#!/usr/bin/env python3

# Copyright 2019 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.

"""Main driver program for the Emboss compiler."""

import argparse
import os
import sys


def _parse_args(argv):
    parser = argparse.ArgumentParser(description="Emboss compiler")
    parser.add_argument(
        "--color-output",
        default="if_tty",
        choices=["always", "never", "if_tty", "auto"],
        help="Print error messages using color.  'auto' is a synonym for 'if_tty'.",
    )
    parser.add_argument(
        "--import-dir",
        "-I",
        dest="import_dirs",
        action="append",
        default=["."],
        help="""A directory to use when searching for imported embs.  If no
                import-dirs are specified, the current directory will be used.""",
    )
    parser.add_argument(
        "--generate",
        nargs=1,
        choices=["cc"],
        default="cc",
        help="Which back end to use.  Currently only C++ is supported.",
    )
    parser.add_argument(
        "--output-path",
        nargs=1,
        default=".",
        help="Prefix path to use for the generated output file.  Defaults to '.'",
    )
    parser.add_argument(
        "--output-file",
        nargs=1,
        help="""File name to be used for the generated output file.  Defaults to
                input_file suffixed by '.h'""",
    )
    parser.add_argument(
        "--cc-enum-traits",
        action=argparse.BooleanOptionalAction,
        default=True,
        help="Controls generation of EnumTraits by the C++ backend",
    )
    parser.add_argument("input_file", type=str, nargs=1, help=".emb file to compile.")
    return parser.parse_args(argv[1:])


def main(argv):
    flags = _parse_args(argv)
    base_path = os.path.dirname(__file__) or "."
    sys.path.append(base_path)

    from compiler.back_end.cpp import ( # pylint:disable=import-outside-toplevel
    emboss_codegen_cpp, header_generator
    )
    from compiler.front_end import ( # pylint:disable=import-outside-toplevel
    emboss_front_end
    )

    ir, _, errors = emboss_front_end.parse_and_log_errors(
        flags.input_file[0], flags.import_dirs, flags.color_output
    )

    if errors:
        return 1

    config = header_generator.Config(include_enum_traits=flags.cc_enum_traits)
    header, errors = emboss_codegen_cpp.generate_headers_and_log_errors(
        ir, flags.color_output, config
    )

    if errors:
        return 1

    if flags.output_file:
        output_file = flags.output_file[0]
    else:
        output_file = flags.input_file[0] + ".h"

    output_filepath = os.path.join(flags.output_path[0], output_file)
    os.makedirs(os.path.dirname(output_filepath), exist_ok=True)

    with open(output_filepath, "w") as output:
        output.write(header)
    return 0


if __name__ == "__main__":
    sys.exit(main(sys.argv))