import gc, types, weakref

from cubicweb.schema import CubicWebRelationSchema, CubicWebEntitySchema

listiterator = type(iter([]))

IGNORE_CLASSES = (

    type, tuple, dict, list, set, frozenset, type(len),

    weakref.ref, weakref.WeakKeyDictionary,

    listiterator,

    property, classmethod,

    types.ModuleType, types.FunctionType, types.MethodType,

    types.MemberDescriptorType, types.GetSetDescriptorType,

    )

def _get_counted_class(obj, classes):

    for cls in classes:

        if isinstance(obj, cls):

            return cls

    raise AssertionError()

def gc_info(countclasses,

            ignoreclasses=IGNORE_CLASSES,

            viewreferrersclasses=(), showobjs=False):

    gc.collect()

    gc.collect()

    counters = {}

    ocounters = {}

    for obj in gc.get_objects():

        if isinstance(obj, countclasses):

            cls = _get_counted_class(obj, countclasses)

            try:

                counters[cls.__name__] += 1

            except KeyError:

                counters[cls.__name__] = 1

        elif not isinstance(obj, ignoreclasses):

            try:

                key = '%s.%s' % (obj.__class__.__module__,

                                 obj.__class__.__name__)

            except AttributeError:

                key = str(obj)

            try:

                ocounters[key] += 1

            except KeyError:

                ocounters[key] = 1

        if isinstance(obj, viewreferrersclasses):

            print '   ', obj, referrers(obj, showobjs)

    return counters, ocounters, gc.garbage

def referrers(obj, showobj=False, maxlevel=1):

    objreferrers = _referrers(obj, maxlevel)

    try:

        return sorted(set((type(x), showobj and x or getattr(x, '__name__', '%#x' % id(x)))

                          for x in objreferrers))

    except TypeError:

        s = set()

        unhashable = []

        for x in objreferrers:

            try:

                s.add(x)

            except TypeError:

                unhashable.append(x)

        return sorted(s) + unhashable

def _referrers(obj, maxlevel, _seen=None, _level=0):

    interesting = []

    if _seen is None:

        _seen = set()

    for x in gc.get_referrers(obj):

        if id(x) in _seen:

            continue

        _seen.add(id(x))

        if isinstance(x, types.FrameType):

            continue

        if isinstance(x, (CubicWebRelationSchema, CubicWebEntitySchema)):

            continue

        if isinstance(x, (list, tuple, set, dict, listiterator)):

            if _level >= maxlevel:

                pass

                #interesting.append(x)

            else:

                interesting += _referrers(x, maxlevel, _seen, _level+1)

        else:

            interesting.append(x)

    return interesting