# -*- coding: utf-8 -*-
#
import re
from collections import OrderedDict
from six import string_types
import base64
import os
from itertools import chain
import logging
import datetime
import time
import hashlib
from email.utils import formatdate
import calendar
import threading
from io import StringIO
import uuid

import paramiko
import sshpubkeys
from itsdangerous import TimedJSONWebSignatureSerializer, JSONWebSignatureSerializer, \
    BadSignature, SignatureExpired
from django.shortcuts import reverse as dj_reverse
from django.conf import settings
from django.utils import timezone


UUID_PATTERN = re.compile(r'[0-9a-zA-Z\-]{36}')


def reverse(view_name, urlconf=None, args=None, kwargs=None,
            current_app=None, external=False):
    url = dj_reverse(view_name, urlconf=urlconf, args=args,
                     kwargs=kwargs, current_app=current_app)

    if external:
        url = settings.SITE_URL.strip('/') + url
    return url


def get_object_or_none(model, **kwargs):
    try:
        obj = model.objects.get(**kwargs)
    except model.DoesNotExist:
        return None
    return obj


class Singleton(type):
    def __init__(cls, *args, **kwargs):
        cls.__instance = None
        super().__init__(*args, **kwargs)

    def __call__(cls, *args, **kwargs):
        if cls.__instance is None:
            cls.__instance = super().__call__(*args, **kwargs)
            return cls.__instance
        else:
            return cls.__instance


class Signer(metaclass=Singleton):
    """用来加密,解密,和基于时间戳的方式验证token"""
    def __init__(self, secret_key=None):
        self.secret_key = secret_key

    def sign(self, value):
        if isinstance(value, bytes):
            value = value.decode("utf-8")
        s = JSONWebSignatureSerializer(self.secret_key)
        return s.dumps(value)

    def unsign(self, value):
        s = JSONWebSignatureSerializer(self.secret_key)
        try:
            return s.loads(value)
        except BadSignature:
            return {}

    def sign_t(self, value, expires_in=3600):
        s = TimedJSONWebSignatureSerializer(self.secret_key, expires_in=expires_in)
        return str(s.dumps(value), encoding="utf8")

    def unsign_t(self, value):
        s = TimedJSONWebSignatureSerializer(self.secret_key)
        try:
            return s.loads(value)
        except (BadSignature, SignatureExpired):
            return {}


def date_expired_default():
    try:
        years = int(settings.DEFAULT_EXPIRED_YEARS)
    except TypeError:
        years = 70
    return timezone.now() + timezone.timedelta(days=365*years)


def combine_seq(s1, s2, callback=None):
    for s in (s1, s2):
        if not hasattr(s, '__iter__'):
            return []

    seq = chain(s1, s2)
    if callback:
        seq = map(callback, seq)
    return seq


def get_logger(name=None):
    return logging.getLogger('jumpserver.%s' % name)


def timesince(dt, since='', default="just now"):
    """
    Returns string representing "time since" e.g.
    3 days, 5 hours.
    """

    if since is '':
        since = datetime.datetime.utcnow()

    if since is None:
        return default

    diff = since - dt

    periods = (
        (diff.days / 365, "year", "years"),
        (diff.days / 30, "month", "months"),
        (diff.days / 7, "week", "weeks"),
        (diff.days, "day", "days"),
        (diff.seconds / 3600, "hour", "hours"),
        (diff.seconds / 60, "minute", "minutes"),
        (diff.seconds, "second", "seconds"),
    )

    for period, singular, plural in periods:
        if period:
            return "%d %s" % (period, singular if period == 1 else plural)
    return default


def ssh_key_string_to_obj(text, password=None):
    key = None
    try:
        key = paramiko.RSAKey.from_private_key(StringIO(text), password=password)
    except paramiko.SSHException:
        pass

    try:
        key = paramiko.DSSKey.from_private_key(StringIO(text), password=password)
    except paramiko.SSHException:
        pass
    return key


def ssh_pubkey_gen(private_key=None, username='jumpserver', hostname='localhost', password=None):
    if isinstance(private_key, bytes):
        private_key = private_key.decode("utf-8")
    if isinstance(private_key, string_types):
        private_key = ssh_key_string_to_obj(private_key, password=password)
    if not isinstance(private_key, (paramiko.RSAKey, paramiko.DSSKey)):
        raise IOError('Invalid private key')

    public_key = "%(key_type)s %(key_content)s %(username)s@%(hostname)s" % {
        'key_type': private_key.get_name(),
        'key_content': private_key.get_base64(),
        'username': username,
        'hostname': hostname,
    }
    return public_key


def ssh_key_gen(length=2048, type='rsa', password=None, username='jumpserver', hostname=None):
    """Generate user ssh private and public key

    Use paramiko RSAKey generate it.
    :return private key str and public key str
    """

    if hostname is None:
        hostname = os.uname()[1]

    f = StringIO()
    try:
        if type == 'rsa':
            private_key_obj = paramiko.RSAKey.generate(length)
        elif type == 'dsa':
            private_key_obj = paramiko.DSSKey.generate(length)
        else:
            raise IOError('SSH private key must be `rsa` or `dsa`')
        private_key_obj.write_private_key(f, password=password)
        private_key = f.getvalue()
        public_key = ssh_pubkey_gen(private_key_obj, username=username, hostname=hostname)
        return private_key, public_key
    except IOError:
        raise IOError('These is error when generate ssh key.')


def validate_ssh_private_key(text, password=None):
    if isinstance(text, bytes):
        try:
            text = text.decode("utf-8")
        except UnicodeDecodeError:
            return False

    key = ssh_key_string_to_obj(text, password=password)
    if key is None:
        return False
    else:
        return True


def validate_ssh_public_key(text):
    ssh = sshpubkeys.SSHKey(text)
    try:
        ssh.parse()
    except (sshpubkeys.InvalidKeyException, UnicodeDecodeError):
        return False
    except NotImplementedError as e:
        return False
    return True


def setattr_bulk(seq, key, value):
    def set_attr(obj):
        setattr(obj, key, value)
        return obj
    return map(set_attr, seq)


def content_md5(data):
    """计算data的MD5值，经过Base64编码并返回str类型。

    返回值可以直接作为HTTP Content-Type头部的值
    """
    if isinstance(data, str):
        data = hashlib.md5(data.encode('utf-8'))
    value = base64.b64encode(data.hexdigest().encode('utf-8'))
    return value.decode('utf-8')


_STRPTIME_LOCK = threading.Lock()

_GMT_FORMAT = "%a, %d %b %Y %H:%M:%S GMT"
_ISO8601_FORMAT = "%Y-%m-%dT%H:%M:%S.000Z"


def to_unixtime(time_string, format_string):
    time_string = time_string.decode("ascii")
    with _STRPTIME_LOCK:
        return int(calendar.timegm(time.strptime(time_string, format_string)))


def http_date(timeval=None):
    """返回符合HTTP标准的GMT时间字符串，用strftime的格式表示就是"%a, %d %b %Y %H:%M:%S GMT"。
    但不能使用strftime，因为strftime的结果是和locale相关的。
    """
    return formatdate(timeval, usegmt=True)


def http_to_unixtime(time_string):
    """把HTTP Date格式的字符串转换为UNIX时间（自1970年1月1日UTC零点的秒数）。

    HTTP Date形如 `Sat, 05 Dec 2015 11:10:29 GMT` 。
    """
    return to_unixtime(time_string, _GMT_FORMAT)


def iso8601_to_unixtime(time_string):
    """把ISO8601时间字符串（形如，2012-02-24T06:07:48.000Z）转换为UNIX时间，精确到秒。"""
    return to_unixtime(time_string, _ISO8601_FORMAT)


def make_signature(access_key_secret, date=None):
    if isinstance(date, bytes):
        date = bytes.decode(date)
    if isinstance(date, int):
        date_gmt = http_date(date)
    elif date is None:
        date_gmt = http_date(int(time.time()))
    else:
        date_gmt = date

    data = str(access_key_secret) + "\n" + date_gmt
    return content_md5(data)


def encrypt_password(password, salt=None):
    from passlib.hash import sha512_crypt
    if password:
        return sha512_crypt.using(rounds=5000).hash(password, salt=salt)
    return None


def capacity_convert(size, expect='auto', rate=1000):
    """
    :param size: '100MB', '1G'
    :param expect: 'K, M, G, T
    :param rate: Default 1000, may be 1024
    :return:
    """
    rate_mapping = (
        ('K', rate),
        ('KB', rate),
        ('M', rate**2),
        ('MB', rate**2),
        ('G', rate**3),
        ('GB', rate**3),
        ('T', rate**4),
        ('TB', rate**4),
    )

    rate_mapping = OrderedDict(rate_mapping)

    std_size = 0  # To KB
    for unit in rate_mapping:
        if size.endswith(unit):
            try:
                std_size = float(size.strip(unit).strip()) * rate_mapping[unit]
            except ValueError:
                pass

    if expect == 'auto':
        for unit, rate_ in rate_mapping.items():
            if rate > std_size/rate_ > 1:
                expect = unit
                break

    if expect not in rate_mapping:
        expect = 'K'

    expect_size = std_size / rate_mapping[expect]
    return expect_size, expect


def sum_capacity(cap_list):
    total = 0
    for cap in cap_list:
        size, _ = capacity_convert(cap, expect='K')
        total += size
    total = '{} K'.format(total)
    return capacity_convert(total, expect='auto')


def get_short_uuid_str():
    return str(uuid.uuid4()).split('-')[-1]


def is_uuid(s):
    if UUID_PATTERN.match(s):
        return True
    else:
        return False


def get_signer():
    signer = Signer(settings.SECRET_KEY)
    return signer

