from collections import defaultdict
from dataclasses import dataclass, field
from typing import Dict, Set

from paircd.client import Client
from paircd.message import Message


@dataclass
class Channel:
    name: str
    topic: str = ""
    modes: Set[str] = field(default_factory=lambda: {"t"})
    clients_by_nick: Dict[str, Client] = field(default_factory=dict)
    modes_by_nick: Dict[str, Set[str]] = field(default_factory=lambda: defaultdict(set))

    def add_client(self, client: Client) -> None:
        self.clients_by_nick[client.nickname] = client
        if len(self.clients_by_nick) == 1:
            self.modes_by_nick[client.nickname].add("o")

    def remove_client_by_nick(self, nick: str) -> None:
        del self.clients_by_nick[nick]
        del self.modes_by_nick[nick]

    def write_message(self, msg: Message) -> None:
        for client in self.clients_by_nick.values():
            # Don't broadcast client's messages back to themselves
            if msg.cmd == "PRIVMSG" and msg.prefix == client.id():
                continue
            client.write_message(msg)

    def get_modes(self) -> Set[str]:
        return self.modes

    def get_mode_settings(self) -> str:
        return f"+{''.join(sorted(self.modes))}"

    def get_user_modes_by_nick(self, nick: str) -> Set[str]:
        return self.modes_by_nick[nick]

    def get_channel_name(self, nick: str) -> str:
        modes = self.get_user_modes_by_nick(nick)
        if "o" in modes:
            return f"@{nick}"
        if "v" in modes:
            return f"+{nick}"
        return nick

    def get_channel_size(self) -> int:
        return len(self.clients_by_nick)

    def rename_client(self, name: str, new_name: str) -> None:
        if name not in self.clients_by_nick:
            raise KeyError(f"No client on channel with nick {name}")
        if new_name in self.clients_by_nick:
            raise KeyError(f"Client already exists with nick {new_name}")
        self.clients_by_nick[new_name] = self.clients_by_nick[name]
        del self.clients_by_nick[name]
        self.modes_by_nick[new_name] = self.modes_by_nick[name]
        del self.modes_by_nick[name]