#!/usr/bin/env python
# encoding: utf-8
# authentication and permission libraries
# Copyright (C) 2009-2010 Marcin Kuzminski <marcin@python-works.com>
#
# 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.
"""
Created on April 4, 2010

@author: marcink
"""
from pylons import config, session, url, request
from pylons.controllers.util import abort, redirect
from rhodecode.lib.exceptions import *
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.caching_query import FromCache
from rhodecode.model.db import User, RepoToPerm, Repository, Permission, \
    UserToPerm
import bcrypt
from decorator import decorator
import logging
import random
import traceback

log = logging.getLogger(__name__)

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 sha1
    :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):
    """
    Authentication function used in Mercurial/Git/ and access control,
    firstly checks for db authentication then if ldap is enabled for ldap
    authentication, also creates ldap user if not in database
    
    :param environ: needed only for using in Basic auth, can be None
    :param username: username
    :param password: password
    """
    user_model = UserModel()
    user = user_model.get_by_username(username, cache=False)

    if user is not None and user.is_ldap is False:
        if user.active:

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

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


    else:

        #since ldap is searching in case insensitive check if this user is still
        #not in our system
        username = username.lower()
        user_obj = user_model.get_by_username(username, cache=False,
                                            case_insensitive=True)
        if user_obj is not None and user_obj.is_ldap is False:
            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 IN ENABLE                
        #======================================================================
        if ldap_settings.get('ldap_active', False):

            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'),
                  'ldap_version':3,
                  }
            log.debug('Checking for ldap authentication')
            try:
                aldap = AuthLdap(**kwargs)
                res = aldap.authenticate_ldap(username, password)

                authenticated = res[1]['uid'][0] == username

                if authenticated and user_model.create_ldap(username, password):
                    log.info('created new ldap user')

                return authenticated
            except (LdapUsernameError, LdapPasswordError):
                return False
            except:
                log.error(traceback.format_exc())
                return False
    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 wannt 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:
    """
    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 set_base_path(config):
    config['base_path'] = config['pylons.app_globals'].base_path


def fill_perms(user):
    """
    Fills user permission attribute with permissions taken from database
    :param user:
    """

    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 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
    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 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