cherry-pick-patch.yml

name: Cherry-pick patch PRs to release branch

on:
  workflow_dispatch:
    inputs:
      pr_number:
        description: 'PR number to cherry-pick onto the release branch'
        required: true
        type: string
  pull_request:
    types: [closed]
    branches: [main]
  issues:
    types: [labeled]

permissions:
  contents: write
  pull-requests: write
  actions: write

jobs:
  cherry-pick:
    name: Cherry-pick onto ${{ vars.RELEASE_BRANCH || 'v5.0' }}
    runs-on: ubuntu-latest
    # Run when a PR with the patch label is merged into main.
    # Handles two triggering paths:
    #   pull_request/closed — PR merged with patch label already present
    #   issues/labeled      — patch label added to an already-merged PR
    #                         (GitHub fires 'issues' not 'pull_request' for label
    #                          changes on closed/merged PRs)
    if: >-
      github.event_name == 'workflow_dispatch' ||
      (github.event_name == 'pull_request' &&
       github.event.pull_request.merged == true &&
       contains(github.event.pull_request.labels.*.name, 'patch')) ||
      (github.event_name == 'issues' &&
       github.event.label.name == 'patch' &&
       github.event.issue.pull_request.merged_at != '')

    env:
      RELEASE_BRANCH: ${{ vars.RELEASE_BRANCH || 'v5.0' }}

    steps:
      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
        with:
          token: ${{ secrets.GITHUB_TOKEN }}

      - name: Configure git
        run: |
          git config user.email "noreply@harperdb.io"
          git config user.name "Harperfast"

      - name: Cherry-pick onto ${{ env.RELEASE_BRANCH }}
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          PR_NUMBER: ${{ github.event.inputs.pr_number || github.event.pull_request.number || github.event.issue.number }}
          MERGE_SHA_FROM_EVENT: ${{ github.event.pull_request.merge_commit_sha }}
          PR_TITLE_FROM_EVENT: ${{ github.event.pull_request.title || github.event.issue.title }}
        run: |
          set -euo pipefail

          # For workflow_dispatch/issues events, some fields aren't in the payload; fetch them.
          if [ -n "$MERGE_SHA_FROM_EVENT" ]; then
            MERGE_SHA="$MERGE_SHA_FROM_EVENT"
            PR_TITLE="$PR_TITLE_FROM_EVENT"
          else
            PR_DATA=$(gh api "repos/$GITHUB_REPOSITORY/pulls/$PR_NUMBER" --jq '{sha: .merge_commit_sha, title: .title, state: .state}')
            MERGE_SHA=$(echo "$PR_DATA" | jq -r '.sha')
            PR_TITLE=$(echo "$PR_DATA" | jq -r '.title')
            STATE=$(echo "$PR_DATA" | jq -r '.state')
            if [ "$STATE" != "closed" ] || [ -z "$MERGE_SHA" ] || [ "$MERGE_SHA" = "null" ]; then
              echo "PR #$PR_NUMBER is not yet merged — aborting."
              exit 1
            fi
          fi

          # Fetch enough history for subject-match checks and ancestor lookups
          # (cherry-pick needs MERGE_SHA^ to compute the diff; rebase merges need
          # up to COMMIT_COUNT ancestors). Full unshallow fetches both branches.
          git fetch --depth=200 origin main "$RELEASE_BRANCH"

          # Skip if this commit is already in the release branch.
          # Subject matching handles cherry-picks whose patch-id changed due to
          # conflict resolution (e.g. package-lock.json merges).
          SUBJECT=$(git log -1 --format=%s "$MERGE_SHA")
          if git log "origin/$RELEASE_BRANCH" --format=%s | grep -qxF "$SUBJECT"; then
            echo "PR #$PR_NUMBER already applied to $RELEASE_BRANCH — skipping."
            exit 0
          fi

          # ── Determine pick strategy ────────────────────────────────────────────
          PARENT_COUNT=$(git cat-file -p "$MERGE_SHA" | grep -c "^parent ")
          PICK_FLAGS=""
          PICK_SHAS="$MERGE_SHA"

          if [ "$PARENT_COUNT" -gt 1 ]; then
            # True merge commit → cherry-pick combined diff
            PICK_FLAGS="-m 1"
          else
            COMMIT_COUNT=$(gh api "repos/$GITHUB_REPOSITORY/pulls/$PR_NUMBER/commits" --jq '. | length')
            if [ "$COMMIT_COUNT" -gt 1 ]; then
              LAST_BRANCH_SUBJECT=$(gh api "repos/$GITHUB_REPOSITORY/pulls/$PR_NUMBER/commits" \
                --jq '.[-1].commit.message | split("\n")[0]')
              # Rebase merge: subject equals last branch commit subject with no "(#N)" suffix.
              # Squash merge: either has "(#N)" suffix, or subject differs from last branch commit.
              if ! echo "$SUBJECT" | grep -qF "(#$PR_NUMBER)" && [ "$SUBJECT" = "$LAST_BRANCH_SUBJECT" ]; then
                # Rebase merge — reconstruct commit list oldest→newest
                PICK_SHAS=""
                for i in $(seq $((COMMIT_COUNT - 1)) -1 0); do
                  SHA=$([ "$i" -eq 0 ] && echo "$MERGE_SHA" || git rev-parse "${MERGE_SHA}~${i}")
                  PICK_SHAS="${PICK_SHAS:+$PICK_SHAS }$SHA"
                done
              fi
              # else: squash — PICK_SHAS stays as $MERGE_SHA
            fi
          fi

          # ── Cherry-pick ────────────────────────────────────────────────────────
          git checkout "$RELEASE_BRANCH"

          # shellcheck disable=SC2086
          if git cherry-pick $PICK_FLAGS $PICK_SHAS; then
            git push origin "$RELEASE_BRANCH"
            echo "✅ Cherry-picked PR #$PR_NUMBER onto $RELEASE_BRANCH"
            gh workflow run integration-tests.yml --ref "$RELEASE_BRANCH" --repo "$GITHUB_REPOSITORY"
            gh workflow run unit-test.yml --ref "$RELEASE_BRANCH" --repo "$GITHUB_REPOSITORY"
          else
            echo "⚠️ Cherry-pick conflict — creating resolution branch"
            git cherry-pick --abort 2>/dev/null || true

            CONFLICT_BRANCH="cherry-pick/${RELEASE_BRANCH}/pr-${PR_NUMBER}"
            git checkout -b "$CONFLICT_BRANCH"

            # Re-apply each commit individually so partial successes are preserved.
            # Conflict markers are staged and committed for the reviewer to resolve.
            for SHA in $PICK_SHAS; do
              # shellcheck disable=SC2086
              git cherry-pick $PICK_FLAGS "$SHA" || {
                git add -A
                git cherry-pick --continue --no-edit || git cherry-pick --skip
              }
            done

            git push origin "$CONFLICT_BRANCH"

            PR_BODY=$(printf '## Resolve cherry-pick conflicts\n\nPR #%s (_%s_) conflicted when cherry-picking onto `%s`.\n\nConflict markers (`<<<<<<<` / `=======` / `>>>>>>>`) have been committed to this branch. Please check out the branch, resolve all conflicts, push, and merge.\n\n**Source PR:** #%s\n**Commit(s):** `%s`' \
              "$PR_NUMBER" "$PR_TITLE" "$RELEASE_BRANCH" "$PR_NUMBER" "$PICK_SHAS")
            gh pr create \
              --title "cherry-pick: \`${PR_TITLE}\` → \`${RELEASE_BRANCH}\` (conflict)" \
              --body "$PR_BODY" \
              --base "$RELEASE_BRANCH" \
              --head "$CONFLICT_BRANCH"
          fi