coverage.yml

name: Code Coverage

on:
  push:
    branches: [main, release-*]
    paths-ignore: ['**.md', '**.png', '**.jpg', '**.svg', '**/docs/**']
  pull_request:
    branches: [main, release-*]
    paths-ignore: ['**.md', '**.png', '**.jpg', '**.svg', '**/docs/**']

# Only read-only permissions needed here.
# PR comments are posted by coverage-comment.yml via workflow_run
# so that fork PRs can also receive comments with write access.
permissions:
  contents: read

env:
  THRESHOLD_TOTAL: 70    # overall coverage threshold (%)
  THRESHOLD_DIFF: 90     # changed-line coverage threshold (%)

jobs:
  coverage:
    runs-on: ubuntu-latest
    timeout-minutes: 60
    steps:
      - name: Checkout code
        uses: actions/checkout@v4
        with:
          fetch-depth: 0   # full history needed for diff coverage

      - name: Set up Go
        uses: actions/setup-go@v5
        with:
          go-version: '1.24.2'

      - name: Cache Go modules
        uses: actions/cache@v4
        with:
          path: |
            ~/.cache/go-build
            ~/go/pkg/mod
          key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
          restore-keys: |
            ${{ runner.os }}-go-

      # ── Run tests ────────────────────────────────────────────────────────────
      - name: Run tests with coverage (excluding pkg/server)
        run: make test-coverage-ci

      # ── Convert coverage format for diff-cover ────────────────────────────
      - name: Install gocover-cobertura
        run: go install github.com/t-yuki/gocover-cobertura@latest

      - name: Convert to Cobertura XML
        run: gocover-cobertura < coverage.out > coverage.xml

      - name: Normalize Cobertura paths for diff-cover
        run: |
          MODULE_PATH=$(go list -m)
          python3 -c "from pathlib import Path; import sys; module = sys.argv[1].rstrip('/') + '/'; path = Path('coverage.xml'); path.write_text(path.read_text(encoding='utf-8').replace(f'filename=\"{module}', 'filename=\"'), encoding='utf-8')" "$MODULE_PATH"

      - name: Install diff-cover
        run: pip install diff-cover

      # ── Check total coverage threshold ───────────────────────────────────
      - name: Check total coverage (>= ${{ env.THRESHOLD_TOTAL }}%)
        id: total_coverage
        run: |
          TOTAL=$(go tool cover -func=coverage.out | tail -1 | awk '{print $3}' | sed 's/%//')
          echo "total=${TOTAL}" >> "$GITHUB_OUTPUT"
          echo "Total coverage: ${TOTAL}%  (threshold: ${{ env.THRESHOLD_TOTAL }}%)"
          if awk "BEGIN { exit !( ${TOTAL} + 0 < ${{ env.THRESHOLD_TOTAL }}) }"; then
            echo "status=fail" >> "$GITHUB_OUTPUT"
            echo "❌ Total coverage ${TOTAL}% is below the required ${{ env.THRESHOLD_TOTAL }}%"
          else
            echo "status=pass" >> "$GITHUB_OUTPUT"
            echo "✅ Total coverage ${TOTAL}% meets the threshold of ${{ env.THRESHOLD_TOTAL }}%"
          fi

      # ── Check diff (changed-line) coverage threshold ─────────────────────
      - name: Fetch base branch for diff
        if: github.event_name == 'pull_request'
        run: git fetch origin ${{ github.base_ref }} --depth=1

      - name: Check diff coverage (>= ${{ env.THRESHOLD_DIFF }}%)
        id: diff_coverage
        if: github.event_name == 'pull_request'
        run: |
          BASE=origin/${{ github.base_ref }}
          DIFF_OUTPUT=$(diff-cover coverage.xml \
            --compare-branch="${BASE}" \
            --format json:diff-cover.json \
            --fail-under=${{ env.THRESHOLD_DIFF }} \
            2>&1) && DIFF_EXIT=0 || DIFF_EXIT=$?

          if [ -f diff-cover.json ]; then
            DIFF_PCT=$(python3 -c "import json; report=json.load(open('diff-cover.json', encoding='utf-8')); num_changed_lines=report.get('num_changed_lines', 0); total_num_lines=report.get('total_num_lines', 0); total_percent_covered=report.get('total_percent_covered', 'N/A'); print('N/A' if num_changed_lines > 0 and total_num_lines == 0 else total_percent_covered)")
          else
            DIFF_PCT="N/A"
          fi

          if [ "$DIFF_PCT" = "N/A" ]; then
            DIFF_DISPLAY="N/A"
          else
            DIFF_DISPLAY="${DIFF_PCT}%"
          fi

          echo "diff_pct=${DIFF_PCT}" >> "$GITHUB_OUTPUT"
          echo "diff_display=${DIFF_DISPLAY}" >> "$GITHUB_OUTPUT"
          echo "$DIFF_OUTPUT"

          if [ "$DIFF_EXIT" -ne 0 ] || [ "$DIFF_PCT" = "N/A" ]; then
            echo "diff_status=fail" >> "$GITHUB_OUTPUT"

            if [ "$DIFF_PCT" = "N/A" ]; then
              echo "❌ Changed-line coverage could not be computed because diff-cover found changed lines without matching coverage information."
            fi
          else
            echo "diff_status=pass" >> "$GITHUB_OUTPUT"
          fi

      # ── Generate per-package coverage table ──────────────────────────────
      - name: Generate coverage report markdown
        run: |
          {
            echo "## 📊 Code Coverage Report"
            echo ""

            TOTAL="${{ steps.total_coverage.outputs.total }}"
            STATUS="${{ steps.total_coverage.outputs.status }}"
            [ -n "$TOTAL" ] || TOTAL="N/A"
            [ "$STATUS" = "pass" ] && ICON="✅" || ICON="❌"

            echo "| Metric | Coverage | Threshold | Status |"
            echo "|--------|----------|-----------|--------|"
            echo "| Overall | **${TOTAL}%** | ${{ env.THRESHOLD_TOTAL }}% | ${ICON} |"

            if [ "${{ github.event_name }}" = "pull_request" ]; then
              DIFF_DISPLAY="${{ steps.diff_coverage.outputs.diff_display }}"
              DIFF_STATUS="${{ steps.diff_coverage.outputs.diff_status }}"
              [ -n "$DIFF_DISPLAY" ] || DIFF_DISPLAY="N/A"
              [ "$DIFF_STATUS" = "pass" ] && DIFF_ICON="✅" || DIFF_ICON="❌"
              echo "| Changed lines | **${DIFF_DISPLAY}** | ${{ env.THRESHOLD_DIFF }}% | ${DIFF_ICON} |"
            fi

            if [ -f coverage.out ]; then
              echo ""
              echo "<details>"
              echo "<summary>📦 Per-package breakdown</summary>"
              echo ""
              echo '```'
              go tool cover -func=coverage.out | grep -v "^total:" | \
                awk '{printf "%-80s %s\n", $1, $3}' | sort
              echo ""
              go tool cover -func=coverage.out | grep "^total:"
              echo '```'
              echo ""
              echo "</details>"
            else
              echo ""
              echo "Coverage artifacts were not generated because the workflow failed before coverage collection completed."
            fi
          } > coverage-report.md

      # ── Write step summary ────────────────────────────────────────────────
      - name: Write job summary
        run: cat coverage-report.md >> "$GITHUB_STEP_SUMMARY"

      # ── Save PR number so the comment workflow can find the right PR ──────
      - name: Save PR number
        if: github.event_name == 'pull_request'
        run: echo "${{ github.event.pull_request.number }}" > pr-number.txt

      # ── Upload artifacts (report + pr-number for comment workflow) ────────
      - name: Upload coverage artifacts
        uses: actions/upload-artifact@v4
        with:
          name: coverage-report
          path: |
            coverage.out
            coverage.xml
            diff-cover.json
            coverage-report.md
            pr-number.txt
          if-no-files-found: warn
          retention-days: 14

      - name: Upload coverage to Codecov
        uses: codecov/codecov-action@v4
        with:
          file: ./coverage.out
          flags: unittests
          name: codecov-umbrella
          fail_ci_if_error: false
        env:
          CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}

      # ── Enforce thresholds (after artifacts uploaded so report is always saved) ──
      - name: Enforce total coverage threshold
        if: steps.total_coverage.outputs.status == 'fail'
        run: |
          echo "❌ Total coverage ${{ steps.total_coverage.outputs.total }}% is below the required ${{ env.THRESHOLD_TOTAL }}%"
          exit 1

      - name: Enforce diff coverage threshold
        if: >
          github.event_name == 'pull_request' &&
          steps.diff_coverage.outputs.diff_status == 'fail'
        run: |
          echo "❌ Changed-line coverage ${{ steps.diff_coverage.outputs.diff_display }} is below the required ${{ env.THRESHOLD_DIFF }}%"
          exit 1