#!/usr/bin/env python3
"""Runs only in the build image, during configure/lsp, never server startup."""
import json
import pathlib
import re
import subprocess
import sys

def header_roots(config):
  roots = set()
  for driver in config["query_drivers"]:
    for language in ("c", "c++"):
      result = subprocess.run([driver, "-E", "-v", "-x", language, "-"], input="",
        stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True, check=True)
      listing = False
      for line in result.stderr.splitlines():
        if line == "#include <...> search starts here:":
          listing = True
        elif line == "End of search list.":
          listing = False
        elif listing:
          roots.add(pathlib.Path(line.strip()).resolve())
  version = subprocess.check_output([config["executable"], "--version"], text=True)
  major = re.search(r"version (\d+)", version).group(1)
  builtin = pathlib.Path(f"/usr/lib/llvm-{major}/lib/clang/{major}/include")
  roots.add(builtin)
  roots.update(pathlib.Path(root) for root in config["header_roots"])
  for root in roots:
    if not root.is_dir() or root == pathlib.Path("/"):
      raise ValueError(f"missing or invalid header directory: {root}")
  return sorted(str(root) for root in roots if not any(parent in roots for parent in root.parents))

if __name__ == "__main__":
  print(json.dumps(header_roots(json.loads(sys.argv[1]))))