name: "F* Meta Extraction"

# Run the Meta-F* reflection-based extraction that generates C++ rewrite rules
# from the F* lemmas in fstar/FPARewriterRules.fst.
#
# The extraction is performed by fstar/RewriteCodeGen.fst which uses
# FStar.Tactics.V2 and FStar.Reflection.V2 to inspect the lemma types
# and emit C++ if-blocks that implement the corresponding rewrite rules.
#
# The generated C++ is printed to the job log and uploaded as an artifact.

on:
  push:
    paths:
      - "fstar/**.fst"
      - "fstar/extract.sh"
      - ".github/workflows/fstar-extract.yml"
  pull_request:
    paths:
      - "fstar/**.fst"
      - "fstar/extract.sh"
      - ".github/workflows/fstar-extract.yml"
  workflow_dispatch:

permissions:
  contents: read

jobs:
  fstar-extract:
    name: "Meta-F* rewrite rule extraction"
    runs-on: ubuntu-latest
    timeout-minutes: 30

    steps:
      - name: Checkout code
        uses: actions/checkout@v6.0.2

      # -----------------------------------------------------------------------
      # Install F*
      #
      # We download the pre-built Linux binary from the F* GitHub releases.
      # The version is pinned to match what the README recommends.
      # If the pinned release is unavailable the step fails clearly.
      # -----------------------------------------------------------------------
      - name: Install F*
        env:
          FSTAR_VERSION: "2026.03.24"
        run: |
          ARCHIVE="fstar-v${FSTAR_VERSION}-Linux-x86_64.tar.gz"
          URL="https://github.com/FStarLang/FStar/releases/download/v${FSTAR_VERSION}/${ARCHIVE}"
          echo "Downloading F* ${FSTAR_VERSION} from ${URL}" >&2
          curl -fsSL -o "/tmp/${ARCHIVE}" "${URL}"
          mkdir -p "$HOME/fstar"
          tar -xzf "/tmp/${ARCHIVE}" -C "$HOME/fstar" --strip-components=2
          echo "$HOME/fstar/bin" >> "$GITHUB_PATH"

      - name: Verify F* installation
        run: fstar.exe --version

      # -----------------------------------------------------------------------
      # Run the Meta-F* extraction
      #
      # RewriteCodeGen.fst contains run_tactic calls that print generated C++
      # to stdout during typechecking.  We capture that output, show it in the
      # log, and upload it as an artifact for inspection.
      # -----------------------------------------------------------------------
      - name: Extract C++ rewrite rules via Meta-F*
        working-directory: fstar
        run: |
          chmod +x extract.sh
          echo "--- generated C++ rules ---"
          ./extract.sh | tee extracted_rules.txt
          echo "--- end of generated rules ---"

      - name: Show extracted rules
        working-directory: fstar
        run: |
          echo "Lines of generated C++ output:"
          wc -l extracted_rules.txt
          echo ""
          echo "Full content:"
          cat extracted_rules.txt

      # -----------------------------------------------------------------------
      # Upload the extracted rules as a build artifact so reviewers can
      # inspect the generated C++ without re-running the workflow.
      # -----------------------------------------------------------------------
      - name: Upload extracted rules artifact
        uses: actions/upload-artifact@v4
        with:
          name: fstar-extracted-cpp-rules
          path: fstar/extracted_rules.txt
          if-no-files-found: error