# python standard library
import random
from  datetime import datetime
import logging

# libraries
import networkx as nx

# this project
import questions

# setup logger for this module
logger = logging.getLogger(__name__)

# ----------------------------------------------------------------------------
# contains the kowledge state of each student.
class Knowledge(object):
    def __init__(self, depgraph, state={}):
        self.depgraph = depgraph
        self.state = state   # {node: level, node: level, ...}
        self.current_question = None

        self.seq = nx.topological_sort(self.depgraph)
        self.topic = None

    def get_current_question(self):
        return self.current_question

    def get_knowledge_state(self):
        return self.state

    # --- generates a new question given the current state
    def new_question(self):
        logger.debug('new_question()')
        if self.current_question is None or self.current_question.get('grade', 0.0) > 0.9999:
            g = self.depgraph
            # choose topic, ie, node of the graph
            # print(g.nodes())
            self.topic = random.choice(g.nodes())  # FIXME
            # print(topic)
            # choose question from that topic
            question = random.choice(g.node[self.topic]['factory'])
            # print(question)

            self.current_question = question.generate()
            # print(self.current_question)

            # self.current_question = g.node[topic]['factory'].generate(ref)
            self.current_question['start_time'] = datetime.now()
            return self.current_question

    # --- checks answer and updates knowledge state
    #     returns current question with correction, time and comments updated
    def check_answer(self, answer):
        logger.debug(f'check_answer("{answer}")')
        question = self.current_question
        if question is not None:
            question['finish_time'] = datetime.now()
            question.correct(answer)

        # logger.debug(f'check_answer returning')
        return question