# -*- coding: utf-8 -*-
# !/usr/bin/env python
import itertools
import math
import re
import time
import codecs
import pickle
from functools import partial

import addressparser
import chardet
import platform

import collections
from collections import OrderedDict
from itertools import islice, takewhile

from typing import NamedTuple, Tuple, Optional

from Crypto.PublicKey import RSA

is_windows = any(platform.win32_ver())


def xor_encrypt_buffer(buffer, offset, key):
    import struct

    lkey = len(key)

    step = 0

    num = offset
    for _ in buffer[offset:]:
        struct.pack_into('<B', buffer, num, ord(_) ^ ord(key[step % lkey]))
        num += 1
        step += 1
    return buffer


def xor_decrypt_buffer(buffer, offset, key):
    return xor_encrypt_buffer(buffer, offset, key)


clock = time.clock if is_windows else time.time


class Timer(object):

    def __init__(self, func = clock):
        self.elapsed = 0.0
        self._func = func
        self._start = None

    def start(self):
        if self._start is not None:
            raise RuntimeError('Already started')
        self._start = self._func()

    def stop(self):
        if self._start is None:
            raise RuntimeError('Not started')
        end = self._func()
        self.elapsed += end - self._start
        self._start = None

    def reset(self):
        self.elapsed = 0.0

    @property
    def running(self):
        return self._start is not None

    def __enter__(self):
        self.start()
        return self

    def __exit__(self, *args):
        self.stop()


def write_file(name, content):
    # type: (str, bytes)->None
    with open(name, 'w') as f:
        f.write(content)


KeyPair = NamedTuple('KeyPair', [('public', str), ('private', str)])


def generate_RSA_key_pairs(bits = 2048):
    # type: (int)->KeyPair
    """

    :param bits:
    :return:
    """

    key = RSA.generate(bits)
    return KeyPair(public = key.publickey().exportKey('PEM').decode('ascii'),
                   private = key.exportKey('PEM').decode('ascii'))


def write_RSA_key_pairs(path, pair = None):
    # type: (str, bool, KeyPair)->Tuple[str, str]

    if pair is None:
        pair = generate_RSA_key_pairs()  # type: KeyPair

    def key_name(name, kind): return '{name}_{kind}.pem'.format(name = name, kind = kind)

    public_key_file_name = key_name(path, 'public')
    private_key_file_name = key_name(path, 'private')

    write_file(public_key_file_name, pair.public)
    write_file(private_key_file_name, pair.private)

    return public_key_file_name, private_key_file_name


def head(iterable, default = None):
    return next(iter(iterable), default)


def first_true(iterable, pred = None, default = None):
    """Returns the first true value in the iterable.
    If no true value is found, returns *default*
    If *pred* is not None, returns the first item
    for which pred(item) is true."""
    # first_true([a,b,c], default=x) --> a or b or c or x
    # first_true([a,b], fn, x) --> a if fn(a) else b if fn(b) else x
    return next(filter(pred, iterable), default)


def nth(iterable, n, default = None):
    """Returns the nth item of iterable, or a default value"""
    return next(islice(iterable, n, None), default)


def upto(iterable, max_val):
    """From a monotonically increasing iterable, generate all the values <= max_val."""
    # Why <= max_val rather than < max_val? In part because that's how Ruby's upto does it.
    return takewhile(lambda x: x <= max_val, iterable)


def ilen(iterable):
    """Length of any iterable (consumes generators)."""
    return sum(1 for _ in iterable)


count_iterable = ilen


def recursive_repr(fill_value = '...'):
    """
    back-ported from Python3
    Decorator to make a repr function return fill_value for a recursive call"""

    from thread import get_ident

    def decorating_function(user_function):
        repr_running = set()

        def wrapper(self):
            key = id(self), get_ident()
            if key in repr_running:
                return fill_value
            repr_running.add(key)
            try:
                result = user_function(self)
            finally:
                repr_running.discard(key)
            return result

        # Can't use functools.wraps() here because of bootstrap issues
        wrapper.__module__ = getattr(user_function, '__module__')
        wrapper.__doc__ = getattr(user_function, '__doc__')
        wrapper.__name__ = getattr(user_function, '__name__')
        wrapper.__annotations__ = getattr(user_function, '__annotations__', {})
        return wrapper

    return decorating_function


class ChainMap(collections.MutableMapping):
    """
    back-ported from Python3
    A ChainMap groups multiple dicts (or other mappings) together
    to create a single, updateable view.
    The underlying mappings are stored in a list.  That list is public and can
    be accessed or updated using the *maps* attribute.  There is no other
    state.
    Lookups search the underlying mappings successively until a key is found.
    In contrast, writes, updates, and deletions only operate on the first
    mapping.
    """

    def __init__(self, *maps):
        """Initialize a ChainMap by setting *maps* to the given mappings.
        If no mappings are provided, a single empty dictionary is used.
        """
        self.maps = list(maps) or [{}]  # always at least one map

    def __missing__(self, key):
        raise KeyError(key)

    def __getitem__(self, key):
        for mapping in self.maps:
            try:
                return mapping[key]  # can't use 'key in mapping' with defaultdict
            except KeyError:
                pass
        return self.__missing__(key)  # support subclasses that define __missing__

    def get(self, key, default = None):
        return self[key] if key in self else default

    def __len__(self):
        return len(set().union(*self.maps))  # reuses stored hash values if possible

    def __iter__(self):
        d = {}
        for mapping in reversed(self.maps):
            d.update(mapping)  # reuses stored hash values if possible
        return iter(d)

    def __contains__(self, key):
        return any(key in m for m in self.maps)

    def __bool__(self):
        return any(self.maps)

    @recursive_repr()
    def __repr__(self):
        return '{name}({maps})'.format(name = self.__class__.__name__, maps = ", ".join(map(repr, self.maps)))

    @classmethod
    def fromkeys(cls, iterable, *args):
        """Create a ChainMap with a single dict created from the iterable."""
        return cls(dict.fromkeys(iterable, *args))

    def copy(self):
        """New ChainMap or subclass with a new copy of maps[0] and refs to maps[1:]"""
        return self.__class__(self.maps[0].copy(), *self.maps[1:])

    __copy__ = copy

    def new_child(self, m = None):  # like Django's Context.push()
        """New ChainMap with a new map followed by all previous maps.
        If no map is provided, an empty dict is used.
        """
        if m is None:
            m = {}
        return self.__class__(m, *self.maps)

    @property
    def parents(self):  # like Django's Context.pop()
        """New ChainMap from maps[1:]."""
        return self.__class__(*self.maps[1:])

    def __setitem__(self, key, value):
        self.maps[0][key] = value

    def __delitem__(self, key):
        try:
            del self.maps[0][key]
        except KeyError:
            raise KeyError('Key not found in the first mapping: {!r}'.format(key))

    def popitem(self):
        """Remove and return an item pair from maps[0]. Raise KeyError is maps[0] is empty."""
        try:
            return self.maps[0].popitem()
        except KeyError:
            raise KeyError('No keys found in the first mapping.')

    def pop(self, key, *args):
        """Remove *key* from maps[0] and return its value. Raise KeyError if *key* not in maps[0]."""
        try:
            return self.maps[0].pop(key, *args)
        except KeyError:
            raise KeyError('Key not found in the first mapping: {!r}'.format(key))

    def clear(self):
        """Clear maps[0], leaving maps[1:] intact."""
        self.maps[0].clear()


class Immutable(object):
    """
    Immutable object which adheres to the Mapping and the Sequence protocols.
    * Attributes are kept in `self._ordered_dict`. NEVER MUTATE THIS!
    * Instantiate with kwargs or args. Instantiating with args preserves order.
    * Mapping methods get(), items(), keys(), and values() are also included.
    * Sequence methods index() and count() are also included.
    """

    class ImmutableError(Exception):
        pass

    def __init__(self, *args, **kwargs):
        """
        Instantiate an Immutable instance.
        >>> # tuple instantiation --> Note that this method preserves order!
        >>> obj = Immutable((('val_0', 0), ('val_1', 1)))
        >>> # key=value pairs
        >>> obj1 = Immutable(val_0=0, val_1=1)
        >>> # same as above, but by upacking a dict
        >>> attribute_dict = {'val_0': 0, 'val_1': 1}
        >>> obj2 = Immutable(**attribute_dict)
        >>> # access via '.' or '[]'
        >>> obj.val_0
        >>> obj['val_0']
        :param args: (<attr>, <val>,) pairs to add *in order*
        :param kwargs: Allows you to unpack a dict to create this.
        """
        reserved_keys = ('get', 'keys', 'values', 'items', 'count', 'index',
                         '_ordered_dict', '_tuple')
        ordered_dict = OrderedDict()
        for key, val in args:
            if key in kwargs:
                raise self.ImmutableError('Key in args duplicated in kwargs.')
            ordered_dict[key] = val
        ordered_dict.update(kwargs)
        for key, val in ordered_dict.items():
            try:
                hash(key)
                hash(val)
            except TypeError:
                raise self.ImmutableError('Keys and vals must be hashable.')
            if isinstance(key, int):
                raise self.ImmutableError('Keys cannot be integers.')
            if key in reserved_keys:
                raise self.ImmutableError('Keys cannot be any of these: {}.'
                                          .format(reserved_keys))
        self.__dict__['_ordered_dict'] = ordered_dict
        self.__dict__['_tuple'] = tuple(ordered_dict.values())

    def __contains__(self, item):
        raise self.ImmutableError('Containment not implemented. Try with '
                                  'keys(), values(), or items().')

    def __reversed__(self):
        raise self.ImmutableError('Reversal not implemented. Try with '
                                  'keys(), values(), or items().')

    def __getitem__(self, key):
        if isinstance(key, int):
            return self.__dict__['_tuple'][key]
        else:
            return self.__dict__['_ordered_dict'][key]

    def __setitem__(self, key, value):
        raise self.ImmutableError('Cannot set items on Immutable.')

    def __getattr__(self, key):
        if key == 'items':
            return self.__dict__['_ordered_dict'].items
        elif key == 'keys':
            return self.__dict__['_ordered_dict'].keys
        elif key == 'values':
            return self.__dict__['_ordered_dict'].values
        elif key == 'index':
            return self.__dict__['_tuple'].index
        elif key == 'count':
            return self.__dict__['_tuple'].count
        else:
            return self.__getitem__(key)

    def __setattr__(self, key, value):
        raise self.ImmutableError('Cannot set attributes on Immutable.')

    def __cmp__(self, other):
        raise self.ImmutableError('Only equality comparisons implemented.')

    def __eq__(self, other):
        if not isinstance(other, Immutable):
            return False
        return hash(self) == hash(other)

    def __ne__(self, other):
        if not isinstance(other, Immutable):
            return True
        return hash(self) != hash(other)

    def __len__(self):
        return len(self.__dict__['_tuple'])

    def __iter__(self):
        raise self.ImmutableError('Iteration not implemented. Try with '
                                  'keys(), values(), or items().')

    def __hash__(self):
        return hash(tuple(self._ordered_dict.items()))

    def __str__(self):
        return bytes('{}'.format(self.__repr__()))

    def __unicode__(self):
        return '{}'.format(self.__repr__())

    def __repr__(self):
        keys_repr = ', '.join('{}={}'.format(key, repr(val))
                              for key, val in self.items())
        return 'Immutable({})'.format(keys_repr)

    def __dir__(self):
        return list(self.keys())


def guess_encoding(file_path):
    # type: (str, int)->str
    """Predict a file's encoding using chardet"""

    # Open the file as binary data
    with open(file_path, 'rb') as f:
        # Join binary lines for specified number of lines
        raw_data = b''.join(f.readlines())

    return chardet.detect(raw_data)['encoding']


def convert_encoding(source_file, target_file = None, source_encoding = None, target_encoding = "utf-8"):
    # type: (str, Optional[str], Optional[str], Optional[str])->str
    """

    :param source_file:
    :param target_file:
    :param source_encoding:
    :param target_encoding:
    :return:
    """

    source_encoding = source_encoding if source_encoding is not None else guess_encoding(source_file)

    if source_encoding in ('gb2312', 'GB2312'):
        #: gb18030 is a superset of gb2312, it can cover more corner cases
        source_encoding = 'gb18030'

    if not target_file:
        filename, suffix = source_file.rsplit('.')
        target_file = 'converted-{filename}-{source_encoding}-{target_encoding}.{suffix}' \
            .format(filename = filename,
                    source_encoding = source_encoding,
                    target_encoding = target_encoding,
                    suffix = suffix)

    BLOCK_SIZE = 1048576
    with codecs.open(source_file, "r", source_encoding) as source:
        with codecs.open(target_file, "w", target_encoding) as target:
            while True:
                contents = source.read(BLOCK_SIZE)
                if not contents:
                    break
                target.write(contents)

    return target_file


def rec_update_dict(d, update_dict, firstLevelOverwrite = False):
    """
    递归地更新字典
    :param firstLevelOverwrite: 特指是否覆盖第一层dict
    :param d:
    :param update_dict:
    :return:
    """
    for k, v in update_dict.iteritems():
        if firstLevelOverwrite:
            d[k] = v
        else:
            if isinstance(v, collections.Mapping):
                d[k] = rec_update_dict(d.get(k, {}), v)
            else:
                d[k] = v
    return d


flatten = itertools.chain.from_iterable


def convert(text):
    return int(text) if text.isdigit() else text


def alphanum_key(key):
    return [convert(c) for c in re.split('([0-9]+)', key)]


def natural_sort(array, key, reverse):
    return sorted(array, key = lambda d: alphanum_key(d[key]), reverse = reverse)


def paginated(dataList, pageIndex, pageSize):
    return dataList[(pageIndex - 1) * pageSize:pageIndex * pageSize]


def is_number(s):
    try:
        float(s)
        return True
    except ValueError:
        pass

    try:
        import unicodedata
        unicodedata.numeric(s)
        return True
    except (TypeError, ValueError, ImportError):
        pass

    return False


def ceil_floor(x): return math.ceil(x) if x < 0 else math.floor(x)


def round_n_digits(x, n): return ceil_floor(x * math.pow(10, n)) / math.pow(10, n)


round_2_digits = partial(round_n_digits, n = 2)


def with_metaclass(meta, *bases):
    """
    Function from jinja2/_compat.py. License: BSD.
    Use it like this::
        class BaseForm(object):
            pass
        class FormType(type):
            pass
        class Form(with_metaclass(FormType, BaseForm)):
            pass
    This requires a bit of explanation: the basic idea is to make a
    dummy metaclass for one level of class instantiation that replaces
    itself with the actual metaclass.  Because of internal type checks
    we also need to make sure that we downgrade the custom metaclass
    for one level to something closer to type (that's why __call__ and
    __init__ comes back from type etc.).
    This has the advantage over six.with_metaclass of not introducing
    dummy classes into the final MRO.
    """

    class Metaclass(meta):
        __call__ = type.__call__
        __init__ = type.__init__

        def __new__(cls, name, this_bases, d):
            if this_bases is None:
                return type.__new__(cls, name, (), d)
            return meta(name, bases, d)

    return Metaclass('temporary_class', None, {})


def load_pickle(filepath):
    with open(filepath) as f:
        return pickle.load(f)


def dump_pickle(obj, filepath):
    with open(filepath, 'w') as f:
        pickle.dump(obj, f)


def split_addr(addr):  # type:(unicode) -> tuple
    addr = [addr]
    df = addressparser.transform(addr)
    df.fillna("", inplace=True)
    return df.values.tolist()[0]


def fix_dict(mydict, check_empty_string = []):
    # type: (dict, list)->dict

    result = {}

    if not mydict:
        return result

    for key, value in mydict.iteritems():
        if key in check_empty_string:
            if value is None or value == '':
                continue
            else:
                result[key] = value
        else:
            if value is not None:
                result[key] = value

    return result