from edmond.plugin import Plugin


class PlusPlugin(Plugin):
    """Plugin to store additional content from other plugins.

    This plugin does not do much on its own, it lets other plugins register additional
    content to compute on the fly when asked, e.g. the Wikipedia plugin can store the
    Web page of the definition they just gave so users wanting to know more about a
    definition can use the "plus" function to get the URL to the Web page.

    There can be only one handle registered at one time by target (so by channel, user,
    etc). External plugins use the `add_handler` to set the current handler for a
    target.
    """

    def __init__(self, bot):
        super().__init__(bot)
        self.handlers = {}

    def on_pubmsg(self, event):
        if not self.should_handle_command(event.arguments[0], no_content=True):
            return False

        if handler := self.handlers.pop(event.target, None):
            handler(event)
        else:
            self.signal_failure(event.target)
        return True

    def add_handler(self, target: str, handler):
        self.handlers[target] = handler