link-check-config.json
        base-branch: ${{ github.base_ref }}