Vkontakte API client for Python

# -*- coding: utf-8 -*-
# @author: noname <tz4678@gmail.com>
# @description: модуль для работы с API Вконтакте
# полный список методов API можно увидеть здесь https://vk.com/dev/methods
import sys
import urllib
import json
from formdata import *
import urllib2

class NeedCaptchaError(Exception):
    def __init__(self, captcha_img, captcha_sid):
        self.captcha_img = captcha_img
        self.captcha_sid = captcha_sid

class AuthorizationError(Exception):
    def __init__(self, error, error_description):
        super(AuthorizationError, self).__init__('%s. Error Description: %s' % (error, error_description))
        self.error = error
        self.error_description = error_description

class ApiError(Exception):
    def __init__(self, error_code, error_msg):
        super(ApiError, self).__init__('%s. Error Code: %s' % (error_msg, error_code))
        self.error_code = error_code
        self.error_msg = error_msg

class VkClient(object):
    def __init__(self, client_id = '', client_secret = '', permissions = '', api_version = '', **kwargs):
        self.client_id = kwargs.get('client_id', client_id)
        self.client_secret = kwargs.get('client_secret', client_secret)
        self.permissions = kwargs.get('permissions', permissions)
        self.api_version = kwargs.get('api_version', api_version)
        self.user_agent = 'VkClient (Python %s.%s.%s)' % sys.version_info[:3]
        self.user_id = None
        self.access_token = None

    def auth(self, username, password, captcha_sid = '', captcha_key = ''):
        params = {
            'username': username,
            'password': password,
            'captcha_sid': captcha_sid,
            'captcha_key': captcha_key,
            'client_id': self.client_id,
            'client_secret': self.client_secret,
            'scope': self.permissions,
            'v': self.api_version,
            'grant_type': 'password'
        }
        request = urllib2.Request('https://oauth.vk.com/token?' + urllib.urlencode(params), headers = {'User-Agent': self.user_agent})
        response = urllib2.urlopen(request);
        content = response.read().decode('utf-8')
        result = json.loads(content)
        # print result
        if 'error' in result:
            if result['error'] == 'need_captcha':
                raise NeedCaptchaError(result['captcha_img'], result['captcha_sid'])
            raise AuthorizationError(result['error'], result.get('error_description', ''))
        self.user_id = result['user_id']
        self.access_token = result['access_token']

    def raw_api(self, rel_uri, fields = {}, files = {}, **kwargs):
        fields = kwargs.get('fields', fields)
        files = kwargs.get('files', files)
        headers = {}
        for k, v in fields.items():
            if type(v) == unicode:
                fields[k] = v.encode('utf-8')
        if len(files):
            body, headers = encode_multipart(fields, files)
        elif len(fields):
            headers = {'Content-Type': 'application/x-www-form-urlencoded'}
            body = urllib.urlencode(fields)
        else:
            body = None
        # print body
        headers['User-Agent'] = self.user_agent
        request = urllib2.Request('https://api.vk.com/method/' + rel_uri, body, headers)
        response = urllib2.urlopen(request)
        content = response.read().decode('utf-8')
        result = json.loads(content)
        # print result
        if 'error' in result:
            error = result['error']
            if error['error_code'] == 14:
                raise NeedCaptchaError(error['captcha_img'], error['captcha_sid'])
            raise ApiError(error['error_code'], error['error_msg'])
        return result['response']

    def api(self, rel_uri, fields = {}, files = {}, **kwargs):
        fields = kwargs.get('fields', fields)
        files = kwargs.get('files', files)
        # автоматически добавляем к запросу токен и версию
        fields['access_token'] = self.access_token
        fields['v'] = self.api_version
        return self.raw_api(rel_uri, fields, files)

if __name__ == '__main__':
    client = VkClient()
    print client.raw_api('users.get', {'user_ids': '205387401', 'fields': 'photo_50,city,verified', 'name_case': 'Nom', 'v': '5.3'})