backport.yml

# Backport pull requests to the next-older release branch by adding
# a "backport" label. Works on PRs against `main` (targets the latest
# release-v* branch) and on PRs against `release-v*` branches
# (targets the next-older release-v* branch).

name: Backport

on:
  pull_request_target:
    types: [closed, labeled]
    branches:
      - main
      - release-v*

concurrency: ${{ github.workflow }}-${{ github.event.pull_request.number }}

permissions:
  contents: read
  pull-requests: write

jobs:
  find-branch:
    name: Find target release branch
    runs-on: ubuntu-latest
    timeout-minutes: 5
    if: |
      github.repository_owner == 'vercel' &&
      github.event.pull_request.merged == true &&
      contains(github.event.pull_request.labels.*.name, 'backport')
    outputs:
      release-branch: ${{ steps.find-target.outputs.release-branch }}

    steps:
      - name: Checkout Repository
        uses: actions/checkout@v5
        with:
          fetch-depth: 0

      - name: Find target release branch
        id: find-target
        run: |
          git fetch --all

          BASE_REF="${{ github.event.pull_request.base.ref }}"
          RELEASE_BRANCHES=$(git branch -r | grep -E 'origin/release-v[0-9]+\.[0-9]+$' | sed 's/.*origin\///' | sort -V)

          if [ -z "$RELEASE_BRANCHES" ]; then
            echo "::error::No release branches found matching pattern release-vX.Y"
            exit 1
          fi

          echo "Found release branches: $RELEASE_BRANCHES"

          if [ "$BASE_REF" = "main" ]; then
            TARGET=$(echo "$RELEASE_BRANCHES" | tail -n 1)
          else
            TARGET=$(echo "$RELEASE_BRANCHES" | grep -B1 "^${BASE_REF}$" | head -n 1)
            if [ "$TARGET" = "$BASE_REF" ] || [ -z "$TARGET" ]; then
              echo "::error::No older release branch found before $BASE_REF"
              exit 1
            fi
          fi

          echo "Target release branch: $TARGET"
          echo "release-branch=$TARGET" >> "$GITHUB_OUTPUT"

  backport:
    name: Backport to ${{ needs.find-branch.outputs.release-branch }}
    runs-on: ubuntu-latest
    timeout-minutes: 10
    needs: find-branch
    if: |
      github.repository_owner == 'vercel' &&
      github.event.pull_request.merged == true &&
      contains(github.event.pull_request.labels.*.name, 'backport')

    steps:
      - name: Create access token for GitHub App
        uses: actions/create-github-app-token@v2
        id: app-token
        with:
          app-id: ${{ vars.VERCEL_AI_SDK_GITHUB_APP_CLIENT_ID }}
          private-key: ${{ secrets.VERCEL_AI_SDK_GITHUB_APP_PRIVATE_KEY_PKCS8 }}

      - name: Get GitHub App User ID
        id: app-user-id
        run: echo "user-id=$(gh api "/users/${{ steps.app-token.outputs.app-slug }}[bot]" --jq .id)" >> "$GITHUB_OUTPUT"
        env:
          GH_TOKEN: ${{ steps.app-token.outputs.token }}

      - name: Configure git user for GitHub App
        run: |
          git config --global user.name '${{ steps.app-token.outputs.app-slug }}[bot]'
          git config --global user.email '${{ steps.app-user-id.outputs.user-id }}+${{ steps.app-token.outputs.app-slug }}[bot]@users.noreply.github.com'

      - name: Check for existing backport PR
        id: check-existing
        run: |
          BACKPORT_BRANCH="backport-pr-${{ github.event.pull_request.number }}-to-${{ needs.find-branch.outputs.release-branch }}"
          EXISTING_PR=$(gh api "repos/${{ github.repository }}/pulls?head=${{ github.repository_owner }}:${BACKPORT_BRANCH}&state=open" --jq '.[0].html_url // empty')
          if [ -n "$EXISTING_PR" ]; then
            echo "Backport PR already exists: $EXISTING_PR — skipping."
            echo "existing-pr=$EXISTING_PR" >> "$GITHUB_OUTPUT"
          fi
        env:
          GH_TOKEN: ${{ steps.app-token.outputs.token }}

      - name: Remove backport label (already backported)
        if: steps.check-existing.outputs.existing-pr
        run: |
          gh pr edit ${{ github.event.pull_request.number }} --remove-label backport || true
        env:
          GH_TOKEN: ${{ steps.app-token.outputs.token }}

      - name: Checkout Repository
        if: '!steps.check-existing.outputs.existing-pr'
        uses: actions/checkout@v5
        with:
          fetch-depth: 0
          token: ${{ steps.app-token.outputs.token }}
          ref: ${{ needs.find-branch.outputs.release-branch }}

      - name: Create backport branch
        if: '!steps.check-existing.outputs.existing-pr'
        run: |
          # Create a new branch from the latest release branch for the backport
          git checkout -b backport-pr-${{ github.event.pull_request.number }}-to-${{ needs.find-branch.outputs.release-branch }} origin/${{ needs.find-branch.outputs.release-branch }}

      - name: Cherry-pick commits
        if: '!steps.check-existing.outputs.existing-pr'
        id: cherry-pick
        run: |
          # Get the merge commit hash
          MERGE_COMMIT="${{ github.event.pull_request.merge_commit_sha }}"

          # Cherry-pick the merge commit and capture output
          CHERRY_PICK_OUTPUT=$(git cherry-pick -m 1 "$MERGE_COMMIT" 2>&1) || CHERRY_PICK_EXIT_CODE=$?
          echo "$CHERRY_PICK_OUTPUT"
          echo "git-output<<EOF" >> "$GITHUB_OUTPUT"
          echo "$CHERRY_PICK_OUTPUT" >> "$GITHUB_OUTPUT"
          echo "EOF" >> "$GITHUB_OUTPUT"

          if [ "${CHERRY_PICK_EXIT_CODE:-0}" -ne 0 ]; then
            echo "Cherry-pick failed. This backport requires manual intervention."
            echo "::error::Failed to cherry-pick merge commit $MERGE_COMMIT to ${{ needs.find-branch.outputs.release-branch }} branch"
            echo "has-conflicts=true" >> "$GITHUB_OUTPUT"
          else
            echo "has-conflicts=false" >> "$GITHUB_OUTPUT"
          fi

      - name: Remap example paths for release-v5.0
        if: "!steps.check-existing.outputs.existing-pr && needs.find-branch.outputs.release-branch == 'release-v5.0' && steps.cherry-pick.outputs.has-conflicts == 'false'"
        run: |
          # On release-v5.0, examples are in examples/ai-core/ but on main they are in examples/ai-functions/
          # If the cherry-pick created examples/ai-functions/, move the files to examples/ai-core/
          if [ -d "examples/ai-functions" ]; then
            echo "Found examples/ai-functions directory, remapping to examples/ai-core..."
            
            # Move all files from ai-functions to ai-core using git mv
            for file in $(find examples/ai-functions -type f); do
              target="${file/examples\/ai-functions/examples/ai-core}"
              mkdir -p "$(dirname "$target")"
              git mv "$file" "$target"
            done
            
            # Remove the now-empty ai-functions directory
            rm -rf examples/ai-functions
            
            # Amend the cherry-pick commit with the corrected paths
            git add .
            git commit --amend --no-edit
            
            echo "Successfully remapped example paths from examples/ai-functions/ to examples/ai-core/"
          else
            echo "No examples/ai-functions directory found, skipping remap"
          fi

      - name: Commit changes in case of errors
        if: "!steps.check-existing.outputs.existing-pr && steps.cherry-pick.outputs.has-conflicts == 'true'"
        run: |
          # In case of failure, commit the conflicts to allow inspection
          git add .
          git commit -m "Backport conflicts for PR #${{ github.event.pull_request.number }} to ${{ needs.find-branch.outputs.release-branch }}"
      - name: Push backport branch
        if: '!steps.check-existing.outputs.existing-pr'
        run: |
          BACKPORT_BRANCH="backport-pr-${{ github.event.pull_request.number }}-to-${{ needs.find-branch.outputs.release-branch }}"
          if git ls-remote --exit-code origin "refs/heads/${BACKPORT_BRANCH}" > /dev/null 2>&1; then
            echo "Branch ${BACKPORT_BRANCH} already exists on remote (orphaned from a previous run). Force-pushing."
            git push --force-with-lease origin "${BACKPORT_BRANCH}"
          else
            git push origin "${BACKPORT_BRANCH}"
          fi

      - name: Determine PR assignee
        if: '!steps.check-existing.outputs.existing-pr'
        id: assignee
        run: |
          if [ "$MERGED_BY_TYPE" = "User" ]; then
            echo "login=$MERGED_BY_LOGIN" >> "$GITHUB_OUTPUT"
          elif [ "$PR_AUTHOR_TYPE" = "User" ]; then
            echo "login=$PR_AUTHOR_LOGIN" >> "$GITHUB_OUTPUT"
          else
            REVIEWER=$(gh api "repos/${{ github.repository }}/pulls/${{ github.event.pull_request.number }}/reviews" \
              --jq '[.[] | select(.user.type == "User")] | last | .user.login // empty')
            if [ -n "$REVIEWER" ]; then
              echo "login=$REVIEWER" >> "$GITHUB_OUTPUT"
            fi
          fi
        env:
          GH_TOKEN: ${{ steps.app-token.outputs.token }}
          MERGED_BY_TYPE: ${{ github.event.pull_request.merged_by.type }}
          MERGED_BY_LOGIN: ${{ github.event.pull_request.merged_by.login }}
          PR_AUTHOR_TYPE: ${{ github.event.pull_request.user.type }}
          PR_AUTHOR_LOGIN: ${{ github.event.pull_request.user.login }}

      - name: Create backport pull request
        if: '!steps.check-existing.outputs.existing-pr'
        id: create-pr
        run: |
          ASSIGNEE_FLAG=""
          if [ -n "$ASSIGNEE_LOGIN" ]; then
            ASSIGNEE_FLAG="--assignee $ASSIGNEE_LOGIN"
          fi

          # Create the backport PR
          if [ "${{ steps.cherry-pick.outputs.has-conflicts }}" = "true" ]; then
            PR_URL=$(gh pr create \
              --title "$PR_TITLE" \
              --body "$PR_BODY_CONFLICTS" \
              --base ${{ needs.find-branch.outputs.release-branch }} \
              --head backport-pr-${{ github.event.pull_request.number }}-to-${{ needs.find-branch.outputs.release-branch }} \
              $ASSIGNEE_FLAG \
              --draft)
          else
            PR_URL=$(gh pr create \
              --title "$PR_TITLE" \
              --body "$PR_BODY_NO_CONFLICTS" \
              --base ${{ needs.find-branch.outputs.release-branch }} \
              --head backport-pr-${{ github.event.pull_request.number }}-to-${{ needs.find-branch.outputs.release-branch }} \
              $ASSIGNEE_FLAG)
          fi
          echo "backport-pr-url=$PR_URL" >> "$GITHUB_OUTPUT"
          gh pr merge "$PR_URL" --auto --squash || echo "Auto-merge could not be enabled"
          echo "Created backport PR $PR_URL"
        env:
          GH_TOKEN: ${{ steps.app-token.outputs.token }}
          ASSIGNEE_LOGIN: ${{ steps.assignee.outputs.login }}
          PR_TITLE: 'Backport: ${{ github.event.pull_request.title }}'
          PR_BODY_NO_CONFLICTS: 'This is an automated backport of #${{ github.event.pull_request.number }} to the ${{ needs.find-branch.outputs.release-branch }} branch. FYI @${{ github.event.pull_request.user.login }}'
          PR_BODY_CONFLICTS: |

            This is an automated backport of #${{ github.event.pull_request.number }} to the ${{ needs.find-branch.outputs.release-branch }} branch. FYI @${{ github.event.pull_request.user.login }}
            This backport has conflicts that need to be resolved manually.

            ### `git cherry-pick` output

            ```
            ${{ steps.cherry-pick.outputs.git-output }}
            ```

      - name: Remove backport label from original PR
        if: '!steps.check-existing.outputs.existing-pr && steps.create-pr.outputs.backport-pr-url'
        run: |
          # Remove the backport label from the original PR
          gh pr edit ${{ github.event.pull_request.number }} --remove-label backport
          echo "Removed backport label from original PR #${{ github.event.pull_request.number }}"
        env:
          GH_TOKEN: ${{ steps.app-token.outputs.token }}

      - name: Success Comment on original PR
        if: "!steps.check-existing.outputs.existing-pr && steps.cherry-pick.outputs.has-conflicts == 'false' && steps.create-pr.outputs.backport-pr-url"
        run: |
          gh pr comment ${{ github.event.pull_request.number }} --body "✅ Backport PR created: ${{ steps.create-pr.outputs.backport-pr-url }}"
        env:
          GH_TOKEN: ${{ steps.app-token.outputs.token }}

      - name: Error Comment on original PR
        if: "!steps.check-existing.outputs.existing-pr && steps.cherry-pick.outputs.has-conflicts == 'true' && steps.create-pr.outputs.backport-pr-url"
        run: |
          gh pr comment ${{ github.event.pull_request.number }} --body "⚠️ Backport to ${{ needs.find-branch.outputs.release-branch }} created but has conflicts: ${{ steps.create-pr.outputs.backport-pr-url }}"
        env:
          GH_TOKEN: ${{ steps.app-token.outputs.token }}

      - name: Pull request failure Comment on original PR
        if: "!steps.check-existing.outputs.existing-pr && steps.cherry-pick.outputs.has-conflicts == 'true' && !steps.create-pr.outputs.backport-pr-url"
        run: |
          gh pr comment ${{ github.event.pull_request.number }} --body "❌ Backport to ${{ needs.find-branch.outputs.release-branch }} failed. This backport requires manual intervention. [View workflow run](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }})"
        env:
          GH_TOKEN: ${{ steps.app-token.outputs.token }}