# -*- coding: utf-8 -*-
#
# Copyright (C) 2007 Edgewall Software
# All rights reserved.
#
# This software is licensed as described in the file COPYING, which
# you should have received as part of this distribution. The terms
# are also available at http://babel.edgewall.org/wiki/License.
#
# This software consists of voluntary contributions made by many
# individuals. For the exact contribution history, see the revision
# history and logs, available at http://babel.edgewall.org/log/.

"""Several classes and functions that help with integrating and using Babel
in applications.

.. note: the code in this module is not used by Babel itself
"""

import gettext

__all__ = ['LazyProxy', 'Translations']
__docformat__ = 'restructuredtext en'


class LazyProxy(object):
    """Class for proxy objects that delegate to a specified function to evaluate
    the actual object.
    
    >>> def greeting(name='world'):
    ...     return 'Hello, %s!' % name
    >>> lazy_greeting = LazyProxy(greeting, name='Joe')
    >>> print lazy_greeting
    Hello, Joe!
    >>> u'  ' + lazy_greeting
    u'  Hello, Joe!'
    >>> u'(%s)' % lazy_greeting
    u'(Hello, Joe!)'
    
    This can be used, for example, to implement lazy translation functions that
    delay the actual translation until the string is actually used. The
    rationale for such behavior is that the locale of the user may not always
    be available. In web applications, you only know the locale when processing
    a request.
    
    The proxy implementation attempts to be as complete as possible, so that
    the lazy objects should mostly work as expected, for example for sorting:
    
    >>> greetings = [
    ...     LazyProxy(greeting, 'world'),
    ...     LazyProxy(greeting, 'Joe'),
    ...     LazyProxy(greeting, 'universe'),
    ... ]
    >>> greetings.sort()
    >>> for greeting in greetings:
    ...     print greeting
    Hello, Joe!
    Hello, universe!
    Hello, world!
    """
    __slots__ = ['_func', '_args', '_kwargs', '_value']

    def __init__(self, func, *args, **kwargs):
        # Avoid triggering our own __setattr__ implementation
        object.__setattr__(self, '_func', func)
        object.__setattr__(self, '_args', args)
        object.__setattr__(self, '_kwargs', kwargs)
        object.__setattr__(self, '_value', None)

    def value(self):
        if self._value is None:
            value = self._func(*self._args, **self._kwargs)
            object.__setattr__(self, '_value', value)
        return self._value
    value = property(value)

    def __contains__(self, key):
        return key in self.value

    def __nonzero__(self):
        return bool(self.value)

    def __dir__(self):
        return dir(self.value)

    def __iter__(self):
        return iter(self.value)

    def __len__(self):
        return len(self.value)

    def __str__(self):
        return str(self.value)

    def __unicode__(self):
        return unicode(self.value)

    def __add__(self, other):
        return self.value + other

    def __radd__(self, other):
        return other + self.value

    def __mod__(self, other):
        return self.value % other

    def __rmod__(self, other):
        return other % self.value

    def __mul__(self, other):
        return self.value * other

    def __rmul__(self, other):
        return other * self.value

    def __call__(self, *args, **kwargs):
        return self.value(*args, **kwargs)

    def __lt__(self, other):
        return self.value < other

    def __le__(self, other):
        return self.value <= other

    def __eq__(self, other):
        return self.value == other

    def __ne__(self, other):
        return self.value != other

    def __gt__(self, other):
        return self.value > other

    def __ge__(self, other):
        return self.value >= other

    def __delattr__(self, name):
        delattr(self.value, name)

    def __getattr__(self, name):
        return getattr(self.value, name)

    def __setattr__(self, key, value):
        setattr(self.value, name, value)

    def __delitem__(self, key):
        del self.value[key]

    def __getitem__(self, key):
        return self.value[key]

    def __setitem__(self, key, value):
        self.value[name] = value


class Translations(gettext.GNUTranslations):
    """An extended translation catalog class."""

    DEFAULT_DOMAIN = 'messages'

    def __init__(self, fileobj=None):
        """Initialize the translations catalog.
        
        :param fileobj: the file-like object the translation should be read
                        from
        """
        gettext.GNUTranslations.__init__(self, fp=fileobj)
        self.files = [getattr(fileobj, 'name')]

    def load(cls, dirname=None, locales=None, domain=DEFAULT_DOMAIN):
        """Load translations from the given directory.
        
        :param dirname: the directory containing the ``MO`` files
        :param locales: the list of locales in order of preference (items in
                        this list can be either `Locale` objects or locale
                        strings)
        :param domain: the message domain
        :return: the loaded catalog, or a ``NullTranslations`` instance if no
                 matching translations were found
        :rtype: `Translations`
        """
        if not isinstance(locales, (list, tuple)):
            locales = [locales]
        locales = [str(locale) for locale in locales]
        filename = gettext.find(domain or self.DEFAULT_DOMAIN, dirname, locales)
        if not filename:
            return gettext.NullTranslations()
        return cls(fileobj=open(filename, 'rb'))
    load = classmethod(load)

    def merge(self, translations):
        """Merge the given translations into the catalog.
        
        Message translations in the specfied catalog override any messages with
        the same identifier in the existing catalog.
        
        :param translations: the `Translations` instance with the messages to
                             merge
        :return: the `Translations` instance (``self``) so that `merge` calls
                 can be easily chained
        :rtype: `Translations`
        """
        if isinstance(translations, Translations):
            self._catalog.update(translations._catalog)
            self.files.extend(translations.files)
        return self

    def __repr__(self):
        return "<%s %r>" % (type(self).__name__)