from dataclasses import dataclass
from pathlib import Path
from typing import Any, Optional

from irc.client import NickMask  # type: ignore


@dataclass
class Question:
    preamble: str
    content: str


@dataclass
class Command:
    # Identifier as set in config. Set even when an alias has been used.
    ident: str
    # Content of the command when it has been parsed, empty str otherwise.
    content: str
    # Raw command content (minus name and suffix), always set.
    raw: str
    # Identifier matched, possibly an alias. Set only when matched.
    matched: str = ""


class Plugin:
    """Base class for the bot plugins.

    This class provides a lot of tools to facilitate the implementation of
    plugins. Callbacks for all events handled by the IRC library can be
    implemented here (if the Bot class supports it). Most bot features are put
    in plugins to avoid cluttering the Bot class, and no plugins should be
    required for the bot to run; plugins can depend on each other though.

    A plugin loads his basic information from the config file. It can use the
    bot's runtime values facilities to make runtime values available to other
    plugins. It can also save data using the Bot's storage feature to be
    available after a restart.

    Initialisation should be very fast, no network connections or anything.
    They are initialised before connecting to the server, so their `is_ready`
    flag is set at that point. The loading order is more or less random, so a
    plugin cannot assume another has been loaded during initialisation. If it
    wants to interact with another plugin, the earliest point to do that is in
    the on_welcome callback which is called after connecting to a server, and
    can disable itself by setting its own `is_ready` flag to false.

    A plugin can access its config once the base `__init__` has been called.
    The configuration is valid only is `is_ready` is True, else accessing its
    content is undefined behaviour.

    Plugins can have priorities and calling their callbacks will respect it.
    For now these levels are used:
    - 0: default
    - -3: low, misc parsing of messages, answer to various messages
    - -6: handling of unknown commands
    - -7: handling of unknown questions
    - -8: handling any message that might match something
    - -10: lowest, e.g. for random reactions usually with a very low rate
    """

    REQUIRED_CONFIGS: list[str] = []

    def __init__(self, bot):
        from edmond.bot import Bot

        self.bot: Bot = bot
        # self.name is the plugin name, lowercased, without the Plugin suffix.
        self.name: str = self.__class__.__name__.lower()[:-6]
        self.priority: int = 0
        self.config: dict = self.__get_config()
        self.is_ready: bool = self.__check_config()

    @property
    def callbacks(self):
        """List of callback types available for this plugin."""
        return {
            cb[3:]: getattr(self, cb)
            for cb in dir(self)
            if cb.startswith("on_") and callable(getattr(self, cb))
        }

    def __get_config(self) -> dict:
        """Return the plugin section from the bot config plus common values."""
        plugins_configs = self.bot.config["plugins"]
        config = plugins_configs["common"].copy()
        config.update(plugins_configs.get(self.name, {}))
        # Load resources as config values.
        res_dir = self.bot.config["resources_dir"]
        for key, res_path in config.get("resources", {}).items():
            res_path = Path(res_dir) / res_path
            try:
                with open(res_path, "rt") as res_file:
                    config[key] = [
                        line.strip() for line in res_file.readlines()
                    ]
            except OSError:
                self.bot.log_e(f"Could not load resource at {res_path}.")
        return config

    def __check_config(self) -> bool:
        """Return True if the plugin config is properly setup."""
        missing = False
        for key in self.REQUIRED_CONFIGS:
            if key not in self.config:
                self.bot.log_e(f"Missing '{key}' in {self.name} config.")
                missing = True
        return not missing

    def get_runtime_value(
        self, key: str, default: Any = None, ns: str = None
    ) -> Any:
        """Get a value from the plugin runtime dict.

        This will get the value from the plugin namespace, but it is possible
        to get runtime values from other plugins using their name as `ns`.
        """
        if ns is None:
            ns = self.name
        return self.bot.values[ns].get(key, default)

    def set_runtime_value(self, key: str, value: Any) -> Any:
        """Set a value in the plugin runtime dict."""
        self.bot.values[self.name][key] = value

    def get_storage_value(self, key: str, default=None, ns: str = None) -> Any:
        """Get a value from the plugin persistent storage.

        This will get the value from the plugin namespace, but it is possible
        to get storage values from other plugins using their name as `ns`.
        """
        if ns is None:
            ns = self.name
        return self.bot.storage.get(ns, {}).get(key, default)

    def set_storage_value(self, key: str, value: Any, ns: str = None) -> None:
        """Set a value in the plugin persistent storage."""
        name = ns or self.name
        if name not in self.bot.storage:
            self.bot.storage[name] = {key: value}
        else:
            self.bot.storage[name][key] = value
        self.bot.save_storage()

    def append_storage_list_value(self, key: str, value: Any) -> None:
        """Append a value to a list in the plugin persistent storage."""
        if self.name not in self.bot.storage:
            self.bot.storage[self.name] = {key: [value]}
        elif key not in self.bot.storage[self.name]:
            self.bot.storage[self.name][key] = [value]
        else:
            self.bot.storage[self.name][key].append(value)
        self.bot.save_storage()

    def remove_storage_list_value(self, key: str, value: Any) -> None:
        """Remove a value from a persistent storage list."""
        if (
            self.name in self.bot.storage
            and key in self.bot.storage[self.name]
        ):
            self.bot.storage[self.name][key].remove(value)
        self.bot.save_storage()

    def should_read_message(self, message: str) -> Optional[str]:
        """Return a message content if it has been addressed to me, else None.

        If the message starts with one of the bot's names, the rest of the
        message is returned. It might be an empty str if the message was only
        someone saying a bot's name. In other cases, return None.

        Note that you do not need to use this method for command/question
        plugins, the next methods already check for this and do more precise
        parsing of the message. This is rather for plugins reacting to a
        message addressed to the bot that are neither commands or questions.
        """
        first_word_and_rest = message.split(maxsplit=1)
        num_parts = len(first_word_and_rest)
        if num_parts == 0:
            return None
        # Are the config conditions to answer a question valid?
        elif not self.respects_handling_conditions():
            return None
        # Is the message addressed to me?
        elif first_word_and_rest[0] in self.bot.names:
            if num_parts == 1:
                content = ""
            else:
                content = first_word_and_rest[1].strip()
            self.bot.log_i(f"Reading message from {self.name}: {content}")
            return content
        return None

    def should_answer_question(self, message: str) -> bool:
        """Store Question in object and return True if I should answer it.

        To answer a question, the message must start with one of the bot's
        names and optionally end with one or more question marks (they are
        discarded). The bot checks that answering conditions are respected, and
        they cannot be bypassed as with commands. A Question created is checked
        from the plugin's registered questions and stored in the instance.
        """
        words = message.split()
        # Is the message addressed to me?
        if len(words) == 0 or words[0].lower() not in self.bot.names:
            return False

        # Are the config conditions to answer a question valid?
        if not self.respects_handling_conditions():
            return False

        # Is it a question I can answer?
        question = message[len(words[0]) :].strip()
        for preamble in self.config.get("questions", []):
            aliases = self.config.get("aliases", {}).get(preamble, [])
            for q in (preamble, *aliases):
                if question.startswith(q):
                    self.__save_question(question, q, preamble)
                    return True
        return False

    def __save_question(self, question: str, matched: str, preamble: str):
        content = question[len(matched) :].strip()
        content = content.rstrip("?").rstrip()
        self.question = Question(preamble, content)
        self.bot.log_i(f"Answering from plugin {self.name}: {self.question}")

    def should_handle_command(
        self,
        message: str,
        no_content: bool = False,
        exclude_conditions: Optional[dict] = None,
    ) -> bool:
        """Store Command in object and return True if I should handle it.

        If no_content is True, the command does not parse command contents and
        put all the command message (without suffix) to the command identifier.
        This is useful for commands that have multiple words in their
        identifier and do not have any content, or when the content parsing
        should be done by the plugin itself.

        If exclude_conditions is a collection of plugin namespaces, the
        conditions of these plugins are not tested. A basic scenario is the
        wakeup command from sleep plugin that requires excluding its own
        condition (i.e. do not handle commands when sleeping).
        """
        # Are the config conditions to handle a command valid?
        if not self.respects_handling_conditions(exclude_conditions):
            return False

        # Is it a valid command?
        parsed_command = self.__parse_command(message, no_content=no_content)
        if not parsed_command:
            return False

        # Is it a command I can handle?
        available_commands = self.config.get("commands", [])
        aliases = self.config.get("aliases", {})
        for ident in available_commands:
            # Match commands differently according to no_content. If no_content
            # is True, check the parsed command (pc) raw data as a string that
            # may contain the available identifier (ai) at its beginning.
            # If no_content is False (default), simply compare the parsed
            # identifier with available identifiers.
            if no_content:
                matches = lambda pc, ai: (
                    pc.raw == ai or pc.raw.startswith(ai + " ")
                )
            else:
                matches = lambda pc, ai: pc.ident == ai
            # First case: the command identifier has been used.
            if matches(parsed_command, ident):
                parsed_command.ident = ident
                parsed_command.matched = ident
                self.__save_command(parsed_command)
                return True
            # Second case: an alias of the identifier has been used.
            ident_aliases = aliases.get(ident, [])
            for alias in ident_aliases:
                if matches(parsed_command, alias):
                    parsed_command.ident = ident
                    parsed_command.matched = alias
                    self.__save_command(parsed_command)
                    return True
        return False

    def __parse_command(
        self, message: str, no_content: bool = False
    ) -> Optional[Command]:
        """Return a parsed Command if this message is a command, else None.

        The command raw field is always set. The ident and content fields are
        empty when no_content is True. The match field is never set by this
        method.
        """
        words = message.split()
        if len(words) == 0:
            return None
        command_suffix = self.config["command_suffix"]
        if words[0].lower() in self.bot.names and words[-1] == command_suffix:
            raw = " ".join(words[1:-1])
            if no_content:
                ident = ""
                content = ""
            else:
                ident = words[1]
                content = " ".join(words[2:-1])
            return Command(ident, content, raw)
        return None

    def __save_command(self, command: Command):
        """Save command in instance for further processing by the plugin."""
        self.command = command
        self.bot.log_i(f"Processing command from p. {self.name}: {command}")

    def respects_handling_conditions(
        self, exclude_conditions: Optional[dict] = None
    ):
        """Check if handling conditions are valid.

        Handling conditions can be specified by each plugin to create states in
        which handling messages can be disabled. It is currently only used by
        the sleep plugin (sleeping must disable most interactions) but every
        plugin is free to introduce their own condition.
        """
        conditions = self.config.get("handling_conditions", {})
        for plugin_ns, plugin_conditions in conditions.items():
            if exclude_conditions and plugin_ns in exclude_conditions:
                continue
            for condition_key, condition_value in plugin_conditions.items():
                value = self.get_runtime_value(condition_key, ns=plugin_ns)
                if condition_value != value:
                    return False
        return True

    def signal_failure(self, target):
        """Signal a plugin failure to target."""
        self.bot.say(target, self.bot.config["error_message"])

    def on_privmsg(self, event):
        """Default behaviour on privmsg is to answer like a pubmsg.

        Because most plugins assume messages are sent publicly, they send their
        replies to `event.target` so we replace it with the event source nick.
        If it causes an issue with a plugin requiring the original target even
        on private message, override this method.
        """
        if on_pubmsg := getattr(self, "on_pubmsg", None):
            event.target = NickMask(event.source).nick
            return on_pubmsg(event)
        return False