# Advisory-only check: flags PRs that change source code (.py / .ts / .tsx)
# without touching any test file. It NEVER fails and is NOT a required check,
# so it cannot block other jobs or the merge — it only posts a sticky PR
# comment + job summary so the author knows tests appear to be missing.
name: Test Coverage Advisor

on:
  pull_request:
    types: [opened, synchronize, reopened, ready_for_review]

# Dedicated concurrency group so this never cancels or queues behind CI.
concurrency:
  group: test-coverage-advisor-${{ github.event.pull_request.number }}
  cancel-in-progress: true

permissions:
  contents: read
  pull-requests: write

jobs:
  advise:
    name: Test Coverage Advisor
    # Skip drafts to avoid noise; they re-run on "ready_for_review".
    if: github.event.pull_request.draft == false
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v6
        with:
          # Full history so merge-base against the PR target works.
          fetch-depth: 0

      - name: Detect missing tests
        id: detect
        shell: bash
        run: |
          set -euo pipefail

          BASE_REF="${{ github.event.pull_request.base.ref }}"
          git fetch --no-tags --depth=50 origin "$BASE_REF" || true
          MERGE_BASE=$(git merge-base HEAD "origin/$BASE_REF" || git rev-parse HEAD~1)

          echo "BASE_REF=$BASE_REF"
          echo "MERGE_BASE=$MERGE_BASE"

          CHANGED=$(git diff --name-only --diff-filter=ACMR "$MERGE_BASE"...HEAD || true)
          echo "=== Changed files ==="
          echo "$CHANGED"

          # --- Backend Python ---------------------------------------------
          # Source: .py under src/backend or src/lfx, excluding tests,
          # migrations and dunder/init plumbing.
          PY_SRC=$(echo "$CHANGED" \
            | grep -E '^(src/backend|src/lfx)/.*\.py$' \
            | grep -Ev '(^|/)tests?/' \
            | grep -Ev '(^|/)(test_[^/]+|conftest)\.py$' \
            | grep -Ev '/alembic/versions/' \
            | grep -Ev '/__init__\.py$' \
            || true)
          PY_TEST=$(echo "$CHANGED" \
            | grep -E '\.py$' \
            | grep -E '((^|/)tests?/|(^|/)test_[^/]+\.py$|(^|/)conftest\.py$)' \
            || true)

          # --- Frontend TS/TSX --------------------------------------------
          # Source: .ts/.tsx under src/frontend/src, excluding *.test.* /
          # *.spec.* / __tests__ and type declaration files.
          FE_SRC=$(echo "$CHANGED" \
            | grep -E '^src/frontend/src/.*\.(ts|tsx)$' \
            | grep -Ev '\.(test|spec)\.(ts|tsx)$' \
            | grep -Ev '(^|/)__tests__/' \
            | grep -Ev '\.d\.ts$' \
            || true)
          FE_TEST=$(echo "$CHANGED" \
            | grep -E '\.(ts|tsx)$' \
            | grep -E '(^src/frontend/tests/|\.(test|spec)\.(ts|tsx)$|(^|/)__tests__/)' \
            || true)

          need_be=false
          need_fe=false
          [ -n "$PY_SRC" ] && [ -z "$PY_TEST" ] && need_be=true
          [ -n "$FE_SRC" ] && [ -z "$FE_TEST" ] && need_fe=true

          {
            echo "need_be=$need_be"
            echo "need_fe=$need_fe"
          } >> "$GITHUB_OUTPUT"

          # Multiline outputs for the comment body.
          {
            echo "py_src<<EOF"
            echo "$PY_SRC"
            echo "EOF"
            echo "fe_src<<EOF"
            echo "$FE_SRC"
            echo "EOF"
          } >> "$GITHUB_OUTPUT"

      - name: Build advisory message
        id: msg
        shell: bash
        run: |
          set -euo pipefail
          NEED_BE="${{ steps.detect.outputs.need_be }}"
          NEED_FE="${{ steps.detect.outputs.need_fe }}"

          BODY_FILE="$(mktemp)"
          echo '<!-- test-coverage-advisor -->' > "$BODY_FILE"

          if [ "$NEED_BE" != "true" ] && [ "$NEED_FE" != "true" ]; then
            {
              echo '### ✅ Test Coverage Advisor'
              echo
              echo 'No source changes detected without accompanying tests. Thanks for keeping coverage up! 🎉'
              echo
              echo '> _Advisory check only — never blocks merge._'
            } >> "$BODY_FILE"
          else
            {
              echo '### ⚠️ Test Coverage Advisor — tests appear to be missing'
              echo
              echo 'This PR changes source code but does **not** add or modify any test files.'
              echo 'This is an **advisory** check: it will **not** block this PR or any other job —'
              echo 'please add tests if the change is testable.'
              echo
            } >> "$BODY_FILE"
            if [ "$NEED_BE" = "true" ]; then
              {
                echo '#### Backend (Python) — no `test_*.py` / `tests/` change found'
                echo '```'
                echo '${{ steps.detect.outputs.py_src }}'
                echo '```'
              } >> "$BODY_FILE"
            fi
            if [ "$NEED_FE" = "true" ]; then
              {
                echo '#### Frontend (TS/TSX) — no `*.test.*` / `*.spec.*` / `tests/` change found'
                echo '```'
                echo '${{ steps.detect.outputs.fe_src }}'
                echo '```'
              } >> "$BODY_FILE"
            fi
            {
              echo
              echo '> _Advisory check only — it always passes and is never a required status._'
            } >> "$BODY_FILE"
          fi

          # Mirror into the run's Job Summary (works even on fork PRs).
          cat "$BODY_FILE" >> "$GITHUB_STEP_SUMMARY"

          echo "body_file=$BODY_FILE" >> "$GITHUB_OUTPUT"

      - name: Find existing advisory comment
        id: find
        uses: peter-evans/find-comment@v3
        continue-on-error: true
        with:
          issue-number: ${{ github.event.pull_request.number }}
          comment-author: github-actions[bot]
          body-includes: "<!-- test-coverage-advisor -->"

      - name: Upsert advisory comment
        uses: peter-evans/create-or-update-comment@v4
        # Fork PRs get a read-only token — don't fail the run if so.
        continue-on-error: true
        with:
          comment-id: ${{ steps.find.outputs.comment-id }}
          issue-number: ${{ github.event.pull_request.number }}
          body-path: ${{ steps.msg.outputs.body_file }}
          edit-mode: replace

      - name: Always succeed
        # Explicit: this job never blocks anything.
        run: 'echo "Advisory check complete — this status is informational only."'