# -*- coding: utf-8 -*-
import ldap
from utils import Service
from uuid import uuid4


SERVICES = [
    #Service('foren', 'Foren', 'http://foren.spline.de/'),
    #Service('jabber', 'Jabber', 'http://jabber.spline.de/'),
    Service('gitlab', 'Gitlab', 'https://gitlab.spline.inf.fu-berlin.de/'),
    Service('osqa', 'OS Q&A', 'http://osqa.spline.de/'),
]



class AccountService:
    """
      To simplify account management through ldap this class can be used.
      The AccountService class is stateless. It means that every request needs
      its own authentication request (bind).

      To test you stuff against our test setup use Port-Forwarding
        ssh spline -L 5678:vm-account:389 -N

      * register a new user
        >> service = AccountService(LDAP_HOST, LDAP_BASE_DN, ADMIN_USER, ADMIN_PW, SERVICES)
        >> foo = Account('foo','foo@bar.de', password='bar')
        >> service.register(foo)

      * authenticate a new user
        >> service = AccountService(LDAP_HOST, LDAP_BASE_DN, ADMIN_USER, ADMIN_PW, SERVICES)
        >> foo = service.auth('foo', 'bar')

      * updates an account
        >> foo.change_mail('a@b.de')
        >> foo.change_password('newpw','oldpw')           # changes root password
        >> foo.change_password('newpw','oldpw', 'gitlab') # changes password for gitlab
        >> service.update(foo)                            # save changes in ldap backend
        # save changes in ldap backend as admin user (no need for old password)
        >> service.update(foo, as_admin=True)

      * delete an account
        >> service = AccountService(LDAP_HOST, LDAP_BASE_DN, LDAP_ADMIN_USER, LDAP_ADMIN_PASS, SERVICES)
        >> service.delete(Account)
        >> service.delete('foo')

      * find accounts
        >> service = AccountService(LDAP_HOST, LDAP_BASE_DN, LDAP_ADMIN_USER, LDAP_ADMIN_PASS, SERVICES)
        >> all_accounts = service.find()         # find all accounts
        >> print([x.uid for x in all_accounts])
        >> service.find_by_uid('test')           # find users by uid
        >> service.get_by_uid('test')            # same, raise NoSuchUserError if no match
        >> service.find_by_mail('test@test.de')  # find users by mail
        >> service.find_by_uid('test*', wildcard=True) # find with wildcards

    """
    def __init__(self, ldap_host, base_dn, admin_user, admin_pass, services):
        self.ldap_host  = ldap_host
        self.base_dn    = base_dn
        self.admin_user = admin_user
        self.admin_pass = admin_pass
        self.services   = services
        self.admin      = False
        self.binded     = False


    def auth(self, username, password):
        """
          Tries to authenticate a user with a given password. If the
          authentication is successful an Account object will be returned.
        """

        self._bind_anonymous()
        dn = self._format_dn([('uid', username), ('ou','users')])
        dn_user, data_user = self.connection.search_s(dn, ldap.SCOPE_SUBTREE)[0]

        self._bind_as_user(username, password)
        uid = data_user['uid'][0]
        mail = data_user['mail'][0]

        dn = self._format_dn([('ou', 'services')])
        filterstr = '(uid=%s)' % self._escape(uid)
        data_service = self.connection.search_s(dn, ldap.SCOPE_SUBTREE, filterstr)

        services = []
        for entry in data_service:
            cn = filter(lambda x: x.startswith('cn='), entry[0].split(','))[0]
            services.append(cn.split('=')[-1])

        acc = Account(uid, mail, services, dn_user, password)

        self._unbind()

        return acc

    def get_by_uid(self, uid):
        """
        Find a single user by uid. Unlike find_by_uid, don't return a list but
        raise NoSuchUserError if there is no such user.
        """
        users = self.find_by_uid(uid)
        if len(users) != 1:
            raise NoSuchUserError('No such user')

        return users[0]

    def get_by_mail(self, mail):
        """
        Find a single user by mail. Unlike find_by_mail, don't return a list but
        raise NoSuchUserError if there is no such user.
        """
        users = self.find_by_mail(mail)
        if len(users) != 1:
            raise NoSuchUserError('No such user')

        return users[0]

    def find_by_uid(self, uid, wildcard=False):
        return self.find({'uid': uid}, wildcard)

    def find_by_mail(self, mail, wildcard=False):
        return self.find({'mail': mail}, wildcard)

    def find(self, filters={}, wildcard=False):
        """
          Find accounts by a given filter with key:value semantic)
        """
        self._bind_anonymous()

        filters['objectClass'] = 'inetOrgPerson'


        filter_as_list = ['(%s=%s)' % (k,self._escape(v, wildcard)) for k,v in filters.items()]
        filterstr = ''.join(filter_as_list)
        if len(filter_as_list) > 1:
            filterstr = '(&%s)' % filterstr

        dn = self._format_dn([('ou','users')])
        data = self.connection.search_s(dn, ldap.SCOPE_SUBTREE, filterstr)

        accounts = []
        for a in data:
            accounts.append(Account(a[1]['uid'][0], a[1]['mail'][0]))

        self._unbind()

        return accounts


    def register(self, account):
        """
          Persists an account in the ldap backend
        """
        self._bind_as_admin()

        dn = self._format_dn([('uid', account.uid),('ou','users')])
        attr =  [
            ('objectClass', ['top','inetOrgPerson']),
            ('uid', self._escape(account.uid)), ('sn', ' '), ('cn', ' '),
            ('mail', account.mail)
        ]
        self.connection.add_s(dn, attr)
        account.dn = dn

        account.new_password_root = (None, account.password)
        self._alter_passwords(account)

        self._unbind()


    def update(self, account, as_admin=False):
        """
          Updates account informations like passwords or email.
        """
        if as_admin:
            self._bind_as_admin()
        else:
            self._bind_as_user(account.uid, account.password)

        attr = [(ldap.MOD_REPLACE, 'mail', account.mail)]
        dn = self._format_dn([('uid',account.uid),('ou','users')])
        self.connection.modify_s(dn, attr)
        self._alter_passwords(account, as_admin=as_admin)

        self._unbind()


    def delete(self, account, password=None, as_admin=False):
        """
          Deletes an account permanently.
        """

        if isinstance(account, basestring):
            raise NotImplementedError()
        else:
            user = account.uid
            password = account.password

        if as_admin:
            self._bind_as_admin()
        else:
            self._bind_as_user(user, password)

        dn = [self._format_dn([('uid',user),('cn',s),('ou','services')]) for s.id in account.services]
        dn.append(self._format_dn([('uid', user), ('ou','users')]))

        for x in dn:
            self.connection.delete_s(x)

        self._unbind()

    def _format_dn(self, attr, with_base_dn = True):
        if with_base_dn:
          attr.extend(self.base_dn)

        dn = ['%s=%s' % (item[0], self._escape(item[1])) for item in attr]

        return ','.join(dn)

    def _bind(self, dn, password):
        self.connection = ldap.initialize(self.ldap_host)
        self.connection.version = ldap.VERSION3

        self.connection.simple_bind_s(dn, password)

    def _bind_as_admin(self):
        if self.binded:
          self._unbind()

        dn = self._format_dn([('cn', self.admin_user)])
        self._bind(dn, self.admin_pass)

        self.admin = True
        self.binded = True

    def _bind_as_user(self, username, password):
        if self.binded:
          self._unbind()

        dn = self._format_dn([('uid', username),('ou', 'users')])
        self._bind(dn, password)

        self.binded = True
        self.admin = True

    def _bind_anonymous(self):
        if self.binded:
          self._unbind()

        self._bind('','')

        self.binded = True


    def _unbind(self):
        self.connection.unbind_s()
        self.admin = False
        self.binded = False


    def _alter_passwords(self, account, as_admin=False):
        if account.new_password_root:
            dn = self._format_dn([('uid',account.uid),('ou','users')])
            old, new = account.new_password_root
            if as_admin:
                self.connection.passwd_s(dn, None, new)
            else:
                try:
                    self.connection.passwd_s(dn, old, new)
                except ldap.UNWILLING_TO_PERFORM:
                    raise InvalidPasswordError()

            account.password = new

        account.new_password_root = None

        for service, passwords in account.new_password_services.items():
            dn = self._format_dn([('uid',account.uid),('cn',service),('ou','services')])
            old, new = passwords

            if new != None:
                if service not in account.services:
                    attr = [('objectClass', ['top', 'servicePassword']), ('uid', account.uid)]
                    self.connection.add_s(dn, attr)

                if as_admin:
                    self.connection.passwd_s(dn, None, new)
                else:
                    self.connection.passwd_s(dn, old, new)

            else:
                s = service.lower()
                if s in account.services:
                    self.connection.delete_s(dn)
                    account.services.remove(s)

        account.new_password_services = {}

    def _escape(self, s, wildcard=False):
        chars_to_escape = ['\\',',','=','+','<','>',';','"','\'','#','(',')','\0']

        if not wildcard:
          chars_to_escape.append('*')

        escape = lambda x,y: x.replace(y,'\%02X' % ord(y))

        return reduce(escape, chars_to_escape, s)




class Account:
    """
      An Account represents a complex ldap tree entry for spline users.
      For each service a spline user can have a different password.
    """
    def __init__(self, uid, mail, services=[], dn=None, password=None):
        self.uid = uid.encode('utf8') if isinstance(uid, unicode) else uid
        self.mail = mail.encode('utf8') if isinstance(mail, unicode) else mail
        self.services = services
        self.dn = dn
        self.password = password.encode('utf8') if isinstance(password, unicode) else password
        self.new_password_root = None
        self.new_password_services = {}


    def __repr__(self):
        return "<Account uid=%s>" % self.uid


    def reset_password(self, service):
         self.new_password_services[service] = (None, None)

    def change_password(self, new_password, old_password='', service=None):
        """
          Changes a password for a given service. You have to use the
          AccountService class to make the changes permanent. If no service is
          given, the root password will be changed.
        """
        if isinstance(new_password, unicode):
            new_password = new_password.encode('utf8')

        if isinstance(old_password, unicode):
            old_password = old_password.encode('utf8')

        if not service:
            self.new_password_root = (old_password, new_password)
        else:
            self.new_password_services[service] = (old_password, new_password)


    def change_email(self, new_mail):
        """
          Changes the mail address of an account. You have to use the
          AccountService class to make changes permanent.
        """
        if isinstance(new_mail, unicode):
            new_mail = new_mail.encode('utf8')

        self.mail = new_mail


class NoSuchUserError(ValueError):
    pass

class InvalidPasswordError(ldap.INVALID_CREDENTIALS):
    pass