gh-pages-cleanup.yml

name: Cleanup GitHub Pages

on:
  schedule:
    # Runs daily at 1AM UTC which is 6PM pacific
    - cron:  '0 1 * * *'

  workflow_dispatch:
    inputs:
      stale_threshold:
        description: 'Threshold after which the preview build is considered to be stale'
        default: '2 weeks'
        type: string

jobs:
  remove_stale_previews:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v4
        with:
          ref: 'gh-pages'
          fetch-depth: 0

      - name: Determine Previews to Delete
        id: find_previews
        run: |
          # Get the stale threshold from the workflow parameter
          # and calculate the timestamp for the threshold
          STALE_THRESHOLD="${{ github.event.inputs.stale_threshold || '2 weeks' }}"
          THRESHOLD_DATE=$(date --date="$STALE_THRESHOLD ago" +%s)

          # Find and collect previews older than the specified threshold, skipping "main" and ".git"
          STALE_PREVIEWS=()
          for dir in $(find . -type d -mindepth 1 -maxdepth 1); do
            # Check if the preview name is "main" or ".git" and skip it
            if [ "$(basename "$dir")" == "main" ] || [ "$(basename "$dir")" == ".git" ]; then
              continue
            fi

            DIR_DATE=$(git log -1 --format="%ct" -- "$dir")
            if [ -n "$DIR_DATE" ] && [ "$DIR_DATE" -lt "$THRESHOLD_DATE" ]; then
              STALE_PREVIEWS+=("$(basename "$dir")")
            fi
          done

          if [ -z "${STALE_PREVIEWS[*]}" ]; then
            echo "Did not find any stale previews based on $STALE_THRESHOLD threshold. Done."
          else
            echo "Previews determined to be stale based on $STALE_THRESHOLD threshold: ${STALE_PREVIEWS[*]}"
          fi

          # Set the list of previews to be removed as an output
          echo "previews_to_delete=${STALE_PREVIEWS[*]}" >> $GITHUB_OUTPUT

      - name: Notify Open Pull Requests of Preview Removal
        if: ${{ steps.find_previews.outputs.previews_to_delete != '' }}
        run: |
          # Notify open pull requests of their preview being deleted
          # but don't fail on this step for any reason
          set +e

          STALE_PREVIEWS=(${{ steps.find_previews.outputs.previews_to_delete }})
          STALE_THRESHOLD="${{ github.event.inputs.stale_threshold || '2 weeks' }}"

          # Iterate through the previews and look for open PRs
          for dir in "${STALE_PREVIEWS[@]}"; do
            if [ -f "$dir/.github_source_repository" ]; then
              # Get the source repository for the preview build
              SOURCE_REPO=$(cat "$dir/.github_source_repository")
              echo "Source repository for $dir is $SOURCE_REPO"
            else
              # Without .github_source_repository we don't know where to post the comment so we'll skip
              echo "Could not determine source repository for $dir. Skipping."
              continue
            fi

            # Check if there are open pull requests for the source repository
            OPEN_PRS=$(curl -s -H "Authorization: token $GITHUB_TOKEN" "https://api.github.com/repos/$SOURCE_REPO/pulls?state=open")

            # Check if any open pull requests match the preview branch name
            PREVIEW_PRS=$(echo $OPEN_PRS | jq -r --arg dir "$dir" '.[] | select(.head.ref == $dir) | .number' 2>/dev/null)

            if [[ -n "$PREVIEW_PRS" ]]; then
              # Comment on the open PRs
              for pr_number in $PREVIEW_PRS; do
                COMMENT_BODY="The preview build for this pull request has been cleaned up due to being stale.\n\nPreview builds that were $STALE_THRESHOLD old or older were automatically removed to maintain a tidy GitHub Pages site.\n\nYou can rebuild the preview at any time by pushing a new commit to this pull request:\n\n\`\`\`\ngit checkout $dir\ngit commit --allow-empty -m 'rebuild preview'\ngit push origin $dir\n\`\`\`"
                curl -X POST -d "{\"body\":\"$COMMENT_BODY\"}" -H "Authorization: token $GITHUB_TOKEN" "https://api.github.com/repos/$SOURCE_REPO/issues/$pr_number/comments"
              done
            else
              echo "No open pull requests for $dir. No notification needed."
            fi
          done

        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      - name: Remove Previews and Push to GitHub Pages
        if: ${{ steps.find_previews.outputs.previews_to_delete != '' }}
        run: |
          # Get the list of directories to delete from the previous step's output
          STALE_PREVIEWS=(${{ steps.find_previews.outputs.previews_to_delete }})

          # Get the stale threshold from the workflow parameter
          # and calculate the timestamp for the threshold
          STALE_THRESHOLD="${{ github.event.inputs.stale_threshold || '2 weeks' }}"

          echo "Removing stale previews based on $STALE_THRESHOLD threshold: ${STALE_PREVIEWS[*]}"

          # Remove the directories and their contents
          for dir in "${STALE_PREVIEWS[@]}"; do
            rm -rf "$dir"
          done

          # Commit and push the changes
          git add .

          if [[ `git status --porcelain` ]]; then
            git config user.name 'github-actions[bot]'
            git config user.email 'github-actions[bot]@users.noreply.github.com'
            git commit -m "Removed previews older than $STALE_THRESHOLD via ${{ github.event_name }} by ${{ github.actor }}"
            git push origin gh-pages
          else
            echo "No previews were deleted."
          fi