#!/usr/bin/env python3

# Converts clang-scan-deps output into response files.
#   * For modules, arguments in the resulting response file are enough to build a PCM.
#   * For translation units, the response file needs to be added to the original Clang invocation from compilation
#     database.
#
# Usage:
#
#   clang-scan-deps -compilation-database compile_commands.json ... > deps.json
#   module-deps-to-rsp.py deps.json --module-name=ModuleName > module_name.cc1.rsp
#   module-deps-to-rsp.py deps.json --tu-index=0 > tu.rsp
#   clang @module_name.cc1.rsp
#   clang ... @tu.rsp

import argparse
import json
import sys

class ModuleNotFoundError(Exception):
  def __init__(self, module_name):
    self.module_name = module_name

class FullDeps:
  def __init__(self):
    self.modules = {}
    self.translation_units = []

def findModule(module_name, full_deps):
  for m in full_deps.modules.values():
    if m['name'] == module_name:
      return m
  raise ModuleNotFoundError(module_name)

def parseFullDeps(json):
  ret = FullDeps()
  for m in json['modules']:
    ret.modules[m['name'] + '-' + m['context-hash']] = m
  ret.translation_units = json['translation-units']
  return ret

def quote(str):
  return '"' + str.replace("\\", "\\\\") + '"'

def main():
  parser = argparse.ArgumentParser()
  parser.add_argument("full_deps_file", help="Path to the full dependencies json file",
                      type=str)
  action = parser.add_mutually_exclusive_group(required=True)
  action.add_argument("--module-name", help="The name of the module to get arguments for",
                      type=str)
  action.add_argument("--tu-index", help="The index of the translation unit to get arguments for",
                      type=int)
  args = parser.parse_args()

  full_deps = parseFullDeps(json.load(open(args.full_deps_file, 'r')))

  try:
    cmd = []

    if args.module_name:
      cmd = findModule(args.module_name, full_deps)['command-line']
    elif args.tu_index != None:
      cmd = full_deps.translation_units[args.tu_index]['command-line']

    print(" ".join(map(quote, cmd)))
  except:
    print("Unexpected error:", sys.exc_info()[0])
    raise

if __name__ == '__main__':
  main()