#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# Copyright 2019 The ChromiumOS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Build script that builds a binary from a bundle."""

from __future__ import print_function

import argparse
import os.path
import re
import subprocess
import sys


def parse_args():
  parser = argparse.ArgumentParser()
  parser.add_argument(
      '--config',
      required=True,
      choices=['cros.hardened', 'cros.nonhardened', 'cros.host', 'android'])
  parser.add_argument('--use_ccache', required=True, choices=['true', 'false'])
  parser.add_argument(
      '--version_suffix',
      help='A string appended to the computed version of the wrapper. This '
      'is appeneded directly without any delimiter.')
  parser.add_argument('--use_llvm_next',
                      required=True,
                      choices=['true', 'false'])
  parser.add_argument('--output_file', required=True, type=str)
  parser.add_argument(
      '--static',
      choices=['true', 'false'],
      help='If true, produce a static wrapper. Autodetects a good value if '
      'unspecified.')
  args = parser.parse_args()

  if args.static is None:
    args.static = 'cros' not in args.config
  else:
    args.static = args.static == 'true'

  return args


def calc_go_args(args, version, build_dir):
  # These seem unnecessary, and might lead to breakages with Go's ldflag
  # parsing. Don't allow them.
  if "'" in version:
    raise ValueError('`version` should not contain single quotes')

  ldFlags = [
      '-X',
      'main.ConfigName=' + args.config,
      '-X',
      'main.UseCCache=' + args.use_ccache,
      '-X',
      'main.UseLlvmNext=' + args.use_llvm_next,
      '-X',
      # Quote this, as `version` may have spaces in it.
      "'main.Version=" + version + "'",
  ]

  # If the wrapper is intended for ChromeOS, we need to use libc's exec.
  extra_args = []
  if not args.static:
    extra_args += ['-tags', 'libc_exec']

  if args.config == 'android':
    # If android_llvm_next_flags.go DNE, we'll get an obscure "no
    # llvmNextFlags" build error; complaining here is clearer.
    if not os.path.exists(os.path.join(build_dir,
                                       'android_llvm_next_flags.go')):
      sys.exit('In order to build the Android wrapper, you must have a local '
               'android_llvm_next_flags.go file; please see '
               'cros_llvm_next_flags.go.')
    extra_args += ['-tags', 'android_llvm_next_flags']

  return [
      'go', 'build', '-o',
      os.path.abspath(args.output_file), '-ldflags', ' '.join(ldFlags)
  ] + extra_args


def read_version(build_dir):
  version_path = os.path.join(build_dir, 'VERSION')
  if os.path.exists(version_path):
    with open(version_path, 'r') as r:
      return r.read()

  last_commit_msg = subprocess.check_output(
      ['git', '-C', build_dir, 'log', '-1', '--pretty=%B'], encoding='utf-8')
  # Use last found change id to support reverts as well.
  change_ids = re.findall(r'Change-Id: (\w+)', last_commit_msg)
  if not change_ids:
    sys.exit("Couldn't find Change-Id in last commit message.")
  return change_ids[-1]


def main():
  args = parse_args()
  build_dir = os.path.dirname(__file__)
  version = read_version(build_dir)
  if args.version_suffix:
    version += args.version_suffix
  # Note: Go does not support using absolute package names.
  # So we run go inside the directory of the the build file.
  sys.exit(
      subprocess.call(calc_go_args(args, version, build_dir), cwd=build_dir))


if __name__ == '__main__':
  main()