update-data.yml

name: Update Station Data

on:
  # Run daily at 03:00 UTC (05:00 Berlin summer time, 04:00 winter)
  schedule:
    - cron: '0 3 * * *'

  # Allow manual trigger from the GitHub Actions tab
  workflow_dispatch:

permissions:
  contents: write  # needed to commit updated data files back

jobs:
  update-data:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout repository
        uses: actions/checkout@v7
        with:
          # Use a token with write access so we can push the commit back
          token: ${{ secrets.GITHUB_TOKEN }}

      - name: Set up Node.js
        uses: actions/setup-node@v6
        with:
          node-version: 24
          cache: 'npm'

      - name: Install dependencies
        run: npm ci

      # ── Step 1: Build lines.json from the VBB HAFAS API ────────────────────
      # fetch-stations.js also writes station_mappings.json (identity map,
      # since stations carry their VBB stop ID natively) and qa-report.json
      # (a cross-check against the Wikipedia line list). No separate mapping
      # step is needed.
      - name: Fetch station data from VBB API
        run: node data/fetch-stations.js
        timeout-minutes: 15

      # ── Step 2: Commit and push only if something actually changed ─────────
      - name: Check for changes
        id: check_changes
        run: |
          git diff --quiet data/lines.json data/station_mappings.json data/qa-report.json \
            && echo "changed=false" >> "$GITHUB_OUTPUT" \
            || echo "changed=true" >> "$GITHUB_OUTPUT"

      - name: Commit updated data files
        if: steps.check_changes.outputs.changed == 'true'
        run: |
          git config user.name  "github-actions[bot]"
          git config user.email "github-actions[bot]@users.noreply.github.com"
          git add data/lines.json data/station_mappings.json data/qa-report.json
          git commit -m "chore: auto-update station data [$(date -u +'%Y-%m-%d')]"

          # The push can race with another commit landing on main (a manual
          # run overlapping the schedule, or a human push). The data files are
          # fully regenerated from source each run, so rebasing our commit onto
          # whatever arrived is always safe. Retry a few times before failing.
          for attempt in 1 2 3 4 5; do
            if git push; then
              echo "Pushed on attempt $attempt."
              exit 0
            fi
            echo "Push attempt $attempt rejected — rebasing onto latest main and retrying…"
            git pull --rebase --autostash origin main
            sleep 5
          done

          echo "::error::Failed to push after 5 attempts."
          exit 1

      - name: No changes detected
        if: steps.check_changes.outputs.changed == 'false'
        run: echo "Station data is already up to date — nothing to commit."