# ========================================================================== #
#                                                                            #
#    KVMD - The main PiKVM daemon.                                           #
#                                                                            #
#    Copyright (C) 2018-2024  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 errno

from .... import usb

from .. import MsdOperationError


# =====
class MsdPermissionsError(MsdOperationError):
    def __init__(self) -> None:
        super().__init__("MSD can't insert the image due to file permissions")


class MsdLockedError(MsdOperationError):
    def __init__(self) -> None:
        super().__init__("MSD is locked on IO operation")


# =====
class Drive:
    def __init__(self, instance: int, lun: int) -> None:
        func = f"mass_storage.usb{instance}"
        self.__profile_func_path = usb.get_gadget_path(usb.G_PROFILE, func)
        self.__profile_path = usb.get_gadget_path(usb.G_PROFILE)
        self.__lun_path = usb.get_gadget_path(usb.G_FUNCTIONS, func, f"lun.{lun}")
        self.__name = os.path.join(func, f"lun.{lun}")

    def get_name(self) -> str:
        return self.__name

    def is_enabled(self) -> bool:
        return (
            os.path.exists(self.__profile_func_path)
            and os.path.exists(self.__lun_path)
        )

    def get_watchable_paths(self) -> list[str]:
        return [self.__lun_path, self.__profile_path]

    # =====

    def set_image_path(self, path: str) -> None:
        if path:
            try:
                self.__set_param("file", path)
            except PermissionError:
                raise MsdPermissionsError()
        else:
            self.__set_param("forced_eject", "")

    def get_image_path(self) -> str:
        path = self.__get_param("file")
        return (os.path.normpath(path) if path else "")

    def set_cdrom_flag(self, flag: bool) -> None:
        self.__set_param("cdrom", str(int(flag)))

    def get_cdrom_flag(self) -> bool:
        return bool(int(self.__get_param("cdrom")))

    def set_rw_flag(self, flag: bool) -> None:
        self.__set_param("ro", str(int(not flag)))

    def get_rw_flag(self) -> bool:
        return (not int(self.__get_param("ro")))

    # =====

    def __get_param(self, param: str) -> str:
        with open(os.path.join(self.__lun_path, param)) as file:
            return file.read().strip()

    def __set_param(self, param: str, value: str) -> None:
        try:
            with open(os.path.join(self.__lun_path, param), "w") as file:
                file.write(value + "\n")
        except OSError as ex:
            if ex.errno == errno.EBUSY:
                raise MsdLockedError()
            raise
