# Copyright 2016 Google LLC
#
# 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.

"""Client for interacting with the Google Cloud Translation API."""


import six

from google.cloud.client import Client as BaseClient

from google.cloud.translate_v2._http import Connection


ENGLISH_ISO_639 = "en"
"""ISO 639-1 language code for English."""

BASE = "base"
"""Base translation model."""

NMT = "nmt"
"""Neural Machine Translation model."""


class Client(BaseClient):
    """Client to bundle configuration needed for API requests.

    :type target_language: str
    :param target_language: (Optional) The target language used for
                            translations and language names. (Defaults to
                            :data:`ENGLISH_ISO_639`.)

    :type credentials: :class:`~google.auth.credentials.Credentials`
    :param credentials: (Optional) The OAuth2 Credentials to use for this
                        client. If not passed (and if no ``_http`` object is
                        passed), falls back to the default inferred from the
                        environment.

    :type _http: :class:`~requests.Session`
    :param _http: (Optional) HTTP object to make requests. Can be any object
                  that defines ``request()`` with the same interface as
                  :meth:`requests.Session.request`. If not passed, an
                  ``_http`` object is created that is bound to the
                  ``credentials`` for the current object.
                  This parameter should be considered private, and could
                  change in the future.

    :type client_info: :class:`~google.api_core.client_info.ClientInfo`
    :param client_info:
        The client info used to send a user-agent string along with API
        requests. If ``None``, then default info will be used. Generally,
        you only need to set this if you're developing your own library
        or partner tool.
    """

    SCOPE = ("https://www.googleapis.com/auth/cloud-platform",)
    """The scopes required for authenticating."""

    def __init__(
        self,
        target_language=ENGLISH_ISO_639,
        credentials=None,
        _http=None,
        client_info=None,
    ):
        self.target_language = target_language
        super(Client, self).__init__(credentials=credentials, _http=_http)
        self._connection = Connection(self, client_info=client_info)

    def get_languages(self, target_language=None):
        """Get list of supported languages for translation.

        Response

        See
        https://cloud.google.com/translate/docs/discovering-supported-languages

        :type target_language: str
        :param target_language: (Optional) The language used to localize
                                returned language names. Defaults to the
                                target language on the current client.

        :rtype: list
        :returns: List of dictionaries. Each dictionary contains a supported
                  ISO 639-1 language code (using the dictionary key
                  ``language``). If ``target_language`` is passed, each
                  dictionary will also contain the name of each supported
                  language (localized to the target language).
        """
        query_params = {}
        if target_language is None:
            target_language = self.target_language
        if target_language is not None:
            query_params["target"] = target_language
        response = self._connection.api_request(
            method="GET", path="/languages", query_params=query_params
        )
        return response.get("data", {}).get("languages", ())

    def detect_language(self, values):
        """Detect the language of a string or list of strings.

        See https://cloud.google.com/translate/docs/detecting-language

        :type values: str or list
        :param values: String or list of strings that will have
                       language detected.

        :rtype: dict or list
        :returns: A list of dictionaries for each queried value. Each
                  dictionary typically contains three keys

                  * ``confidence``: The confidence in language detection, a
                    float between 0 and 1.
                  * ``input``: The corresponding input value.
                  * ``language``: The detected language (as an ISO 639-1
                    language code).

                  though the key ``confidence`` may not always be present.

                  If only a single value is passed, then only a single
                  dictionary will be returned.
        :raises: :class:`ValueError <exceptions.ValueError>` if the number of
                 detections is not equal to the number of values.
                 :class:`ValueError <exceptions.ValueError>` if a value
                 produces a list of detections with 0 or multiple results
                 in it.
        """
        single_value = False
        if isinstance(values, six.string_types):
            single_value = True
            values = [values]

        data = {"q": values}

        response = self._connection.api_request(
            method="POST", path="/detect", data=data
        )

        detections = response.get("data", {}).get("detections", ())

        if len(values) != len(detections):
            raise ValueError(
                "Expected same number of values and detections", values, detections
            )

        for index, value in enumerate(values):
            # Empirically, even clearly ambiguous text like "no" only returns
            # a single detection, so we replace the list of detections with
            # the single detection contained.
            if len(detections[index]) == 1:
                detections[index] = detections[index][0]
            else:
                message = (
                    "Expected a single detection per value, API " "returned %d"
                ) % (len(detections[index]),)
                raise ValueError(message, value, detections[index])

            detections[index]["input"] = value
            # The ``isReliable`` field is deprecated.
            detections[index].pop("isReliable", None)

        if single_value:
            return detections[0]
        else:
            return detections

    def translate(
        self,
        values,
        target_language=None,
        format_=None,
        source_language=None,
        customization_ids=(),
        model=None,
    ):
        """Translate a string or list of strings.

        See https://cloud.google.com/translate/docs/translating-text

        :type values: str or list
        :param values: String or list of strings to translate.

        :type target_language: str
        :param target_language: The language to translate results into. This
                                is required by the API and defaults to
                                the target language of the current instance.

        :type format_: str
        :param format_: (Optional) One of ``text`` or ``html``, to specify
                        if the input text is plain text or HTML.

        :type source_language: str
        :param source_language: (Optional) The language of the text to
                                be translated.

        :type customization_ids: str or list
        :param customization_ids: (Optional) ID or list of customization IDs
                                  for translation. Sets the ``cid`` parameter
                                  in the query.

        :type model: str
        :param model: (Optional) The model used to translate the text, such
                      as ``'base'`` or ``'nmt'``.

        :rtype: str or list
        :returns: A list of dictionaries for each queried value. Each
                  dictionary typically contains three keys (though not
                  all will be present in all cases)

                  * ``detectedSourceLanguage``: The detected language (as an
                    ISO 639-1 language code) of the text.
                  * ``translatedText``: The translation of the text into the
                    target language.
                  * ``input``: The corresponding input value.
                  * ``model``: The model used to translate the text.

                  If only a single value is passed, then only a single
                  dictionary will be returned.
        :raises: :class:`~exceptions.ValueError` if the number of
                 values and translations differ.
        """
        single_value = False
        if isinstance(values, six.string_types):
            single_value = True
            values = [values]

        if target_language is None:
            target_language = self.target_language
        if isinstance(customization_ids, six.string_types):
            customization_ids = [customization_ids]

        data = {
            "target": target_language,
            "q": values,
            "cid": customization_ids,
            "format": format_,
            "source": source_language,
            "model": model,
        }

        response = self._connection.api_request(method="POST", path="", data=data)

        translations = response.get("data", {}).get("translations", ())
        if len(values) != len(translations):
            raise ValueError(
                "Expected iterations to have same length", values, translations
            )
        for value, translation in six.moves.zip(values, translations):
            translation["input"] = value

        if single_value:
            return translations[0]
        else:
            return translations
