"""
New, fast version of the CloudPickler.

This new CloudPickler class can now extend the fast C Pickler instead of the
previous Python implementation of the Pickler class. Because this functionality
is only available for Python versions 3.8+, a lot of backward-compatibility
code is also removed.

Note that the C Pickler sublassing API is CPython-specific. Therefore, some
guards present in cloudpickle.py that were written to handle PyPy specificities
are not present in cloudpickle_fast.py
"""
import abc
import copyreg
import io
import itertools
import logging
import _pickle
import pickle
import sys
import types
import weakref

from _pickle import Pickler

from .cloudpickle import (
    _is_dynamic, _extract_code_globals, _BUILTIN_TYPE_NAMES, DEFAULT_PROTOCOL,
    _find_imported_submodules, _get_cell_contents, _is_global, _builtin_type,
    Enum, _ensure_tracking,  _make_skeleton_class, _make_skeleton_enum,
    _extract_class_dict, string_types, dynamic_subimport, subimport
)

load, loads = _pickle.load, _pickle.loads


# Shorthands similar to pickle.dump/pickle.dumps
def dump(obj, file, protocol=None):
    """Serialize obj as bytes streamed into file

    protocol defaults to cloudpickle.DEFAULT_PROTOCOL which is an alias to
    pickle.HIGHEST_PROTOCOL. This setting favors maximum communication speed
    between processes running the same Python version.

    Set protocol=pickle.DEFAULT_PROTOCOL instead if you need to ensure
    compatibility with older versions of Python.
    """
    CloudPickler(file, protocol=protocol).dump(obj)


def dumps(obj, protocol=None):
    """Serialize obj as a string of bytes allocated in memory

    protocol defaults to cloudpickle.DEFAULT_PROTOCOL which is an alias to
    pickle.HIGHEST_PROTOCOL. This setting favors maximum communication speed
    between processes running the same Python version.

    Set protocol=pickle.DEFAULT_PROTOCOL instead if you need to ensure
    compatibility with older versions of Python.
    """
    with io.BytesIO() as file:
        cp = CloudPickler(file, protocol=protocol)
        cp.dump(obj)
        return file.getvalue()


# COLLECTION OF OBJECTS __getnewargs__-LIKE METHODS
# -------------------------------------------------

def _class_getnewargs(obj):
    type_kwargs = {}
    if hasattr(obj, "__slots__"):
        type_kwargs["__slots__"] = obj.__slots__

    __dict__ = obj.__dict__.get('__dict__', None)
    if isinstance(__dict__, property):
        type_kwargs['__dict__'] = __dict__

    return (type(obj), obj.__name__, obj.__bases__, type_kwargs,
            _ensure_tracking(obj), None)


def _enum_getnewargs(obj):
    members = dict((e.name, e.value) for e in obj)
    return (obj.__bases__, obj.__name__, obj.__qualname__, members,
            obj.__module__, _ensure_tracking(obj), None)


# COLLECTION OF OBJECTS RECONSTRUCTORS
# ------------------------------------
def _file_reconstructor(retval):
    return retval


# COLLECTION OF OBJECTS STATE GETTERS
# -----------------------------------
def _function_getstate(func):
    # - Put func's dynamic attributes (stored in func.__dict__) in state. These
    #   attributes will be restored at unpickling time using
    #   f.__dict__.update(state)
    # - Put func's members into slotstate. Such attributes will be restored at
    #   unpickling time by iterating over slotstate and calling setattr(func,
    #   slotname, slotvalue)
    slotstate = {
        "__name__": func.__name__,
        "__qualname__": func.__qualname__,
        "__annotations__": func.__annotations__,
        "__kwdefaults__": func.__kwdefaults__,
        "__defaults__": func.__defaults__,
        "__module__": func.__module__,
        "__doc__": func.__doc__,
        "__closure__": func.__closure__,
    }

    f_globals_ref = _extract_code_globals(func.__code__)
    f_globals = {k: func.__globals__[k] for k in f_globals_ref if k in
                 func.__globals__}

    closure_values = (
        list(map(_get_cell_contents, func.__closure__))
        if func.__closure__ is not None else ()
    )

    # Extract currently-imported submodules used by func. Storing these modules
    # in a smoke _cloudpickle_subimports attribute of the object's state will
    # trigger the side effect of importing these modules at unpickling time
    # (which is necessary for func to work correctly once depickled)
    slotstate["_cloudpickle_submodules"] = _find_imported_submodules(
        func.__code__, itertools.chain(f_globals.values(), closure_values))
    slotstate["__globals__"] = f_globals

    state = func.__dict__
    return state, slotstate


def _class_getstate(obj):
    clsdict = _extract_class_dict(obj)
    clsdict.pop('__weakref__', None)

    # For ABCMeta in python3.7+, remove _abc_impl as it is not picklable.
    # This is a fix which breaks the cache but this only makes the first
    # calls to issubclass slower.
    if "_abc_impl" in clsdict:
        (registry, _, _, _) = abc._get_dump(obj)
        clsdict["_abc_impl"] = [subclass_weakref()
                                for subclass_weakref in registry]
    if hasattr(obj, "__slots__"):
        # pickle string length optimization: member descriptors of obj are
        # created automatically from obj's __slots__ attribute, no need to
        # save them in obj's state
        if isinstance(obj.__slots__, string_types):
            clsdict.pop(obj.__slots__)
        else:
            for k in obj.__slots__:
                clsdict.pop(k, None)

    clsdict.pop('__dict__', None)  # unpicklable property object

    return (clsdict, {})


def _enum_getstate(obj):
    clsdict, slotstate = _class_getstate(obj)

    members = dict((e.name, e.value) for e in obj)
    # Cleanup the clsdict that will be passed to _rehydrate_skeleton_class:
    # Those attributes are already handled by the metaclass.
    for attrname in ["_generate_next_value_", "_member_names_",
                     "_member_map_", "_member_type_",
                     "_value2member_map_"]:
        clsdict.pop(attrname, None)
    for member in members:
        clsdict.pop(member)
        # Special handling of Enum subclasses
    return clsdict, slotstate


# COLLECTIONS OF OBJECTS REDUCERS
# -------------------------------
# A reducer is a function taking a single argument (obj), and that returns a
# tuple with all the necessary data to re-construct obj. Apart from a few
# exceptions (list, dict, bytes, int, etc.), a reducer is necessary to
# correctly pickle an object.
# While many built-in objects (Exceptions objects, instances of the "object"
# class, etc), are shipped with their own built-in reducer (invoked using
# obj.__reduce__), some do not. The following methods were created to "fill
# these holes".

def _code_reduce(obj):
    """codeobject reducer"""
    args = (
        obj.co_argcount, obj.co_posonlyargcount,
        obj.co_kwonlyargcount, obj.co_nlocals, obj.co_stacksize,
        obj.co_flags, obj.co_code, obj.co_consts, obj.co_names,
        obj.co_varnames, obj.co_filename, obj.co_name,
        obj.co_firstlineno, obj.co_lnotab, obj.co_freevars,
        obj.co_cellvars
    )
    return types.CodeType, args


def _cell_reduce(obj):
    """Cell (containing values of a function's free variables) reducer"""
    try:
        obj.cell_contents
    except ValueError:  # cell is empty
        return types.CellType, ()
    else:
        return types.CellType, (obj.cell_contents,)


def _classmethod_reduce(obj):
    orig_func = obj.__func__
    return type(obj), (orig_func,)


def _file_reduce(obj):
    """Save a file"""
    import io

    if not hasattr(obj, "name") or not hasattr(obj, "mode"):
        raise pickle.PicklingError(
            "Cannot pickle files that do not map to an actual file"
        )
    if obj is sys.stdout:
        return getattr, (sys, "stdout")
    if obj is sys.stderr:
        return getattr, (sys, "stderr")
    if obj is sys.stdin:
        raise pickle.PicklingError("Cannot pickle standard input")
    if obj.closed:
        raise pickle.PicklingError("Cannot pickle closed files")
    if hasattr(obj, "isatty") and obj.isatty():
        raise pickle.PicklingError(
            "Cannot pickle files that map to tty objects"
        )
    if "r" not in obj.mode and "+" not in obj.mode:
        raise pickle.PicklingError(
            "Cannot pickle files that are not opened for reading: %s"
            % obj.mode
        )

    name = obj.name

    retval = io.StringIO()

    try:
        # Read the whole file
        curloc = obj.tell()
        obj.seek(0)
        contents = obj.read()
        obj.seek(curloc)
    except IOError:
        raise pickle.PicklingError(
            "Cannot pickle file %s as it cannot be read" % name
        )
    retval.write(contents)
    retval.seek(curloc)

    retval.name = name
    return _file_reconstructor, (retval,)


def _getset_descriptor_reduce(obj):
    return getattr, (obj.__objclass__, obj.__name__)


def _mappingproxy_reduce(obj):
    return types.MappingProxyType, (dict(obj),)


def _memoryview_reduce(obj):
    return bytes, (obj.tobytes(),)


def _module_reduce(obj):
    if _is_dynamic(obj):
        return dynamic_subimport, (obj.__name__, vars(obj))
    else:
        return subimport, (obj.__name__,)


def _method_reduce(obj):
    return (types.MethodType, (obj.__func__, obj.__self__))


def _logger_reduce(obj):
    return logging.getLogger, (obj.name,)


def _root_logger_reduce(obj):
    return logging.getLogger, ()


def _weakset_reduce(obj):
    return weakref.WeakSet, (list(obj),)


def _dynamic_class_reduce(obj):
    """
    Save a class that can't be stored as module global.

    This method is used to serialize classes that are defined inside
    functions, or that otherwise can't be serialized as attribute lookups
    from global modules.
    """
    if Enum is not None and issubclass(obj, Enum):
        return (
            _make_skeleton_enum, _enum_getnewargs(obj), _enum_getstate(obj),
            None, None, _class_setstate
        )
    else:
        return (
            _make_skeleton_class, _class_getnewargs(obj), _class_getstate(obj),
            None, None, _class_setstate
        )


def _class_reduce(obj):
    """Select the reducer depending on the dynamic nature of the class obj"""
    if obj is type(None):  # noqa
        return type, (None,)
    elif obj is type(Ellipsis):
        return type, (Ellipsis,)
    elif obj is type(NotImplemented):
        return type, (NotImplemented,)
    elif obj in _BUILTIN_TYPE_NAMES:
        return _builtin_type, (_BUILTIN_TYPE_NAMES[obj],)
    elif not _is_global(obj):
        return _dynamic_class_reduce(obj)
    return NotImplemented


# COLLECTIONS OF OBJECTS STATE SETTERS
# ------------------------------------
# state setters are called at unpickling time, once the object is created and
# it has to be updated to how it was at unpickling time.


def _function_setstate(obj, state):
    """Update the state of a dynaamic function.

    As __closure__ and __globals__ are readonly attributes of a function, we
    cannot rely on the native setstate routine of pickle.load_build, that calls
    setattr on items of the slotstate. Instead, we have to modify them inplace.
    """