# -*- coding: utf-8 -*-
"""
    rhodecode.lib.auth
    ~~~~~~~~~~~~~~~~~~
    
    authentication and permission libraries
    
    :created_on: Apr 4, 2010
    :copyright: (c) 2010 by marcink.
    :license: LICENSE_NAME, see LICENSE_FILE for more details.
"""
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; version 2
# of the License or (at your opinion) any later version of the license.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
# MA  02110-1301, USA.

import bcrypt
import random
import logging
import traceback

from decorator import decorator

from pylons import config, session, url, request
from pylons.controllers.util import abort, redirect

from rhodecode.lib.exceptions import LdapPasswordError, LdapUsernameError
from rhodecode.lib.utils import get_repo_slug
from rhodecode.lib.auth_ldap import AuthLdap

from rhodecode.model import meta
from rhodecode.model.user import UserModel
from rhodecode.model.db import User, RepoToPerm, Repository, Permission, \
    UserToPerm, UsersGroupToPerm, UsersGroupMember


log = logging.getLogger(__name__)


PERM_WEIGHTS = {'repository.none':0,
                'repository.read':1,
                'repository.write':3,
                'repository.admin':3}


class PasswordGenerator(object):
    """This is a simple class for generating password from
        different sets of characters
        usage:
        passwd_gen = PasswordGenerator()
        #print 8-letter password containing only big and small letters of alphabet
        print passwd_gen.gen_password(8, passwd_gen.ALPHABETS_BIG_SMALL)        
    """
    ALPHABETS_NUM = r'''1234567890'''#[0]
    ALPHABETS_SMALL = r'''qwertyuiopasdfghjklzxcvbnm'''#[1]
    ALPHABETS_BIG = r'''QWERTYUIOPASDFGHJKLZXCVBNM'''#[2]
    ALPHABETS_SPECIAL = r'''`-=[]\;',./~!@#$%^&*()_+{}|:"<>?'''    #[3]
    ALPHABETS_FULL = ALPHABETS_BIG + ALPHABETS_SMALL + ALPHABETS_NUM + ALPHABETS_SPECIAL#[4]
    ALPHABETS_ALPHANUM = ALPHABETS_BIG + ALPHABETS_SMALL + ALPHABETS_NUM#[5]
    ALPHABETS_BIG_SMALL = ALPHABETS_BIG + ALPHABETS_SMALL
    ALPHABETS_ALPHANUM_BIG = ALPHABETS_BIG + ALPHABETS_NUM#[6]
    ALPHABETS_ALPHANUM_SMALL = ALPHABETS_SMALL + ALPHABETS_NUM#[7]

    def __init__(self, passwd=''):
        self.passwd = passwd

    def gen_password(self, len, type):
        self.passwd = ''.join([random.choice(type) for _ in xrange(len)])
        return self.passwd


def get_crypt_password(password):
    """Cryptographic function used for password hashing based on pybcrypt
    
    :param password: password to hash
    """
    return bcrypt.hashpw(password, bcrypt.gensalt(10))

def check_password(password, hashed):
    return bcrypt.hashpw(password, hashed) == hashed

def authfunc(environ, username, password):
    """Dummy authentication function used in Mercurial/Git/ and access control,
    
    :param environ: needed only for using in Basic auth
    """
    return authenticate(username, password)


def authenticate(username, password):
    """Authentication function used for access control,
    firstly checks for db authentication then if ldap is enabled for ldap
    authentication, also creates ldap user if not in database
    
    :param username: username
    :param password: password
    """
    user_model = UserModel()
    user = user_model.get_by_username(username, cache=False)

    log.debug('Authenticating user using RhodeCode account')
    if user is not None and not user.ldap_dn:
        if user.active:

            if user.username == 'default' and user.active:
                log.info('user %s authenticated correctly as anonymous user',
                         username)
                return True

            elif user.username == username and check_password(password, user.password):
                log.info('user %s authenticated correctly', username)
                return True
        else:
            log.warning('user %s is disabled', username)

    else:
        log.debug('Regular authentication failed')
        user_obj = user_model.get_by_username(username, cache=False,
                                            case_insensitive=True)

        if user_obj is not None and not user_obj.ldap_dn:
            log.debug('this user already exists as non ldap')
            return False

        from rhodecode.model.settings import SettingsModel
        ldap_settings = SettingsModel().get_ldap_settings()

        #======================================================================
        # FALLBACK TO LDAP AUTH IF ENABLE                
        #======================================================================
        if ldap_settings.get('ldap_active', False):
            log.debug("Authenticating user using ldap")
            kwargs = {
                  'server':ldap_settings.get('ldap_host', ''),
                  'base_dn':ldap_settings.get('ldap_base_dn', ''),
                  'port':ldap_settings.get('ldap_port'),
                  'bind_dn':ldap_settings.get('ldap_dn_user'),
                  'bind_pass':ldap_settings.get('ldap_dn_pass'),
                  'use_ldaps':ldap_settings.get('ldap_ldaps'),
                  'tls_reqcert':ldap_settings.get('ldap_tls_reqcert'),
                  'ldap_filter':ldap_settings.get('ldap_filter'),
                  'search_scope':ldap_settings.get('ldap_search_scope'),
                  'attr_login':ldap_settings.get('ldap_attr_login'),
                  'ldap_version':3,
                  }
            log.debug('Checking for ldap authentication')
            try:
                aldap = AuthLdap(**kwargs)
                (user_dn, ldap_attrs) = aldap.authenticate_ldap(username, password)
                log.debug('Got ldap DN response %s', user_dn)

                user_attrs = {
                    'name'     : ldap_attrs[ldap_settings.get('ldap_attr_firstname')][0],
                    'lastname' : ldap_attrs[ldap_settings.get('ldap_attr_lastname')][0],
                    'email'    : ldap_attrs[ldap_settings.get('ldap_attr_email')][0],
                    }

                if user_model.create_ldap(username, password, user_dn, user_attrs):
                    log.info('created new ldap user %s', username)

                return True
            except (LdapUsernameError, LdapPasswordError,):
                pass
            except (Exception,):
                log.error(traceback.format_exc())
                pass
    return False

class  AuthUser(object):
    """A simple object that handles a mercurial username for authentication
    """

    def __init__(self):
        self.username = 'None'
        self.name = ''
        self.lastname = ''
        self.email = ''
        self.user_id = None
        self.is_authenticated = False
        self.is_admin = False
        self.permissions = {}

    def __repr__(self):
        return "<AuthUser('id:%s:%s')>" % (self.user_id, self.username)

def set_available_permissions(config):
    """This function will propagate pylons globals with all available defined
    permission given in db. We don't want to check each time from db for new 
    permissions since adding a new permission also requires application restart
    ie. to decorate new views with the newly created permission
    
    :param config: current pylons config instance
    
    """
    log.info('getting information about all available permissions')
    try:
        sa = meta.Session()
        all_perms = sa.query(Permission).all()
    except:
        pass
    finally:
        meta.Session.remove()

    config['available_permissions'] = [x.permission_name for x in all_perms]

def fill_perms(user):
    """Fills user permission attribute with permissions taken from database
    works for permissions given for repositories, and for permissions that
    as part of beeing group member
    
    :param user: user instance to fill his perms
    """

    sa = meta.Session()
    user.permissions['repositories'] = {}
    user.permissions['global'] = set()

    #===========================================================================
    # fetch default permissions
    #===========================================================================
    default_user = UserModel().get_by_username('default', cache=True)

    default_perms = sa.query(RepoToPerm, Repository, Permission)\
        .join((Repository, RepoToPerm.repository_id == Repository.repo_id))\
        .join((Permission, RepoToPerm.permission_id == Permission.permission_id))\
        .filter(RepoToPerm.user == default_user).all()

    if user.is_admin:
        #=======================================================================
        # #admin have all default rights set to admin        
        #=======================================================================
        user.permissions['global'].add('hg.admin')

        for perm in default_perms:
            p = 'repository.admin'
            user.permissions['repositories'][perm.RepoToPerm.repository.repo_name] = p

    else:
        #=======================================================================
        # set default permissions
        #=======================================================================

        #default global
        default_global_perms = sa.query(UserToPerm)\
            .filter(UserToPerm.user == sa.query(User)\
                   .filter(User.username == 'default').one())

        for perm in default_global_perms:
            user.permissions['global'].add(perm.permission.permission_name)

        #default for repositories
        for perm in default_perms:
            if perm.Repository.private and not perm.Repository.user_id == user.user_id:
                #disable defaults for private repos,
                p = 'repository.none'
            elif perm.Repository.user_id == user.user_id:
                #set admin if owner
                p = 'repository.admin'
            else:
                p = perm.Permission.permission_name

            user.permissions['repositories'][perm.RepoToPerm.repository.repo_name] = p

        #=======================================================================
        # overwrite default with user permissions if any
        #=======================================================================
        user_perms = sa.query(RepoToPerm, Permission, Repository)\
            .join((Repository, RepoToPerm.repository_id == Repository.repo_id))\
            .join((Permission, RepoToPerm.permission_id == Permission.permission_id))\
            .filter(RepoToPerm.user_id == user.user_id).all()

        for perm in user_perms:
            if perm.Repository.user_id == user.user_id:#set admin if owner
                p = 'repository.admin'
            else:
                p = perm.Permission.permission_name
            user.permissions['repositories'][perm.RepoToPerm.repository.repo_name] = p


        #=======================================================================
        # check if user is part of groups for this repository and fill in 
        # (or replace with higher) permissions
        #=======================================================================
        user_perms_from_users_groups = sa.query(UsersGroupToPerm, Permission, Repository,)\
            .join((Repository, UsersGroupToPerm.repository_id == Repository.repo_id))\
            .join((Permission, UsersGroupToPerm.permission_id == Permission.permission_id))\
            .join((UsersGroupMember, UsersGroupToPerm.users_group_id == UsersGroupMember.users_group_id))\
            .filter(UsersGroupMember.user_id == user.user_id).all()

        for perm in user_perms_from_users_groups:
            p = perm.Permission.permission_name
            cur_perm = user.permissions['repositories'][perm.UsersGroupToPerm.repository.repo_name]
            #overwrite permission only if it's greater than permission given from other sources
            if PERM_WEIGHTS[p] > PERM_WEIGHTS[cur_perm]:
                user.permissions['repositories'][perm.UsersGroupToPerm.repository.repo_name] = p

    meta.Session.remove()
    return user

def get_user(session):
    """Gets user from session, and wraps permissions into user
    
    :param session:
    """
    user = session.get('rhodecode_user', AuthUser())
    #if the user is not logged in we check for anonymous access
    #if user is logged and it's a default user check if we still have anonymous
    #access enabled
    if user.user_id is None or user.username == 'default':
        anonymous_user = UserModel().get_by_username('default', cache=True)
        if anonymous_user.active is True:
            #then we set this user is logged in
            user.is_authenticated = True
            user.user_id = anonymous_user.user_id
        else:
            user.is_authenticated = False

    if user.is_authenticated:
        user = UserModel().fill_data(user)

    user = fill_perms(user)
    session['rhodecode_user'] = user
    session.save()
    return user

#===============================================================================
# CHECK DECORATORS
#===============================================================================
class LoginRequired(object):
    """Must be logged in to execute this function else 
    redirect to login page"""

    def __call__(self, func):
        return decorator(self.__wrapper, func)

    def __wrapper(self, func, *fargs, **fkwargs):
        user = session.get('rhodecode_user', AuthUser())
        log.debug('Checking login required for user:%s', user.username)
        if user.is_authenticated:
            log.debug('user %s is authenticated', user.username)
            return func(*fargs, **fkwargs)
        else:
            log.warn('user %s not authenticated', user.username)

            p = ''
            if request.environ.get('SCRIPT_NAME') != '/':
                p += request.environ.get('SCRIPT_NAME')

            p += request.environ.get('PATH_INFO')
            if request.environ.get('QUERY_STRING'):
                p += '?' + request.environ.get('QUERY_STRING')

            log.debug('redirecting to login page with %s', p)
            return redirect(url('login_home', came_from=p))

class NotAnonymous(object):
    """Must be logged in to execute this function else 
    redirect to login page"""

    def __call__(self, func):
        return decorator(self.__wrapper, func)

    def __wrapper(self, func, *fargs, **fkwargs):
        user = session.get('rhodecode_user', AuthUser())
        log.debug('Checking if user is not anonymous')

        anonymous = user.username == 'default'

        if anonymous:
            p = ''
            if request.environ.get('SCRIPT_NAME') != '/':
                p += request.environ.get('SCRIPT_NAME')

            p += request.environ.get('PATH_INFO')
            if request.environ.get('QUERY_STRING'):
                p += '?' + request.environ.get('QUERY_STRING')
            return redirect(url('login_home', came_from=p))
        else:
            return func(*fargs, **fkwargs)

class PermsDecorator(object):
    """Base class for decorators"""

    def __init__(self, *required_perms):
        available_perms = config['available_permissions']
        for perm in required_perms:
            if perm not in available_perms:
                raise Exception("'%s' permission is not defined" % perm)
        self.required_perms = set(required_perms)
        self.user_perms = None

    def __call__(self, func):
        return decorator(self.__wrapper, func)


    def __wrapper(self, func, *fargs, **fkwargs):
#        _wrapper.__name__ = func.__name__
#        _wrapper.__dict__.update(func.__dict__)
#        _wrapper.__doc__ = func.__doc__
        self.user = session.get('rhodecode_user', AuthUser())
        self.user_perms = self.user.permissions
        log.debug('checking %s permissions %s for %s %s',
           self.__class__.__name__, self.required_perms, func.__name__,
               self.user)

        if self.check_permissions():
            log.debug('Permission granted for %s %s', func.__name__, self.user)

            return func(*fargs, **fkwargs)

        else:
            log.warning('Permission denied for %s %s', func.__name__, self.user)
            #redirect with forbidden ret code
            return abort(403)



    def check_permissions(self):
        """Dummy function for overriding"""
        raise Exception('You have to write this function in child class')

class HasPermissionAllDecorator(PermsDecorator):
    """Checks for access permission for all given predicates. All of them 
    have to be meet in order to fulfill the request
    """

    def check_permissions(self):
        if self.required_perms.issubset(self.user_perms.get('global')):
            return True
        return False


class HasPermissionAnyDecorator(PermsDecorator):
    """Checks for access permission for any of given predicates. In order to 
    fulfill the request any of predicates must be meet
    """

    def check_permissions(self):
        if self.required_perms.intersection(self.user_perms.get('global')):
            return True
        return False

class HasRepoPermissionAllDecorator(PermsDecorator):
    """Checks for access permission for all given predicates for specific 
    repository. All of them have to be meet in order to fulfill the request
    """

    def check_permissions(self):
        repo_name = get_repo_slug(request)
        try:
            user_perms = set([self.user_perms['repositories'][repo_name]])
        except KeyError:
            return False
        if self.required_perms.issubset(user_perms):
            return True
        return False


class HasRepoPermissionAnyDecorator(PermsDecorator):
    """Checks for access permission for any of given predicates for specific 
    repository. In order to fulfill the request any of predicates must be meet
    """

    def check_permissions(self):
        repo_name = get_repo_slug(request)

        try:
            user_perms = set([self.user_perms['repositories'][repo_name]])
        except KeyError:
            return False
        if self.required_perms.intersection(user_perms):
            return True
        return False
#===============================================================================
# CHECK FUNCTIONS
#===============================================================================

class PermsFunction(object):
    """Base function for other check functions"""

    def __init__(self, *perms):
        available_perms = config['available_permissions']

        for perm in perms:
            if perm not in available_perms:
                raise Exception("'%s' permission in not defined" % perm)
        self.required_perms = set(perms)
        self.user_perms = None
        self.granted_for = ''
        self.repo_name = None

    def __call__(self, check_Location=''):
        user = session.get('rhodecode_user', False)
        if not user:
            return False
        self.user_perms = user.permissions
        self.granted_for = user.username
        log.debug('checking %s %s %s', self.__class__.__name__,
                  self.required_perms, user)

        if self.check_permissions():
            log.debug('Permission granted for %s @ %s %s', self.granted_for,
                      check_Location, user)
            return True

        else:
            log.warning('Permission denied for %s @ %s %s', self.granted_for,
                        check_Location, user)
            return False

    def check_permissions(self):
        """Dummy function for overriding"""
        raise Exception('You have to write this function in child class')

class HasPermissionAll(PermsFunction):
    def check_permissions(self):
        if self.required_perms.issubset(self.user_perms.get('global')):
            return True
        return False

class HasPermissionAny(PermsFunction):
    def check_permissions(self):
        if self.required_perms.intersection(self.user_perms.get('global')):
            return True
        return False

class HasRepoPermissionAll(PermsFunction):

    def __call__(self, repo_name=None, check_Location=''):
        self.repo_name = repo_name
        return super(HasRepoPermissionAll, self).__call__(check_Location)

    def check_permissions(self):
        if not self.repo_name:
            self.repo_name = get_repo_slug(request)

        try:
            self.user_perms = set([self.user_perms['repositories']\
                                   [self.repo_name]])
        except KeyError:
            return False
        self.granted_for = self.repo_name
        if self.required_perms.issubset(self.user_perms):
            return True
        return False

class HasRepoPermissionAny(PermsFunction):

    def __call__(self, repo_name=None, check_Location=''):
        self.repo_name = repo_name
        return super(HasRepoPermissionAny, self).__call__(check_Location)

    def check_permissions(self):
        if not self.repo_name:
            self.repo_name = get_repo_slug(request)

        try:
            self.user_perms = set([self.user_perms['repositories']\
                                   [self.repo_name]])
        except KeyError:
            return False
        self.granted_for = self.repo_name
        if self.required_perms.intersection(self.user_perms):
            return True
        return False

#===============================================================================
# SPECIAL VERSION TO HANDLE MIDDLEWARE AUTH
#===============================================================================

class HasPermissionAnyMiddleware(object):
    def __init__(self, *perms):
        self.required_perms = set(perms)

    def __call__(self, user, repo_name):
        usr = AuthUser()
        usr.user_id = user.user_id
        usr.username = user.username
        usr.is_admin = user.admin

        try:
            self.user_perms = set([fill_perms(usr)\
                                   .permissions['repositories'][repo_name]])
        except:
            self.user_perms = set()
        self.granted_for = ''
        self.username = user.username
        self.repo_name = repo_name
        return self.check_permissions()

    def check_permissions(self):
        log.debug('checking mercurial protocol '
                  'permissions for user:%s repository:%s',
                                                self.username, self.repo_name)
        if self.required_perms.intersection(self.user_perms):
            log.debug('permission granted')
            return True
        log.debug('permission denied')
        return False