# Copyright (C) 2020 by eichhornchen, ÿnérant
# SPDX-License-Identifier: GPL-3.0-or-later

import curses
import re
import socket
from argparse import ArgumentParser
from enum import Enum
from ipaddress import IPv6Address
from threading import Thread
from typing import Any, List, Optional, Tuple

import emoji

from squinnondation.term_manager import TermManager


class Squinnondation:
    args: Any
    bind_address: str
    bind_port: int
    no_emoji: bool
    no_markdown: bool
    screen: Any

    def parse_arguments(self) -> None:
        parser = ArgumentParser(description="MIRC client.")
        parser.add_argument('bind_address', type=str, default="localhost",
                            help="Address of the client.")
        parser.add_argument('bind_port', type=int, default=2500,
                            help="Port of the client. Must be between 1024 and 65535.")
        parser.add_argument('--client_address', type=str, default=None,
                            help="Address of the first neighbour.")
        parser.add_argument('--client_port', type=int, default=0,
                            help="Port of the first neighbour. Must be between 1024 and 65535.")
        parser.add_argument('--no-emoji', '-ne', action='store_true',
                            help="Don't replace emojis.")
        parser.add_argument('--no-markdown', '-nm', action='store_true',
                            help="Don't replace emojis.")
        self.args = parser.parse_args()

        if not (1024 <= self.args.bind_port <= 65535) or\
                not (not self.args.client_port or 1024 <= self.args.client_port <= 65535):
            raise ValueError("Ports must be between 1024 and 65535.")

        self.bind_address = self.args.bind_address
        self.bind_port = self.args.bind_port
        self.no_emoji = self.args.no_emoji
        self.no_markdown = self.args.no_markdown

    @staticmethod
    def main() -> None:  # pragma: no cover
        instance = Squinnondation()
        instance.parse_arguments()

        with TermManager() as term_manager:
            screen = term_manager.screen
            instance.screen = screen
            screen.addstr(0, 0, "Enter your nickname: ")
            curses.echo()
            nickname = screen.getstr().decode("UTF-8")
            curses.noecho()

            squirrel = Squirrel(instance, nickname)
            squirrel.refresh_history()
            squirrel.refresh_input()

            if instance.args.client_address and instance.args.client_port:
                hazelnut = Hazelnut(address=instance.args.client_address, port=instance.args.client_port)
                squirrel.hazelnuts[(instance.args.client_address, instance.args.client_port)] = hazelnut

            Worm(squirrel).start()

            while True:
                squirrel.refresh_history()
                squirrel.refresh_input()
                key = screen.getkey(curses.LINES - 1, 3 + len(squirrel.nickname) + len(squirrel.input_buffer))
                if key == "\x7f":  # backspace
                    squirrel.input_buffer = squirrel.input_buffer[:-1]
                    continue
                elif len(key) > 1:
                    squirrel.history.append(f"<system> *unmanaged key press: {key}*")
                    continue
                elif key != "\n":
                    squirrel.input_buffer += key
                    continue

                msg = squirrel.input_buffer
                squirrel.input_buffer = ""

                if not msg:
                    continue

                msg = f"<{squirrel.nickname}> {msg}"
                squirrel.history.append(msg)

                for hazelnut in list(squirrel.hazelnuts.values()):
                    pkt = Packet()
                    pkt.magic = 95
                    pkt.version = 0
                    tlv = DataTLV()
                    tlv.data = msg.encode("UTF-8")
                    tlv.sender_id = 42
                    tlv.nonce = 18
                    tlv.length = len(tlv.data) + 1 + 1 + 8 + 4
                    pkt.body = [tlv]
                    pkt.body_length = tlv.length + 2
                    squirrel.send_packet(hazelnut, pkt)


class TLV:
    """
    The Tag-Length-Value contains the different type of data that can be sent.
    TODO: add subclasses for each type of TLV
    """
    type: int

    def unmarshal(self, raw_data: bytes) -> None:
        """
        Parse data and construct TLV.
        """
        raise NotImplementedError

    def marshal(self) -> bytes:
        """
        Translate the TLV into a byte array.
        """
        raise NotImplementedError

    def validate_data(self) -> bool:
        """
        Ensure that the TLV is well-formed.
        Raises a ValueError if it is not the case.
        TODO: Make some tests
        """
        return True

    @staticmethod
    def tlv_classes():
        return [Pad1TLV, PadNTLV, HelloTLV, NeighbourTLV, DataTLV, AckTLV, GoAwayTLV, WarningTLV]


class Pad1TLV(TLV):
    """
    This TLV is simply ignored.
    """
    type: int = 0

    def unmarshal(self, raw_data: bytes) -> None:
        """
        There is nothing to do. We ignore the packet.
        """
        self.type = raw_data[0]

    def marshal(self) -> bytes:
        """
        The TLV is empty.
        """
        return self.type.to_bytes(1, "big")


class PadNTLV(TLV):
    """
    This TLV is filled with zeros. It is ignored.
    """
    type: int = 1
    length: int
    mbz: bytes

    def validate_data(self) -> bool:
        if self.mbz != int(0).to_bytes(self.length, "big"):
            raise ValueError("The body of a PadN TLV is not filled with zeros.")
        return True

    def unmarshal(self, raw_data: bytes) -> None:
        """
        Store the zero-array, then ignore the packet.
        """
        self.type = raw_data[0]
        self.length = raw_data[1]
        self.mbz = raw_data[2:2 + self.length]

    def marshal(self) -> bytes:
        """
        Construct the byte array filled by zeros.
        """
        return self.type.to_bytes(1, "big") + self.length.to_bytes(1, "big") + self.mbz[:self.length]


class HelloTLV(TLV):
    type: int = 2
    length: int
    source_id: int
    dest_id: Optional[int]

    def validate_data(self) -> bool:
        if self.length != 8 and self.length != 16:
            raise ValueError("The length of a Hello TLV must be 8 for a short Hello, or 16 for a long Hello,"
                             f"found {self.length}")
        return True

    def unmarshal(self, raw_data: bytes) -> None:
        self.type = raw_data[0]
        self.length = raw_data[1]
        self.source_id = int.from_bytes(raw_data[2:10], "big")
        if self.length == 16:
            self.dest_id = int.from_bytes(raw_data[10:18], "big")

    def marshal(self) -> bytes:
        data = self.type.to_bytes(1, "big") + self.length.to_bytes(1, "big") + self.source_id.to_bytes(8, "big")
        if self.dest_id:
            data += self.dest_id.to_bytes(8, "big")
        return data


class NeighbourTLV(TLV):
    type: int = 3
    length: int
    ip_address: IPv6Address
    port: int

    def unmarshal(self, raw_data: bytes) -> None:
        self.type = raw_data[0]
        self.length = raw_data[1]
        self.ip_address = IPv6Address(raw_data[2:18])
        self.port = int.from_bytes(raw_data[18:20], "big")

    def marshal(self) -> bytes:
        return self.type.to_bytes(1, "big") + \
            self.length.to_bytes(1, "big") + \
            self.ip_address.packed + \
            self.port.to_bytes(2, "big")


class DataTLV(TLV):
    type: int = 4
    length: int
    sender_id: int
    nonce: int
    data: bytes

    def unmarshal(self, raw_data: bytes) -> None:
        self.type = raw_data[0]
        self.length = raw_data[1]
        self.sender_id = int.from_bytes(raw_data[2:10], "big")
        self.nonce = int.from_bytes(raw_data[10:14], "big")
        self.data = raw_data[14:2 + self.length]

    def marshal(self) -> bytes:
        return self.type.to_bytes(1, "big") + \
            self.length.to_bytes(1, "big") + \
            self.sender_id.to_bytes(8, "big") + \
            self.nonce.to_bytes(4, "big") + \
            self.data


class AckTLV(TLV):
    type: int = 5
    length: int
    sender_id: int
    nonce: int

    def unmarshal(self, raw_data: bytes) -> None:
        self.type = raw_data[0]
        self.length = raw_data[1]
        self.sender_id = int.from_bytes(raw_data[2:10], "big")
        self.nonce = int.from_bytes(raw_data[10:14], "big")

    def marshal(self) -> bytes:
        return self.type.to_bytes(1, "big") + \
            self.length.to_bytes(1, "big") + \
            self.sender_id.to_bytes(8, "big") + \
            self.nonce.to_bytes(4, "big")


class GoAwayTLV(TLV):
    class GoAwayType(Enum):
        UNKNOWN = 0
        EXIT = 1
        TIMEOUT = 2
        PROTOCOL_VIOLATION = 3

    type: int = 6
    length: int
    code: GoAwayType
    message: str

    def unmarshal(self, raw_data: bytes) -> None:
        self.type = raw_data[0]
        self.length = raw_data[1]
        self.code = GoAwayTLV.GoAwayType(raw_data[2])
        self.message = raw_data[3:self.length - 1].decode("UTF-8")

    def marshal(self) -> bytes:
        return self.type.to_bytes(1, "big") + \
            self.length.to_bytes(1, "big") + \
            self.code.value.to_bytes(1, "big") + \
            self.message.encode("UTF-8")[:self.length - 1]


class WarningTLV(TLV):
    type: int = 7
    length: int
    message: str

    def unmarshal(self, raw_data: bytes) -> None:
        self.type = raw_data[0]
        self.length = raw_data[1]
        self.message = raw_data[2:self.length].decode("UTF-8")

    def marshal(self) -> bytes:
        return self.type.to_bytes(1, "big") + \
            self.length.to_bytes(1, "big") + \
            self.message.encode("UTF-8")[:self.length]


class Packet:
    """
    A Packet is a wrapper around the
    """
    magic: int
    version: int
    body_length: int
    body: List[TLV]

    def validate_data(self) -> bool:
        """
        Ensure that the packet is well-formed.
        Raises a ValueError if the packet contains bad data.
        """
        if self.magic != 95:
            raise ValueError("The magic code of the packet must be 95, found: {:d}".format(self.magic))
        if self.version != 0:
            raise ValueError("The version of the packet is not supported: {:d}".format(self.version))
        if not (0 <= self.body_length <= 120):
            raise ValueError("The body length of the packet is negative or too high. It must be between 0 and 1020,"
                             "found: {:d}".format(self.body_length))
        return all(tlv.validate_data() for tlv in self.body)

    @staticmethod
    def unmarshal(data: bytes) -> "Packet":
        """
        Read raw data and build the packet wrapper.
        Raises a ValueError whenever the data is invalid.
        """
        pkt = Packet()
        pkt.magic = data[0]
        pkt.version = data[1]
        pkt.body_length = int.from_bytes(data[2:4], byteorder="big")
        pkt.body = []
        read_bytes = 0
        while read_bytes <= min(len(data) - 4, pkt.body_length):
            tlv_type = data[4]
            if not (0 <= tlv_type < len(TLV.tlv_classes())):
                raise ValueError(f"TLV type is not supported: {tlv_type}")
            tlv = TLV.tlv_classes()[tlv_type]()
            tlv.unmarshal(data[4:4 + pkt.body_length])
            pkt.body.append(tlv)
            # Pad1TLV has no length
            read_bytes += 1 if tlv_type == 0 else tlv.length + 2

        pkt.validate_data()

        return pkt

    def marshal(self) -> bytes:
        """
        Compute the byte array data associated to the packet.
        """
        data = self.magic.to_bytes(1, "big")
        data += self.version.to_bytes(1, "big")
        data += self.body_length.to_bytes(2, "big")
        data += b"".join(tlv.marshal() for tlv in self.body)
        return data


class Hazelnut:
    """
    A hazelnut is a connected client, with its socket.
    """
    def __init__(self, nickname: str = "anonymous", address: str = "localhost", port: int = 2500):
        self.nickname = nickname

        try:
            # Resolve DNS as an IPv6
            address = socket.getaddrinfo(address, None, socket.AF_INET6)[0][4][0]
        except socket.gaierror:
            # This is not a valid IPv6. Assume it can be resolved as an IPv4, and we use IPv4-mapping
            # to compute a valid IPv6.
            # See https://fr.wikipedia.org/wiki/Adresse_IPv6_mappant_IPv4
            address = "::ffff:" + socket.getaddrinfo(address, None, socket.AF_INET)[0][4][0]

        self.address = IPv6Address(address)
        self.port = port


class Squirrel(Hazelnut):
    """
    The squirrel is the user of the program. It can speak with other clients, that are called hazelnuts.
    """
    def __init__(self, instance: Squinnondation, nickname: str):
        super().__init__(nickname, instance.bind_address, instance.bind_port)
        # Create UDP socket
        self.socket = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
        # Bind the socket
        self.socket.bind((str(self.address), self.port))

        self.squinnondation = instance

        self.input_buffer = ""

        self.history = []
        self.history_pad = curses.newpad(curses.LINES - 2, curses.COLS)
        self.input_pad = curses.newpad(1, curses.COLS)
        curses.init_color(curses.COLOR_WHITE, 1000, 1000, 1000)
        for i in range(curses.COLOR_BLACK + 1, curses.COLOR_WHITE):
            curses.init_pair(i + 1, i, curses.COLOR_BLACK)

        self.hazelnuts = dict()
        self.history.append(f"<system> *Listening on {self.address}:{self.port}*")

    def find_hazelnut(self, address: str, port: int) -> Hazelnut:
        """
        Translate an address into a hazelnut, and store it in the list of the hazelnuts, ie. the neighbours.
        """
        if (address, port) in self.hazelnuts:
            return self.hazelnuts[(address, port)]
        hazelnut = Hazelnut(address=address, port=port)
        self.hazelnuts[(address, port)] = hazelnut
        return hazelnut

    def send_packet(self, client: Hazelnut, pkt: Packet) -> int:
        """
        Send a formatted packet to a client.
        """
        return self.send_raw_data(client, pkt.marshal())

    def send_raw_data(self, client: Hazelnut, data: bytes) -> int:
        """
        Send a raw packet to a client.
        """
        return self.socket.sendto(data, (str(client.address), client.port))

    def receive_packet(self) -> Tuple[Packet, Hazelnut]:
        """
        Receive a packet from the socket and translate it into a Python object.
        Warning: the process is blocking, it should be ran inside a dedicated thread.
        """
        data, addr = self.receive_raw_data()
        return Packet.unmarshal(data), self.find_hazelnut(addr[0], addr[1])

    def receive_raw_data(self) -> Tuple[bytes, Any]:
        """
        Receive a packet from the socket.
        """
        return self.socket.recvfrom(1024)

    def print_markdown(self, pad: Any, y: int, x: int, msg: str,
                       bold: bool = False, italic: bool = False, underline: bool = False, strike: bool = False) -> int:
        """
        Parse a markdown-formatted text and format the text as bold, italic or text text.
        ***text***: bold, italic
        **text**: bold
        *text*: italic
        __text__: underline
        _text_: italic
        ~~text~~: strikethrough
        """
        # Replace :emoji_name: by the good emoji
        if not self.squinnondation.no_emoji:
            msg = emoji.emojize(msg, use_aliases=True)

        if self.squinnondation.no_markdown:
            pad.addstr(y, x, msg)
            return len(msg)

        underline_match = re.match("(.*)__(.*)__(.*)", msg)
        if underline_match:
            before, text, after = underline_match.group(1), underline_match.group(2), underline_match.group(3)
            len_before = self.print_markdown(pad, y, x, before, bold, italic, underline)
            len_mid = self.print_markdown(pad, y, x + len_before, text, bold, italic, not underline)
            len_after = self.print_markdown(pad, y, x + len_before + len_mid, after, bold, italic, underline)
            return len_before + len_mid + len_after

        italic_match = re.match("(.*)_(.*)_(.*)", msg)
        if italic_match:
            before, text, after = italic_match.group(1), italic_match.group(2), italic_match.group(3)
            len_before = self.print_markdown(pad, y, x, before, bold, italic, underline)
            len_mid = self.print_markdown(pad, y, x + len_before, text, bold, not italic, underline)
            len_after = self.print_markdown(pad, y, x + len_before + len_mid, after, bold, italic, underline)
            return len_before + len_mid + len_after

        bold_italic_match = re.match("(.*)\\*\\*\\*(.*)\\*\\*\\*(.*)", msg)
        if bold_italic_match:
            before, text, after = bold_italic_match.group(1), bold_italic_match.group(2),\
                bold_italic_match.group(3)
            len_before = self.print_markdown(pad, y, x, before, bold, italic, underline, strike)
            len_mid = self.print_markdown(pad, y, x + len_before, text, not bold, not italic, underline, strike)
            len_after = self.print_markdown(pad, y, x + len_before + len_mid, after, bold, italic, underline, strike)
            return len_before + len_mid + len_after

        bold_match = re.match("(.*)\\*\\*(.*)\\*\\*(.*)", msg)
        if bold_match:
            before, text, after = bold_match.group(1), bold_match.group(2), bold_match.group(3)
            len_before = self.print_markdown(pad, y, x, before, bold, italic, underline, strike)
            len_mid = self.print_markdown(pad, y, x + len_before, text, not bold, italic, underline, strike)
            len_after = self.print_markdown(pad, y, x + len_before + len_mid, after, bold, italic, underline, strike)
            return len_before + len_mid + len_after

        italic_match = re.match("(.*)\\*(.*)\\*(.*)", msg)
        if italic_match:
            before, text, after = italic_match.group(1), italic_match.group(2), italic_match.group(3)
            len_before = self.print_markdown(pad, y, x, before, bold, italic, underline, strike)
            len_mid = self.print_markdown(pad, y, x + len_before, text, bold, not italic, underline, strike)
            len_after = self.print_markdown(pad, y, x + len_before + len_mid, after, bold, italic, underline, strike)
            return len_before + len_mid + len_after

        strike_match = re.match("(.*)~~(.*)~~(.*)", msg)
        if strike_match:
            before, text, after = strike_match.group(1), strike_match.group(2), strike_match.group(3)
            len_before = self.print_markdown(pad, y, x, before, bold, italic, underline, strike)
            len_mid = self.print_markdown(pad, y, x + len_before, text, bold, italic, underline, not strike)
            len_after = self.print_markdown(pad, y, x + len_before + len_mid, after, bold, italic, underline, strike)
            return len_before + len_mid + len_after

        size = len(msg)

        attrs = 0
        attrs |= curses.A_BOLD if bold else 0
        attrs |= curses.A_ITALIC if italic else 0
        attrs |= curses.A_UNDERLINE if underline else 0
        if strike:
            msg = "".join(c + "\u0336" for c in msg)
        pad.addstr(y, x, msg, attrs)
        return size

    def refresh_history(self) -> None:
        """
        Rewrite the history of the messages.
        """
        y, x = self.squinnondation.screen.getmaxyx()
        if curses.is_term_resized(curses.LINES, curses.COLS):
            curses.resizeterm(y, x)
            self.history_pad.resize(curses.LINES - 2, curses.COLS - 1)
            self.input_pad.resize(1, curses.COLS - 1)

        self.history_pad.erase()
        for i, msg in enumerate(self.history[max(0, len(self.history) - curses.LINES + 2):]):
            if not re.match("<.*> .*", msg):
                msg = "<unknown> " + msg
            match = re.match("<(.*)> (.*)", msg)
            nickname = match.group(1)
            msg = match.group(2)
            color_id = sum(ord(c) for c in nickname) % 6 + 1
            self.history_pad.addstr(i, 0, "<")
            self.history_pad.addstr(i, 1, nickname, curses.A_BOLD | curses.color_pair(color_id + 1))
            self.history_pad.addstr(i, 1 + len(nickname), "> ")
            self.print_markdown(self.history_pad, i, 3 + len(nickname), msg)
        self.history_pad.refresh(0, 0, 0, 0, curses.LINES - 2, curses.COLS)

    def refresh_input(self) -> None:
        """
        Redraw input line. Must not be called while the message is not sent.
        """
        self.input_pad.erase()
        color_id = sum(ord(c) for c in self.nickname) % 6 + 1
        self.input_pad.addstr(0, 0, "<")
        self.input_pad.addstr(0, 1, self.nickname, curses.A_BOLD | curses.color_pair(color_id + 1))
        self.input_pad.addstr(0, 1 + len(self.nickname), "> ")
        self.input_pad.addstr(0, 3 + len(self.nickname), self.input_buffer)
        self.input_pad.refresh(0, 0, curses.LINES - 1, 0, curses.LINES - 1, curses.COLS - 1)


class Worm(Thread):
    """
    The worm is the hazel listener.
    It always waits for an incoming packet, then it  treats it, and continues to wait.
    It is in a dedicated thread.
    """
    def __init__(self, squirrel: Squirrel, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.squirrel = squirrel

    def run(self) -> None:
        while True:
            try:
                pkt, hazelnut = self.squirrel.receive_packet()
            except ValueError as error:
                self.squirrel.history.append("<system> *An error occured while receiving a packet: {}*".format(error))
            else:
                self.squirrel.history.append(pkt.body[0].data.decode('UTF-8'))
                self.squirrel.refresh_history()
                self.squirrel.refresh_input()