from opsdroid.skill import Skill
from opsdroid.matchers import match_rasanlu, match_parse
import random
import importlib

class Respond(Skill):
    # Constructor gets configs for the skill and applies the decorator
    # to match using rasa.
    def __init__(self, opsdroid, config):
        super().__init__(opsdroid, config)
        self._get_configs()
        self.respond = match_rasanlu(self.intent)(self.respond)

    # This utility function will grab the relevent config variables
    # for this skill to function.
    def _get_configs(self):
        # The intent to match.
        self.intent = self.config.get("intent")
        # Possible responses given a match.
        self.response_options = self.config.get("response_options")
        # A bool to check if we want to use entities in our response.
        self.use_entities = self.config.get("use_entities", False)
        # Fallback responses if we do not get the required entities
        # from Rasa.
        self.fallback_response_options = self.config.get("fallback_response_options", 
                ["Sorry, Rasa did not extract sufficient entities to fulfil your request"])
        # An optional callback used for more advanced responses. Such
        # functions should simply return the final response string and
        # will be given the message and extracted entities (if enabled).
        self.callback_file = self.config.get("callback_file", None)
        self.callback_name = self.config.get("callback_name", None)


    # Extract the entities from the rasanlu response
    def _get_entities(self, message):
        # This includes data such as the extractor used, which we
        # don't need.
        raw_entities = message.rasanlu["entities"]
        entities = {}
        for entity in raw_entities:
            entity_type = entity["entity"]
            unique_entity_type = self._get_unique_key(entity_type, entities)
            entity_value = entity["value"]
            entities[unique_entity_type] = entity_value
        return entities

                
    # Appends the smallest integer to the name of the key in order to
    # create a new key that is not already in the dictionary.
    def _get_unique_key(self, base_key, dictionary):
        counter = 0
        while True:
            unique_key_attempt = base_key + str(counter)
            if unique_key_attempt in dictionary:
                counter += 1
                continue
            return unique_key_attempt


    # Takes the response and attempts to replace all entities in it
    # with the extracted entities. Failing that, we will fall back to a
    # fallback response.
    def _substitute_entities(self, response, entities):
        try:
            response = response.format(**entities)
        except KeyError as e:
            chosen_fallback = random.choice(self.fallback_response_options)
            return chosen_fallback
        return response


    # This line is to add properties to respond on declaration
    # as doing this in __init__ would cause an exception to be
    # raised. If you don't believe me, remove it!
    @match_parse("hgftgyhjknbvhgftyuihjkvhgftyuijkbjhgtyyuijhkjghfdtrytyihujkbvncgfxdtrytuyiuhkbjvbhcfdytryuhjkbvhcfdyrtuyiuhkbhj")
    async def respond(self, message):
        chosen_response = random.choice(self.response_options)
        entities = None # In case we want callbacks without entities
        if self.use_entities:
            entities = self._get_entities(message)
            chosen_response = self._substitute_entities(chosen_response, entities)
        if self.callback_file != None and self.callback_name != None:
            # The following three lines allow us to import the module using an absolute path dynamically
            spec = importlib.util.spec_from_file_location("callback", self.callback_file)
            callback_module = importlib.util.module_from_spec(spec)
            spec.loader.exec_module(callback_module)
            # Now we can get the response from the callback.
            chosen_response = eval("callback_module." + self.callback_name + "(message, entities)")
        await message.respond(chosen_response)