#!/usr/bin/python2.6
# $Id$
"MediaWiki communication functions"
import datetime
import re

from authkit.users import UsersReadOnly, md5, AuthKitError
import formencode, formencode.national

import logging
log = logging.getLogger(__name__)

import wradmin.model as model
import wradmin.model.validators


# User management
# ---------------

class MediaWikiUsers(UsersReadOnly):
    def __init__(self, data=None, encrypt=None):
        UsersReadOnly.__init__(self, data, encrypt)

        # Initialize class fields
        self.usernames = []
        self.passwords = {}
        self.roles = {}
        self.groups = {}
        self.user_ids = {} # MediaWiki user_id field of the database
        self.real_names = {} # Real names of the users
        self.emails = {} # E-Mail addresses of the users
        
        # Query database
        con = model.meta.engine.connect()
        sql = "SELECT user_id, user_name, user_real_name, user_password, user_email FROM user, user_groups WHERE ug_user=user_id AND ug_group='beauftragte'"
        result = con.execute(sql)
        for row in result:
            user_id, username, real_name, password, email = row
            username = username.lower()
            role = []
            group = None
            
            self.usernames.append(username)
            self.passwords[username] = password
            self.roles[username] = role
            self.groups[username] = group
            self.user_ids[username] = user_id
            self.real_names[username] = real_name
            self.emails[username] = email
        con.close()
        log.info("%d users loaded from the MediaWiki database" % len(self.usernames))
    
    @staticmethod
    def password_is_correct(password_plain, password_db):
        """Returns true if a plain text password corresponds to the hash of the password as stored in the MediaWiki db.

        :param password_plain: plain text password, e.g. 'abc'
        :param password_db: complete password line as stored in the database, e.g. ':pbkdf2:sha256:10000:128:EXgVGhc2mAs710feKvkiaw==:J5fYth9pg/R2d0F8bSsYfTR8SBpTBNIcdv/DgJ0tOPC1rtajl2Dr0RLqOozLb8O0XpDhtv4a3JJd/M0b58WebfNWAcdJBJI9nNeC0EYYD7OCYZGVAaRhiYtK4m53KZBBL6x/k2j4RjHPT1NmgV8Fr1DPqBNOlOHxUIh5z5oslM4='
        """
        if not password_db.startswith(':'):
            raise AuthKitError("Password entry in the database does have an unexpected format (does not start with ':').")
        pwd_parts = password_db[1:].split(':')
        pwd_type = pwd_parts[0]
        if pwd_type == 'B':
            # legacy
            # example: password_db == ':B:d25b2886:41e46c952790b1b442aac4f24f7ea7a8'
            # pwd_parts == ['B', 'd25b2886', '41e46c952790b1b442aac4f24f7ea7a8']
            if len(pwd_parts) != 3:
                raise AuthKitError("Password entry in the database does have an unexpected format (too few ':').")
            salt, pwd_md5 = tuple(pwd_parts[1:3]) # salt = 'd25b2886'; pwd_md5 = '41e46c952790b1b442aac4f24f7ea7a8'
            # log.info("user: '%s'; md5 of salt+' '+entered_pwd: '%s'; md5-part of DB-pwd: %s" % (username, md5(salt + '-' + md5(password)), pwd_md5))
            return md5(salt + '-' + md5(password_plain)) == pwd_md5
        elif pwd_type == 'pbkdf2':
            if len(pwd_parts) != 6:
                raise AuthKitError("Password entry in the database does have an unexpected format (too few ':').")
            _, algorithm, rounds, num_bit, salt, pwd_hash = pwd_parts
            from base64 import b64decode, b64encode
            from hashlib import pbkdf2_hmac
            salt = b64decode(salt)
            hash = pbkdf2_hmac(algorithm, password_plain, salt, int(rounds), int(num_bit))
            hash = b64encode(hash)
            return hash == pwd_hash


    def user_has_password(self, username, password):
        """
        Passwords are case sensitive.
        Returns ``True`` if the user has the password specified, ``False`` otherwise.
        Raises an exception if the user doesn't exist.

        See http://www.winterrodeln.org/trac/wiki/MediaWikiAuthorization
        """
        password_db = self.user_password(username)
        return self.password_is_correct(password, password_db)