from __future__ import (
    absolute_import, print_function, division, unicode_literals
)

import logging
import re
import sys
from datetime import datetime

logging.basicConfig(level=logging.DEBUG)
logger = logging.getLogger(__name__)

CURRENT_YEAR = datetime.today().year

LICENSE_BLOB = """Copyright (c) %d Uber Technologies, Inc.

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.""" % CURRENT_YEAR


def comment_block(license_blob):
    lines = ['/*\n']
    lines += [(' * ' + l).rstrip() + '\n'
              for l in license_blob.split('\n')]
    lines.append(' */\n')
    return lines


LICENSE_BLOB_LINES_CPP = comment_block(LICENSE_BLOB)

COPYRIGHT_RE = re.compile(r'Copyright \(c\) (\d+)', re.I)


def update_cpp_license(name, force=False):
    with open(name) as f:
        orig_lines = list(f)
    lines = list(orig_lines)

    found = False
    changed = False
    for i, line in enumerate(lines[:5]):
        m = COPYRIGHT_RE.search(line)
        if not m:
            continue

        found = True
        year = int(m.group(1))
        if year == CURRENT_YEAR:
            break

        new_line = COPYRIGHT_RE.sub('Copyright (c) %d' % CURRENT_YEAR, line)
        assert line != new_line, ('Could not change year in: %s' % line)
        lines[i] = new_line
        changed = True
        break

    if not found:
        if 'Code generated by' in lines[0]:
            lines[1:1] = ['\n'] + LICENSE_BLOB_LINES_CPP
        else:
            lines[0:0] = LICENSE_BLOB_LINES_CPP + ['\n']
        changed = True

    if changed:
        with open(name, 'w') as f:
            for line in lines:
                f.write(line)
        print(name)


def main():
    if len(sys.argv) == 1:
        print('USAGE: %s FILE ...' % sys.argv[0])
        sys.exit(1)

    for name in sys.argv[1:]:
        if name.endswith('.cpp') or \
           name.endswith('.h') or \
           name.endswith('.h.in'):
            try:
                update_cpp_license(name)
            except Exception as error:
                logger.error('Failed to process file %s', name)
                logger.exception(error)
                raise error
        else:
            raise NotImplementedError('Unsupported file type: %s' % name)


if __name__ == "__main__":
    main()