# 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/>.

"""Some utilities for the CubicWeb server."""

__docformat__ = "restructuredtext en"

import sys

import logging

from threading import Timer, Thread

from getpass import getpass

from passlib.utils import handlers as uh, to_hash_str

from passlib.context import CryptContext

from cubicweb.md5crypt import crypt as md5crypt

class CustomMD5Crypt(uh.HasSalt, uh.GenericHandler):

    name = 'cubicwebmd5crypt'

    setting_kwds = ('salt',)

    min_salt_size = 0

    max_salt_size = 8

    salt_chars = uh.H64_CHARS

    @classmethod

    def from_string(cls, hash):

        salt, chk = uh.parse_mc2(hash, u'')

        if chk is None:

            raise ValueError('missing checksum')

        return cls(salt=salt, checksum=chk)

    def to_string(self):

        return to_hash_str(u'%s$%s' % (self.salt, self.checksum or u''))

    # passlib 1.5 wants calc_checksum, 1.6 wants _calc_checksum

    def calc_checksum(self, secret):

        return md5crypt(secret, self.salt.encode('ascii')).decode('utf-8')

    _calc_checksum = calc_checksum

_CRYPTO_CTX = CryptContext(['sha512_crypt', CustomMD5Crypt, 'des_crypt', 'ldap_salted_sha1'],

                           deprecated=['cubicwebmd5crypt', 'des_crypt'])

verify_and_update = _CRYPTO_CTX.verify_and_update

def crypt_password(passwd, salt=None):

    """return the encrypted password using the given salt or a generated one

    """

    if salt is None:

        return _CRYPTO_CTX.encrypt(passwd)

    # empty hash, accept any password for backwards compat

    if salt == '':

        return salt

    try:

        if _CRYPTO_CTX.verify(passwd, salt):

            return salt

    except ValueError: # e.g. couldn't identify hash

        pass

    # wrong password

    return ''

def cartesian_product(seqin):

    """returns a generator which returns the cartesian product of `seqin`

    for more details, see :

    http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/302478

    """

    def rloop(seqin, comb):

        """recursive looping function"""

        if seqin:                   # any more sequences to process?

            for item in seqin[0]:

                newcomb = comb + [item] # add next item to current combination

                # call rloop w/ remaining seqs, newcomb

                for item in rloop(seqin[1:], newcomb):

                    yield item          # seqs and newcomb

        else:                           # processing last sequence

            yield comb                  # comb finished, add to list

    return rloop(seqin, [])

def eschema_eid(session, eschema):

    """get eid of the CWEType entity for the given yams type. You should use

    this because when schema has been loaded from the file-system, not from the

    database, (e.g. during tests), eschema.eid is not set.

    """

    if eschema.eid is None:

        eschema.eid = session.execute(

            'Any X WHERE X is CWEType, X name %(name)s',

            {'name': str(eschema)})[0][0]

    return eschema.eid

DEFAULT_MSG = 'we need a manager connection on the repository \

(the server doesn\'t have to run, even should better not)'

def manager_userpasswd(user=None, msg=DEFAULT_MSG, confirm=False,

                       passwdmsg='password'):

    if not user:

        if msg:

            print msg

        while not user:

            user = raw_input('login: ')

        user = unicode(user, sys.stdin.encoding)

    passwd = getpass('%s: ' % passwdmsg)

    if confirm:

        while True:

            passwd2 = getpass('confirm password: ')

            if passwd == passwd2:

                break

            print 'password doesn\'t match'

            passwd = getpass('password: ')

    # XXX decode password using stdin encoding then encode it using appl'encoding

    return user, passwd

_MARKER=object()

def func_name(func):

    name = getattr(func, '__name__', _MARKER)

    if name is _MARKER:

        name = getattr(func, 'func_name', _MARKER)

    if name is _MARKER:

        name = repr(func)

    return name

class LoopTask(object):

    """threaded task restarting itself once executed"""

    def __init__(self, tasks_manager, interval, func, args):

        if interval < 0:

            raise ValueError('Loop task interval must be >= 0 '

                             '(current value: %f for %s)' % \

                             (interval, func_name(func)))

        self._tasks_manager = tasks_manager

        self.interval = interval

        def auto_restart_func(self=self, func=func, args=args):

            restart = True

            try:

                func(*args)

            except Exception:

                logger = logging.getLogger('cubicweb.repository')

                logger.exception('Unhandled exception in LoopTask %s', self.name)

                raise

            except BaseException:

                restart = False

            finally:

                if restart and tasks_manager.running:

                    self.start()

        self.func = auto_restart_func

        self.name = func_name(func)

    def __str__(self):

        return '%s (%s seconds)' % (self.name, self.interval)

    def start(self):

        self._t = Timer(self.interval, self.func)

        self._t.setName('%s-%s[%d]' % (self._t.getName(), self.name, self.interval))

        self._t.start()

    def cancel(self):

        self._t.cancel()

    def join(self):

        if self._t.isAlive():

            self._t.join()

class RepoThread(Thread):

    """subclass of thread so it auto remove itself from a given list once

    executed

    """

    def __init__(self, target, running_threads):

        def auto_remove_func(self=self, func=target):

            try:

                func()

            except Exception:

                logger = logging.getLogger('cubicweb.repository')

                logger.exception('Unhandled exception in RepoThread %s', self._name)

                raise

            finally:

                self.running_threads.remove(self)

        Thread.__init__(self, target=auto_remove_func)

        self.running_threads = running_threads

        self._name = func_name(target)

    def start(self):

        self.running_threads.append(self)

        self.daemon = True

        Thread.start(self)

    def getName(self):

        return '%s(%s)' % (self._name, Thread.getName(self))

class TasksManager(object):

    """Object dedicated manage background task"""

    def __init__(self):

        self.running = False

        self._tasks = []

        self._looping_tasks = []

    def add_looping_task(self, interval, func, *args):

        """register a function to be called every `interval` seconds.

        If interval is negative, no looping task is registered.

        """

        if interval < 0:

            self.debug('looping task %s ignored due to interval %f < 0',

                       func_name(func), interval)

            return

        task = LoopTask(self, interval, func, args)

        if self.running:

            self._start_task(task)

        else:

            self._tasks.append(task)

    def _start_task(self, task):

        self._looping_tasks.append(task)

        self.info('starting task %s with interval %.2fs', task.name,

                  task.interval)

        task.start()

    def start(self):

        """Start running looping task"""

        assert self.running == False # bw compat purpose maintly

        while self._tasks:

            task = self._tasks.pop()

            self._start_task(task)

        self.running = True

    def stop(self):

        """Stop all running task.

        returns when all task have been cancel and none are running anymore"""

        if self.running:

            while self._looping_tasks:

                looptask = self._looping_tasks.pop()

                self.info('canceling task %s...', looptask.name)

                looptask.cancel()

                looptask.join()

                self.info('task %s finished', looptask.name)

from logging import getLogger

from cubicweb import set_log_methods

set_log_methods(TasksManager, getLogger('cubicweb.repository'))