name: Backend Tests

# Always triggers on PRs so it can be a required check; the `changes` job below
# decides whether backend/extension paths actually changed (test-only changes
# match the same globs, since tests are co-located with the code), and `test`
# still reports success when they didn't. Pushes to main produce the coverage
# PRs compare against. puter.js SDK changes are covered by puterjs-tests.yaml.
on:
  pull_request:
    types: [opened, synchronize, reopened]
  push:
    branches: [main]

permissions:
  contents: read
  pull-requests: write
  # Reads main's coverage artifact for the PR comparison.
  actions: read

jobs:
  changes:
    runs-on: ubuntu-latest
    outputs:
      backend: ${{ steps.filter.outputs.backend }}
    steps:
      - uses: actions/checkout@v7
      - uses: dorny/paths-filter@v4
        id: filter
        with:
          filters: |
            backend:
              - 'src/backend/**'
              - 'extensions/**'
              - 'tools/**'
              - 'package.json'
              - 'package-lock.json'
              - 'tsconfig.json'
              - 'tsconfig.build.json'
              - '.github/workflows/backend-tests.yaml'

  # `tsconfig.build.json` builds with `noCheck: true`, so nothing else in CI
  # runs the type checker and a missing export compiles to `undefined`,
  # surfacing only when the call is finally reached at runtime. This diffs
  # against tools/typecheck-baseline.json and fails only on *new* errors.
  #
  # The consuming repo runs an equivalent gate, but only once someone bumps the
  # submodule pointer — too late to keep the error off this repo's default
  # branch. Hence a gate here, on this repo's own pull requests.
  typecheck:
    needs: changes
    if: github.event_name == 'pull_request' && needs.changes.outputs.backend == 'true'
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v7

      - name: Set up Node.js
        uses: actions/setup-node@v7
        with:
          node-version: '24'
          cache: 'npm'

      - name: Install dependencies
        run: npm ci

      - name: Type check (new errors only)
        run: npm run typecheck

  # The suite is CPU-bound, so it's split across runners. Each shard writes a
  # blob report (results plus coverage) that the `coverage` job merges.
  test-shard:
    needs: changes
    if: needs.changes.outputs.backend == 'true'
    name: test shard ${{ matrix.shard }}/${{ strategy.job-total }}
    runs-on: ubuntu-latest
    strategy:
      fail-fast: false
      matrix:
        shard: [1, 2, 3, 4]

    steps:
      - name: Checkout
        uses: actions/checkout@v7
        with:
          ref: ${{ github.event.pull_request.head.sha || github.sha }}
          repository: ${{ github.event.pull_request.head.repo.full_name || github.repository }}

      - name: Set up Node.js
        uses: actions/setup-node@v7
        with:
          node-version: '24'
          cache: 'npm'

      - name: Install dependencies
        run: npm ci

      - name: Run backend tests with coverage
        run: >-
          npm run test:backend --
          --coverage
          --shard=${{ matrix.shard }}/${{ strategy.job-total }}
          --reporter=default
          --reporter=blob
        env:
          CI: 'true'

      - name: Upload blob report
        if: ${{ !cancelled() }}
        uses: actions/upload-artifact@v7
        with:
          name: backend-blob-${{ matrix.shard }}
          path: .vitest-reports/
          include-hidden-files: true
          retention-days: 1

  # Required check, so its PR name is pinned. A skipped job would satisfy it,
  # so this always runs and fails on any shard that didn't pass.
  test:
    needs: [changes, test-shard]
    if: ${{ !cancelled() }}
    name: test (${{ github.event_name == 'push' && 'main' || 'pr' }})
    runs-on: ubuntu-latest
    steps:
      - name: Check shard results
        env:
          CHANGES_RESULT: ${{ needs.changes.result }}
          BACKEND_CHANGED: ${{ needs.changes.outputs.backend }}
          SHARDS_RESULT: ${{ needs.test-shard.result }}
        run: |
          if [ "$CHANGES_RESULT" != "success" ]; then
            echo "changes job: $CHANGES_RESULT"
            exit 1
          fi
          if [ "$BACKEND_CHANGED" != "true" ]; then
            echo "No backend changes."
            exit 0
          fi
          if [ "$SHARDS_RESULT" != "success" ]; then
            echo "test shards: $SHARDS_RESULT"
            exit 1
          fi

  coverage:
    needs: [changes, test-shard]
    if: ${{ !cancelled() && needs.test-shard.result == 'success' }}
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v7
        with:
          ref: ${{ github.event.pull_request.head.sha || github.sha }}
          repository: ${{ github.event.pull_request.head.repo.full_name || github.repository }}

      - name: Set up Node.js
        uses: actions/setup-node@v7
        with:
          node-version: '24'
          cache: 'npm'

      - name: Install dependencies
        run: npm ci

      - name: Download blob reports
        uses: actions/download-artifact@v8
        with:
          pattern: backend-blob-*
          path: .vitest-reports
          merge-multiple: true

      - name: Merge shard coverage
        run: npx vitest run --config src/backend/vitest.config.ts --merge-reports --coverage
        env:
          CI: 'true'

      - name: Upload coverage artifact
        uses: actions/upload-artifact@v7
        with:
          name: backend-coverage-${{ github.event_name == 'push' && 'main' || 'pr' }}
          path: src/backend/coverage/
          retention-days: ${{ github.event_name == 'push' && 30 || 14 }}

      # Latest main coverage from this repo's own runs; a fork can't publish
      # under this repository id.
      - name: Download main coverage
        id: base
        if: github.event_name == 'pull_request'
        env:
          GH_TOKEN: ${{ github.token }}
          REPO: ${{ github.repository }}
        run: |
          id=$(gh api "repos/$REPO/actions/artifacts?name=backend-coverage-main&per_page=20" --jq '
            [.artifacts[]
              | select(.expired | not)
              | select(.workflow_run.head_branch == "main")
              | select(.workflow_run.head_repository_id == .workflow_run.repository_id)
            ][0].id // empty')
          if [ -z "$id" ]; then
            echo "No main coverage artifact; reporting without a comparison."
            exit 0
          fi
          gh api "repos/$REPO/actions/artifacts/$id/zip" > coverage-base.zip
          unzip -q coverage-base.zip -d coverage-base
          echo "found=true" >> "$GITHUB_OUTPUT"

      - name: Report coverage on PR
        if: github.event_name == 'pull_request'
        uses: davelosert/vitest-coverage-report-action@v2
        with:
          json-summary-path: src/backend/coverage/coverage-summary.json
          json-final-path: src/backend/coverage/coverage-final.json
          json-summary-compare-path: ${{ steps.base.outputs.found == 'true' && 'coverage-base/coverage-summary.json' || '' }}