import copy
import datetime
import json
import logging
import os
import sys
from collections import Mapping
from functools import wraps
from threading import Thread

import six
from dateutil.parser import parse as parse_date


def attrs_to_dir(mod):
    data = {}
    for attr in dir(mod):
        if attr == attr.upper():
            data[attr] = getattr(mod, attr)
    return data


def dict_rec_update(d, u):
    """Nested update of a dict, handy for overriding settings"""
    # https://stackoverflow.com/questions/3232943/update-value-of-a-nested-dictionary-of-varying-depth
    for k, v in u.items():
        if isinstance(v, Mapping):
            r = dict_rec_update(d.get(k, {}), v)
            d[k] = r
        else:
            d[k] = u[k]
    return d


class Task(Thread):
    """
    The Threaded object returned by the @threaded decorator below
    """

    def __init__(self, method, *args, **kwargs):
        super(Task, self).__init__()
        self.method = method
        self.args = args
        self.kwargs = kwargs
        self._result = None
        self.__exc_info = None

    def run(self):
        try:
            self._result = self.method(*self.args, **self.kwargs)
        except:
            self.__exc_info = sys.exc_info()

    @property
    def result(self):
        self.join()
        if self.__exc_info is not None:
            six.reraise(*self.__exc_info)
        return self._result


def threaded(function=None, daemon=False):

    def wrapper_factory(func):

        @wraps(func)
        def get_thread(*args, **kwargs):
            t = Task(func, *args, **kwargs)
            if daemon:
                t.daemon = True
            t.start()
            return t

        return get_thread

    if function:
        return wrapper_factory(function)
    else:
        return wrapper_factory


class CustomJSONEncoder(json.JSONEncoder):

    custom_type_key = '_custom_type'
    custom_type_value_key = 'value'
    DECODERS = {'datetime': parse_date}

    def default(self, obj):
        if isinstance(obj, datetime.datetime):
            return {self.custom_type_key: 'datetime',
                    self.custom_type_value_key: obj.isoformat()}
        else:
            return super(CustomJSONEncoder, self).default(obj)


def custom_json_decoder_hook(obj):

    ct = obj.get(CustomJSONEncoder.custom_type_key, None)
    if ct is not None:
        value = obj.get(CustomJSONEncoder.custom_type_value_key)
        return CustomJSONEncoder.DECODERS[ct](value)
    else:
        return obj


def find_project_root(root_indicator='manage.py', current=os.getcwd()):
    parent = os.path.dirname(current)
    if root_indicator in os.listdir(current):
        return current
    elif current == parent:
        # We are at '/' already!
        raise IOError('Not found: {}'.format(root_indicator))
    else:
        return find_project_root(root_indicator, parent)


def copy_if_mutable(value):
    """
    Copy function handling mutable values (only dicts and lists).
    """
    if type(value) in (dict, list):
        return copy.deepcopy(value)
    return value


def byteify(input):
    if isinstance(input, dict):
        return {byteify(key): byteify(value) for key, value in input.items()}
    elif isinstance(input, list):
        return [byteify(element) for element in input]
    elif (sys.version_info.major == 2) and (isinstance(input, unicode)):
        return input.encode('utf-8')
    else:
        return input


class IgnoreMaxEtcdRetries(logging.Filter):
    """
    Skip etcd.client MaxRetryError on timeout
    """

    def __init__(self, name='etcd.client'):
        super(IgnoreMaxEtcdRetries, self).__init__(name)

    def filter(self, record):
        msg = '{}'.format(record.args)
        return not (
            'MaxRetryError' in msg and
            'Read timed out' in msg
        )