import dataclasses
from pathlib import Path
from typing import IO, Any, Mapping, Sequence, Set

import toml


PluginConfig = Mapping[str, Any]


class ConfigError(Exception):
    def __init__(self, which: str, hint: str | None, plugin: str | None = None):
        self.which = which
        self.hint = hint
        self.plugin = plugin
        msg = f"{self.which}"
        if self.hint:
            msg = f"{msg}: {self.hint}"
        if self.plugin:
            msg = f"in config for plugin {plugin}: {msg}"
        else:
            msg = f"in server config: {msg}"
        super(ConfigError, self).__init__(msg)


@dataclasses.dataclass
class ServerConfig:
    server: str = ""
    use_ssl: bool = False
    port: int = 6667
    plugins: Sequence[PluginConfig] = dataclasses.field(default_factory=list)
    channels: Sequence[str] = dataclasses.field(default_factory=list)
    nick: str = "omnibot"
    loglevel: str | None = None

    def load(self, fp: IO[str]):
        obj = toml.load(fp)

        if "server" not in obj:
            raise ConfigError("server", "must be present")
        if not isinstance(obj["server"], str):
            raise ConfigError("server", "must be a string")
        self.server = obj["server"]

        if "use_ssl" in obj:
            if not isinstance(obj["use_ssl"], bool):
                raise ConfigError("use_ssl", "must be a boolean")
            self.use_ssl = obj["use_ssl"]
        else:
            # Don't use SSL by default
            self.use_ssl = False

        if "port" in obj:
            if not isinstance(obj["port"], int):
                raise ConfigError("port", "must be an integer")
            if not (0 < obj["port"] <= 65535):
                raise ConfigError("port", "must be between 0 and 65535")
            self.port = obj["port"]
        else:
            if self.use_ssl:
                self.port = 6697
            else:
                self.port = 6667

        if "plugins" in obj:
            if not isinstance(obj["plugins"], Sequence):
                raise ConfigError(
                    "plugins", "must be a mapping of configuration values"
                )
            self.plugins = obj["plugins"]

        if "channels" in obj:
            if not isinstance(obj["channels"], Sequence):
                raise ConfigError("channels", "must by a list of strings")
            self.channels = obj["channels"]

        if "nick" in obj:
            if not isinstance(obj["nick"], str):
                raise ConfigError("nick", "must be a string")
            self.nick = obj["nick"]

        if "loglevel" in obj:
            if not isinstance(obj["loglevel"], str):
                raise ConfigError("loglevel", "must be a string")
            loglevels = ["DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"]
            if obj["loglevel"] not in loglevels:
                raise ConfigError("loglevel", "must be one of: " + " ".join(loglevels))
            self.loglevel = obj["loglevel"]

    @property
    def all_channels(self) -> Set[str]:
        channels = set(self.channels)
        for plugin in self.plugins:
            if "channels" in plugin:
                channels |= set(plugin["channels"])
        return channels