# JTFTP - Python/AsyncIO TFTP Server
# Copyright (C) 2022 Jeffrey C. Ollie
#
# 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/>.


class TFTPError(Exception):
    """Base exception class for this package"""


class WireProtocolError(TFTPError):
    """Base exception class for wire-protocol level errors"""


class InvalidOpcodeError(WireProtocolError):
    """An invalid opcode was encountered"""

    opcode: int

    def __init__(self, opcode: int):
        self.opcode = opcode
        super().__init__(f"Invalid opcode: {opcode}")


class PayloadDecodeError(WireProtocolError):
    """Failed to parse the payload"""


class OptionsDecodeError(PayloadDecodeError):
    """Failed to parse options in the WRQ/RRQ datagram. It is distinct from
    L{PayloadDecodeError} so that it can be caught and dealt with gracefully
    (pretend we didn't see any options at all, perhaps).

    """


class InvalidErrorcodeError(PayloadDecodeError):
    """An ERROR datagram has an error code, that does not correspond to any known
    error code values.

    @ivar errorcode: The error code, that we were unable to parse
    @type errorcode: C{int}

    """

    error_code: int

    def __init__(self, error_code: int):
        self.error_code = error_code
        super().__init__(f"unknown error code: {error_code}")


class BackendError(TFTPError):
    """Base exception class for backend errors"""


class Unsupported(BackendError):
    """Requested operation (read/write) is not supported"""


class AccessViolation(BackendError):
    """Illegal filesystem operation. Corresponds to the "(2) Access violation"
    TFTP error code.

    One of the prime examples of these is an attempt at directory traversal.

    """


class FileNotFound(BackendError):
    """File not found.

    Corresponds to the "(1) File not found" TFTP error code.

    @ivar file_path: Path to the file, that was requested
    @type file_path: C{bytes} or L{twisted.python.filepath.FilePath}

    """

    def __init__(self, file_path):
        self.file_path = file_path

    def __str__(self):
        return f"File not found: {self.file_path}"


class FileExists(BackendError):
    """File exists.

    Corresponds to the "(6) File already exists" TFTP error code.

    @ivar file_path: Path to file
    @type file_path: C{bytes} or L{twisted.python.filepath.FilePath}

    """

    def __init__(self, file_path):
        self.file_path = file_path

    def __str__(self):
        return f"File already exists: {self.file_path}"