name: Block AI Attribution

on:
  pull_request:
    branches: [main]
  push:
    branches: [main]

jobs:
  scan:
    name: Scan commits for AI authorship markers
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Compute commit range
        id: range
        env:
          EVENT_NAME: ${{ github.event_name }}
          PR_BASE: ${{ github.event.pull_request.base.sha }}
          PR_HEAD: ${{ github.event.pull_request.head.sha }}
          PUSH_BEFORE: ${{ github.event.before }}
          PUSH_AFTER: ${{ github.event.after }}
        run: |
          set -euo pipefail
          if [ "$EVENT_NAME" = "pull_request" ]; then
            range="${PR_BASE}..${PR_HEAD}"
          else
            if [ -z "${PUSH_BEFORE:-}" ] || [ "$PUSH_BEFORE" = "0000000000000000000000000000000000000000" ]; then
              range="${PUSH_AFTER}~1..${PUSH_AFTER}"
            else
              range="${PUSH_BEFORE}..${PUSH_AFTER}"
            fi
          fi
          echo "range=$range" >> "$GITHUB_OUTPUT"
          echo "Scanning range: $range"

      - name: Run scanner
        run: bash scripts/check-no-ai-attribution.sh '${{ steps.range.outputs.range }}'