# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.
name: Enforce single Alembic migration head
on:
  push:
    branches:
      - "master"
      - "[0-9].[0-9]*"
  pull_request:
    types: [synchronize, opened, reopened, ready_for_review]

# No `paths:` filter on purpose: this job is a required status check, and a
# required check that never runs for a given PR blocks that PR from merging
# forever. It has to fire on every PR so it always reports a status; whether
# migrations changed is decided inside the job, not the trigger.

# cancel previous workflow jobs for PRs
concurrency:
  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.run_id }}
  cancel-in-progress: true

permissions:
  contents: read

jobs:
  enforce-single-migration-head:
    runs-on: ubuntu-26.04
    permissions:
      contents: read
      pull-requests: read
    steps:
      - name: "Checkout ${{ github.ref }} ( ${{ github.sha }} )"
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          persist-credentials: false
      - name: Check for migration file changes
        id: check
        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
        with:
          github-token: ${{ github.token }}
          script: |
            if (context.eventName === 'push') {
              core.setOutput('changed', 'true');
              return;
            }
            const files = await github.paginate(github.rest.pulls.listFiles, {
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: context.issue.number,
            });
            const changed = files.some((f) => f.filename.startsWith('superset/migrations/'));
            core.setOutput('changed', String(changed));
      - name: Setup Python
        if: steps.check.outputs.changed == 'true'
        uses: ./.github/actions/setup-backend/
        with:
          requirements-type: base
      - name: Assert a single Alembic head
        if: steps.check.outputs.changed == 'true'
        env:
          SUPERSET__SQLALCHEMY_DATABASE_URI: "sqlite:///:memory:"
        run: |
          heads="$(superset db heads)"
          echo "$heads"
          head_count=$(printf '%s\n' "$heads" | grep -c .)
          if [ "$head_count" -ne 1 ]; then
            echo "::error::superset/migrations resolves to $head_count Alembic heads (expected exactly 1)."
            echo "Another migration already landed with the same down_revision this branch was cut from."
            echo "Add a no-op merge revision joining the heads: https://superset.apache.org/docs/contributing/development#merging-db-migrations"
            exit 1
          fi