pr-preview-reaper.yml

name: Reap stale PR previews

on:
  schedule:
    - cron: "17 3 * * *"
  workflow_dispatch:
    inputs:
      dry_run:
        description: Report stale previews without changing gh-pages
        required: false
        default: false
        type: boolean

permissions:
  contents: write
  pull-requests: read

concurrency:
  group: pr-preview-reaper
  cancel-in-progress: false

defaults:
  run:
    shell: bash

jobs:
  reap:
    runs-on: ubuntu-latest
    env:
      GH_TOKEN: ${{ github.token }}
      REPOSITORY: ${{ github.repository }}
      DRY_RUN: ${{ inputs.dry_run || false }}
    steps:
      - name: Check out gh-pages
        uses: actions/checkout@v7
        with:
          ref: gh-pages
          fetch-depth: 1
          token: ${{ github.token }}

      - name: Remove previews for closed or missing pull requests
        run: |
          set -Eeuo pipefail

          preview_root='pr-preview'
          if [[ ! -d "$preview_root" ]]; then
            echo "No $preview_root/ directory exists; would delete: none."
            exit 0
          fi
          if [[ -L "$preview_root" ]]; then
            echo '::error::Refusing to operate on a symlinked pr-preview/ directory.'
            exit 1
          fi

          root_realpath="$(realpath -- "$preview_root")"
          removals=()
          shopt -s nullglob

          for preview_path in "$preview_root"/pr-*; do
            [[ -d "$preview_path" ]] || continue

            preview_name="${preview_path##*/}"
            if [[ ! "$preview_name" =~ ^pr-([0-9]+)$ ]]; then
              echo "::warning::Ignoring unexpected preview path: $preview_path"
              continue
            fi
            pr_number="${BASH_REMATCH[1]}"

            response_file="$(mktemp)"
            api_exit=0
            # No --silent here. It suppresses the response body, which leaves the
            # file holding headers only, so the state parse below finds nothing
            # and every run dies on the first preview it inspects.
            gh api --include "repos/$REPOSITORY/pulls/$pr_number" >"$response_file" || api_exit=$?
            status_code="$(awk '/^HTTP\/[^ ]+ / { code=$2 } END { print code }' "$response_file")"

            if (( api_exit == 0 )); then
              if [[ "$status_code" != '200' ]]; then
                rm -f -- "$response_file"
                echo "::error::GitHub API returned HTTP $status_code for PR #$pr_number"
                exit 1
              fi
              state="$(awk 'body || /^\{/ { body=1 } body' "$response_file" | jq -r '.state // empty')"
              if [[ -z "$state" ]]; then
                rm -f -- "$response_file"
                echo "::error::GitHub API returned no pull request state for PR #$pr_number"
                exit 1
              fi
            elif [[ "$status_code" == '404' ]]; then
              state='missing'
            else
              rm -f -- "$response_file"
              echo "::error::Could not read PR #$pr_number from the GitHub API (HTTP ${status_code:-unknown})"
              exit 1
            fi
            rm -f -- "$response_file"

            case "$state" in
              open)
                echo "Keeping $preview_path because PR #$pr_number is open."
                ;;
              closed|missing)
                echo "Stale preview: $preview_path (PR #$pr_number is $state)."
                removals+=("$preview_path")
                ;;
              *)
                echo "::error::Unexpected state '$state' for PR #$pr_number"
                exit 1
                ;;
            esac
          done

          guard_preview_path() {
            local candidate="$1"
            local candidate_realpath

            if [[ ! "$candidate" =~ ^pr-preview/pr-[0-9]+$ ]]; then
              echo "::error::Refusing to delete outside pr-preview/: $candidate"
              return 1
            fi
            if [[ -L "$candidate" ]]; then
              echo "::error::Refusing to delete symlinked preview: $candidate"
              return 1
            fi

            candidate_realpath="$(realpath -- "$candidate")"
            case "$candidate_realpath" in
              "$root_realpath"/pr-*)
                ;;
              *)
                echo "::error::Refusing to delete outside pr-preview/: $candidate"
                return 1
                ;;
            esac
            if [[ ! "$(basename -- "$candidate_realpath")" =~ ^pr-[0-9]+$ ]]; then
              echo "::error::Refusing to delete outside pr-preview/: $candidate"
              return 1
            fi
          }

          if [[ "$DRY_RUN" == 'true' ]]; then
            echo 'Dry run requested; no files or commits will be changed.'
            if (( ${#removals[@]} == 0 )); then
              echo 'WOULD DELETE: none'
            else
              for preview_path in "${removals[@]}"; do
                guard_preview_path "$preview_path"
                echo "WOULD DELETE $preview_path"
              done
            fi
            exit 0
          fi

          if (( ${#removals[@]} == 0 )); then
            echo 'No stale PR previews found; no commit created.'
            exit 0
          fi

          for preview_path in "${removals[@]}"; do
            guard_preview_path "$preview_path"
            git rm -r -- "$preview_path"
          done

          if git diff --cached --quiet; then
            echo '::error::Stale previews were found, but no deletion was staged.'
            exit 1
          fi

          git config user.name 'github-actions[bot]'
          git config user.email '41898282+github-actions[bot]@users.noreply.github.com'
          git commit -m 'Remove stale PR previews'
          git push origin HEAD:gh-pages