#!/usr/bin/env python3

from pathlib import Path

flake = Path("flake.nix").read_text()
start = flake.index("devShells.default = pkgs.mkShell {")
depth = 0
end = None
for index, character in enumerate(flake[start:], start):
    if character == "{":
        depth += 1
    elif character == "}":
        depth -= 1
        if depth == 0:
            end = index + 1
            break
if end is None:
    raise SystemExit("FAIL: devShells.default block is not balanced")
block = flake[start:end]

for marker in ("inputsFrom", "self.packages", "ldrawOracle", "packages.default"):
    if marker in block:
        raise SystemExit(f"FAIL: devShells.default depends on repository output via {marker}")

print("PASS: devShells.default contains tools and external libraries only")