# encoding: utf-8
"""Pickle related utilities. Perhaps this should be called 'can'."""

# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.

import warnings
warnings.warn("ipykernel.pickleutil is deprecated. It has moved to ipyparallel.", DeprecationWarning)

import copy
import logging
import sys
from types import FunctionType

try:
    import cPickle as pickle
except ImportError:
    import pickle

from ipython_genutils import py3compat
from ipython_genutils.importstring import import_item
from ipython_genutils.py3compat import string_types, iteritems, buffer_to_bytes, buffer_to_bytes_py2

from . import codeutil  # This registers a hook when it's imported

from traitlets.config import Application
from traitlets.log import get_logger

if py3compat.PY3:
    buffer = memoryview
    class_type = type
else:
    from types import ClassType
    class_type = (type, ClassType)

try:
    PICKLE_PROTOCOL = pickle.DEFAULT_PROTOCOL
except AttributeError:
    PICKLE_PROTOCOL = pickle.HIGHEST_PROTOCOL

def _get_cell_type(a=None):
    """the type of a closure cell doesn't seem to be importable,
    so just create one
    """
    def inner():
        return a
    return type(py3compat.get_closure(inner)[0])

cell_type = _get_cell_type()

#-------------------------------------------------------------------------------
# Functions
#-------------------------------------------------------------------------------


def interactive(f):
    """decorator for making functions appear as interactively defined.
    This results in the function being linked to the user_ns as globals()
    instead of the module globals().
    """
    
    # build new FunctionType, so it can have the right globals
    # interactive functions never have closures, that's kind of the point
    if isinstance(f, FunctionType):
        mainmod = __import__('__main__')
        f = FunctionType(f.__code__, mainmod.__dict__,
            f.__name__, f.__defaults__,
        )
    # associate with __main__ for uncanning
    f.__module__ = '__main__'
    return f


def use_dill():
    """use dill to expand serialization support
    
    adds support for object methods and closures to serialization.
    """
    # import dill causes most of the magic
    import dill
    
    # dill doesn't work with cPickle,
    # tell the two relevant modules to use plain pickle
    
    global pickle
    pickle = dill

    try:
        from ipykernel import serialize
    except ImportError:
        pass
    else:
        serialize.pickle = dill
    
    # disable special function handling, let dill take care of it
    can_map.pop(FunctionType, None)

def use_cloudpickle():
    """use cloudpickle to expand serialization support
    
    adds support for object methods and closures to serialization.
    """
    import cloudpickle
    
    global pickle
    pickle = cloudpickle

    try:
        from ipykernel import serialize
    except ImportError:
        pass
    else:
        serialize.pickle = cloudpickle
    
    # disable special function handling, let cloudpickle take care of it
    can_map.pop(FunctionType, None)


#-------------------------------------------------------------------------------
# Classes
#-------------------------------------------------------------------------------


class CannedObject(object):
    def __init__(self, obj, keys=[], hook=None):
        """can an object for safe pickling
        
        Parameters
        ==========
        
        obj:
            The object to be canned
        keys: list (optional)
            list of attribute names that will be explicitly canned / uncanned
        hook: callable (optional)
            An optional extra callable,
            which can do additional processing of the uncanned object.
        
        large data may be offloaded into the buffers list,
        used for zero-copy transfers.
        """
        self.keys = keys
        self.obj = copy.copy(obj)
        self.hook = can(hook)
        for key in keys:
            setattr(self.obj, key, can(getattr(obj, key)))
        
        self.buffers = []

    def get_object(self, g=None):
        if g is None:
            g = {}
        obj = self.obj
        for key in self.keys:
            setattr(obj, key, uncan(getattr(obj, key), g))
        
        if self.hook:
            self.hook = uncan(self.hook, g)
            self.hook(obj, g)
        return self.obj
    

class Reference(CannedObject):
    """object for wrapping a remote reference by name."""
    def __init__(self, name):
        if not isinstance(name, string_types):
            raise TypeError("illegal name: %r"%name)
        self.name = name
        self.buffers = []

    def __repr__(self):
        return "<Reference: %r>"%self.name

    def get_object(self, g=None):
        if g is None:
            g = {}
        
        return eval(self.name, g)


class CannedCell(CannedObject):
    """Can a closure cell"""
    def __init__(self, cell):
        self.cell_contents = can(cell.cell_contents)
    
    def get_object(self, g=None):
        cell_contents = uncan(self.cell_contents, g)
        def inner():
            return cell_contents
        return py3compat.get_closure(inner)[0]


class CannedFunction(CannedObject):

    def __init__(self, f):
        self._check_type(f)
        self.code = f.__code__
        if f.__defaults__:
            self.defaults = [ can(fd) for fd in f.__defaults__ ]
        else:
            self.defaults = None
        
        closure = py3compat.get_closure(f)
        if closure:
            self.closure = tuple( can(cell) for cell in closure )
        else:
            self.closure = None
        
        self.module = f.__module__ or '__main__'
        self.__name__ = f.__name__
        self.buffers = []

    def _check_type(self, obj):
        assert isinstance(obj, FunctionType), "Not a function type"

    def get_object(self, g=None):
        # try to load function back into its module:
        if not self.module.startswith('__'):
            __import__(self.module)
            g = sys.modules[self.module].__dict__

        if g is None:
            g = {}
        if self.defaults:
            defaults = tuple(uncan(cfd, g) for cfd in self.defaults)
        else:
            defaults = None
        if self.closure:
            closure = tuple(uncan(cell, g) for cell in self.closure)
        else:
            closure = None
        newFunc = FunctionType(self.code, g, self.__name__, defaults, closure)
        return newFunc

class CannedClass(CannedObject):

    def __init__(self, cls):
        self._check_type(cls)
        self.name = cls.__name__
        self.old_style = not isinstance(cls, type)
        self._canned_dict = {}
        for k,v in cls.__dict__.items():
            if k not in ('__weakref__', '__dict__'):
                self._canned_dict[k] = can(v)
        if self.old_style:
            mro = []
        else:
            mro = cls.mro()
        
        self.parents = [ can(c) for c in mro[1:] ]
        self.buffers = []

    def _check_type(self, obj):
        assert isinstance(obj, class_type), "Not a class type"

    def get_object(self, g=None):
        parents = tuple(uncan(p, g) for p in self.parents)
        return type(self.name, parents, uncan_dict(self._canned_dict, g=g))

class CannedArray(CannedObject):
    def __init__(self, obj):
        from numpy import ascontiguousarray
        self.shape = obj.shape
        self.dtype = obj.dtype.descr if obj.dtype.fields else obj.dtype.str
        self.pickled = False
        if sum(obj.shape) == 0:
            self.pickled = True
        elif obj.dtype == 'O':
            # can't handle object dtype with buffer approach
            self.pickled = True
        elif obj.dtype.fields and any(dt == 'O' for dt,sz in obj.dtype.fields.values()):
            self.pickled = True
        if self.pickled:
            # just pickle it
            self.buffers = [pickle.dumps(obj, PICKLE_PROTOCOL)]
        else:
            # ensure contiguous
            obj = ascontiguousarray(obj, dtype=None)
            self.buffers = [buffer(obj)]
    
    def get_object(self, g=None):
        from numpy import frombuffer
        data = self.buffers[0]
        if self.pickled:
            # we just pickled it
            return pickle.loads(buffer_to_bytes_py2(data))
        else:
            if not py3compat.PY3 and isinstance(data, memoryview):
                # frombuffer doesn't accept memoryviews on Python 2,
                # so cast to old-style buffer
                data = buffer(data.tobytes())
            return frombuffer(data, dtype=self.dtype).reshape(self.shape)


class CannedBytes(CannedObject):
    wrap = staticmethod(buffer_to_bytes)

    def __init__(self, obj):
        self.buffers = [obj]
    
    def get_object(self, g=None):
        data = self.buffers[0]
        return self.wrap(data)

class CannedBuffer(CannedBytes):
    wrap = buffer

class CannedMemoryView(CannedBytes):
    wrap = memoryview

#-------------------------------------------------------------------------------
# Functions
#-------------------------------------------------------------------------------

def _import_mapping(mapping, original=None):
    """import any string-keys in a type mapping
    
    """
    log = get_logger()
    log.debug("Importing canning map")
    for key,value in list(mapping.items()):
        if isinstance(key, string_types):
            try:
                cls = import_item(key)
            except Exception:
                if original and key not in original:
                    # only message on user-added classes
                    log.error("canning class not importable: %r", key, exc_info=True)
                mapping.pop(key)
            else:
                mapping[cls] = mapping.pop(key)

def istype(obj, check):
    """like isinstance(obj, check), but strict
    
    This won't catch subclasses.
    """
    if isinstance(check, tuple):
        for cls in check:
            if type(obj) is cls:
                return True
        return False
    else:
        return type(obj) is check

def can(obj):
    """prepare an object for pickling"""
    
    import_needed = False
    
    for cls,canner in iteritems(can_map):
        if isinstance(cls, string_types):
            import_needed = True
            break
        elif istype(obj, cls):
            return canner(obj)
    
    if import_needed:
        # perform can_map imports, then try again
        # this will usually only happen once
        _import_mapping(can_map, _original_can_map)
        return can(obj)
    
    return obj

def can_class(obj):
    if isinstance(obj, class_type) and obj.__module__ == '__main__':
        return CannedClass(obj)
    else:
        return obj

def can_dict(obj):
    """can the *values* of a dict"""
    if istype(obj, dict):
        newobj = {}
        for k, v in iteritems(obj):
            newobj[k] = can(v)
        return newobj
    else:
        return obj

sequence_types = (list, tuple, set)

def can_sequence(obj):
    """can the elements of a sequence"""
    if istype(obj, sequence_types):
        t = type(obj)
        return t([can(i) for i in obj])
    else:
        return obj

def uncan(obj, g=None):
    """invert canning"""
    
    import_needed = False
    for cls,uncanner in iteritems(uncan_map):
        if isinstance(cls, string_types):
            import_needed = True
            break
        elif isinstance(obj, cls):
            return uncanner(obj, g)
    
    if import_needed:
        # perform uncan_map imports, then try again
        # this will usually only happen once
        _import_mapping(uncan_map, _original_uncan_map)
        return uncan(obj, g)
    
    return obj

def uncan_dict(obj, g=None):
    if istype(obj, dict):
        newobj = {}
        for k, v in iteritems(obj):
            newobj[k] = uncan(v,g)
        return newobj
    else:
        return obj

def uncan_sequence(obj, g=None):
    if istype(obj, sequence_types):
        t = type(obj)
        return t([uncan(i,g) for i in obj])
    else:
        return obj

#-------------------------------------------------------------------------------
# API dictionaries
#-------------------------------------------------------------------------------

# These dicts can be extended for custom serialization of new objects

can_map = {
    'numpy.ndarray' : CannedArray,
    FunctionType : CannedFunction,
    bytes : CannedBytes,
    memoryview : CannedMemoryView,
    cell_type : CannedCell,
    class_type : can_class,
}
if buffer is not memoryview:
    can_map[buffer] = CannedBuffer

uncan_map = {
    CannedObject : lambda obj, g: obj.get_object(g),
    dict : uncan_dict,
}

# for use in _import_mapping:
_original_can_map = can_map.copy()
_original_uncan_map = uncan_map.copy()
