name: CodeQL SAST

# One analysis per language: c-cpp, javascript-typescript (graph-ui, pkg/npm),
# python, actions. Scope: .github/codeql/codeql-config.yml (first-party source).
#
# FULL scan -- push to main, weekly, dry run, release: every language; c-cpp
#   traces the whole production build, vendored C included.
# PR scan -- pr.yml's `codeql` job (light: true), needed by ci-ok. One leg per
#   language whose scope the PR changes (codeql-* lanes of
#   scripts/ci/select-lanes.sh; an undeterminable diff or a change to the
#   workflows, the build or the CodeQL machinery selects every language).
#   Each leg analyses its language's WHOLE first-party scope, so cross-file
#   data flow is kept; c-cpp compiles the vendored objects before tracing
#   starts, except vendored files the PR changes. Diff-informed analysis then
#   restricts the REPORTED alerts to the changed lines; what is extracted and
#   analysed is never narrowed by the diff.
# There is no pull_request trigger and no job anywhere that polls for a CodeQL
# run: the former PR gate waited up to 150 min per PR for a full analysis and,
# with ~30 PRs pushed at once, starved PR CI for hours.
on:
  push:
    branches: [main]
  schedule:
    - cron: "23 5 * * 1"
  workflow_dispatch:
    inputs:
      light:
        description: "PR-style c-cpp build (vendored objects compiled untraced) -- to time it"
        type: boolean
        default: false
  workflow_call:
    inputs:
      light:
        description: "PR scan: vendored C compiled untraced except changed files; diff-informed results"
        type: boolean
        default: false
      matrix:
        description: 'The legs to run, {"include":[...]} (pr.yml: the selected codeql-* lanes); empty = every language'
        type: string
        default: ""

permissions:
  contents: read

jobs:
  analyze:
    runs-on: ubuntu-latest
    strategy:
      fail-fast: false
      # The same legs (and keys) everywhere, so a PR's analysis and main's
      # share one code-scanning configuration per language.
      matrix: ${{ fromJSON(inputs.matrix || '{"include":[{"language":"c-cpp","build-mode":"manual","lane":"codeql-cpp"},{"language":"javascript-typescript","build-mode":"none","lane":"codeql-js"},{"language":"python","build-mode":"none","lane":"codeql-py"},{"language":"actions","build-mode":"none","lane":"codeql-actions"}]}') }}
    # Superseded runs are always cancelled: a newer push to main cancels the
    # analysis of an older main commit (batched merges -> only the newest main
    # commit is scanned), a newer push to a PR cancels that PR's scan. Every
    # other trigger gets a group of its own and is never cancelled: a dry run
    # or a release tests ONE commit, and two dispatched together must not
    # cancel each other's gate. Per language, so legs never cancel each other.
    # In a called workflow `github` is the CALLER's context: event_name is
    # pull_request for pr.yml, github.workflow names the dry run or release.
    concurrency:
      group: codeql-${{ matrix.language }}-${{ github.event_name == 'push' && github.ref || github.event_name == 'pull_request' && format('pr-{0}', github.event.pull_request.number) || format('{0}-{1}', github.workflow, github.run_id) }}
      cancel-in-progress: ${{ github.event_name == 'push' || github.event_name == 'pull_request' }}
    # CodeQL needs security-events: write to upload results (and read for the
    # alert check); scoped to this job so the workflow's top-level token stays
    # read-only (Scorecard TokenPermissions).
    permissions:
      security-events: write
      actions: read
      contents: read
    env:
      # One code-scanning configuration for every trigger. The action derives
      # the key from the RUN's workflow file, which for a called workflow is
      # the caller: pr.yml / dry-run.yml / release.yml would each open a
      # configuration of their own, and on main an alert fixed by a later push
      # would stay open in a stale one. The value is the key the push-to-main
      # analysis has always used (the action documents this variable as
      # settable for non-standard setups).
      CODEQL_ACTION_ANALYSIS_KEY: .github/workflows/codeql.yml:analyze
      # Diff-informed analysis: codeql-action v4.38.1 (CLI 2.27.0) reports a
      # pull request's alerts only on its changed lines when the
      # diff_informed_queries feature is on (default on; this variable forces
      # it, src/feature-flags.ts). It applies only when the event payload is a
      # pull request -- pr.yml's call -- and is inert on main, dry run, release.
      CODEQL_ACTION_DIFF_INFORMED_QUERIES: ${{ inputs.light && 'true' || '' }}
      # No compiler cache: a cache hit skips the compiler, and CodeQL extracts
      # only what a traced compiler invocation actually compiles.
      CBM_NO_CCACHE: "1"
    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          # The PR scan reads the merge commit's first parent (the base) to
          # find the vendored files the PR changes.
          fetch-depth: ${{ inputs.light && 2 || 1 }}

      - name: Install build dependencies
        if: ${{ matrix.language == 'c-cpp' }}
        timeout-minutes: 10
        run: APT_RETRIES=3; [ -f /etc/apt/apt-mirrors.txt ] && APT_RETRIES=0; sudo apt-get -o Acquire::Retries=$APT_RETRIES -o Acquire::http::Timeout=30 -o Acquire::https::Timeout=30 --error-on=any update && sudo apt-get -o Acquire::Retries=$APT_RETRIES -o Acquire::http::Timeout=30 -o Acquire::https::Timeout=30 install -y zlib1g-dev

      # PR c-cpp: compile the third-party objects (tree-sitter grammars,
      # sqlite, mimalloc, lz4, zstd, the tree-sitter runtime: ~1.3 GB of
      # vendored C against ~45 MB first-party) BEFORE tracing starts, so the
      # traced build below compiles first-party code only ...
      - name: Build third-party objects (PR scan, untraced)
        if: ${{ matrix.language == 'c-cpp' && inputs.light }}
        run: scripts/build.sh --vendored-only

      # ... except the vendored files this PR changes: those are rebuilt
      # under tracing (an undeterminable diff leaves the list empty; the scan
      # still covers all first-party C).
      - name: Vendored files this PR changes (traced too)
        if: ${{ matrix.language == 'c-cpp' && inputs.light }}
        run: scripts/ci/codeql-retrace-vendored.sh "$RUNNER_TEMP/codeql-retrace.txt"

      - name: Initialize CodeQL
        uses: github/codeql-action/init@9b3254085494b55a0f7c4c2b3d2d52cc712ce370 # v4
        with:
          languages: ${{ matrix.language }}
          build-mode: ${{ matrix.build-mode }}
          config-file: ./.github/codeql/codeql-config.yml

      - name: Build for CodeQL analysis (full)
        if: ${{ matrix.language == 'c-cpp' && !inputs.light }}
        run: scripts/build.sh

      - name: Build for CodeQL analysis (PR scan, first-party + changed vendored)
        if: ${{ matrix.language == 'c-cpp' && inputs.light }}
        run: scripts/build.sh --reuse-vendored --retrace-from "$RUNNER_TEMP/codeql-retrace.txt"

      - name: Perform CodeQL Analysis
        uses: github/codeql-action/analyze@9b3254085494b55a0f7c4c2b3d2d52cc712ce370 # v4
        with:
          category: "/language:${{ matrix.language }}"

      # Alert policy: the default branch carries ZERO open code-scanning
      # alerts. Any open alert on the analysed ref fails this leg: on main the
      # commit turns red and GitHub notifies whoever triggered the run; the
      # dry run and the release cannot pass; a PR (refs/pull/<n>/merge: what
      # its changed lines introduce) fails ci-ok. With a zero baseline "any
      # open alert" is exactly "a new alert"; a dismissal (with a reason, in
      # the Security tab) holds on every ref. Every leg checks after its own
      # upload, so each language's alerts are seen by at least its own leg.
      # Moved from _security.yml's former PR-CI codeql-gate job.
      - name: Check for open code scanning alerts
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          ALERT_REF: ${{ github.ref }}
        run: |
          # FAIL CLOSED. The previous form was `gh api ... 2>/dev/null || echo "0"`,
          # which looks defensive and is the opposite. gh writes the API error
          # BODY to stdout, so a 403 made ALERTS the string
          #   {"message":"Resource not accessible by integration",...,"status":"403"}0
          # every `[` comparison then failed as non-integer, the `if` took its
          # false branch, and the step printed "CodeQL gate passed (0 alerts)"
          # and exited 0. That is exactly how a security gate should NEVER fail:
          # silently, in the direction of "everything is fine". An unreadable
          # alert list is now an error, not a zero.
          # NOTE: this runs in a command substitution, so it must `return`, not
          # `exit` -- an `exit` here would only end the subshell and let the
          # caller continue with an empty count, recreating the very bug this
          # replaces. The callers below check the status explicitly.
          count_open_alerts() {
            local body status
            body=$(gh api "repos/${{ github.repository }}/code-scanning/alerts?state=open&ref=$ALERT_REF" \
                     --jq 'length' 2>/dev/null)
            status=$?
            if [ $status -ne 0 ]; then
              echo "BLOCKED: cannot read code scanning alerts (gh exit $status)." >&2
              echo "  Refusing to treat an unreadable alert list as zero." >&2
              echo "  Most likely cause: the job lacks security-events:read." >&2
              return 1
            fi
            case "$body" in
              ''|*[!0-9]*)
                echo "BLOCKED: alert count was not a number: ${body:-<empty>}" >&2
                return 1
                ;;
            esac
            printf '%s' "$body"
          }
          echo "Waiting 60s for alert API to settle..."
          sleep 60
          ALERTS=$(count_open_alerts) || exit 1
          sleep 15
          ALERTS2=$(count_open_alerts) || exit 1
          [ "$ALERTS" -lt "$ALERTS2" ] && ALERTS=$ALERTS2
          if [ "$ALERTS" -gt 0 ]; then
            echo "::error title=Open code scanning alerts::$ALERTS open alert(s) on $ALERT_REF -- fix, or dismiss with a reason in the Security tab"
            echo "BLOCKED: $ALERTS open alert(s)"
            gh api "repos/${{ github.repository }}/code-scanning/alerts?state=open&ref=$ALERT_REF" \
              --jq '.[] | "  #\(.number) [\(.rule.security_severity_level // .rule.severity)] \(.rule.id) — \(.most_recent_instance.location.path):\(.most_recent_instance.location.start_line)"' 2>/dev/null || true
            exit 1
          fi
          echo "=== CodeQL gate passed (0 alerts) ==="