name: Server Test Merge Template

on:
  workflow_call:
    inputs:
      artifact-pattern:
        description: "Glob pattern to download shard artifacts"
        required: true
        type: string
      artifact-name:
        description: "Name for the merged output artifact"
        required: true
        type: string
      save-timing-cache:
        description: "Whether to save timing cache for future shard balancing"
        required: false
        type: boolean
        default: false
      all-shards-passed:
        description: "Whether every upstream shard succeeded. Used to gate the timing-cache save so a single shard failure doesn't poison the cache with missing-package data."
        required: false
        type: boolean
        default: false

permissions:
  contents: read
  actions: write

jobs:
  merge:
    name: Merge
    if: always()
    runs-on: ubuntu-22.04
    steps:
      - name: Download all shard artifacts
        uses: actions/download-artifact@70fc10c6e5e1ce46ad2ea6f2b72d43f7d47b13c3 # v8.0.0
        with:
          pattern: ${{ inputs.artifact-pattern }}
          path: shards

      - name: Merge JUnit reports
        run: |
          python3 -c "
          import glob, sys
          from xml.etree import ElementTree as ET

          root = ET.Element('testsuites')
          for path in sorted(glob.glob('shards/*/report.xml')):
              tree = ET.parse(path)
              r = tree.getroot()
              if r.tag == 'testsuites':
                  root.extend(r)
              else:
                  root.append(r)

          ET.ElementTree(root).write('merged-report.xml', xml_declaration=True, encoding='UTF-8')
          "

      - name: Prepare merged artifact
        run: |
          mkdir -p merged
          cp merged-report.xml merged/report.xml
          for dir in shards/*/; do
            if [[ -f "${dir}test-name" ]]; then
              cp "${dir}test-name" merged/test-name
              cp "${dir}pr-number" merged/pr-number
              break
            fi
          done

      - name: Upload merged test logs
        uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
        with:
          name: ${{ inputs.artifact-name }}
          path: merged/

      - name: Prepare timing cache
        if: inputs.save-timing-cache
        id: timing-prep
        run: |
          mkdir -p server
          echo "date=$(date -u +%Y-%m-%d)" >> "$GITHUB_OUTPUT"
          if [[ -f merged-report.xml && $(stat -c%s merged-report.xml) -gt 1024 ]]; then
            cp merged-report.xml server/prev-report.xml
            cat shards/*/gotestsum.json > server/prev-gotestsum.json 2>/dev/null || true
            echo "has_timing=true" >> "$GITHUB_OUTPUT"
          else
            echo "Skipping timing cache — merged report too small or missing"
            echo "has_timing=false" >> "$GITHUB_OUTPUT"
          fi

      # Only save when every upstream shard succeeded. If even one shard
      # failed/was killed, its gotestsum.json is missing and the merged report
      # has no timings for that shard's packages — saving that would poison
      # future shard splits (missing packages default to 1ms, all bin-pack
      # onto the lightest shard, overloading it and repeating the failure).
      - name: Save test timing cache
        if: inputs.save-timing-cache && inputs.all-shards-passed && steps.timing-prep.outputs.has_timing == 'true' && github.ref_name == github.event.repository.default_branch
        uses: actions/cache/save@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
        with:
          path: |
            server/prev-report.xml
            server/prev-gotestsum.json
          # Bucket by UTC date (not run id) so we save at most one cache per day.
          key: server-test-timing-v2-master-${{ steps.timing-prep.outputs.date }}