backport-to-develop.yml

name: Automatic Backport to Develop

on:
  pull_request:
    types: [closed]
    branches: [main]

permissions:
  contents: read
  pull-requests: write
  issues: write

jobs:
  create-backport-pr:
    # Only run if the PR was actually merged (not just closed)
    if: github.event.pull_request.merged == true
    runs-on: ubuntu-latest
    
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          fetch-depth: 0
          token: ${{ secrets.GITHUB_TOKEN }}

      - name: Get merged branch name
        id: get-branch
        run: |
          # Get the head branch name from the merged PR
          BRANCH_NAME="${{ github.event.pull_request.head.ref }}"
          echo "branch-name=$BRANCH_NAME" >> $GITHUB_OUTPUT
          echo "Merged branch: $BRANCH_NAME"

      - name: Check if branch exists
        id: check-branch
        run: |
          BRANCH_NAME="${{ steps.get-branch.outputs.branch-name }}"
          
          # Check if the branch still exists on the remote
          if git ls-remote --heads origin "$BRANCH_NAME" | grep -q "$BRANCH_NAME"; then
            echo "branch-exists=true" >> $GITHUB_OUTPUT
            echo "Branch $BRANCH_NAME exists and can be used for backport"
          else
            echo "branch-exists=false" >> $GITHUB_OUTPUT
            echo "Branch $BRANCH_NAME no longer exists, cannot create backport PR"
          fi

      - name: Create backport PR
        if: steps.check-branch.outputs.branch-exists == 'true'
        uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const branchName = '${{ steps.get-branch.outputs.branch-name }}';
            const originalPrNumber = context.payload.pull_request.number;
            const originalPrTitle = context.payload.pull_request.title;
            const originalPrBody = context.payload.pull_request.body || '';
            const originalPrAuthor = context.payload.pull_request.user.login;
            
            // Create the backport PR
            try {
              const response = await github.rest.pulls.create({
                owner: context.repo.owner,
                repo: context.repo.repo,
                title: `[Backport] ${originalPrTitle}`,
                head: branchName,
                base: 'develop',
                body: `## Automatic Backport\n\nThis is an automatic backport of PR #${originalPrNumber} by @${originalPrAuthor} to the \`develop\` branch.\n\n### Original PR Details:\n${originalPrBody}\n\n---\n*This PR was created automatically when #${originalPrNumber} was merged into \`main\`.*`,
                maintainer_can_modify: true
              });
              
              console.log(`✅ Successfully created backport PR #${response.data.number}`);
              console.log(`🔗 PR URL: ${response.data.html_url}`);
              
              // Add labels to the backport PR
              await github.rest.issues.addLabels({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: response.data.number,
                labels: ['backport', 'automated']
              });
              
            } catch (error) {
              console.error('❌ Failed to create backport PR:', error.message);
              
              // Check if it's a conflict or other specific error
              if (error.message.includes('No commits between')) {
                console.log('ℹ️ The branch is already up to date with develop - no backport needed');
              } else if (
                error.status === 422 &&
                error.response &&
                Array.isArray(error.response.data?.errors) &&
                error.response.data.errors.some(e =>
                  e.message && e.message.includes('A pull request already exists')
                )
              ) {
                console.log('ℹ️ A pull request already exists for this branch to develop');
              } else {
                // Re-throw for other errors to fail the workflow
                throw error;
              }
            }

      - name: Handle missing branch
        if: steps.check-branch.outputs.branch-exists == 'false'
        run: |
          echo "⚠️ Cannot create backport PR because the source branch no longer exists."
          echo "This typically happens when the branch was deleted after merging."
          echo "If a backport to develop is needed, it should be done manually."