#!/usr/bin/env python3

# Copyright 2016 gRPC authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

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


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_core_re = re.compile(
            r'#endif /\* (?: *\\\n *)?([A-Z][A-Z_1-9]*) (?:\\\n *)?\*/$')
        self.endif_re = re.compile(r'#endif  // ([A-Z][A-Z_1-9]*)')
        self.failed = False

    def _is_c_core_header(self, fpath):
        return 'include' in fpath and not ('grpc++' in fpath or 'grpcpp'
                                           in fpath or 'event_engine' in fpath)

    def fail(self, fpath, regexp, fcontents, match_txt, correct, fix):
        c_core_header = self._is_c_core_header(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 c_core_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):
        c_core_header = self._is_c_core_header(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?
        flines = fcontents.rstrip().splitlines()
        match = self.endif_c_core_re.search('\n'.join(flines[-3:]))
        if not match and not c_core_header:
            match = self.endif_re.search('\n'.join(flines[-3:]))
        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 c_core_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,
                    self.endif_c_core_re if c_core_header else self.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, self.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()

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).decode().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:
    # Skip check for upb generated code.
    if (filename.endswith('.upb.h') or filename.endswith('.upb.c') or
            filename.endswith('.upbdefs.h') or filename.endswith('.upbdefs.c')):
        continue
    ok = ok and validator.check(filename, args.fix)

sys.exit(0 if ok else 1)
