name: Maxwell's Demon

on:
  issues:
    types: [opened]

concurrency:
  group: demon-state
  cancel-in-progress: false

permissions:
  contents: write
  issues: write

jobs:
  sort:
    if: "startsWith(github.event.issue.title, 'demon: sort 12 bits')"
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Sort 12 bits into the lattice
        run: |
          python3 - <<'EOF'
          import datetime
          import json

          path = "state/demon.json"
          with open(path) as fh:
              state = json.load(fh)
          state["bits_sorted"] += 12
          state["generation"] += 1
          state["demons"] += 1
          state["last_sorted_at"] = datetime.datetime.now(
              datetime.timezone.utc
          ).isoformat(timespec="seconds")
          with open(path, "w") as fh:
              json.dump(state, fh, indent=2)
              fh.write("\n")
          EOF
          python3 engine/generate_entropy_svg.py

      - name: Commit lowered entropy
        env:
          AUTHOR: ${{ github.event.issue.user.login }}
        run: |
          git config user.name "github-actions[bot]"
          git config user.email "41898470+github-actions[bot]@users.noreply.github.com"
          git add state/demon.json assets/entropy.svg
          git commit -m "chore: demon sorted 12 bits (S lowered by @${AUTHOR})"
          git pull --rebase origin "${GITHUB_REF_NAME}"
          git push

      - name: Thank the demon and close the gate
        env:
          GH_TOKEN: ${{ github.token }}
          ISSUE: ${{ github.event.issue.number }}
        run: |
          gh issue comment "$ISSUE" --repo "$GITHUB_REPOSITORY" --body \
            "12 bits sorted. Entropy of this README decreased by 34.4 zJ (12 × kT ln 2 at 300 K). The second law remains statistical. Thank you, demon."
          gh issue edit "$ISSUE" --repo "$GITHUB_REPOSITORY" --add-label demon
          gh issue close "$ISSUE" --repo "$GITHUB_REPOSITORY"