preview-theme.yml

name: Preview Theme Changes

on:
  pull_request:
    types: [opened, synchronize]
permissions:
  pull-requests: write

jobs:
  check-for-changes-to-themes:
    runs-on: ubuntu-latest
    outputs:
      HAS_THEME_CHANGES: ${{ steps.check-for-changes.outputs.HAS_THEME_CHANGES }}
      CHANGED_THEMES: ${{ steps.check-for-changes.outputs.CHANGED_THEMES }}
    steps:
      - name: Checkout
        uses: actions/checkout@v2
        with:
          ref: ${{ github.event.pull_request.head.sha }}

      - name: Retrieved Theme Changes
        id: check-for-changes
        run: |
          # Retrieve list of all changed files
          git fetch origin
          changed_files=$(git diff --name-only HEAD origin/trunk)
          
          # Loop through changed files and identify parent directories
          declare -A unique_dirs
          for file in $changed_files; do
            dir_name=$(dirname "$file")
            while [[ "$dir_name" != "." ]]; do
              if [[ -f "$dir_name/style.css" ]]; then 
                # Get theme name from style.css
                theme_name=$(grep -m 1 "Theme Name:" "$dir_name/style.css" | sed 's/Theme Name: //')
                parent_theme=$(grep -m 1 "Template:" "$dir_name/style.css" | sed 's/Template: //')
                # Append parent theme to the theme name if it exists
                [ -n "$parent_theme" ] && theme_name="${theme_name}_childof_${parent_theme}"
                # Store theme name and directory in associative array
                unique_dirs["$theme_name"]=$dir_name
                break
              fi
              dir_name=$(dirname "$dir_name")
            done
          done
          # Check if themes have changed
          if [[ ${#unique_dirs[@]} -eq 0 ]]; then
              echo "No theme changes detected"
              echo "HAS_THEME_CHANGES=false" >> $GITHUB_OUTPUT
              exit 0
          fi
          # Output list of theme slugs with changes
          echo "HAS_THEME_CHANGES=true" >> $GITHUB_OUTPUT

          # Serialize associative array of theme dirs to a string
          declare -A CHANGED_THEMES
          for theme in "${!unique_dirs[@]}"; do
              # Append each entry as key:value,
              CHANGED_THEMES+="$theme:${unique_dirs[$theme]},"
          done
          # Remove the last comma for correct JSON formatting
          CHANGED_THEMES=${CHANGED_THEMES%,}
          echo "CHANGED_THEMES=$CHANGED_THEMES" >> $GITHUB_OUTPUT

          echo "Theme directories with changes: $CHANGED_THEMES"
  
  handle-pr-comment:
    runs-on: ubuntu-latest
    needs: check-for-changes-to-themes
    steps:
      - name: Checkout create-preview-links script from trunk
        uses: actions/checkout@v3
        with:
          repository: Automattic/themes
          sparse-checkout: .github/scripts/create-preview-links
          ref: trunk

      - name: Add Preview Links comment
        id: comment-on-pr
        if: ${{ needs.check-for-changes-to-themes.outputs.HAS_THEME_CHANGES == 'true' }}
        uses: actions/github-script@v7
        env:
          CHANGED_THEMES: ${{ needs.check-for-changes-to-themes.outputs.CHANGED_THEMES }}
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const createPreviewLinks = require('.github/scripts/create-preview-links');
            createPreviewLinks(github, context, process.env.CHANGED_THEMES);

      - name: Remove comment if no changes are detected
        if: ${{ needs.check-for-changes-to-themes.outputs.HAS_THEME_CHANGES == 'false' }}
        uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const { data: comments } = await github.rest.issues.listComments({
              issue_number: context.payload.pull_request.number,
              owner: context.repo.owner,
              repo: context.repo.repo
            });
            
            const existingComment = comments.find(comment => comment.user.login === 'github-actions[bot]' && comment.body.startsWith('### Preview changes'));
            
            if (existingComment) {
              await github.rest.issues.deleteComment({
                comment_id: existingComment.id,
                owner: context.repo.owner,
                repo: context.repo.repo
              });
            }