# -*- coding: utf-8 -*-
# vim:set expandtab tabstop=4 shiftwidth=4:
#
# The MIT License (MIT)
# LdapCherry
# Copyright (c) 2014 Carpentier Pierre-Francois

import cherrypy
import ldap
import ldap.modlist as modlist
import logging
import ldapcherry.backend
import os
import re


class DelUserDontExists(Exception):
    def __init__(self, user):
        self.user = user
        self.log = "cannot remove user, user <%(user)s> does not exist" % \
            {'user': user}


class CaFileDontExist(Exception):
    def __init__(self, cafile):
        self.cafile = cafile
        self.log = "CA file %(cafile)s don't exist" % {'cafile': cafile}

NO_ATTR = 0
DISPLAYED_ATTRS = 1
LISTED_ATTRS = 2
ALL_ATTRS = 3


class Backend(ldapcherry.backend.Backend):

    def __init__(self, config, logger, name, attrslist, key):
        self.config = config
        self._logger = logger
        self.backend_name = name
        self.binddn = self.get_param('binddn')
        self.bindpassword = self.get_param('password')
        self.ca = self.get_param('ca', False)
        self.checkcert = self.get_param('checkcert', 'on')
        self.starttls = self.get_param('starttls', 'off')
        self.uri = self.get_param('uri')
        self.timeout = self.get_param('timeout', 1)
        self.userdn = self.get_param('userdn')
        self.groupdn = self.get_param('groupdn')
        self.user_filter_tmpl = self.get_param('user_filter_tmpl')
        self.group_filter_tmpl = self.get_param('group_filter_tmpl')
        self.search_filter_tmpl = self.get_param('search_filter_tmpl')
        self.dn_user_attr = self.get_param('dn_user_attr')
        self.objectclasses = []
        self.key = key
        for o in re.split('\W+', self.get_param('objectclasses')):
            self.objectclasses.append(self._str(o))
        self.group_attrs = {}
        for param in config:
            name, sep, group = param.partition('.')
            if name == 'group_attr':
                self.group_attrs[group] = self.get_param(param)

        self.attrlist = []
        for a in attrslist:
            self.attrlist.append(self._str(a))

    def _exception_handler(self, e):
        et = type(e)
        if et is ldap.OPERATIONS_ERROR:
            self._logger(
                severity=logging.ERROR,
                msg="cannot use starttls with ldaps://"
                    " uri (uri: " + self.uri + ")",
            )
        elif et is ldap.INVALID_CREDENTIALS:
            self._logger(
                severity=logging.ERROR,
                msg="Configuration error, wrong credentials,"
                " unable to connect to ldap with '" + self.binddn + "'",
            )
        elif et is ldap.SERVER_DOWN:
            self._logger(
                severity=logging.ERROR,
                msg="Unable to contact ldap server '" +
                    self.uri +
                    "', check 'auth.ldap.uri'"
                    " and ssl/tls configuration",
                )
        elif et is ldap.FILTER_ERROR:
            self._logger(
                severity=logging.ERROR,
                msg="Bad search filter, check '" +
                    self.backend_name +
                    ".*_filter_tmpl' params",
                )
        elif et is ldap.NO_SUCH_OBJECT:
            self._logger(
                severity=logging.ERROR,
                msg="Search DN '" + basedn +
                    "' doesn't exist, check '" +
                    self.backend_name +
                    ".userdn' or '" +
                    self.backend_name +
                    ".groupdn'",
                )
        elif et is ldap.OBJECT_CLASS_VIOLATION:
            info = e[0]['info']
            desc = e[0]['desc']
            self._logger(
                severity=logging.ERROR,
                msg="Configuration error, " + desc + ", " + info,
                )
        elif et is ldap.INSUFFICIENT_ACCESS:
            self._logger(
                severity=logging.ERROR,
                msg="Access error on '" +
                    self.backend_name +
                    "' backend, please check your acls in this backend",
                )
        elif et is ldap.ALREADY_EXISTS:
            desc = e[0]['desc']
            self._logger(
                severity=logging.ERROR,
                msg="adding user failed, " + desc,
                )
        else:
            self._logger(
                severity=logging.ERROR,
                msg="unknow ldap exception in ldap backend",
                )
        raise e

    def _connect(self):
        ldap_client = ldap.initialize(self.uri)
        ldap.set_option(ldap.OPT_REFERRALS, 0)
        ldap.set_option(ldap.OPT_TIMEOUT, self.timeout)
        if self.starttls == 'on':
            ldap.set_option(ldap.OPT_X_TLS_DEMAND, True)
        else:
            ldap.set_option(ldap.OPT_X_TLS_DEMAND, False)
        if self.ca and self.checkcert == 'on':
            if os.path.isfile(self.ca):
                ldap.set_option(ldap.OPT_X_TLS_CACERTFILE, self.ca)
            else:
                raise CaFileDontExist(self.ca)
        if self.checkcert == 'off':
            # this is dark magic
            # remove any of these two lines and it doesn't work
            ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, ldap.OPT_X_TLS_NEVER)
            ldap_client.set_option(
                ldap.OPT_X_TLS_REQUIRE_CERT,
                ldap.OPT_X_TLS_NEVER
                )
        else:
            # this is even darker magic
            ldap_client.set_option(
                ldap.OPT_X_TLS_REQUIRE_CERT,
                ldap.OPT_X_TLS_DEMAND
                )
            # it doesn't make sense to set it to never
            # (== don't check certifate)
            # but it only works with this option...
            # ... and it checks the certificat
            # (I've lost my sanity over this)
            ldap.set_option(
                ldap.OPT_X_TLS_REQUIRE_CERT,
                ldap.OPT_X_TLS_NEVER
                )
        if self.starttls == 'on':
            try:
                ldap_client.start_tls_s()
            except Exception as e:
                self._exception_handler(e)
        return ldap_client

    def _bind(self):
        ldap_client = self._connect()
        try:
            ldap_client.simple_bind_s(self.binddn, self.bindpassword)
        except Exception as e:
            ldap_client.unbind_s()
            self._exception_handler(e)
        return ldap_client

    def _search(self, searchfilter, attrs, basedn):
        if attrs == NO_ATTR:
            attrlist = []
        elif attrs == DISPLAYED_ATTRS:
            # fix me later (to much attributes)
            attrlist = self.attrlist
        elif attrs == LISTED_ATTRS:
            attrlist = self.attrlist
        elif attrs == ALL_ATTRS:
            attrlist = None
        else:
            attrlist = None

        ldap_client = self._bind()
        try:
            r = ldap_client.search_s(
                basedn,
                ldap.SCOPE_SUBTREE,
                searchfilter,
                attrlist=attrlist
                )
        except Exception as e:
            ldap_client.unbind_s()
            self._exception_handler(e)

        ldap_client.unbind_s()
        return r

    def _get_user(self, username, attrs=ALL_ATTRS):

        user_filter = self.user_filter_tmpl % {
            'username': username
        }

        r = self._search(user_filter, attrs, self.userdn)

        if len(r) == 0:
            return None

        if attrs == NO_ATTR:
            dn_entry = r[0][0]
        else:
            dn_entry = r[0]
        return dn_entry

    def _str(self, s):
        return s.encode('utf-8')

    def _uni(self, s):
        return s.decode('utf-8')

    def auth(self, username, password):

        binddn = self._get_user(username, NO_ATTR)
        if binddn is not None:
            ldap_client = self._connect()
            try:
                ldap_client.simple_bind_s(binddn, password)
            except ldap.INVALID_CREDENTIALS:
                ldap_client.unbind_s()
                return False
            ldap_client.unbind_s()
            return True
        else:
            return False

    def add_user(self, attrs):
        ldap_client = self._bind()
        attrs_str = {}
        for a in attrs:
            attrs_str[self._str(a)] = self._str(attrs[a])
        attrs_str['objectClass'] = self.objectclasses
        dn = \
            self.dn_user_attr +\
            '=' +\
            attrs[self.dn_user_attr] +\
            ',' +\
            self.userdn
        ldif = modlist.addModlist(attrs_str)
        try:
            ldap_client.add_s(dn, ldif)
        except Exception as e:
            ldap_client.unbind_s()
            self._exception_handler(e)
        ldap_client.unbind_s()

    def del_user(self, username):
        ldap_client = self._bind()
        dn = self._get_user(username, NO_ATTR)
        if dn is not None:
            ldap_client.delete_s(dn)
        else:
            raise DelUserDontExists(username)
        ldap_client.unbind_s()

    def set_attrs(self, username, attrs):
        ldap_client = self._bind()
        tmp = self._get_user(username, ALL_ATTRS)
        dn = tmp[0]
        old_attrs = tmp[1]
        for attr in attrs:
            content = self._str(attrs[attr])
            attr = self._str(attr)
            new = {attr: content}
            if attr in old_attrs:
                old = {attr: old_attrs[attr]}
            else:
                old = {}
            ldif = modlist.modifyModlist(old, new)
            try:
                ldap_client.modify_s(dn, ldif)
            except Exception as e:
                ldap_client.unbind_s()
                self._exception_handler(e)

        ldap_client.unbind_s()

    def add_to_groups(self, username, groups):
        ldap_client = self._bind()
        tmp = self._get_user(username, ALL_ATTRS)
        dn = tmp[0]
        attrs = tmp[1]
        attrs['dn'] = dn
        for group in groups:
            group = self._str(group)
            for attr in self.group_attrs:
                content = self._str(self.group_attrs[attr] % attrs)
                self._logger(
                    severity=logging.DEBUG,
                    msg="%(backend)s: adding user '%(user)s'"
                        " with dn '%(dn)s' to group '%(group)s' by"
                        " setting '%(attr)s' to '%(content)s'" % {
                            'user': username,
                            'dn': dn,
                            'group': group,
                            'attr': attr,
                            'content': content,
                            'backend': self.backend_name
                            }
                )
                ldif = modlist.modifyModlist({}, {attr: content})
                try:
                    ldap_client.modify_s(group, ldif)
                except ldap.TYPE_OR_VALUE_EXISTS as e:
                    self._logger(
                        severity=logging.INFO,
                        msg="%(backend)s: user '%(user)s'"
                            " already member of group '%(group)s'"
                            "(attribute '%(attr)s')" % {
                                'user': username,
                                'group': group,
                                'attr': attr,
                                'backend': self.backend_name
                                }
                    )
                except Exception as e:
                    ldap_client.unbind_s()
                    self._exception_handler(e)
        ldap_client.unbind_s()

    def del_from_groups(self, username, groups):
        ldap_client = self._bind()
        tmp = self._get_user(username, ALL_ATTRS)
        dn = tmp[0]
        attrs = tmp[1]
        attrs['dn'] = dn
        for group in groups:
            group = self._str(group)
            for attr in self.group_attrs:
                content = self._str(self.group_attrs[attr] % attrs)
                ldif = [(ldap.MOD_DELETE, attr, content)]
                try:
                    ldap_client.modify_s(group, ldif)
                except ldap.NO_SUCH_ATTRIBUTE as e:
                    self._logger(
                        severity=logging.INFO,
                        msg="%(backend)s: user '%(user)s'"
                        " wasn't member of group '%(group)s'"
                        " (attribute '%(attr)s')" % {
                            'user': username,
                            'group': group,
                            'attr': attr,
                            'backend': self.backend_name
                            }
                    )
                except Exception as e:
                    ldap_client.unbind_s()
                    self._exception_handler(e)
        ldap_client.unbind_s()

    def search(self, searchstring):
        ret = {}

        searchfilter = self.search_filter_tmpl % {
            'searchstring': searchstring
        }
        for u in self._search(searchfilter, DISPLAYED_ATTRS, self.userdn):
            attrs = {}
            attrs_tmp = u[1]
            for attr in attrs_tmp:
                value_tmp = attrs_tmp[attr]
                if len(value_tmp) == 1:
                    attrs[attr] = self._uni(value_tmp[0])
                else:
                    attrs[attr] = map(self._uni, value_tmp)

            if self.key in attrs:
                ret[attrs[self.key]] = attrs
        return ret

    def get_user(self, username):
        ret = {}
        attrs_tmp = self._get_user(username, ALL_ATTRS)[1]
        for attr in attrs_tmp:
            value_tmp = attrs_tmp[attr]
            if len(value_tmp) == 1:
                ret[attr] = self._uni(value_tmp[0])
            else:
                ret[attr] = map(self._uni, value_tmp)
        return ret

    def get_groups(self, username):
        userdn = self._get_user(username, NO_ATTR)

        searchfilter = self.group_filter_tmpl % {
            'userdn': userdn,
            'username': username
        }

        groups = self._search(searchfilter, NO_ATTR, self.groupdn)
        ret = []
        for entry in groups:
            ret.append(self._uni(entry[0]))
        return ret