# 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 = 99
group = 'family_relations'
number = 6
visible = True
facts = 'family_relations'

solution = '''\
sister99(X, Y) :-
  parent(P, X),
  parent(P, Y),
  female(X),
  X \== Y.

brother99(X, Y) :-
  parent(P, X),
  parent(P, Y),
  male(X),
  X \== Y.

cousin(X, Y) :-
  parent(PX, X),
  parent(PY, Y),
  ( brother99(PX, PY)
    ;
    sister99(PX, PY) ).
'''

hint_type = {
    'gender_is_irrelevant': Hint('gender_is_irrelevant'),
    'precedence_fail': Hint('precedence_fail'),
    'cousin_vs_sibling': Hint('cousin_vs_sibling'),
    'cousin_to_oneself': Hint('cousin_to_oneself'),
    'cousin_need_not_be_parent': Hint('cousin_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.')

        # 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}]

        # precedence fail (AND block vs OR block)
        # case in point: parent(PX, X), parent(PY, Y), brother(PX, PY) ; sister(PX, PY)
        #  or this case: parent(PX, X), parent(PY, Y), sister(PX, PY) ; brother(PX, PY)
        # warning: knowledge base dependent
        if prolog.util.Token('SEMI', ';') in tokens and prolog.engine.ask_truth(engine_id,
            'findall(_, cousin(X, Y), L), (length(L, 14) ; length(L, 16))'):
            return [{'id', 'precedence_fail'}]

        # cousin should not be brother or sister
        # common parent, probably solved via grandparent
        if prolog.engine.ask_truth(engine_id,
            'cousin(X, Y), (brother(X, Y) ; sister(X, Y))'):
            return [{'id', 'cousin_vs_sibling'}]

        # cousin to him/herself
        # just common grandparent is not enough
        if prolog.engine.ask_truth(engine_id, 'cousin(X, X)'):
            return [{'id', 'cousin_to_oneself'}]


        # X (or Y) does not necessarily need to be a parent
        # cousin is a symmetrical relation, so X and Y are covered by this
        if prolog.engine.ask_one(engine_id,
            'cousin(X, _), \+ parent(X, _)') == 'false':
            return [{'id': 'cousin_need_not_be_parent'}]

    except socket.timeout as ex:
        pass

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

    return None