# -*- coding: utf-8 -*-

"""
oss2.utils
----------

工具函数模块。
"""

from email.utils import formatdate

import os.path
import mimetypes
import socket
import hashlib
import base64
import threading
import calendar
import datetime
import time
import errno

import binascii
import crcmod
import re
import random

from Crypto.Cipher import AES
from Crypto import Random
from Crypto.Util import Counter

from .compat import to_string, to_bytes
from .exceptions import ClientError, InconsistentError, RequestError, OpenApiFormatError


_EXTRA_TYPES_MAP = {
    ".js": "application/javascript",
    ".xlsx": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
    ".xltx": "application/vnd.openxmlformats-officedocument.spreadsheetml.template",
    ".potx": "application/vnd.openxmlformats-officedocument.presentationml.template",
    ".ppsx": "application/vnd.openxmlformats-officedocument.presentationml.slideshow",
    ".pptx": "application/vnd.openxmlformats-officedocument.presentationml.presentation",
    ".sldx": "application/vnd.openxmlformats-officedocument.presentationml.slide",
    ".docx": "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
    ".dotx": "application/vnd.openxmlformats-officedocument.wordprocessingml.template",
    ".xlam": "application/vnd.ms-excel.addin.macroEnabled.12",
    ".xlsb": "application/vnd.ms-excel.sheet.binary.macroEnabled.12",
    ".apk": "application/vnd.android.package-archive"
}


def b64encode_as_string(data):
    return to_string(base64.b64encode(to_bytes(data)))


def b64decode_from_string(data):
    try:
        return base64.b64decode(to_string(data))
    except (TypeError, binascii.Error) as e:
        raise OpenApiFormatError('Base64 Error: ' + to_string(data))


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
    """
    m = hashlib.md5(to_bytes(data))
    return b64encode_as_string(m.digest())


def md5_string(data):
    """返回 `data` 的MD5值，以十六进制可读字符串（32个小写字符）的方式。"""
    return hashlib.md5(to_bytes(data)).hexdigest()


def content_type_by_name(name):
    """根据文件名，返回Content-Type。"""
    ext = os.path.splitext(name)[1].lower()
    if ext in _EXTRA_TYPES_MAP:
        return _EXTRA_TYPES_MAP[ext]

    return mimetypes.guess_type(name)[0]


def set_content_type(headers, name):
    """根据文件名在headers里设置Content-Type。如果headers中已经存在Content-Type，则直接返回。"""
    headers = headers or {}

    if 'Content-Type' in headers:
        return headers

    content_type = content_type_by_name(name)
    if content_type:
        headers['Content-Type'] = content_type

    return headers


def is_ip_or_localhost(netloc):
    """判断网络地址是否为IP或localhost。"""
    loc = netloc.split(':')[0]
    if loc == 'localhost':
        return True

    try:
        socket.inet_aton(loc)
    except socket.error:
        return False

    return True


_ALPHA_NUM = 'abcdefghijklmnopqrstuvwxyz0123456789'
_HYPHEN = '-'
_BUCKET_NAME_CHARS = set(_ALPHA_NUM + _HYPHEN)


def is_valid_bucket_name(name):
    """判断是否为合法的Bucket名"""
    if len(name) < 3 or len(name) > 63:
        return False

    if name[-1] == _HYPHEN:
        return False

    if name[0] not in _ALPHA_NUM:
        return False

    return set(name) <= _BUCKET_NAME_CHARS


class SizedFileAdapter(object):
    """通过这个适配器（Adapter），可以把原先的 `file_object` 的长度限制到等于 `size`。"""
    def __init__(self, file_object, size):
        self.file_object = file_object
        self.size = size
        self.offset = 0

    def read(self, amt=None):
        if self.offset >= self.size:
            return ''

        if (amt is None or amt < 0) or (amt + self.offset >= self.size):
            data = self.file_object.read(self.size - self.offset)
            self.offset = self.size
            return data

        self.offset += amt
        return self.file_object.read(amt)

    @property
    def len(self):
        return self.size


def how_many(m, n):
    return (m + n - 1) // n


def file_object_remaining_bytes(fileobj):
    current = fileobj.tell()

    fileobj.seek(0, os.SEEK_END)
    end = fileobj.tell()
    fileobj.seek(current, os.SEEK_SET)

    return end - current


def _has_data_size_attr(data):
    return hasattr(data, '__len__') or hasattr(data, 'len') or (hasattr(data, 'seek') and hasattr(data, 'tell'))


def _get_data_size(data):
    if hasattr(data, '__len__'):
        return len(data)

    if hasattr(data, 'len'):
        return data.len

    if hasattr(data, 'seek') and hasattr(data, 'tell'):
        return file_object_remaining_bytes(data)

    return None


_CHUNK_SIZE = 8 * 1024


def make_progress_adapter(data, progress_callback, size=None):
    """返回一个适配器，从而在读取 `data` ，即调用read或者对其进行迭代的时候，能够
     调用进度回调函数。当 `size` 没有指定，且无法确定时，上传回调函数返回的总字节数为None。

    :param data: 可以是bytes、file object或iterable
    :param progress_callback: 进度回调函数，参见 :ref:`progress_callback`
    :param size: 指定 `data` 的大小，可选

    :return: 能够调用进度回调函数的适配器
    """
    data = to_bytes(data)

    if size is None:
        size = _get_data_size(data)

    if size is None:
        if hasattr(data, 'read'):
            return _FileLikeAdapter(data, progress_callback)
        elif hasattr(data, '__iter__'):
            return _IterableAdapter(data, progress_callback)
        else:
            raise ClientError('{0} is not a file object, nor an iterator'.format(data.__class__.__name__))
    else:
        return _BytesAndFileAdapter(data, progress_callback, size)


def make_crc_adapter(data, init_crc=0):
    """返回一个适配器，从而在读取 `data` ，即调用read或者对其进行迭代的时候，能够计算CRC。

    :param data: 可以是bytes、file object或iterable
    :param init_crc: 初始CRC值，可选

    :return: 能够调用计算CRC函数的适配器
    """
    data = to_bytes(data)

    # bytes or file object
    if _has_data_size_attr(data):
        return _BytesAndFileAdapter(data, 
                                    size=_get_data_size(data), 
                                    crc_callback=Crc64(init_crc))
    # file-like object
    elif hasattr(data, 'read'): 
        return _FileLikeAdapter(data, crc_callback=Crc64(init_crc))
    # iterator
    elif hasattr(data, '__iter__'):
        return _IterableAdapter(data, crc_callback=Crc64(init_crc))
    else:
        raise ClientError('{0} is not a file object, nor an iterator'.format(data.__class__.__name__))


def make_cipher_adapter(data, cipher_callback):
    """返回一个适配器，从而在读取 `data` ，即调用read或者对其进行迭代的时候，能够进行加解密操作。

        :param data: 可以是bytes、file object或iterable
        :param operation: 进行加密或解密操作
        :param key: 对称加密中的密码，长度必须为16/24/32 bytes
        :param start: 计数器初始值

        :return: 能够客户端加密函数的适配器
        """
    data = to_bytes(data)

    # bytes or file object
    if _has_data_size_attr(data):
        return _BytesAndFileAdapter(data,
                                    size=_get_data_size(data),
                                    cipher_callback=cipher_callback)
    # file-like object
    elif hasattr(data, 'read'):
        return _FileLikeAdapter(data, cipher_callback=cipher_callback)
    # iterator
    elif hasattr(data, '__iter__'):
        return _IterableAdapter(data, cipher_callback=cipher_callback)
    else:
        raise ClientError('{0} is not a file object, nor an iterator'.format(data.__class__.__name__))


def check_crc(operation, client_crc, oss_crc, request_id):
    if client_crc is not None and oss_crc is not None and client_crc != oss_crc:
        raise InconsistentError('the crc of {0} between client and oss is not inconsistent'.format(operation),
                                request_id)

def _invoke_crc_callback(crc_callback, content):
    if crc_callback:
        crc_callback(content)


def _invoke_progress_callback(progress_callback, consumed_bytes, total_bytes):
    if progress_callback:
        progress_callback(consumed_bytes, total_bytes)


def _invoke_cipher_callback(cipher_callback, content):
    if cipher_callback:
        content = cipher_callback(content)
    return content


class _IterableAdapter(object):
    def __init__(self, data, progress_callback=None, crc_callback=None, cipher_callback=None):
        self.iter = iter(data)
        self.progress_callback = progress_callback
        self.offset = 0
        
        self.crc_callback = crc_callback
        self.cipher_callback = cipher_callback

    def __iter__(self):
        return self

    def __next__(self):
        return self.next()

    def next(self):            
        _invoke_progress_callback(self.progress_callback, self.offset, None)

        content = next(self.iter)
        self.offset += len(content)
                
        _invoke_crc_callback(self.crc_callback, content)

        content = _invoke_cipher_callback(self.cipher_callback, content)

        return content
    
    @property
    def crc(self):
        if self.crc_callback:
            return self.crc_callback.crc
        elif self.iter:
            return self.iter.crc
        else:
            return None


class _FileLikeAdapter(object):
    """通过这个适配器，可以给无法确定内容长度的 `fileobj` 加上进度监控。

    :param fileobj: file-like object，只要支持read即可
    :param progress_callback: 进度回调函数
    """
    def __init__(self, fileobj, progress_callback=None, crc_callback=None, cipher_callback=None):
        self.fileobj = fileobj
        self.progress_callback = progress_callback
        self.offset = 0
        
        self.crc_callback = crc_callback
        self.cipher_callback = cipher_callback

    def __iter__(self):
        return self

    def __next__(self):
        return self.next()

    def next(self):
        content = self.read(_CHUNK_SIZE)

        if content:
            return content
        else:
            raise StopIteration

    def read(self, amt=None):
        content = self.fileobj.read(amt)
        if not content:
            _invoke_progress_callback(self.progress_callback, self.offset, None) 
        else:
            _invoke_progress_callback(self.progress_callback, self.offset, None)
                
            self.offset += len(content)
                                   
            _invoke_crc_callback(self.crc_callback, content)

            content = _invoke_cipher_callback(self.cipher_callback, content)

        return content
    
    @property
    def crc(self):
        if self.crc_callback:
            return self.crc_callback.crc
        elif self.fileobj:
            return self.fileobj.crc
        else:
            return None


class _BytesAndFileAdapter(object):
    """通过这个适配器，可以给 `data` 加上进度监控。

    :param data: 可以是unicode字符串（内部会转换为UTF-8编码的bytes）、bytes或file object
    :param progress_callback: 用户提供的进度报告回调，形如 callback(bytes_read, total_bytes)。
        其中bytes_read是已经读取的字节数；total_bytes是总的字节数。
    :param int size: `data` 包含的字节数。
    """
    def __init__(self, data, progress_callback=None, size=None, crc_callback=None, cipher_callback=None):
        self.data = to_bytes(data)
        self.progress_callback = progress_callback
        self.size = size
        self.offset = 0
        
        self.crc_callback = crc_callback
        self.cipher_callback = cipher_callback

    @property
    def len(self):
        return self.size

    # for python 2.x
    def __bool__(self):
        return True
    # for python 3.x
    __nonzero__=__bool__

    def __iter__(self):
        return self

    def __next__(self):
        return self.next()

    def next(self):
        content = self.read(_CHUNK_SIZE)

        if content:
            return content
        else:
            raise StopIteration

    def read(self, amt=None):
        if self.offset >= self.size:
            return ''

        if amt is None or amt < 0:
            bytes_to_read = self.size - self.offset
        else:
            bytes_to_read = min(amt, self.size - self.offset)

        if isinstance(self.data, bytes):
            content = self.data[self.offset:self.offset+bytes_to_read]
        else:
            content = self.data.read(bytes_to_read)

        self.offset += bytes_to_read
            
        _invoke_progress_callback(self.progress_callback, min(self.offset, self.size), self.size)

        _invoke_crc_callback(self.crc_callback, content)

        content = _invoke_cipher_callback(self.cipher_callback, content)

        return content
    
    @property
    def crc(self):
        if self.crc_callback:
            return self.crc_callback.crc
        elif self.data:
            return self.data.crc
        else:
            return None


class Crc64(object):

    _POLY = 0x142F0E1EBA9EA3693
    _XOROUT = 0XFFFFFFFFFFFFFFFF
    
    def __init__(self, init_crc=0):
        self.crc64 = crcmod.Crc(self._POLY, initCrc=init_crc, rev=True, xorOut=self._XOROUT)

    def __call__(self, data):
        self.update(data)
    
    def update(self, data):
        self.crc64.update(data)
    
    @property
    def crc(self):
        return self.crc64.crcValue


def random_aes256_key():
    return Random.new().read(_AES_256_KEY_SIZE)


def random_counter(begin=1, end=10):
    return random.randint(begin, end)


# aes 256, key always is 32 bytes
_AES_256_KEY_SIZE = 32

_AES_CTR_COUNTER_BITS_LEN = 8 * 16

_AES_GCM = 'AES/GCM/NoPadding'


class AESCipher:
    """AES256 加密实现。
        :param str key: 对称加密数据密钥
        :param str start: 对称加密初始随机值
    .. note::
        用户可自行实现对称加密算法，需服务如下规则：
        1、提供对称加密算法名，ALGORITHM
        2、提供静态方法，返回加密密钥和初始随机值（若算法不需要初始随机值，也需要提供）
        3、提供加密解密方法
    """
    ALGORITHM = _AES_GCM

    @staticmethod
    def get_key():
        return random_aes256_key()

    @staticmethod
    def get_start():
        return random_counter()

    def __init__(self, key=None, start=None):
        self.key = key
        if not self.key:
            self.key = random_aes256_key()
        if not start:
            self.start = random_counter()
        else:
            self.start = int(start)
        ctr = Counter.new(_AES_CTR_COUNTER_BITS_LEN, initial_value=self.start)
        self.__cipher = AES.new(self.key, AES.MODE_CTR, counter=ctr)

    def encrypt(self, raw):
        return self.__cipher.encrypt(raw)

    def decrypt(self, enc):
        return self.__cipher.decrypt(enc)


_STRPTIME_LOCK = threading.Lock()

_ISO8601_FORMAT = "%Y-%m-%dT%H:%M:%S.000Z"

# A regex to match HTTP Last-Modified header, whose format is 'Sat, 05 Dec 2015 11:10:29 GMT'.
# Its strftime/strptime format is '%a, %d %b %Y %H:%M:%S GMT'

_HTTP_GMT_RE = re.compile(
    r'(?:Mon|Tue|Wed|Thu|Fri|Sat|Sun), (?P<day>0[1-9]|([1-2]\d)|(3[0-1])) (?P<month>Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec) (?P<year>\d+) (?P<hour>([0-1]\d)|(2[0-3])):(?P<minute>[0-5]\d):(?P<second>[0-5]\d) GMT$'
)

_ISO8601_RE = re.compile(
    r'(?P<year>\d+)-(?P<month>01|02|03|04|05|06|07|08|09|10|11|12)-(?P<day>0[1-9]|([1-2]\d)|(3[0-1]))T(?P<hour>([0-1]\d)|(2[0-3])):(?P<minute>[0-5]\d):(?P<second>[0-5]\d)\.000Z$'
)

_MONTH_MAPPING = {
    'Jan': 1,
    'Feb': 2,
    'Mar': 3,
    'Apr': 4,
    'May': 5,
    'Jun': 6,
    'Jul': 7,
    'Aug': 8,
    'Sep': 9,
    'Oct': 10,
    'Nov': 11,
    'Dec': 12
}


def to_unixtime(time_string, format_string):
    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` 。
    """
    m = _HTTP_GMT_RE.match(time_string)

    if not m:
        raise ValueError(time_string + " is not in valid HTTP date format")

    day = int(m.group('day'))
    month = _MONTH_MAPPING[m.group('month')]
    year = int(m.group('year'))
    hour = int(m.group('hour'))
    minute = int(m.group('minute'))
    second = int(m.group('second'))

    tm = datetime.datetime(year, month, day, hour, minute, second).timetuple()

    return calendar.timegm(tm)


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。"""

    m = _ISO8601_RE.match(time_string)

    if not m:
        raise ValueError(time_string + " is not in valid ISO8601 format")

    day = int(m.group('day'))
    month = int(m.group('month'))
    year = int(m.group('year'))
    hour = int(m.group('hour'))
    minute = int(m.group('minute'))
    second = int(m.group('second'))

    tm = datetime.datetime(year, month, day, hour, minute, second).timetuple()

    return calendar.timegm(tm)


def date_to_iso8601(d):
    return d.strftime(_ISO8601_FORMAT)  # It's OK to use strftime, since _ISO8601_FORMAT is not locale dependent


def iso8601_to_date(time_string):
    timestamp = iso8601_to_unixtime(time_string)
    return datetime.date.fromtimestamp(timestamp)


def makedir_p(dirpath):
    try:
        os.makedirs(dirpath)
    except os.error as e:
        if e.errno != errno.EEXIST:
            raise


def silently_remove(filename):
    """删除文件，如果文件不存在也不报错。"""
    try:
        os.remove(filename)
    except OSError as e:
        if e.errno != errno.ENOENT:
            raise


def force_rename(src, dst):
    try:
        os.rename(src, dst)
    except OSError as e:
        if e.errno == errno.EEXIST:
            silently_remove(dst)
            os.rename(src, dst)
        else:
            raise


def copyfileobj_and_verify(fsrc, fdst, expected_len,
                           chunk_size=16*1024,
                           request_id=''):
    """copy data from file-like object fsrc to file-like object fdst, and verify length"""

    num_read = 0

    while 1:
        buf = fsrc.read(chunk_size)
        if not buf:
            break

        num_read += len(buf)
        fdst.write(buf)

    if num_read != expected_len:
        raise InconsistentError("IncompleteRead from source", request_id)