import enum

from ..tokenization_utils import TruncationStrategy
from ..utils import add_end_docstrings, is_tf_available, is_torch_available, logging
from .base import PIPELINE_INIT_ARGS, Pipeline


if is_tf_available():
    import tensorflow as tf

    from ..models.auto.modeling_tf_auto import TF_MODEL_FOR_SEQ_TO_SEQ_CAUSAL_LM_MAPPING

if is_torch_available():
    from ..models.auto.modeling_auto import MODEL_FOR_SEQ_TO_SEQ_CAUSAL_LM_MAPPING

logger = logging.get_logger(__name__)


class ReturnType(enum.Enum):
    TENSORS = 0
    TEXT = 1


@add_end_docstrings(PIPELINE_INIT_ARGS)
class Text2TextGenerationPipeline(Pipeline):
    """
    Pipeline for text to text generation using seq2seq models.

    This Text2TextGenerationPipeline pipeline can currently be loaded from [`pipeline`] using the following task
    identifier: `"text2text-generation"`.

    The models that this pipeline can use are models that have been fine-tuned on a translation task. See the
    up-to-date list of available models on
    [huggingface.co/models](https://huggingface.co/models?filter=text2text-generation).

    Usage:

    ```python
    text2text_generator = pipeline("text2text-generation")
    text2text_generator("question: What is 42 ? context: 42 is the answer to life, the universe and everything")
    ```"""

    # Used in the return key of the pipeline.
    return_name = "generated"

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self.check_model_type(
            TF_MODEL_FOR_SEQ_TO_SEQ_CAUSAL_LM_MAPPING
            if self.framework == "tf"
            else MODEL_FOR_SEQ_TO_SEQ_CAUSAL_LM_MAPPING
        )

    def _sanitize_parameters(
        self,
        return_tensors=None,
        return_text=None,
        return_type=None,
        clean_up_tokenization_spaces=None,
        truncation=None,
        **generate_kwargs
    ):
        preprocess_params = {}
        if truncation is not None:
            preprocess_params["truncation"] = truncation

        forward_params = generate_kwargs

        postprocess_params = {}
        if return_tensors is not None and return_type is None:
            return_type = ReturnType.TENSORS if return_tensors else ReturnType.TEXT
        if return_type is not None:
            postprocess_params["return_type"] = return_type

        if clean_up_tokenization_spaces is not None:
            postprocess_params["clean_up_tokenization_spaces"] = clean_up_tokenization_spaces

        return preprocess_params, forward_params, postprocess_params

    def check_inputs(self, input_length: int, min_length: int, max_length: int):
        """
        Checks whether there might be something wrong with given input with regard to the model.
        """
        return True

    def _parse_and_tokenize(self, *args, truncation):
        prefix = self.model.config.prefix if self.model.config.prefix is not None else ""
        if isinstance(args[0], list):
            if self.tokenizer.pad_token_id is None:
                raise ValueError("Please make sure that the tokenizer has a pad_token_id when using a batch input")
            args = ([prefix + arg for arg in args[0]],)
            padding = True

        elif isinstance(args[0], str):
            args = (prefix + args[0],)
            padding = False
        else:
            raise ValueError(
                f" `args[0]`: {args[0]} have the wrong format. The should be either of type `str` or type `list`"
            )
        inputs = self.tokenizer(*args, padding=padding, truncation=truncation, return_tensors=self.framework)
        # This is produced by tokenizers but is an invalid generate kwargs
        if "token_type_ids" in inputs:
            del inputs["token_type_ids"]
        return inputs

    def __call__(self, *args, **kwargs):
        r"""
        Generate the output text(s) using text(s) given as inputs.

        Args:
            args (`str` or `List[str]`):
                Input text for the encoder.
            return_tensors (`bool`, *optional*, defaults to `False`):
                Whether or not to include the tensors of predictions (as token indices) in the outputs.
            return_text (`bool`, *optional*, defaults to `True`):
                Whether or not to include the decoded texts in the outputs.
            clean_up_tokenization_spaces (`bool`, *optional*, defaults to `False`):
                Whether or not to clean up the potential extra spaces in the text output.
            truncation (`TruncationStrategy`, *optional*, defaults to `TruncationStrategy.DO_NOT_TRUNCATE`):
                The truncation strategy for the tokenization within the pipeline. `TruncationStrategy.DO_NOT_TRUNCATE`
                (default) will never truncate, but it is sometimes desirable to truncate the input to fit the model's
                max_length instead of throwing an error down the line.
            generate_kwargs:
                Additional keyword arguments to pass along to the generate method of the model (see the generate method
                corresponding to your framework [here](./model#generative-models)).

        Return:
            A list or a list of list of `dict`: Each result comes as a dictionary with the following keys:

            - **generated_text** (`str`, present when `return_text=True`) -- The generated text.
            - **generated_token_ids** (`torch.Tensor` or `tf.Tensor`, present when `return_tensors=True`) -- The token
              ids of the generated text.
        """

        result = super().__call__(*args, **kwargs)
        if (
            isinstance(args[0], list)
            and all(isinstance(el, str) for el in args[0])
            and all(len(res) == 1 for res in result)
        ):
            return [res[0] for res in result]
        return result

    def preprocess(self, inputs, truncation=TruncationStrategy.DO_NOT_TRUNCATE, **kwargs):
        inputs = self._parse_and_tokenize(inputs, truncation=truncation, **kwargs)
        return inputs

    def _forward(self, model_inputs, **generate_kwargs):
        if self.framework == "pt":
            in_b, input_length = model_inputs["input_ids"].shape
        elif self.framework == "tf":
            in_b, input_length = tf.shape(model_inputs["input_ids"]).numpy()

        generate_kwargs["min_length"] = generate_kwargs.get("min_length", self.model.config.min_length)
        generate_kwargs["max_length"] = generate_kwargs.get("max_length", self.model.config.max_length)
        self.check_inputs(input_length, generate_kwargs["min_length"], generate_kwargs["max_length"])
        output_ids = self.model.generate(**model_inputs, **generate_kwargs)
        out_b = output_ids.shape[0]
        if self.framework == "pt":
            output_ids = output_ids.reshape(in_b, out_b // in_b, *output_ids.shape[1:])
        elif self.framework == "tf":
            output_ids = tf.reshape(output_ids, (in_b, out_b // in_b, *output_ids.shape[1:]))
        return {"output_ids": output_ids}

    def postprocess(self, model_outputs, return_type=ReturnType.TEXT, clean_up_tokenization_spaces=False):
        records = []
        for output_ids in model_outputs["output_ids"][0]:
            if return_type == ReturnType.TENSORS:
                record = {f"{self.return_name}_token_ids": output_ids}
            elif return_type == ReturnType.TEXT:
                record = {
                    f"{self.return_name}_text": self.tokenizer.decode(
                        output_ids,
                        skip_special_tokens=True,
                        clean_up_tokenization_spaces=clean_up_tokenization_spaces,
                    )
                }
            records.append(record)
        return records


@add_end_docstrings(PIPELINE_INIT_ARGS)
class SummarizationPipeline(Text2TextGenerationPipeline):
    """
    Summarize news articles and other documents.

    This summarizing pipeline can currently be loaded from [`pipeline`] using the following task identifier:
    `"summarization"`.

    The models that this pipeline can use are models that have been fine-tuned on a summarization task, which is
    currently, '*bart-large-cnn*', '*t5-small*', '*t5-base*', '*t5-large*', '*t5-3b*', '*t5-11b*'. See the up-to-date
    list of available models on [huggingface.co/models](https://huggingface.co/models?filter=summarization).

    Usage:

    ```python
    # use bart in pytorch
    summarizer = pipeline("summarization")
    summarizer("An apple a day, keeps the doctor away", min_length=5, max_length=20)

    # use t5 in tf
    summarizer = pipeline("summarization", model="t5-base", tokenizer="t5-base", framework="tf")
    summarizer("An apple a day, keeps the doctor away", min_length=5, max_length=20)
    ```"""

    # Used in the return key of the pipeline.
    return_name = "summary"

    def __call__(self, *args, **kwargs):
        r"""
        Summarize the text(s) given as inputs.

        Args:
            documents (*str* or `List[str]`):
                One or several articles (or one list of articles) to summarize.
            return_text (`bool`, *optional*, defaults to `True`):
                Whether or not to include the decoded texts in the outputs
            return_tensors (`bool`, *optional*, defaults to `False`):
                Whether or not to include the tensors of predictions (as token indices) in the outputs.
            clean_up_tokenization_spaces (`bool`, *optional*, defaults to `False`):
                Whether or not to clean up the potential extra spaces in the text output.
            generate_kwargs:
                Additional keyword arguments to pass along to the generate method of the model (see the generate method
                corresponding to your framework [here](./model#generative-models)).

        Return:
            A list or a list of list of `dict`: Each result comes as a dictionary with the following keys:

            - **summary_text** (`str`, present when `return_text=True`) -- The summary of the corresponding input.
            - **summary_token_ids** (`torch.Tensor` or `tf.Tensor`, present when `return_tensors=True`) -- The token
              ids of the summary.
        """
        return super().__call__(*args, **kwargs)

    def check_inputs(self, input_length: int, min_length: int, max_length: int) -> bool:
        """
        Checks whether there might be something wrong with given input with regard to the model.
        """
        if max_length < min_length:
            logger.warning(f"Your min_length={min_length} must be inferior than your max_length={max_length}.")

        if input_length < max_length:
            logger.warning(
                f"Your max_length is set to {max_length}, but you input_length is only {input_length}. You might "
                f"consider decreasing max_length manually, e.g. summarizer('...', max_length={input_length//2})"
            )


@add_end_docstrings(PIPELINE_INIT_ARGS)
class TranslationPipeline(Text2TextGenerationPipeline):
    """
    Translates from one language to another.

    This translation pipeline can currently be loaded from [`pipeline`] using the following task identifier:
    `"translation_xx_to_yy"`.

    The models that this pipeline can use are models that have been fine-tuned on a translation task. See the
    up-to-date list of available models on [huggingface.co/models](https://huggingface.co/models?filter=translation).

    Usage:

    ```python
    en_fr_translator = pipeline("translation_en_to_fr")
    en_fr_translator("How old are you?")
    ```"""

    # Used in the return key of the pipeline.
    return_name = "translation"

    def check_inputs(self, input_length: int, min_length: int, max_length: int):
        if input_length > 0.9 * max_length:
            logger.warning(
                f"Your input_length: {input_length} is bigger than 0.9 * max_length: {max_length}. You might consider "
                "increasing your max_length manually, e.g. translator('...', max_length=400)"
            )
        return True

    def preprocess(self, *args, truncation=TruncationStrategy.DO_NOT_TRUNCATE, src_lang=None, tgt_lang=None):
        if getattr(self.tokenizer, "_build_translation_inputs", None):
            return self.tokenizer._build_translation_inputs(
                *args, return_tensors=self.framework, truncation=truncation, src_lang=src_lang, tgt_lang=tgt_lang
            )
        else:
            return super()._parse_and_tokenize(*args, truncation=truncation)

    def _sanitize_parameters(self, src_lang=None, tgt_lang=None, **kwargs):
        preprocess_params, forward_params, postprocess_params = super()._sanitize_parameters(**kwargs)
        if src_lang is not None:
            preprocess_params["src_lang"] = src_lang
        if tgt_lang is not None:
            preprocess_params["tgt_lang"] = tgt_lang
        if src_lang is None and tgt_lang is None:
            # Backward compatibility, direct arguments use is preferred.
            task = kwargs.get("task", self.task)
            items = task.split("_")
            if task and len(items) == 4:
                # translation, XX, to YY
                preprocess_params["src_lang"] = items[1]
                preprocess_params["tgt_lang"] = items[3]
        return preprocess_params, forward_params, postprocess_params

    def __call__(self, *args, **kwargs):
        r"""
        Translate the text(s) given as inputs.

        Args:
            args (`str` or `List[str]`):
                Texts to be translated.
            return_tensors (`bool`, *optional*, defaults to `False`):
                Whether or not to include the tensors of predictions (as token indices) in the outputs.
            return_text (`bool`, *optional*, defaults to `True`):
                Whether or not to include the decoded texts in the outputs.
            clean_up_tokenization_spaces (`bool`, *optional*, defaults to `False`):
                Whether or not to clean up the potential extra spaces in the text output.
            src_lang (`str`, *optional*):
                The language of the input. Might be required for multilingual models. Will not have any effect for
                single pair translation models
            tgt_lang (`str`, *optional*):
                The language of the desired output. Might be required for multilingual models. Will not have any effect
                for single pair translation models
            generate_kwargs:
                Additional keyword arguments to pass along to the generate method of the model (see the generate method
                corresponding to your framework [here](./model#generative-models)).

        Return:
            A list or a list of list of `dict`: Each result comes as a dictionary with the following keys:

            - **translation_text** (`str`, present when `return_text=True`) -- The translation.
            - **translation_token_ids** (`torch.Tensor` or `tf.Tensor`, present when `return_tensors=True`) -- The
              token ids of the translation.
        """
        return super().__call__(*args, **kwargs)
