# coding=utf-8

from operator import itemgetter
import socket
import prolog.engine
import prolog.util
from server.hints import Hint, HintSequence
import server.problems

id = 181
group = 'family_relations'
number = 2
visible = True
facts = 'family_relations'

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

hint_type = {
    'or_instead_of_and': Hint('or_instead_of_and'),
    'x_must_be_male': Hint('x_must_be_male'),
    'x_must_be_parent': Hint('x_must_be_parent'),
    'y_can_be_of_any_gender': Hint('y_can_be_of_any_gender'),
    'y_need_not_be_parent': Hint('y_need_not_be_parent'),
}

test_cases = [
    # TODO
]

def test(program, solved_problems):
    code = (program + '\n' +
            server.problems.solutions_for_problems('prolog', solved_problems) + '\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 or 'error' in map(itemgetter(0), output):
            # Engine creation failed, or syntax error in code.
            return 0, len(test_cases)

        n_correct = 0
        for query, answers in test_cases:
            # Limit inferences for each solution to curb unbounded recursion.
            limited = 'call_with_inference_limit(({}), 100000, _)'.format(query)
            if prolog.engine.check_answers(engine_id, query=limited, answers=answers, timeout=1.0):
                n_correct += 1
    finally:
        if engine_id:
            prolog.engine.destroy(engine_id)

    passed = n_correct == len(test_cases)
    hints = [{'id': 'test_results', 'args': {'passed': n_correct, 'total': len(test_cases)}}]
    return passed, hints

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

    code = (program + '\n' +
            server.problems.solutions_for_problems('prolog', solved_problems) + '\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.')

        # OR (;) instead of AND (,)
        # this hint has to be before the next two
        # as otherwise those two would always override it
        # and not convey the same (amount of) help/information
        if prolog.util.Token('SEMI', ';') in tokens and prolog.engine.ask_truth(engine_id,
            'findall(_, father(X, Y), L1), length(L1, N), \
             findall(_, (parent(X, Y) ; male(X)), L2), length(L2, N)'):
            return [{'id': 'or_instead_of_and'}]

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

        # X must be a parent
        if prolog.engine.ask_truth(engine_id,
            'father(X, _), \+ parent(X, _)'):
            return [{'id': 'x_must_be_parent'}]

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

        # Y does not necessarily need to be a parent
        if prolog.engine.ask_one(engine_id,
            'father(_, Y), \+ parent(Y, _)') == 'false':
            return [{'id': 'y_need_not_be_parent'}]

    except socket.timeout as ex:
        pass

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

    return None