# 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 = 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.
'''

hint_type = {
    'x_must_be_male': Hint('x_must_be_male'),
    'common_parent_needed': Hint('common_parent_needed'),
    'Y_can_be_of_any_gender': Hint('Y_can_be_of_any_gender'),
    'x_y_must_be_different': Hint('x_y_must_be_different'),
}

test_cases = [
    ('brother(X, _)',
        [{'X': 'alessandro'}, {'X': 'andrew'}, {'X': 'jeffrey'},
         {'X': 'kramer'}, {'X': 'michael'}, {'X': 'william'}]),
    ('brother(andrew, X)',
        [{'X': 'melanie'}]),
]

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.')

        # 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).')
        # TODO this barfs if ans is 'false'
        #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