# coding=utf-8

id = 97
group = 'family_relations'
number = 4
visible = True
facts = 'family_relations'

solution = '''\
brother(X, Y) :-
  parent(P, X),
  parent(P, Y),
  male(X),
  X \== Y.
'''

import prolog.engine
import prolog.util
import server.problems
import socket

def test(session, program):
    # TODO: change queries and answers (these are for sister/2)
    # Test queries and expected answers (values of X).
    queries = [
        ('sister(melanie, X)', set(['andrew'])),
        ('sister(X, andrew)', set(['melanie'])),
        ('sister(X, _)', set(['michelle', 'daniela', 'patricia', 'luana', 'sally', 'melanie', 'nevia', 'vanessa', 'anna'])),
    ]

    code = program + '\n' + server.problems.load_facts('prolog', facts).facts

    engine_id = None
    try:
        engine_id, output = prolog.engine.create(code=code, timeout=1.0)
        if not engine_id:
            return 0, len(queries)

        n_correct = 0
        for query, solution in queries:
            answers, error = prolog.engine.ask_all(engine_id, query=query, timeout=1.0)
            if answers and answers[-1] != 'timed out':
                values_x = set([ans.get('X') for ans, constraints in answers])
                if values_x == solution:
                    n_correct += 1
    finally:
        if engine_id:
            prolog.engine.destroy(engine_id)

    return n_correct, len(queries)

def general_hint():
    pass

def hint(session, program):
    # tokens = prolog.util.tokenize(program)

    code = program + '\n' + server.problems.load_facts('prolog', facts).facts
    engine_id = None
    try:
        engine_id, output = prolog.engine.create(code=code, timeout=1.0)
        if not engine_id:
            raise Exception('Prolog engine failed to create.')

        # X must be male
        if prolog.engine.ask_truth(engine_id, 'female(X), brother(X, _)'):
            return [{'id': 'x_must_be_male'}]

        # X and Y must have a common parent
        if prolog.engine.ask_truth(engine_id,
            'brother(X, Y), \+ (parent(P, X), parent(P, Y))'):
            return [{'id': 'common_parent_needed'}]

        # Y can be of any gender, incl. female
        if prolog.engine.ask_one(engine_id,
            'brother(_, Y), female(Y)') == 'false':
            return [{'id': 'Y_can_be_of_any_gender'}]

        # X and Y must be different
        ans = prolog.engine.ask_one(engine_id,
            'setof(X, (member(X, [william, alessandro, andrew]), brother(X, X)), L), length(L, N).')
        if ans.get('N') == '3':
            return [{'id': 'x_y_must_be_different'}]

    except socket.timeout as ex:
        pass

    finally:
        if engine_id:
            prolog.engine.destroy(engine_id)

    return None