# Copyright 2012 Red Hat, Inc.
# Copyright 2013 IBM Corp.
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.
"""Translation function factory
"""

import gettext
import os

from oslo_i18n import _lazy
from oslo_i18n import _locale
from oslo_i18n import _message


__all__ = [
    'TranslatorFactory',
]

# magic gettext number to separate context from message
CONTEXT_SEPARATOR = _message.CONTEXT_SEPARATOR


class TranslatorFactory:
    "Create translator functions"

    def __init__(self, domain, localedir=None):
        """Establish a set of translation functions for the domain.

        :param domain: Name of translation domain,
                       specifying a message catalog.
        :type domain: str
        :param localedir: Directory with translation catalogs.
        :type localedir: str
        """
        self.domain = domain
        if localedir is None:
            variable_name = _locale.get_locale_dir_variable_name(domain)
            localedir = os.environ.get(variable_name)
        self.localedir = localedir

    def _make_translation_func(self, domain=None):
        """Return a translation function ready for use with messages.

        The returned function takes a single value, the unicode string
        to be translated.  The return type varies depending on whether
        lazy translation is being done. When lazy translation is
        enabled, :class:`Message` objects are returned instead of
        regular :class:`unicode` strings.

        The domain argument can be specified to override the default
        from the factory, but the localedir from the factory is always
        used because we assume the log-level translation catalogs are
        installed in the same directory as the main application
        catalog.

        """
        if domain is None:
            domain = self.domain
        t = gettext.translation(domain,
                                localedir=self.localedir,
                                fallback=True)
        # Use the appropriate method of the translation object based
        # on the python version.
        m = t.gettext

        def f(msg):
            """oslo_i18n.gettextutils translation function."""
            if _lazy.USE_LAZY:
                return _message.Message(msg, domain=domain)
            return m(msg)
        return f

    def _make_contextual_translation_func(self, domain=None):
        """Return a translation function ready for use with context messages.

        The returned function takes two values, the context of
        the unicode string, the unicode string to be translated.
        The returned type is the same as
        :method:`TranslatorFactory._make_translation_func`.

        The domain argument is the same as
        :method:`TranslatorFactory._make_translation_func`.

        """
        if domain is None:
            domain = self.domain
        t = gettext.translation(domain,
                                localedir=self.localedir,
                                fallback=True)
        # Use the appropriate method of the translation object based
        # on the python version.
        m = t.gettext

        def f(ctx, msg):
            """oslo.i18n.gettextutils translation with context function."""
            if _lazy.USE_LAZY:
                msgid = (ctx, msg)
                return _message.Message(msgid, domain=domain,
                                        has_contextual_form=True)

            msgctx = "{}{}{}".format(ctx, CONTEXT_SEPARATOR, msg)
            s = m(msgctx)
            if CONTEXT_SEPARATOR in s:
                # Translation not found
                return msg
            return s
        return f

    def _make_plural_translation_func(self, domain=None):
        """Return a plural translation function ready for use with messages.

        The returned function takes three values, the single form of
        the unicode string, the plural form of the unicode string,
        the count of items to be translated.
        The returned type is the same as
        :method:`TranslatorFactory._make_translation_func`.

        The domain argument is the same as
        :method:`TranslatorFactory._make_translation_func`.

        """
        if domain is None:
            domain = self.domain
        t = gettext.translation(domain,
                                localedir=self.localedir,
                                fallback=True)
        # Use the appropriate method of the translation object based
        # on the python version.
        m = t.ngettext

        def f(msgsingle, msgplural, msgcount):
            """oslo.i18n.gettextutils plural translation function."""
            if _lazy.USE_LAZY:
                msgid = (msgsingle, msgplural, msgcount)
                return _message.Message(msgid, domain=domain,
                                        has_plural_form=True)
            return m(msgsingle, msgplural, msgcount)
        return f

    @property
    def primary(self):
        "The default translation function."
        return self._make_translation_func()

    @property
    def contextual_form(self):
        """The contextual translation function.

        The returned function takes two values, the context of
        the unicode string, the unicode string to be translated.

        .. versionadded:: 2.1.0

        """
        return self._make_contextual_translation_func()

    @property
    def plural_form(self):
        """The plural translation function.

        The returned function takes three values, the single form of
        the unicode string, the plural form of the unicode string,
        the count of items to be translated.

        .. versionadded:: 2.1.0

        """
        return self._make_plural_translation_func()

    def _make_log_translation_func(self, level):
        return self._make_translation_func(self.domain + '-log-' + level)

    @property
    def log_info(self):
        "Translate info-level log messages."
        return self._make_log_translation_func('info')

    @property
    def log_warning(self):
        "Translate warning-level log messages."
        return self._make_log_translation_func('warning')

    @property
    def log_error(self):
        "Translate error-level log messages."
        return self._make_log_translation_func('error')

    @property
    def log_critical(self):
        "Translate critical-level log messages."
        return self._make_log_translation_func('critical')
