# copyright 2003-2013 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr

#

# This file is part of CubicWeb.

#

# CubicWeb is free software: you can redistribute it and/or modify it under the

# terms of the GNU Lesser General Public License as published by the Free

# Software Foundation, either version 2.1 of the License, or (at your option)

# any later version.

#

# CubicWeb 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 Lesser General Public License for more

# details.

#

# You should have received a copy of the GNU Lesser General Public License along

# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.

"""Server subcube of cubicweb : defines objects used only on the server

(repository) side

The server module contains functions to initialize a new repository.

"""

__docformat__ = "restructuredtext en"

import sys

from os.path import join, exists

from glob import glob

from contextlib import contextmanager

from logilab.common.modutils import LazyObject

from logilab.common.textutils import splitstrip

from logilab.common.registry import yes

from yams import BASE_GROUPS

from cubicweb import CW_SOFTWARE_ROOT

from cubicweb.appobject import AppObject

class ShuttingDown(BaseException):

    """raised when trying to access some resources while the repository is

    shutting down. Inherit from BaseException so that `except Exception` won't

    catch it.

    """

# server-side services #########################################################

class Service(AppObject):

    """Base class for services.

    A service is a selectable object that performs an action server-side.

    Use :class:`cubicweb.dbapi.Connection.call_service` to call them from

    the web-side.

    When inheriting this class, do not forget to define at least the __regid__

    attribute (and probably __select__ too).

    """

    __registry__ = 'services'

    __select__ = yes()

    def call(self, **kwargs):

        raise NotImplementedError

# server-side debugging ########################################################

# server debugging flags. They may be combined using binary operators.

#:no debug information

DBG_NONE = 0  #: no debug information

#: rql execution information

DBG_RQL  = 1

#: executed sql

DBG_SQL  = 2

#: repository events

DBG_REPO = 4

#: multi-sources

DBG_MS   = 8

#: hooks

DBG_HOOKS = 16

#: operations

DBG_OPS = 32

#: security

DBG_SEC = 64

#: more verbosity

DBG_MORE = 128

#: all level enabled

DBG_ALL  = DBG_RQL + DBG_SQL + DBG_REPO + DBG_MS + DBG_HOOKS + DBG_OPS + DBG_SEC + DBG_MORE

_SECURITY_ITEMS = []

_SECURITY_CAPS = ['read', 'add', 'update', 'delete']

#: current debug mode

DEBUG = 0

@contextmanager

def tunesecurity(items=(), capabilities=()):

    """Context manager to use in conjunction with DBG_SEC.

    This allows some tuning of:

    * the monitored capabilities ('read', 'add', ....)

    * the object being checked by the security checkers

    When no item is given, all of them will be watched.

    By default all capabilities are monitored, unless specified.

    Example use::

      from cubicweb.server import debugged, DBG_SEC, tunesecurity

      with debugged(DBG_SEC):

          with tunesecurity(items=('Elephant', 'trumps'),

                            capabilities=('update', 'delete')):

              babar.cw_set(trumps=celeste)

              flore.cw_delete()

      ==>

      check_perm: 'update' 'relation Elephant.trumps.Elephant'

       [(ERQLExpression(Any X WHERE U has_update_permission X, X eid %(x)s, U eid %(u)s),

       {'eid': 2167}, True)]

      check_perm: 'delete' 'Elephant'

       [(ERQLExpression(Any X WHERE U has_delete_permission X, X eid %(x)s, U eid %(u)s),

       {'eid': 2168}, True)]

    """

    olditems = _SECURITY_ITEMS[:]

    _SECURITY_ITEMS.extend(list(items))

    oldactions = _SECURITY_CAPS[:]

    _SECURITY_CAPS[:] = capabilities

    yield

    _SECURITY_ITEMS[:] = olditems

    _SECURITY_CAPS[:] = oldactions

def set_debug(debugmode):

    """change the repository debugging mode"""

    global DEBUG

    if not debugmode:

        DEBUG = 0

        return

    if isinstance(debugmode, basestring):

        for mode in splitstrip(debugmode, sep='|'):

            DEBUG |= globals()[mode]

    else:

        DEBUG |= debugmode

class debugged(object):

    """Context manager and decorator to help debug the repository.

    It can be used either as a context manager:

    >>> with debugged('DBG_RQL | DBG_REPO'):

    ...     # some code in which you want to debug repository activity,

    ...     # seing information about RQL being executed an repository events.

    or as a function decorator:

    >>> @debugged('DBG_RQL | DBG_REPO')

    ... def some_function():

    ...     # some code in which you want to debug repository activity,

    ...     # seing information about RQL being executed an repository events

    The debug mode will be reset to its original value when leaving the "with"

    block or the decorated function.

    """

    def __init__(self, debugmode):

        self.debugmode = debugmode

        self._clevel = None

    def __enter__(self):

        """enter with block"""

        self._clevel = DEBUG

        set_debug(self.debugmode)

    def __exit__(self, exctype, exc, traceback):

        """leave with block"""

        set_debug(self._clevel)

        return traceback is None

    def __call__(self, func):

        """decorate function"""

        def wrapped(*args, **kwargs):

            _clevel = DEBUG

            set_debug(self.debugmode)

            try:

                return func(*args, **kwargs)

            finally:

                set_debug(self._clevel)

        return wrapped

# database initialization ######################################################

def create_user(session, login, pwd, *groups):

    # monkey patch this method if you want to customize admin/anon creation

    # (that maybe necessary if you change CWUser's schema)

    user = session.create_entity('CWUser', login=login, upassword=pwd)

    for group in groups:

        session.execute('SET U in_group G WHERE U eid %(u)s, G name %(group)s',

                        {'u': user.eid, 'group': group})

    return user

def init_repository(config, interactive=True, drop=False, vreg=None):

    """initialise a repository database by creating tables add filling them

    with the minimal set of entities (ie at least the schema, base groups and

    a initial user)

    """

    from cubicweb.repoapi import get_repository, connect

    from cubicweb.server.repository import Repository

    from cubicweb.server.utils import manager_userpasswd

    from cubicweb.server.sqlutils import sqlexec, sqlschema, sql_drop_all_user_tables

    from cubicweb.server.sqlutils import _SQL_DROP_ALL_USER_TABLES_FILTER_FUNCTION as drop_filter

    # configuration to avoid db schema loading and user'state checking

    # on connection

    config.creating = True

    config.consider_user_state = False

    config.cubicweb_appobject_path = set(('hooks', 'entities'))

    config.cube_appobject_path = set(('hooks', 'entities'))

    # only enable the system source at initialization time

    repo = Repository(config, vreg=vreg)

    schema = repo.schema

    sourcescfg = config.read_sources_file()

    source = sourcescfg['system']

    driver = source['db-driver']

    sqlcnx = repo.system_source.get_connection()

    sqlcursor = sqlcnx.cursor()

    execute = sqlcursor.execute

    if drop:

        helper = database.get_db_helper(driver)

        dropsql = sql_drop_all_user_tables(helper, sqlcursor)

        # We may fail dropping some tables because of table dependencies, in a first pass.

        # So, we try a second drop sequence to drop remaining tables if needed.

        # Note that 2 passes is an arbitrary choice as it seems enougth for our usecases.

        # (looping may induce infinite recursion when user have no right for example)

        # Here we try to keep code simple and backend independant. That why we don't try to

        # distinguish remaining tables (wrong right, dependencies, ...).

        failed = sqlexec(dropsql, execute, cnx=sqlcnx,

                         pbtitle='-> dropping tables (first pass)')

        if failed:

            failed = sqlexec(failed, execute, cnx=sqlcnx,

                             pbtitle='-> dropping tables (second pass)')

            remainings = filter(drop_filter, helper.list_tables(sqlcursor))

            assert not remainings, 'Remaining tables: %s' % ', '.join(remainings)

    _title = '-> creating tables '

    print _title,

    # schema entities and relations tables

    # can't skip entities table even if system source doesn't support them,

    # they are used sometimes by generated sql. Keeping them empty is much

    # simpler than fixing this...

    schemasql = sqlschema(schema, driver)

    #skip_entities=[str(e) for e in schema.entities()

    #               if not repo.system_source.support_entity(str(e))])

    failed = sqlexec(schemasql, execute, pbtitle=_title, delimiter=';;')

    if failed:

        print 'The following SQL statements failed. You should check your schema.'

        print failed

        raise Exception('execution of the sql schema failed, you should check your schema')

    sqlcursor.close()

    sqlcnx.commit()

    sqlcnx.close()

    with repo.internal_cnx() as cnx:

        # insert entity representing the system source

        ssource = cnx.create_entity('CWSource', type=u'native', name=u'system')

        repo.system_source.eid = ssource.eid

        cnx.execute('SET X cw_source X WHERE X eid %(x)s', {'x': ssource.eid})

        # insert base groups and default admin

        print '-> inserting default user and default groups.'

        try:

            login = unicode(sourcescfg['admin']['login'])

            pwd = sourcescfg['admin']['password']

        except KeyError:

            if interactive:

                msg = 'enter login and password of the initial manager account'

                login, pwd = manager_userpasswd(msg=msg, confirm=True)

            else:

                login, pwd = unicode(source['db-user']), source['db-password']

        # sort for eid predicatability as expected in some server tests

        for group in sorted(BASE_GROUPS):

            cnx.create_entity('CWGroup', name=unicode(group))

        admin = create_user(cnx, login, pwd, 'managers')

        cnx.execute('SET X owned_by U WHERE X is IN (CWGroup,CWSource), U eid %(u)s',

                        {'u': admin.eid})

        cnx.commit()

    repo.shutdown()

    # reloging using the admin user

    config._cubes = None # avoid assertion error

    repo = get_repository(config=config)

    with connect(repo, login, password=pwd) as cnx:

        with cnx.security_enabled(False, False):

            repo.system_source.eid = ssource.eid # redo this manually

            handler = config.migration_handler(schema, interactive=False,

                                               cnx=cnx, repo=repo)

            # install additional driver specific sql files

            handler.cmd_install_custom_sql_scripts()

            for cube in reversed(config.cubes()):

                handler.cmd_install_custom_sql_scripts(cube)

            # serialize the schema

            initialize_schema(config, schema, handler)

            # yoo !

            cnx.commit()

            repo.system_source.init_creating()

            cnx.commit()

    repo.shutdown()

    # restore initial configuration

    config.creating = False

    config.consider_user_state = True

    # (drop instance attribute to get back to class attribute)

    del config.cubicweb_appobject_path

    del config.cube_appobject_path

    print '-> database for instance %s initialized.' % config.appid

def initialize_schema(config, schema, mhandler, event='create'):

    from cubicweb.server.schemaserial import serialize_schema

    cnx = mhandler.cnx

    cubes = config.cubes()

    # deactivate every hooks but those responsible to set metadata

    # so, NO INTEGRITY CHECKS are done, to have quicker db creation.

    # Active integrity is kept else we may pb such as two default

    # workflows for one entity type.

    with cnx.deny_all_hooks_but('metadata', 'activeintegrity'):

        # execute cubicweb's pre<event> script

        mhandler.cmd_exec_event_script('pre%s' % event)

        # execute cubes pre<event> script if any

        for cube in reversed(cubes):

            mhandler.cmd_exec_event_script('pre%s' % event, cube)

        # execute instance's pre<event> script (useful in tests)

        mhandler.cmd_exec_event_script('pre%s' % event, apphome=True)

        # enter instance'schema into the database

        serialize_schema(cnx, schema)

        # execute cubicweb's post<event> script

        mhandler.cmd_exec_event_script('post%s' % event)

        # execute cubes'post<event> script if any

        for cube in reversed(cubes):

            mhandler.cmd_exec_event_script('post%s' % event, cube)

        # execute instance's post<event> script (useful in tests)

        mhandler.cmd_exec_event_script('post%s' % event, apphome=True)

# sqlite'stored procedures have to be registered at connection opening time

from logilab.database import SQL_CONNECT_HOOKS

# add to this set relations which should have their add security checking done

# *BEFORE* adding the actual relation (done after by default)

BEFORE_ADD_RELATIONS = set(('owned_by',))

# add to this set relations which should have their add security checking done

# *at COMMIT TIME* (done after by default)

ON_COMMIT_ADD_RELATIONS = set(())

# available sources registry

SOURCE_TYPES = {'native': LazyObject('cubicweb.server.sources.native', 'NativeSQLSource'),

                'datafeed': LazyObject('cubicweb.server.sources.datafeed', 'DataFeedSource'),

                'ldapfeed': LazyObject('cubicweb.server.sources.ldapfeed', 'LDAPFeedSource'),

                }