#!/usr/bin/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.

import argparse
import os
from os import path
import subprocess
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 to use for the generated output file.")
    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 = path.dirname(__file__) or "."
    subprocess_environment = {k: v for k, v in os.environ.items()}
    if subprocess_environment.get("PYTHONPATH"):
        subprocess_environment["PYTHONPATH"] = (
            base_path + ":" + subprocess_environment.get("PYTHONPATH"))
    else:
        subprocess_environment["PYTHONPATH"] = base_path
    front_end_args = [
        sys.executable,
        path.join(base_path, "front_end", "emboss_front_end.py"),
        "--output-ir-to-stdout",
        "--color-output", flags.color_output,
    ]
    for import_dir in flags.import_dirs:
        front_end_args.extend([
            "--import-dir",
            import_dir
        ])
    front_end_args.append(flags.input_file[0])
    front_end_status = subprocess.run(front_end_args,
                                      stdout=subprocess.PIPE,
                                      env=subprocess_environment)
    if front_end_status.returncode != 0:
        return front_end_status.returncode
    back_end_status = subprocess.run(
        [
            sys.executable,
            path.join(base_path, "back_end", "cpp", "emboss_codegen_cpp.py"),
        ],
        input=front_end_status.stdout,
        stdout=subprocess.PIPE,
        env=subprocess_environment)
    if back_end_status.returncode != 0:
        return back_end_status.returncode
    output_file = path.join(flags.output_path[0], flags.input_file[0]) + ".h"
    os.makedirs(path.dirname(output_file), exist_ok=True)
    with open(output_file, "wb") as output:
        output.write(back_end_status.stdout)
    return 0


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