# -*- coding: UTF-8 -*-

# Copyright (c) 2007 - 2010, Pascal Volk

# See COPYING for distribution information.

"""vmm's configuration module for simplified configuration access.

This module defines a few classes:

``LazyConfig``

    This class provides the following additonal methods

    * `LazyConfig.pget()`

        polymorphic getter which returns the value with the appropriate

        type.

    * `LazyConfig.dget()`

        like *pget()*, but checks additonal for default values in

        `LazyConfig._cfg`.

    * `LazyConfig.set()`

        like `RawConfigParser.set()`, but converts the new value to the

        appropriate type/class and optional validates the new value.

    * `LazyConfig.bool_new()`

        converts data from raw_input into boolean values.

    * `LazyConfig.get_boolean()`

        like `RawConfigParser.getboolean()`, but doesn't fail on real

        `bool` values.

``Config``

    The Config class used by vmm.

``LazyConfigOption``

    The class for the configuration objects in the ``Config`` class'

    ``_cfg`` dictionary.

"""

from shutil import copy2

from ConfigParser import (Error, MissingSectionHeaderError, NoOptionError,

                          NoSectionError, ParsingError, RawConfigParser)

from cStringIO import StringIO

from __main__ import os, ENCODING, ERR, get_unicode, w_std

from Exceptions import VMMConfigException

class BadOptionError(Error):

    """Raised when a option isn't in the format 'section.option'."""

    pass

class ConfigValueError(Error):

    """Raised when creating or validating of new values fails."""

    pass

class NoDefaultError(Error):

    """Raised when the requested option has no default value."""

    def __init__(self, section, option):

        Error.__init__(self, 'Option %r in section %r has no default value' %(

                       option, section))

class LazyConfig(RawConfigParser):

    """The **lazy** derivate of the `RawConfigParser`.

    There are two additional getters:

    `LazyConfig.pget()`

        The polymorphic getter, which returns a option's value with the

        appropriate type.

    `LazyConfig.dget()`

        Like `LazyConfig.pget()`, but returns the option's default, from

        `LazyConfig._cfg['sectionname']['optionname'].default`, if the

        option is not configured in a ini-like configuration file.

    `LazyConfig.set()` differs from ``RawConfigParser``'s ``set()`` method.

    ``LazyConfig.set()`` takes the ``section`` and ``option`` arguments

    combined to a single string in the form

    "``section``\ **.**\ ``option``".

    """

    def __init__(self):

        RawConfigParser.__init__(self)

        self._modified = False

        self._cfg = {

            'sectionname': {

                'optionname': LazyConfigOption(int, 1, self.getint)

            }

        }

        """sample _cfg dictionary. Create your own in your derived class."""

    def bool_new(self, value):

        """Converts the string `value` into a `bool` and returns it.

        | '1', 'on', 'yes' and 'true' will become ``True``

        | '0', 'off', 'no' and 'false' will become ``False``

        Throws a `ConfigValueError` for all other values, except ``bool``\ s.

        """

        if isinstance(value, bool):

            return value

        if value.lower() in self._boolean_states:

            return self._boolean_states[value.lower()]

        else:

            raise ConfigValueError(_(u'Not a boolean: “%s”') % \

                                   get_unicode(value))

    def get_boolean(self, section, option):

        # if the setting was not written to the configuration file, it may

        # be still a boolean value - lets see

        if self._modified:

           tmp = self.get(section, option)

           if isinstance(tmp, bool):

               return tmp

        return self.getboolean(section, option)

    def __get_section_option(self, section_option):

        """splits ``section_option`` (section\ **.**\ option) in two parts

        and returns them as list ``[section, option]``, if:

            * it likes the format of ``section_option``

            * the ``section`` is known

            * the ``option`` is known

        Else one of the following exceptions will be thrown:

            * `BadOptionError`

            * `NoSectionError`

            * `NoOptionError`

        """ 

        sect_opt = section_option.lower().split('.')

        if len(sect_opt) != 2:# do we need a regexp to check the format?

            raise BadOptionError(

                        _(u'Bad format: “%s” - expected: section.option') % \

                        get_unicode(section_option))

        if not sect_opt[0] in self._cfg:

            raise NoSectionError(sect_opt[0])

        if not sect_opt[1] in self._cfg[sect_opt[0]]:

            raise NoOptionError(sect_opt[1], sect_opt[0])

        return sect_opt

    def items(self, section):

        """returns an iterable that returns key, value ``tuples`` from the

        given ``section``."""

        if section in self._sections:# check if the section was parsed

            d2 = self._sections[section]

        elif not section in self._cfg:

            raise NoSectionError(section)

        else:

            return ((k, self._cfg[section][k].default) \

                    for k in self._cfg[section].iterkeys())

        # still here? Get defaults and merge defaults with configured setting

        d = dict((k, self._cfg[section][k].default) \

                 for k in self._cfg[section].iterkeys())

        d.update(d2)

        if '__name__' in d: del d['__name__']

        return d.iteritems()

    def dget(self, option):

        """Returns the value of the `option`.

        If the option could not be found in the configuration file, the

        configured default value, from ``LazyConfig._cfg`` will be

        returned.

        Arguments:

        `option` : string

            the configuration option in the form

            "``section``\ **.**\ ``option``"

        Throws a `NoDefaultError`, if no default value was passed to

        `LazyConfigOption.__init__()` for the `option`.

        """

        section, option = self.__get_section_option(option)

        try:

            return self._cfg[section][option].getter(section, option)

        except (NoSectionError, NoOptionError):

            if not self._cfg[section][option].default is None:

                return self._cfg[section][option].default

            else:

                raise NoDefaultError(section, option)

    def pget(self, option):

        """Returns the value of the `option`."""

        section, option = self.__get_section_option(option)

        return self._cfg[section][option].getter(section, option)

    def set(self, option, value):

        """Set the value of an option.

        Throws a ``ValueError`` if `value` couldn't be converted to

        ``LazyConfigOption.cls``"""

        section, option = self.__get_section_option(option)

        val = self._cfg[section][option].cls(value)

        if not self._cfg[section][option].validate is None:

            val = self._cfg[section][option].validate(val)

        if not RawConfigParser.has_section(self, section):

            self.add_section(section)

        RawConfigParser.set(self, section, option, val)

        self._modified = True

    def has_section(self, section):

        """Checks if ``section`` is a known configuration section."""

        return section.lower() in self._cfg 

    def has_option(self, option):

        """Checks if the option (section\ **.**\ option) is a known

        configuration option."""

        try:

            self.__get_section_option(option)

            return True

        except(BadOptionError, NoSectionError, NoOptionError):

            return False

class LazyConfigOption(object):

    """A simple container class for configuration settings.

   ``LazyConfigOption`` instances are required by `LazyConfig` instances,

   and instances of classes derived from ``LazyConfig``, like the

   `Config` class.

    """

    __slots__ = ('cls', 'default', 'getter', 'validate')

    def __init__(self, cls, default, getter, validate=None):

        """Creates a new ``LazyConfigOption`` instance.

        Arguments:

        ``cls`` : type

            The class/type of the option's value

        ``default``

            Default value of the option. Use ``None`` if the option should

            not have a default value.

        ``getter`` : callable

            A method's name of `RawConfigParser` and derived classes, to

            get a option's value, e.g. `self.getint`.

        ``validate`` : NoneType or a callable

            None or any method, that takes one argument, in order to check

            the value, when `LazyConfig.set()` is called.

        """

        self.cls = cls

        """The class of the option's value e.g. `str`, `unicode` or `bool`"""

        self.default = default

        """The option's default value, may be ``None``"""

        if callable(getter):

            self.getter = getter

            """The getter method to get the option's value"""

        else:

            raise TypeError('getter has to be a callable, got a %r'\

                            % getter.__class__.__name__)

        if validate is None or callable(validate):

            self.validate = validate

            """A method to validate the value"""

        else:

            raise TypeError('validate has to be callable or None, got a %r'\

                            % validate.__class__.__name__)

class Config(LazyConfig):

    """This class is for reading and modifying vmm's configuration file."""

    def __init__(self, filename):

        """Creates a new Config instance

        Arguments:

        ``filename``

            path to the configuration file

        """

        LazyConfig.__init__(self)

        self.__cfgFileName = filename

        self.__cfgFile = None

        self.__missing = {}

        LCO = LazyConfigOption

        bool_t = self.bool_new

        self._cfg = {

            'account': {

                'delete_directory': LCO(bool_t, False, self.get_boolean),

                'directory_mode':   LCO(int,    448,   self.getint),

                'disk_usage':       LCO(bool_t, False, self.get_boolean),

                'password_length':  LCO(int,    8,     self.getint),

                'random_password':  LCO(bool_t, False, self.get_boolean),

                'imap' :            LCO(bool_t, True,  self.get_boolean),

                'pop3' :            LCO(bool_t, True,  self.get_boolean),

                'sieve':            LCO(bool_t, True,  self.get_boolean),

                'smtp' :            LCO(bool_t, True,  self.get_boolean),

            },

            'bin': {

                'dovecotpw': LCO(str, '/usr/sbin/dovecotpw', self.get,

                                 self.exec_ok),

                'du':        LCO(str, '/usr/bin/du', self.get, self.exec_ok),

                'postconf':  LCO(str, '/usr/sbin/postconf', self.get,

                                 self.exec_ok),

            },

            'database': {

                'host': LCO(str, 'localhost', self.get),

                'name': LCO(str, 'mailsys',   self.get),

                'pass': LCO(str, None,        self.get),

                'user': LCO(str, None,        self.get),

            },

            'domain': {

                'auto_postmaster':  LCO(bool_t, True,  self.get_boolean),

                'delete_directory': LCO(bool_t, False, self.get_boolean),

                'directory_mode':   LCO(int,    504,   self.getint),

                'force_deletion':   LCO(bool_t, False, self.get_boolean),

            },

            'maildir': {

                'folders': LCO(str, 'Drafts:Sent:Templates:Trash', self.get),

                'name':    LCO(str, 'Maildir',                     self.get),

            },

            'misc': {

                'base_directory':  LCO(str, '/srv/mail', self.get, self.is_dir),

                'dovecot_version': LCO(int, 12,          self.getint),

                'gid_mail':        LCO(int, 8,           self.getint),

                'password_scheme': LCO(str, 'CRAM-MD5',  self.get,

                                       self.known_scheme),

                'transport':       LCO(str, 'dovecot:',  self.get),

            },

            'config': {'done': LCO(bool_t, False, self.get_boolean)}

        }

    def load(self):

        """Loads the configuration, read only.

        Raises a VMMConfigException if the configuration syntax is invalid.

        """

        try:

            self.__cfgFile = open(self.__cfgFileName, 'r')

            self.readfp(self.__cfgFile)

        except (MissingSectionHeaderError, ParsingError), e:

            raise VMMConfigException(str(e), ERR.CONF_ERROR)

        finally:

            if not self.__cfgFile is None and not self.__cfgFile.closed:

                self.__cfgFile.close()

    def check(self):

        """Performs a configuration check.

        Raises a VMMConfigException if the check fails.

        """

        if not self.__chkCfg():

            errmsg = StringIO()

            errmsg.write(_(u'Missing options, which have no default value.\n'))

            errmsg.write(_(u'Using configuration file: %s\n') %\

                         self.__cfgFileName)

            for section, options in self.__missing.iteritems():

                errmsg.write(_(u'* Section: %s\n') % section)

                for option in options:

                    errmsg.write((u'    %s\n') % option)

            raise VMMConfigException(errmsg.getvalue(), ERR.CONF_ERROR)

    def getsections(self):

        """Returns a generator object for all configurable sections."""

        return (s for s in self._cfg.iterkeys() if s != 'config')

    def is_dir(self, path):

        """Checks if ``path`` is a directory.

        Throws a `ConfigValueError` if ``path`` is not a directory.

        """

        path = self.__expand_path(path)

        if not os.path.isdir(path):

            raise ConfigValueError(_(u'“%s” is not a directory') % \

                                   get_unicode(path))

        return path

    def exec_ok(self, binary):

        """Checks if the ``binary`` exists and if it is executable.

        Throws a `ConfigValueError` if the ``binary`` isn't a file or is

        not executable.

        """

        binary = self.__expand_path(binary)

        if not os.path.isfile(binary):

            raise ConfigValueError(_(u'“%s” is not a file') % \

                                   get_unicode(binary))

        if not os.access(binary, os.X_OK):

            raise ConfigValueError(_(u'File is not executable: “%s”') % \

                                   get_unicode(binary))

        return binary

    def known_scheme(self, scheme):

        """Converts ``scheme`` to upper case and checks if is known by

        Dovecot (listed in VirtualMailManager.SCHEMES).