# python standard library from os import path, sys import logging from contextlib import contextmanager # `with` statement in db sessions import asyncio from datetime import datetime # user installed libraries import bcrypt from sqlalchemy import create_engine from sqlalchemy.orm import sessionmaker import networkx as nx # this project from models import Student, Answer, Topic, StudentTopic from knowledge import StudentKnowledge from factory import QFactory from tools import load_yaml # setup logger for this module logger = logging.getLogger(__name__) # ============================================================================ # class LearnAppException(Exception): # pass # ============================================================================ # helper functions # ============================================================================ async def _bcrypt_hash(a, b): loop = asyncio.get_running_loop() return await loop.run_in_executor(None, bcrypt.hashpw, a.encode('utf-8'), b) async def check_password(try_pw, pw): return pw == await _bcrypt_hash(try_pw, pw) async def bcrypt_hash_gen(new_pw): return await _bcrypt_hash(new_pw, bcrypt.gensalt()) # ============================================================================ # LearnApp - application logic # ============================================================================ class LearnApp(object): # ------------------------------------------------------------------------ # helper to manage db sessions using the `with` statement, for example # with self.db_session() as s: s.query(...) # ------------------------------------------------------------------------ @contextmanager def db_session(self, **kw): session = self.Session(**kw) try: yield session session.commit() except: session.rollback() logger.error('DB rollback!!!') finally: session.close() # ------------------------------------------------------------------------ def __init__(self, config_files, prefix): self.db_setup() # setup database and check students self.online = dict() # online students self.deps = nx.DiGraph(prefix=prefix) for c in config_files: self.populate_graph(c) self.db_add_missing_topics(self.deps.nodes()) # ------------------------------------------------------------------------ # login # ------------------------------------------------------------------------ async def login(self, uid, try_pw): if uid.startswith('l'): # remove prefix 'l' uid = uid[1:] with self.db_session() as s: try: name, password = s.query(Student.name, Student.password).filter_by(id=uid).one() except: logger.info(f'User "{uid}" does not exist!') return False pw_ok = await check_password(try_pw, password) # async bcrypt if pw_ok: if uid in self.online: logger.warning(f'User "{uid}" already logged in, overwriting state') else: logger.info(f'User "{uid}" logged in successfully') with self.db_session() as s: tt = s.query(StudentTopic).filter_by(student_id=uid) state = {t.topic_id: { 'level': t.level, 'date': datetime.strptime(t.date, "%Y-%m-%d %H:%M:%S.%f") } for t in tt} self.online[uid] = { 'number': uid, 'name': name, 'state': StudentKnowledge(self.deps, state=state), } else: logger.info(f'User "{uid}" wrong password!') return pw_ok # ------------------------------------------------------------------------ # logout # ------------------------------------------------------------------------ def logout(self, uid): del self.online[uid] logger.info(f'User "{uid}" logged out') # ------------------------------------------------------------------------ # change_password. returns True if password is successfully changed. # ------------------------------------------------------------------------ async def change_password(self, uid, pw): if not pw: return False pw = await bcrypt_hash_gen(pw) with self.db_session() as s: u = s.query(Student).get(uid) u.password = pw logger.info(f'User "{uid}" changed password') return True # ------------------------------------------------------------------------ # checks answer (updating student state) and returns grade. # ------------------------------------------------------------------------ async def check_answer(self, uid, answer): knowledge = self.online[uid]['state'] q = await knowledge.check_answer(answer) # also moves to next question logger.info(f'User "{uid}" got {q["grade"]:.2} in question "{q["ref"]}"') topic = knowledge.get_current_topic() # always save grade of answered question with self.db_session() as s: s.add(Answer( ref=q['ref'], grade=q['grade'], starttime=str(q['start_time']), finishtime=str(q['finish_time']), student_id=uid, topic_id=topic)) logger.debug(f'Saved "{q["ref"]}" into database') if knowledge.get_current_question() is None: # finished topic, save into database logger.info(f'User "{uid}" finished "{topic}"') level = knowledge.get_topic_level(topic) date = str(knowledge.get_topic_date(topic)) with self.db_session() as s: a = s.query(StudentTopic).filter_by(student_id=uid, topic_id=topic).one_or_none() if a is None: # insert new studenttopic into database logger.debug('Database insert new studenttopic') t = s.query(Topic).get(topic) u = s.query(Student).get(uid) a = StudentTopic(level=level, date=date, topic=t, student=u) # association object u.topics.append(a) else: # update studenttopic in database logger.debug('Database update studenttopic') a.level = level a.date = date s.add(a) logger.debug(f'Saved topic "{topic}" into database') return 'finished_topic' if q['tries'] > 0 and q['grade'] <= 0.999: return 'wrong' # elif q['tries'] <= 0 and q['grade'] <= 0.999: # return 'max_tries_exceeded' else: return 'new_question' # return q['grade'] # ------------------------------------------------------------------------ # Start new topic # ------------------------------------------------------------------------ async def start_topic(self, uid, topic): student = self.online[uid]['state'] try: await student.init_topic(topic) except KeyError as e: logger.warning(f'User "{uid}" tried to open nonexistent topic: "{topic}"') raise e else: logger.info(f'User "{uid}" started "{topic}"') # ------------------------------------------------------------------------ # Fill db table 'Topic' with topics from the graph if not already there. # ------------------------------------------------------------------------ def db_add_missing_topics(self, topics): with self.db_session() as s: dbtopics = [t[0] for t in s.query(Topic.id)] # get topics from DB missing_topics = [Topic(id=t) for t in topics if t not in dbtopics] if missing_topics: s.add_all(missing_topics) logger.info(f'Added {len(missing_topics)} new topics to the database') # ------------------------------------------------------------------------ # setup and check database # ------------------------------------------------------------------------ def db_setup(self, db='students.db'): logger.info(f'Checking database "{db}":') engine = create_engine(f'sqlite:///{db}', echo=False) self.Session = sessionmaker(bind=engine) try: with self.db_session() as s: n = s.query(Student).count() m = s.query(Topic).count() q = s.query(Answer).count() except Exception as e: logger.critical(f'Database "{db}" not usable!') raise e else: logger.info(f'{n:6} students') logger.info(f'{m:6} topics') logger.info(f'{q:6} answers') # ======================================================================== # methods that do not change state (pure functions) # ======================================================================== # ------------------------------------------------------------------------ def get_student_name(self, uid): return self.online[uid].get('name', '') # ------------------------------------------------------------------------ def get_student_state(self, uid): return self.online[uid]['state'].get_knowledge_state() # ------------------------------------------------------------------------ def get_student_progress(self, uid): return self.online[uid]['state'].get_topic_progress() # ------------------------------------------------------------------------ def get_current_question(self, uid): return self.online[uid]['state'].get_current_question() # dict # ------------------------------------------------------------------------ def get_student_question_type(self, uid): return self.online[uid]['state'].get_current_question()['type'] # ------------------------------------------------------------------------ def get_student_topic(self, uid): return self.online[uid]['state'].get_current_topic() # str # ------------------------------------------------------------------------ def get_title(self): return self.deps.graph.get('title', '') # FIXME # ------------------------------------------------------------------------ def get_topic_name(self, ref): return self.deps.node[ref]['name'] # # ------------------------------------------------------------------------ # def get_topic_type(self, ref): # return self.deps.node[ref]['type'] # ------------------------------------------------------------------------ def get_current_public_dir(self, uid): topic = self.online[uid]['state'].get_current_topic() p = self.deps.graph['prefix'] # FIXME not defined!!! return path.join(p, topic, 'public') # ============================================================================ # Populates a digraph. # # First, topics such as `computer/mips/exceptions` are added as nodes # together with dependencies. Then, questions are loaded to a factory. # # g.graph['path'] base path where topic directories are located # g.graph['title'] title defined in the configuration YAML # g.graph['database'] sqlite3 database file to use # # Nodes are the topic references e.g. 'my/topic' # g.node['my/topic']['name'] name of the topic # g.node['my/topic']['questions'] list of question refs defined in YAML # g.node['my/topic']['factory'] dict with question factories # # Edges are obtained from the deps defined in the YAML file for each topic. # ---------------------------------------------------------------------------- def populate_graph(self, conffile): logger.info(f'Loading {conffile} and populating graph:') g = self.deps # the graph config = load_yaml(conffile) # course configuration # default attributes that apply to the topics default_file = config.get('file', 'questions.yaml') default_shuffle = config.get('shuffle', True) default_choose = config.get('choose', 9999) default_forgetting_factor = config.get('forgetting_factor', 1.0) # iterate over topics and populate graph topics = config.get('topics', {}) tcount = qcount = 0 # topic and question counters for tref, attr in topics.items(): if tref in g: logger.error(f'--> Topic {tref} already exists. Skipped.') continue # add topic to the graph g.add_node(tref) t = g.node[tref] # current topic node topicpath = path.join(g.graph['prefix'], tref) t['type'] = attr.get('type', 'topic') t['name'] = attr.get('name', tref) t['path'] = topicpath # prefix/topic t['file'] = attr.get('file', default_file) # questions.yaml t['shuffle'] = attr.get('shuffle', default_shuffle) t['forgetting_factor'] = attr.get('forgetting_factor', default_forgetting_factor) g.add_edges_from((d,tref) for d in attr.get('deps', [])) # load questions as list of dicts questions = load_yaml(path.join(topicpath, t['file']), default=[]) # if questions are left undefined, include all. # refs undefined in questions.yaml are set to topic:n t['questions'] = attr.get('questions', [q.setdefault('ref', f'{tref}:{i}') for i, q in enumerate(questions)]) # topic will generate a certain amount of questions t['choose'] = min(attr.get('choose', default_choose), len(t['questions'])) # make questions factory (without repeating same question) FIXME move to somewhere else? t['factory'] = {} for q in questions: if q['ref'] in t['questions']: q['path'] = topicpath # fullpath added to each question t['factory'][q['ref']] = QFactory(q) logger.info(f'{len(t["questions"]):6} {tref}') qcount += len(t["questions"]) # count total questions tcount += 1 logger.info(f'Total loaded: {tcount} topics, {qcount} questions')