# 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 = 101
group = 'family_relations'
number = 8
visible = True
facts = 'family_relations'

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

hint_type = {
    'gender_is_irrelevant': Hint('gender_is_irrelevant'),
    'grandparent_used': Hint('grandparent_used'),
    'base_case': Hint('base_case'),
    'descendant_of_oneself': Hint('ancestor_to_oneself'),
    'descendant_need_not_be_parent': Hint('descendant_need_not_be_parent'),
    'wrong_direction': Hint('wrong_direction'),
}

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}]

        # grandparent is a sign of complications
        # it's likely used instead of recursion
        targets = [prolog.util.Token('NAME', 'grandparent')]
        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': 'grandparent_used', 'highlight': pos}]

        # missing/failed base case
        # TODO: how will ask_truth handle/return timeouts...
        # TODO: timeout is the same as fail in this particular case
        if prolog.engine.ask_truth(engine_id,
            'parent(Y, X), \+ descendant(X, Y)'):
            return [{'id', 'base_case'}]

        # descendant of oneself
        if prolog.engine.ask_truth(engine_id, 'descendant(X, X)'):
            return [{'id', 'descendant_of_oneself'}]

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

        # ancestor instead of descendant (wrong direction)
        # warning: knowledge base dependent
        if prolog.engine.ask_truth(engine_id,
            'findall(_, descendant(william, X), L1), length(L1, 6), \
             findall(_, descendant(X, william), L2), length(L2, 2)'):
            return [{'id', 'wrong_direction'}]

    except socket.timeout as ex:
        pass

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

    return None