#!/usr/bin/env python2.7

# Copyright 2016, Google Inc.
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import argparse
import os
import os.path
import re
import sys
import subprocess


def build_valid_guard(fpath):
  prefix = 'GRPC_' if not fpath.startswith('include/') else ''
  return prefix + '_'.join(fpath.replace('++', 'XX').replace('.', '_').upper().split('/')[1:])


def load(fpath):
  with open(fpath, 'r') as f:
    return f.read()


def save(fpath, contents):
  with open(fpath, 'w') as f:
    f.write(contents)


class GuardValidator(object):
  def __init__(self):
    self.ifndef_re = re.compile(r'#ifndef ([A-Z][A-Z_1-9]*)')
    self.define_re = re.compile(r'#define ([A-Z][A-Z_1-9]*)')
    self.endif_c_re = re.compile(r'#endif /\* ([A-Z][A-Z_1-9]*) (?:\\ *\n *)?\*/')
    self.endif_cpp_re = re.compile(r'#endif  // ([A-Z][A-Z_1-9]*)')
    self.failed = False

  def fail(self, fpath, regexp, fcontents, match_txt, correct, fix):
    cpp_header = 'grpc++' in fpath
    self.failed = True
    invalid_guards_msg_template = (
        '{0}: Missing preprocessor guards (RE {1}). '
        'Please wrap your code around the following guards:\n'
        '#ifndef {2}\n'
        '#define {2}\n'
        '...\n'
        '... epic code ...\n'
        '...\n') + ('#endif  // {2}' if cpp_header else '#endif /* {2} */')
    if not match_txt:
      print invalid_guards_msg_template.format(fpath, regexp.pattern,
                                               build_valid_guard(fpath))
      return fcontents

    print ('{}: Wrong preprocessor guards (RE {}):'
           '\n\tFound {}, expected {}').format(
        fpath, regexp.pattern, match_txt, correct)
    if fix:
      print 'Fixing {}...\n'.format(fpath)
      fixed_fcontents = re.sub(match_txt, correct, fcontents)
      if fixed_fcontents:
        self.failed = False
      return fixed_fcontents
    else:
      print
    return fcontents

  def check(self, fpath, fix):
    cpp_header = 'grpc++' in fpath
    valid_guard = build_valid_guard(fpath)

    fcontents = load(fpath)

    match = self.ifndef_re.search(fcontents)
    if not match:
      print 'something drastically wrong with: %s' % fpath
      return False # failed
    if match.lastindex is None:
      # No ifndef. Request manual addition with hints
      self.fail(fpath, match.re, match.string, '', '', False)
      return False  # failed

    # Does the guard end with a '_H'?
    running_guard = match.group(1)
    if not running_guard.endswith('_H'):
      fcontents = self.fail(fpath, match.re, match.string, match.group(1),
                            valid_guard, fix)
      if fix: save(fpath, fcontents)

    # Is it the expected one based on the file path?
    if running_guard != valid_guard:
      fcontents = self.fail(fpath, match.re, match.string, match.group(1),
                            valid_guard, fix)
      if fix: save(fpath, fcontents)

    # Is there a #define? Is it the same as the #ifndef one?
    match = self.define_re.search(fcontents)
    if match.lastindex is None:
      # No define. Request manual addition with hints
      self.fail(fpath, match.re, match.string, '', '', False)
      return False  # failed

    # Is the #define guard the same as the #ifndef guard?
    if match.group(1) != running_guard:
      fcontents = self.fail(fpath, match.re, match.string, match.group(1),
                            valid_guard, fix)
      if fix: save(fpath, fcontents)

    # Is there a properly commented #endif?
    endif_re = self.endif_cpp_re if cpp_header else self.endif_c_re
    flines = fcontents.rstrip().splitlines()
    match = endif_re.search('\n'.join(flines[-2:]))
    if not match:
      # No endif. Check if we have the last line as just '#endif' and if so
      # replace it with a properly commented one.
      if flines[-1] == '#endif':
        flines[-1] = ('#endif' +
                      ('  // {}\n'.format(valid_guard) if cpp_header
                       else ' /* {} */\n'.format(valid_guard)))
        if fix:
            fcontents = '\n'.join(flines)
            save(fpath, fcontents)
      else:
        # something else is wrong, bail out
        self.fail(fpath, endif_re, flines[-1], '', '', False)
    elif match.group(1) != running_guard:
      # Is the #endif guard the same as the #ifndef and #define guards?
      fcontents = self.fail(fpath, endif_re, fcontents, match.group(1),
                            valid_guard, fix)
      if fix: save(fpath, fcontents)

    return not self.failed  # Did the check succeed? (ie, not failed)

# find our home
ROOT = os.path.abspath(
    os.path.join(os.path.dirname(sys.argv[0]), '../..'))
os.chdir(ROOT)

# parse command line
argp = argparse.ArgumentParser(description='include guard checker')
argp.add_argument('-f', '--fix',
                  default=False,
                  action='store_true');
argp.add_argument('--precommit',
                  default=False,
                  action='store_true')
args = argp.parse_args()

KNOWN_BAD = set([
    'src/core/ext/lb_policy/grpclb/proto/grpc/lb/v1/load_balancer.pb.h',
    'include/grpc++/ext/reflection.grpc.pb.h',
    'include/grpc++/ext/reflection.pb.h',
])


grep_filter = r"grep -E '^(include|src/core)/.*\.h$'"
if args.precommit:
  git_command = 'git diff --name-only HEAD'
else:
  git_command = 'git ls-tree -r --name-only -r HEAD'

FILE_LIST_COMMAND = ' | '.join((git_command, grep_filter))

# scan files
ok = True
filename_list = []
try:
  filename_list = subprocess.check_output(FILE_LIST_COMMAND,
                                          shell=True).splitlines()
  # Filter out non-existent files (ie, file removed or renamed)
  filename_list = (f for f in filename_list if os.path.isfile(f))
except subprocess.CalledProcessError:
  sys.exit(0)

validator = GuardValidator()

for filename in filename_list:
  if filename in KNOWN_BAD: continue
  ok = validator.check(filename, args.fix)

sys.exit(0 if ok else 1)