# Copyright 2018 Google LLC
#
# 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
#
#     https://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 importlib.util
import os
import sys
from typing import List, Sequence

import click
import pkg_resources
from synthtool.log import logger
import synthtool.metadata
from synthtool import preconfig

try:
    VERSION = pkg_resources.get_distribution("gcp-synthtool").version
except pkg_resources.DistributionNotFound:
    VERSION = "0.0.0+dev"


_extra_args: List[str] = []


def extra_args() -> List[str]:
    """Return any additional arguments specified to synthtool."""
    # Return a copy so these don't get modified.
    # A little trickery. If __name__ isn't __main__, import __main__ and return
    # its extra_args(). This ensures that both `from __main__ import extra_args()`
    # and `from synthtool.__main__ import extra_args()` works as expected. This
    # is needed because *technically* Python can have two copies of this module
    # in sys.modules when it's executed as main. Weird, I know.
    if __name__ != "__main__":  # pragma: no cover
        try:
            import __main__

            return __main__.extra_args()
        except AttributeError:
            # __main__ didn't have an extra_args() attribute, so this means
            # synthtool is not the main module. Just return what's in this
            # module.
            pass

    return list(_extra_args)


@click.command()
@click.version_option(message="%(version)s", version=VERSION)
@click.argument("synthfile", default="synth.py")
@click.option(
    "--metadata",
    default="synth.metadata",
    help="Path to metadata file that will be read and overwritten.",
)
@click.argument("extra_args", nargs=-1)
def main(synthfile: str, metadata: str, extra_args: Sequence[str]):
    f"""Synthesizes source code according to the instructions in synthfile arg.

    Optional environment variables:
      SYNTHTOOL_ARTMAN_VERSION:  The version of artman to use.
      SYNTHTOOL_GOOGLEAPIS:      Path to local clone of https://github.com/googleapis/googleapis
      SYNTHTOOL_GENERATOR:       Path to local gapic-generator directory to use for generation.
                By default, the latest version of gapic-generator will be used.
      AUTOSYNTH_USE_SSH:         Access github repos via ssh instead of https.
      {preconfig.PRECONFIG_ENVIRONMENT_VARIABLE}:  Path to a json file.


    {preconfig.PRECONFIG_HELP}
    """
    _extra_args.extend(extra_args)

    synth_file = os.path.abspath(synthfile)

    if os.path.lexists(synth_file):
        logger.debug(f"Executing {synth_file}.")
        # https://docs.python.org/3/library/importlib.html#importing-a-source-file-directly
        spec = importlib.util.spec_from_file_location("synth", synth_file)
        synth_module = importlib.util.module_from_spec(spec)

        if spec.loader is None:
            raise ImportError("Could not import synth.py")

        with synthtool.metadata.MetadataTrackerAndWriter(metadata):
            spec.loader.exec_module(synth_module)  # type: ignore

    else:
        logger.exception(f"{synth_file} not found.")
        sys.exit(1)


if __name__ == "__main__":
    main()