from operator import itemgetter
import socket

import prolog.engine
import prolog.util
from server.hints import Hint, HintPopup

id = 104
number = 5
visible = True
facts = None

solution = '''\
conc([], L, L).
conc([H|T], L2, [H|L]) :-
  conc(T, L2, L).
'''

hint_type = {
    'eq_instead_of_equ_markup': HintPopup('eq_instead_of_equ_markup'),
    'eq_instead_of_equ': Hint('eq_instead_of_equ'),
    'predicate_always_false': Hint('predicate_always_false'),
    'base_case': Hint('base_case'),
    'timeout': Hint('timeout'),
    'final_hint': Hint('final_hint'),
    'second_list_iteration': Hint('second_list_iteration'),
    'forcing_result_onto_recursion': Hint('forcing_result_onto_recursion'),
    'two_heads_markup': HintPopup('two_heads_markup'),
    'two_heads': Hint('two_heads'),
    'insertion_into_second_list': Hint('insertion_into_second_list'),
    'base_case_arbitrary': Hint('base_case_arbitrary'),
}

test_cases = [
    ('conc([j, b], [l], X)',
        [{'X': '[j, b, l]'}]),
    ('conc([a, r, u, e], [c, f], X)',
        [{'X': '[a, r, u, e, c, f]'}]),
    ('conc([a, r, u], [c, f], X)',
        [{'X': '[a, r, u, c, f]'}]),
    ('conc(X, [], [g, r])',
        [{'X': '[g, r]'}]),
    ('conc([], [], [])',
        [{}]),
]

def test(code, aux_code):
    n_correct = 0
    engine_id = None
    try:
        engine_id, output = prolog.engine.create(code=code+aux_code, timeout=1.0)
        if engine_id is not None and 'error' not in map(itemgetter(0), output):
            # Engine successfully created, and no syntax error in program.
            for query, answers in test_cases:
                if prolog.engine.check_answers(engine_id, query=query, answers=answers, timeout=1.0):
                    n_correct += 1
    except socket.timeout:
        pass
    finally:
        if engine_id:
            prolog.engine.destroy(engine_id)

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

def hint(code, aux_code):
    tokens = prolog.util.tokenize(code)

    try:
        engine_id, output = prolog.engine.create(code=code+aux_code, timeout=1.0)

        # strict equality testing instead of simple matching
        # this is usually (but not necessarily) wrong
        targets = [prolog.util.Token('EQ', '==')]
        marks = [(t.pos, t.pos + len(t.val)) for t in tokens if t in targets]
        if marks:
            return [{'id': 'eq_instead_of_equ_markup', 'start': m[0], 'end': m[1]} for m in marks] + \
                   [{'id': 'eq_instead_of_equ'}]

        # recursion is getting bigger and bigger


        # base case succeeds with arbitrary result
        if prolog.engine.ask_truthTO(engine_id, 'conc([], [a,b,c], L), var(L)'):
            return [{'id': 'base_case_arbitrary'}]

        # shortening the second list instead of first list
        if prolog.engine.ask_truthTO(engine_id,
           'conc([a,b,c], [1,2,3,4], L), (L = [1,2,3,4,a,b,c] ; L = [4,3,2,1,a,b,c])'):
            return [{'id': 'second_list_iteration'}]

        # inserting first list's head into the second list in recursive call: conc(T, [H\L2], L)
        if prolog.engine.ask_truthTO(engine_id,
           'conc([a,b,c,d,e], [1,2,3,4], [e,d,c,b,a,1,2,3,4])'):
            return [{'id': 'insertion_into_second_list'}]

        # forcing result onto recursion; case of conc(T, L2, [H|L])
        if not prolog.engine.ask_truthTO(engine_id, 'conc([a,b,c,d,e], _, _)') and \
           prolog.engine.ask_truthTO(engine_id,
           'asserta( conc([b,c],[1,2],[yowza,b,c,1,2]) ), conc([yowza,b,c],[1,2],L), retract( conc([b,c],[1,2],[yowza,b,c,1,2]) )'):
            return [{'id': 'forcing_result_onto_recursion'}]

        # using two heads indicating that the user wants heads from both lists
        # TODO: Tim, it would be nice/safer to catch this just for a single clause, not whole code.
        if prolog.util.Token('NAME', 'H1') in tokens and \
           (prolog.util.Token('NAME', 'H') in tokens or prolog.util.Token('NAME', 'H2') in tokens):
            targets = [prolog.util.Token('NAME', 'H1'), prolog.util.Token('NAME', 'H2')]
            marks = [(t.pos, t.pos + len(t.val)) for t in tokens if t in targets]
            if marks:
                return [{'id': 'two_heads_markup', 'start': m[0], 'end': m[1]} for m in marks] + \
                       [{'id': 'two_heads'}]

        # missing/failed base case
        if not prolog.engine.ask_one(engine_id, 'conc([], [qa,qb,qc], [qa,qb,qc])'):
            return [{'id': 'base_case'}]

        # target predicate seems to always be false
        if not prolog.engine.ask_truth(engine_id, 'conc([_,_,_,_,_,_], [_,_,_], _)'):
            return [{'id': 'predicate_always_false'}]

    except socket.timeout as ex:
        return [{'id': 'timeout'}]

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

    return []