name: CodeQL

# Advanced-setup replacement for CodeQL default setup. Default setup analyzes
# every detected language on every PR, including Swift (macos-app/), which
# autobuilds on a macOS runner for ~13 minutes per PR and has hung for 55 on
# main; that single job was the longest check on most PRs. Here a PR analyzes
# only the languages it touches (scripts/ci-surfaces.sh), while push to main
# and the weekly schedule analyze every language, so main's code-scanning
# baseline stays complete.
#
# Requires CodeQL default setup to be DISABLED (Settings -> Code security ->
# Code scanning): GitHub rejects advanced-setup uploads while it is enabled.
#
# A PR that skips a language may show "configuration not found" on the CodeQL
# check for that language; that is informational and expected.

on:
  pull_request:
    branches: [main]
  push:
    branches: [main]
  schedule:
    - cron: "17 4 * * 1"
  workflow_dispatch:

permissions:
  contents: read

concurrency:
  group: codeql-${{ github.ref }}
  cancel-in-progress: ${{ github.event_name == 'pull_request' }}

jobs:
  changes:
    name: changed languages
    runs-on: ubuntu-latest
    timeout-minutes: 5
    outputs:
      codeql: ${{ steps.surfaces.outputs.codeql }}
      matrix: ${{ steps.surfaces.outputs.codeql_matrix }}
    steps:
      - name: Check out repository
        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
        with:
          persist-credentials: false
          fetch-depth: 2

      - name: Map changed paths to languages
        id: surfaces
        env:
          EVENT_NAME: ${{ github.event_name }}
        run: |
          set -euo pipefail
          if [ "$EVENT_NAME" = "pull_request" ]; then
            # -z: literal paths; plain --name-only C-quotes unusual names.
            git diff -z --name-only --no-renames HEAD^1 HEAD > changed-paths
            tr '\0' '\n' < changed-paths >&2
            scripts/ci-surfaces.sh < changed-paths > surfaces.out
          else
            scripts/ci-surfaces.sh --all > surfaces.out
          fi
          cat surfaces.out
          grep -E '^(codeql|codeql_matrix)=' surfaces.out >> "$GITHUB_OUTPUT"

  analyze:
    name: Analyze (${{ matrix.language }})
    needs: changes
    if: needs.changes.outputs.codeql == 'true'
    runs-on: ${{ matrix.runner }}
    # Normal runs take <=14 min (Swift autobuild is the longest); cap a hung
    # autobuild instead of letting it hold a runner for an hour.
    timeout-minutes: 30
    permissions:
      contents: read
      security-events: write
      actions: read
      packages: read
    strategy:
      fail-fast: false
      matrix: ${{ fromJSON(needs.changes.outputs.matrix) }}
    steps:
      - name: Check out repository
        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
        with:
          persist-credentials: false

      - name: Initialize CodeQL
        uses: github/codeql-action/init@9b3254085494b55a0f7c4c2b3d2d52cc712ce370 # v4.39.1
        with:
          languages: ${{ matrix.language }}
          build-mode: ${{ matrix.build-mode }}

      - name: Autobuild
        if: matrix.build-mode == 'autobuild'
        uses: github/codeql-action/autobuild@9b3254085494b55a0f7c4c2b3d2d52cc712ce370 # v4.39.1

      - name: Perform CodeQL Analysis
        uses: github/codeql-action/analyze@9b3254085494b55a0f7c4c2b3d2d52cc712ce370 # v4.39.1
        with:
          category: "/language:${{ matrix.language }}"