# coding=utf-8

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

id = 95
group = 'family_relations'
number = 30
visible = True
facts = 'family_relations'

solution = '''\
grandparent(X, Y) :-
  parent(X, Z),
  parent(Z, Y).
'''

hint_type = {
    'no_common_z': Hint('no_common_z'),
    'gender_is_irrelevant': Hint('gender_is_irrelevant'),
    'or_instead_of_and': Hint('or_instead_of_and'),
    'x_must_be_parent': Hint('x_must_be_parent'),
    'x_need_not_have_parent': Hint('x_need_not_have_parent'),
    'y_must_have_parent': Hint('y_must_have_parent'),
    '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.')

        # TODO: generic hint for:
        # TODO: parent(X, Z1), parent(Z2, Y), Z1 = Z2

        # broken "link" mistake -- no common parent/child Z
        # warning: due to speed considerations this (1024) is knowledge base dependent
        # independent: findall(_, (parent(X, Z1), parent(Z2, Y)), L)
        if prolog.engine.ask_truth(engine_id,
            'findall(_, grandparent(X, Y), L), length(L, 1024)'):
            return [{'id': 'no_common_z'}]

        # gender testing is redundant
        # this is not necessarily wrong, but worth mentioning anyway
        targets = [prolog.util.Token('NAME', 'male'), prolog.util.Token('NAME', 'female')]
        pos = [(t.pos, t.pos + len(t.val)) for t in tokens if t in targets]
        if pos:
            # TODO: resolve how highlighting info is communicated
            return [{'id': 'gender_is_irrelevant', 'highlight': pos}]

        # 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
        # warning: due to speed considerations this (64) is knowledge base dependent
        if prolog.util.Token('SEMI', ';') in tokens and prolog.engine.ask_truth(engine_id,
            'findall(_, grandparent(X, Y), L), length(L, 64)'):
            return [{'id': 'or_instead_of_and'}]

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

        # X does not necessarily need to have a parent
        if prolog.engine.ask_one(engine_id,
            'grandparent(X, _), \+ parent(_, X)') == 'false':
            return [{'id': 'x_need_not_have_parent'}]

        # Y must have a parent
        if prolog.engine.ask_truth(engine_id,
            'grandparent(_, Y), \+ parent(_, Y)'):
            return [{'id': 'y_must_have_parent'}]

        # Y does not necessarily need to be a parent
        if prolog.engine.ask_one(engine_id,
            'grandparent(_, 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