# copyright 2003-2016 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr

#

# This file is part of CubicWeb.

#

# CubicWeb is free software: you can redistribute it and/or modify it under the

# terms of the GNU Lesser General Public License as published by the Free

# Software Foundation, either version 2.1 of the License, or (at your option)

# any later version.

#

# CubicWeb is distributed in the hope that it will be useful, but WITHOUT

# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more

# details.

#

# You should have received a copy of the GNU Lesser General Public License along

# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.

"""CubicWeb is a generic framework to quickly build applications which describes

relations between entitites.

"""

import imp

import logging

import os

import pickle

import sys

import types

import warnings

import zlib

from six import PY2, binary_type, text_type

from logilab.common.logging_ext import set_log_methods

from yams.constraints import BASE_CONVERTERS, BASE_CHECKERS

from yams.schema import role_name as rname

from cubicweb.__pkginfo__ import version as __version__   # noqa

# make all exceptions accessible from the package

from logilab.common.registry import ObjectNotFound, NoSelectableObject, RegistryNotFound  # noqa

from yams import ValidationError

from cubicweb._exceptions import *  # noqa

if PY2:

    # http://bugs.python.org/issue10211

    from StringIO import StringIO as BytesIO

else:

    from io import BytesIO

# ignore the pygments UserWarnings

warnings.filterwarnings('ignore', category=UserWarning,

                        message='.*was already imported',

                        module='.*pygments')

# pre python 2.7.2 safety

logging.basicConfig()

set_log_methods(sys.modules[__name__], logging.getLogger('cubicweb'))

# this is necessary for i18n devtools test where chdir is done while __path__ is relative, which

# breaks later imports

__path__[0] = os.path.abspath(__path__[0])  # noqa

CW_SOFTWARE_ROOT = __path__[0]  # noqa

# '_' is available to mark internationalized string but should not be used to

# do the actual translation

_ = text_type

class Binary(BytesIO):

    """class to hold binary data. Use BytesIO to prevent use of unicode data"""

    _allowed_types = (binary_type, bytearray, buffer if PY2 else memoryview)  # noqa: F405

    def __init__(self, buf=b''):

        assert isinstance(buf, self._allowed_types), \

            "Binary objects must use bytes/buffer objects, not %s" % buf.__class__

        # don't call super, BytesIO may be an old-style class (on python < 2.7.4)

        BytesIO.__init__(self, buf)

    def write(self, data):

        assert isinstance(data, self._allowed_types), \

            "Binary objects must use bytes/buffer objects, not %s" % data.__class__

        # don't call super, BytesIO may be an old-style class (on python < 2.7.4)

        BytesIO.write(self, data)

    def to_file(self, fobj):

        """write a binary to disk

        the writing is performed in a safe way for files stored on

        Windows SMB shares

        """

        pos = self.tell()

        self.seek(0)

        if sys.platform == 'win32':

            while True:

                # the 16kB chunksize comes from the shutil module

                # in stdlib

                chunk = self.read(16 * 1024)

                if not chunk:

                    break

                fobj.write(chunk)

        else:

            fobj.write(self.read())

        self.seek(pos)

    @staticmethod

    def from_file(filename):

        """read a file and returns its contents in a Binary

        the reading is performed in a safe way for files stored on

        Windows SMB shares

        """

        binary = Binary()

        with open(filename, 'rb') as fobj:

            if sys.platform == 'win32':

                while True:

                    # the 16kB chunksize comes from the shutil module

                    # in stdlib

                    chunk = fobj.read(16 * 1024)

                    if not chunk:

                        break

                    binary.write(chunk)

            else:

                binary.write(fobj.read())

        binary.seek(0)

        return binary

    def __eq__(self, other):

        if not isinstance(other, Binary):

            return False

        return self.getvalue() == other.getvalue()

    # Binary helpers to store/fetch python objects

    @classmethod

    def zpickle(cls, obj):

        """ return a Binary containing a gzipped pickle of obj """

        retval = cls()

        retval.write(zlib.compress(pickle.dumps(obj, protocol=2)))

        return retval

    def unzpickle(self):

        """ decompress and loads the stream before returning it """

        return pickle.loads(zlib.decompress(self.getvalue()))

def check_password(eschema, value):

    return isinstance(value, (binary_type, Binary))

BASE_CHECKERS['Password'] = check_password

def str_or_binary(value):

    if isinstance(value, Binary):

        return value

    return binary_type(value)

BASE_CONVERTERS['Password'] = str_or_binary

# use this dictionary to rename entity types while keeping bw compat

ETYPE_NAME_MAP = {}

# XXX cubic web cube migration map. See if it's worth keeping this mecanism

#     to help in cube renaming

CW_MIGRATION_MAP = {}

def neg_role(role):

    if role == 'subject':

        return 'object'

    return 'subject'

def role(obj):

    try:

        return obj.role

    except AttributeError:

        return neg_role(obj.target)

def target(obj):

    try:

        return obj.target

    except AttributeError:

        return neg_role(obj.role)

class CubicWebEventManager(object):

    """simple event / callback manager.

    Typical usage to register a callback::

      >>> from cubicweb import CW_EVENT_MANAGER

      >>> CW_EVENT_MANAGER.bind('after-registry-reload', mycallback)

    Typical usage to emit an event::

      >>> from cubicweb import CW_EVENT_MANAGER

      >>> CW_EVENT_MANAGER.emit('after-registry-reload')

    emit() accepts an additional context parameter that will be passed

    to the callback if specified (and only in that case)

    """

    def __init__(self):

        self.callbacks = {}

    def bind(self, event, callback, *args, **kwargs):

        self.callbacks.setdefault(event, []).append((callback, args, kwargs))

    def emit(self, event, context=None):

        for callback, args, kwargs in self.callbacks.get(event, ()):

            if context is None:

                callback(*args, **kwargs)

            else:

                callback(context, *args, **kwargs)

CW_EVENT_MANAGER = CubicWebEventManager()

def onevent(event, *args, **kwargs):

    """decorator to ease event / callback binding

    >>> from cubicweb import onevent

    >>> @onevent('before-registry-reload')

    ... def mycallback():

    ...     print 'hello'

    ...

    >>>

    """

    def _decorator(func):

        CW_EVENT_MANAGER.bind(event, func, *args, **kwargs)

        return func

    return _decorator

def validation_error(entity, errors, substitutions=None, i18nvalues=None):

    """easy way to retrieve a :class:`cubicweb.ValidationError` for an entity or eid.

    You may also have 2-tuple as error keys, :func:`yams.role_name` will be

    called automatically for them.

    Messages in errors **should not be translated yet**, though marked for

    internationalization. You may give an additional substition dictionary that

    will be used for interpolation after the translation.

    """

    if substitutions is None:

        # set empty dict else translation won't be done for backward

        # compatibility reason (see ValidationError.translate method)

        substitutions = {}

    for key in list(errors):

        if isinstance(key, tuple):

            errors[rname(*key)] = errors.pop(key)

    return ValidationError(getattr(entity, 'eid', entity), errors,

                           substitutions, i18nvalues)

# exceptions ##################################################################

class ProgrammingError(Exception):

    """Exception raised for errors that are related to the database's operation

    and not necessarily under the control of the programmer, e.g. an unexpected

    disconnect occurs, the data source name is not found, a transaction could

    not be processed, a memory allocation error occurred during processing,

    etc.

    """

# Import hook for "legacy" cubes ##############################################

class _CubesLoader(object):

    def __init__(self, *modinfo):

        self.modinfo = modinfo

    def load_module(self, fullname):

        try:

            # If there is an existing module object named 'fullname' in

            # sys.modules , the loader must use that existing module.

            # Otherwise, the reload() builtin will not work correctly.

            return sys.modules[fullname]

        except KeyError:

            pass

        if fullname == 'cubes':

            mod = sys.modules[fullname] = types.ModuleType(

                fullname, doc='CubicWeb cubes')

        else:

            modname, file, pathname, description = self.modinfo

            try:

                mod = sys.modules[fullname] = imp.load_module(

                    modname, file, pathname, description)

            finally:

                # https://docs.python.org/2/library/imp.html#imp.load_module

                # Important: the caller is responsible for closing the file

                # argument, if it was not None, even when an exception is

                # raised. This is best done using a try ... finally statement

                if file is not None:

                    file.close()

        return mod

class _CubesImporter(object):

    """Module finder handling redirection of import of "cubes.<name>"

    to "cubicweb_<name>".

    """

    @classmethod

    def install(cls):

        if not any(isinstance(x, cls) for x in sys.meta_path):

            self = cls()

            sys.meta_path.append(self)

    def find_module(self, fullname, path=None):

        if fullname == 'cubes':

            return _CubesLoader()

        elif fullname.startswith('cubes.') and fullname.count('.') == 1:

            modname = 'cubicweb_' + fullname.split('.', 1)[1]

            try:

                modinfo = imp.find_module(modname)

            except ImportError:

                return None

            else:

                return _CubesLoader(modname, *modinfo)