# Copyright 2015 Google Inc. All rights reserved.
#
# 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.

"""Get the inserted gRPC lines for datastore pb2 file."""

import os
import shutil
import subprocess
import tempfile


ROOT_DIR = os.path.abspath(
    os.path.join(os.path.dirname(__file__), '..'))
PROTOS_DIR = os.path.join(ROOT_DIR, 'cloud-bigtable-client',
                          'bigtable-protos', 'src', 'main', 'proto')
PROTO_PATH = os.path.join(PROTOS_DIR, 'google', 'longrunning',
                          'operations.proto')
GRPC_ONLY_FILE = os.path.join(ROOT_DIR, 'gcloud', 'bigtable',
                              '_generated', 'operations_grpc_pb2.py')
PROTOC_CMD = 'protoc'
GRPC_PLUGIN = 'grpc_python_plugin'


def get_pb2_contents_with_grpc():
    """Get pb2 lines generated by protoc with gRPC plugin.

    :rtype: list
    :returns: A list of lines in the generated file.
    """
    temp_dir = tempfile.mkdtemp()
    generated_path = os.path.join(temp_dir, 'google', 'longrunning',
                                  'operations_pb2.py')
    try:
        subprocess.check_output([
            PROTOC_CMD,
            '--proto_path',
            PROTOS_DIR,
            '--python_out',
            temp_dir,
            '--plugin',
            'protoc-gen-grpc=' + GRPC_PLUGIN,
            '--grpc_out',
            temp_dir,
            PROTO_PATH,
        ])
        with open(generated_path, 'rb') as file_obj:
            return file_obj.readlines()
    finally:
        shutil.rmtree(temp_dir, ignore_errors=True)


def get_pb2_contents_without_grpc():
    """Get pb2 lines generated by protoc without gRPC plugin.

    :rtype: list
    :returns: A list of lines in the generated file.
    """
    temp_dir = tempfile.mkdtemp()
    generated_path = os.path.join(temp_dir, 'google', 'longrunning',
                                  'operations_pb2.py')
    try:
        subprocess.check_output([
            PROTOC_CMD,
            '--proto_path',
            PROTOS_DIR,
            '--python_out',
            temp_dir,
            PROTO_PATH,
        ])
        with open(generated_path, 'rb') as file_obj:
            return file_obj.readlines()
    finally:
        shutil.rmtree(temp_dir, ignore_errors=True)


def get_pb2_grpc_only():
    """Get pb2 lines that are only in gRPC.

    :rtype: list
    :returns: A list of lines that are only in the pb2 file
              generated with the gRPC plugin.
    """
    grpc_contents = get_pb2_contents_with_grpc()
    non_grpc_contents = get_pb2_contents_without_grpc()

    grpc_only_lines = []
    curr_non_grpc_line = 0
    for line in grpc_contents:
        if line == non_grpc_contents[curr_non_grpc_line]:
            curr_non_grpc_line += 1
        else:
            grpc_only_lines.append(line)

    return grpc_only_lines


def main():
    """Write gRPC-only lines to custom module."""
    grpc_only_lines = get_pb2_grpc_only()
    with open(GRPC_ONLY_FILE, 'wb') as file_obj:
        file_obj.writelines(grpc_only_lines)


if __name__ == '__main__':
    main()
