# ========================================================================== #
#                                                                            #
#    KVMD - The main PiKVM daemon.                                           #
#                                                                            #
#    Copyright (C) 2018-2022  Maxim Devaev <mdevaev@gmail.com>               #
#                                                                            #
#    This program is free software: you can redistribute it and/or modify    #
#    it under the terms of the GNU General Public License as published by    #
#    the Free Software Foundation, either version 3 of the License, or       #
#    (at your option) any later version.                                     #
#                                                                            #
#    This program is distributed in the hope that it will be useful,         #
#    but WITHOUT ANY WARRANTY; without even the implied warranty of          #
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           #
#    GNU General Public License for more details.                            #
#                                                                            #
#    You should have received a copy of the GNU General Public License       #
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.  #
#                                                                            #
# ========================================================================== #


import os
import json
import contextlib
import argparse
import time

from typing import List
from typing import Dict
from typing import Generator
from typing import Optional

import yaml

from ...validators.basic import valid_stripped_string_not_empty

from ... import usb

from .. import init


# =====
class _GadgetControl:
    def __init__(self, meta_path: str, gadget: str, udc: str, init_delay: float) -> None:
        self.__meta_path = meta_path
        self.__gadget = gadget
        self.__udc = udc
        self.__init_delay = init_delay

    @contextlib.contextmanager
    def __udc_stopped(self) -> Generator[None, None, None]:
        udc = usb.find_udc(self.__udc)
        udc_path = usb.get_gadget_path(self.__gadget, usb.G_UDC)
        with open(udc_path) as udc_file:
            enabled = bool(udc_file.read().strip())
        if enabled:
            with open(udc_path, "w") as udc_file:
                udc_file.write("\n")
        try:
            yield
        finally:
            time.sleep(self.__init_delay)
            with open(udc_path, "w") as udc_file:
                udc_file.write(udc)

    def __read_metas(self) -> Generator[Dict, None, None]:
        for meta_name in sorted(os.listdir(self.__meta_path)):
            with open(os.path.join(self.__meta_path, meta_name)) as meta_file:
                yield json.loads(meta_file.read())

    def enable_function(self, func: str) -> None:
        with self.__udc_stopped():
            os.symlink(
                usb.get_gadget_path(self.__gadget, usb.G_FUNCTIONS, func),
                usb.get_gadget_path(self.__gadget, usb.G_PROFILE, func),
            )

    def disable_function(self, func: str) -> None:
        with self.__udc_stopped():
            os.unlink(usb.get_gadget_path(self.__gadget, usb.G_PROFILE, func))

    def list_functions(self) -> None:
        for meta in self.__read_metas():
            enabled = os.path.exists(usb.get_gadget_path(self.__gadget, usb.G_PROFILE, meta["func"]))
            print(f"{'+' if enabled else '-'} {meta['func']}  # {meta['name']}")

    def make_gpio_config(self) -> None:
        config = {
            "drivers": {"otgconf": {"type": "otgconf"}},
            "scheme": {},
            "view": {"table": []},
        }
        for meta in self.__read_metas():
            config["scheme"][meta["func"]] = {  # type: ignore
                "driver": "otgconf",
                "pin": meta["func"],
                "mode": "output",
                "pulse": {"delay": 0},
            }
            config["view"]["table"].append([  # type: ignore
                "#" + meta["name"],
                "#" + meta["func"],
                meta["func"],
            ])
        print(yaml.dump({"kvmd": {"gpio": config}}, indent=4))

    def reset(self) -> None:
        with self.__udc_stopped():
            pass


# =====
def main(argv: Optional[List[str]]=None) -> None:
    (parent_parser, argv, config) = init(
        add_help=False,
        cli_logging=True,
        argv=argv,
    )
    parser = argparse.ArgumentParser(
        prog="kvmd-otgconf",
        description="KVMD OTG low-level runtime configuration tool",
        parents=[parent_parser],
    )
    parser.add_argument("-l", "--list-functions", action="store_true", help="List functions")
    parser.add_argument("-e", "--enable-function", type=valid_stripped_string_not_empty,
                        metavar="<name>", help="Enable function")
    parser.add_argument("-d", "--disable-function", type=valid_stripped_string_not_empty,
                        metavar="<name>", help="Disable function")
    parser.add_argument("-r", "--reset-gadget", action="store_true", help="Reset gadget")
    parser.add_argument("--make-gpio-config", action="store_true")
    options = parser.parse_args(argv[1:])

    gc = _GadgetControl(config.otg.meta, config.otg.gadget, config.otg.udc, config.otg.init_delay)

    if options.list_functions:
        gc.list_functions()

    elif options.enable_function:
        gc.enable_function(options.enable_function)
        gc.list_functions()

    elif options.disable_function:
        gc.disable_function(options.disable_function)
        gc.list_functions()

    elif options.reset_gadget:
        gc.reset()

    elif options.make_gpio_config:
        gc.make_gpio_config()

    else:
        gc.list_functions()