auto-merge.yml

name: Auto Merge Approved PRs

on:
  pull_request_review:
    types: [submitted]

jobs:
  auto-merge:
    if: github.event.review.state == 'approved' &&
      (github.event.pull_request.base.ref == 'test' || github.event.pull_request.base.ref == 'main')
    runs-on: ubuntu-latest
    permissions:
      pull-requests: write
      contents: write

    steps:
      - name: Checkout
        uses: actions/checkout@v6

      - name: Wait for all required status checks to pass
        run: |
          PR_NUMBER=${{ github.event.pull_request.number }}
          HEAD_SHA=${{ github.event.pull_request.head.sha }}
          echo "Waiting for required status checks on PR #$PR_NUMBER (SHA: $HEAD_SHA)..."

          # Guard the empty-checks race: if approval lands before any check
          # registers, pending=0/failed=0 reads as vacuously green. This check
          # always runs on these PRs, so require it green before merging.
          ANCHOR_CHECK="validate_merge_origin"

          MAX_WAIT=1800  # 30 min - covers a deploy-docs build finishing mid-review
          INTERVAL=15
          ELAPSED=0

          while true; do
            CHECKS=$(gh api \
              "repos/${{ github.repository }}/commits/$HEAD_SHA/check-runs" \
              --jq '[.check_runs[] | {name: .name, status: .status, conclusion: .conclusion}]')

            TOTAL=$(echo   "$CHECKS" | jq 'length')
            PENDING=$(echo "$CHECKS" | jq '[.[] | select(.status != "completed")] | length')
            FAILED=$(echo  "$CHECKS" | jq '[.[] | select(.status == "completed" and (.conclusion != "success" and .conclusion != "skipped" and .conclusion != "neutral"))] | length')
            ANCHOR_OK=$(echo "$CHECKS" | jq --arg n "$ANCHOR_CHECK" '[.[] | select(.name == $n and .status == "completed" and .conclusion == "success")] | length')

            echo "  checks total=$TOTAL pending=$PENDING failed=$FAILED anchor_ok=$ANCHOR_OK  (elapsed=${ELAPSED}s)"

            if [[ "$FAILED" -gt 0 ]]; then
              echo "❌ One or more required checks failed — aborting merge."
              echo "$CHECKS" | jq '.[] | select(.conclusion != "success" and .conclusion != "skipped" and .conclusion != "neutral")'
              exit 1
            fi

            if [[ "$ANCHOR_OK" -ge 1 && "$PENDING" -eq 0 ]]; then
              echo "✅ Anchor check '$ANCHOR_CHECK' passed and all checks completed."
              break
            fi

            if [[ "$ANCHOR_OK" -eq 0 ]]; then
              echo "  ⏳ Anchor check '$ANCHOR_CHECK' not yet present/successful — waiting."
            fi

            if [[ "$ELAPSED" -ge "$MAX_WAIT" ]]; then
              echo "⏰ Timed out waiting for checks after ${MAX_WAIT}s — aborting merge."
              exit 1
            fi

            sleep $INTERVAL
            ELAPSED=$((ELAPSED + INTERVAL))
          done
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      - name: Get PR title and description
        id: pr_info
        run: |
          title=$(gh pr view ${{ github.event.pull_request.number }} --json title -q .title)
          # test->main: the body may carry the BREAKING CHANGE marker (major release).
          pr_body=$(gh pr view ${{ github.event.pull_request.number }} --json body -q .body)
          echo "title=$title" >> "$GITHUB_OUTPUT"
          {
            echo 'pr_body<<PR_BODY_EOF'
            echo "$pr_body"
            echo 'PR_BODY_EOF'
          } >> "$GITHUB_OUTPUT"
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      - name: Generate commit message body
        id: commit_body
        run: |
          file_list=$(.github/scripts/generate_commit_message.sh ${{ github.event.pull_request.number }})
          {
            echo 'body<<EOF'
            echo "$file_list"
            echo 'EOF'
          } >> "$GITHUB_OUTPUT"
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      - name: Auto-merge the PR
        run: |
          # develop->test: squash (title = subject, body = file list).
          # test->main:    merge commit, --subject avoids "Merge pull request #N".
          #                body = PR description + file list, so semantic-release sees the bump.
          if [[ "${{ github.event.pull_request.base.ref }}" == "main" ]]; then
            cat > /tmp/commit_msg.txt << 'EOF'
          ${{ steps.pr_info.outputs.pr_body }}

          ## Changed documents
          ${{ steps.commit_body.outputs.body }}
          EOF
            gh pr merge ${{ github.event.pull_request.number }} \
              --merge \
              --subject "${{ steps.pr_info.outputs.title }}" \
              --body "$(cat /tmp/commit_msg.txt)"
          else
            gh pr merge ${{ github.event.pull_request.number }} \
              --squash \
              --body "${{ steps.commit_body.outputs.body }}"
          fi
        env:
          GH_TOKEN: ${{ secrets.GH_PAT }}