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

# Copyright (c) 2007 - 2013, Pascal Volk

# See COPYING for distribution information.

"""

    VirtualMailManager.config

    ~~~~~~~~~~~~~~~~~~~~~~~~~

    VMM's configuration module for simplified configuration access.

"""

import collections

from configparser import \

     Error, MissingSectionHeaderError, NoOptionError, NoSectionError, \

     ParsingError, RawConfigParser

from io import StringIO

from VirtualMailManager.common import VERSION_RE, \

     exec_ok, expand_path, get_unicode, lisdir, size_in_bytes, version_hex

from VirtualMailManager.constants import CONF_ERROR

from VirtualMailManager.errors import ConfigError, VMMError

from VirtualMailManager.maillocation import known_format

from VirtualMailManager.password import verify_scheme as _verify_scheme

DB_MODULES = ('psycopg2', 'pypgsql')

DB_SSL_MODES = ('allow', 'disabled', 'prefer', 'require', 'verify-ca',

                'verify-full')

_ = lambda msg: msg

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:

    `pget()`

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

      appropriate type.

    `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.

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

        # sample _cfg dict.  Create your own in your derived class.

        self._cfg = {

            'sectionname': {

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

            }

        }

    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 bools.

        """

        if isinstance(value, bool):

            return value

        if value.lower() in self.BOOLEAN_STATES:

            return self.BOOLEAN_STATES[value.lower()]

        else:

            raise ConfigValueError(_("Not a boolean: '%s'") %

                                   get_unicode(value))

    def getboolean(self, section, option):

        """Returns the boolean value of the option, in the given

        section.

        For a boolean True, the value must be set to '1', 'on', 'yes',

        'true' or True. For a boolean False, the value must set to '0',

        'off', 'no', 'false' or False.

        If the option has another value assigned this method will raise

        a ValueError.

        """

        # if the setting was modified it may be still a boolean value lets see

        tmp = self.get(section, option)

        if isinstance(tmp, bool):

            return tmp

        if not tmp.lower() in self.BOOLEAN_STATES:

            raise ValueError('Not a boolean: %s' % tmp)

        return self.BOOLEAN_STATES[tmp.lower()]

    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('.')

        # TODO: cache it

        if len(sect_opt) != 2 or not sect_opt[0] or not sect_opt[1]:

            raise BadOptionError(_("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

            sect = 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].keys())

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

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

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

        defaults.update(sect)

        if '__name__' in defaults:

            del defaults['__name__']

        return iter(defaults.items())

    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:  # may be False

                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 the `option`.

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

        `LazyConfigOption.cls`.

        """

        # pylint: disable=W0221

        # @pylint: _L A Z Y_

        section, option = self._get_section_option(option)

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

        if self._cfg[section][option].validate:

            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.

        """

        # pylint: disable=W0221

        # @pylint: _L A Z Y_

        try:

            self._get_section_option(option)

            return True

        except(BadOptionError, NoSectionError, NoOptionError):

            return False

    def sections(self):

        """Returns an iterator object for all configuration sections."""

        return iter(self._cfg.keys())

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

        self.__default = default if default is None else self.__cls(default)

        if not isinstance(getter, collections.Callable):

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

                            getter.__class__.__name__)

        self.__getter = getter

        if validate and not isinstance(validate, collections.Callable):

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

                            validate.__class__.__name__)

        self.__validate = validate

    @property

    def cls(self):

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

        return self.__cls

    @property

    def default(self):

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

        return self.__default

    @property

    def getter(self):

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

        return self.__getter

    @property

    def validate(self):

        """A method or function to validate the value"""

        return self.__validate

class Config(LazyConfig):

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

    def __init__(self, filename):

        """Creates a new Config instance

        Arguments:

        `filename` : str

          path to the configuration file

        """

        LazyConfig.__init__(self)

        self._cfg_filename = filename

        self._cfg_file = None

        self._missing = {}

        LCO = LazyConfigOption

        bool_t = self.bool_new

        self._cfg = {

            'account': {

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

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

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

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

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

            },

            'bin': {

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

                                 exec_ok),

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

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

            },

            'database': {

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

                'module': LCO(str, 'psycopg2', self.get, check_db_module),

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

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

                'port': LCO(int, 5432, self.getint),

                'sslmode': LCO(str, 'prefer', self.get, check_db_ssl_mode),

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

            },

            'domain': {

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

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

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

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

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

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

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

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

                'quota_bytes': LCO(str, '0', self.get_in_bytes,

                                   check_size_value),

                'quota_messages': LCO(int, 0, self.getint),

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

            },

            'mailbox': {

                'folders': LCO(str, 'Drafts:Sent:Templates:Trash',

                               self.str),

                'format': LCO(str, 'maildir', self.get, check_mailbox_format),

                'root': LCO(str, 'Maildir', self.str),

                'subscribe': LCO(bool_t, True, self.getboolean),

            },

            'misc': {

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

                'crypt_blowfish_rounds': LCO(int, 5, self.getint),

                'crypt_sha256_rounds': LCO(int, 5000, self.getint),

                'crypt_sha512_rounds': LCO(int, 5000, self.getint),

                'dovecot_version': LCO(str, None, self.hexversion,

                                       check_version_format),

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

                                       verify_scheme),

            },

        }

    def load(self):

        """Loads the configuration, read only.

        Raises a ConfigError if the configuration syntax is

        invalid.

        """

        with open(self._cfg_filename, 'r', encoding='utf-8') as self._cfg_file:

            try:

                self.readfp(self._cfg_file)

            except (MissingSectionHeaderError, ParsingError) as err:

                raise ConfigError(str(err), CONF_ERROR)

    def check(self):

        """Performs a configuration check.

        Raises a ConfigError if settings w/o a default value are missed.

        Or some settings have a invalid value.

        """

        def iter_dict():

            for section, options in self._missing.items():

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

                errmsg.writelines('    %s\n' % option for option in options)

            self._missing.clear()