# ========================================================================== #
#                                                                            #
#    KVMD - The main Pi-KVM daemon.                                          #
#                                                                            #
#    Copyright (C) 2018  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 dataclasses
import struct

from ....keyboard.mappings import KEYMAP


# =====
class BaseEvent:
    def make_request(self) -> bytes:
        raise NotImplementedError


class ClearEvent(BaseEvent):
    def make_request(self) -> bytes:
        return _make_request(b"\x10\x00\x00\x00\x00")


@dataclasses.dataclass(frozen=True)
class KeyEvent(BaseEvent):
    name: str
    state: bool

    def __post_init__(self) -> None:
        assert self.name in KEYMAP

    def make_request(self) -> bytes:
        code = KEYMAP[self.name].mcu.code
        return _make_request(struct.pack(">BBBxx", 0x11, code, int(self.state)))


@dataclasses.dataclass(frozen=True)
class MouseButtonEvent(BaseEvent):
    name: str
    state: bool

    def __post_init__(self) -> None:
        assert self.name in ["left", "right", "middle", "up", "down"]

    def make_request(self) -> bytes:
        (code, state_pressed, is_main) = {
            "left":   (0b10000000, 0b00001000, True),
            "right":  (0b01000000, 0b00000100, True),
            "middle": (0b00100000, 0b00000010, True),
            "up":     (0b10000000, 0b00001000, False),  # Back
            "down":   (0b01000000, 0b00000100, False),  # Forward
        }[self.name]
        if self.state:
            code |= state_pressed
        if is_main:
            main_code = code
            extra_code = 0
        else:
            main_code = 0
            extra_code = code
        return _make_request(struct.pack(">BBBxx", 0x13, main_code, extra_code))


@dataclasses.dataclass(frozen=True)
class MouseMoveEvent(BaseEvent):
    to_x: int
    to_y: int

    def __post_init__(self) -> None:
        assert -32768 <= self.to_x <= 32767
        assert -32768 <= self.to_y <= 32767

    def make_request(self) -> bytes:
        return _make_request(struct.pack(">Bhh", 0x12, self.to_x, self.to_y))


@dataclasses.dataclass(frozen=True)
class MouseRelativeEvent(BaseEvent):
    delta_x: int
    delta_y: int

    def __post_init__(self) -> None:
        assert -127 <= self.delta_x <= 127
        assert -127 <= self.delta_y <= 127

    def make_request(self) -> bytes:
        return _make_request(struct.pack(">Bbbxx", 0x15, self.delta_x, self.delta_y))


@dataclasses.dataclass(frozen=True)
class MouseWheelEvent(BaseEvent):
    delta_x: int
    delta_y: int

    def __post_init__(self) -> None:
        assert -127 <= self.delta_x <= 127
        assert -127 <= self.delta_y <= 127

    def make_request(self) -> bytes:
        # Горизонтальная прокрутка пока не поддерживается
        return _make_request(struct.pack(">Bxbxx", 0x14, self.delta_y))


# =====
def check_response(response: bytes) -> bool:
    assert len(response) in (4, 8), response
    return (_make_crc16(response[:-2]) == struct.unpack(">H", response[-2:])[0])


def _make_request(command: bytes) -> bytes:
    assert len(command) == 5, command
    request = b"\x33" + command
    request += struct.pack(">H", _make_crc16(request))
    assert len(request) == 8, request
    return request


def _make_crc16(data: bytes) -> int:
    crc = 0xFFFF
    for byte in data:
        crc = crc ^ byte
        for _ in range(8):
            if crc & 0x0001 == 0:
                crc = crc >> 1
            else:
                crc = crc >> 1
                crc = crc ^ 0xA001
    return crc


# =====
REQUEST_PING = _make_request(b"\x01\x00\x00\x00\x00")
REQUEST_REPEAT = _make_request(b"\x02\x00\x00\x00\x00")

RESPONSE_LEGACY_OK = b"\x33\x20" + struct.pack(">H", _make_crc16(b"\x33\x20"))