"""
Author: Speech Lab, Alibaba Group, China
"""

import logging
from contextlib import contextmanager
from distutils.version import LooseVersion
from typing import Dict
from typing import List
from typing import Optional
from typing import Tuple
from typing import Union

import torch

from funasr_detach.layers.abs_normalize import AbsNormalize
from funasr_detach.losses.label_smoothing_loss import (
    LabelSmoothingLoss,  # noqa: H301
)
from funasr_detach.models.ctc import CTC
from funasr_detach.models.decoder.abs_decoder import AbsDecoder
from funasr_detach.models.encoder.abs_encoder import AbsEncoder
from funasr_detach.frontends.abs_frontend import AbsFrontend
from funasr_detach.models.postencoder.abs_postencoder import AbsPostEncoder
from funasr_detach.models.preencoder.abs_preencoder import AbsPreEncoder
from funasr_detach.models.specaug.abs_specaug import AbsSpecAug
from funasr_detach.models.transformer.utils.add_sos_eos import add_sos_eos
from funasr_detach.metrics import ErrorCalculator
from funasr_detach.metrics.compute_acc import th_accuracy
from funasr_detach.train_utils.device_funcs import force_gatherable
from funasr_detach.models.base_model import FunASRModel

if LooseVersion(torch.__version__) >= LooseVersion("1.6.0"):
    from torch.cuda.amp import autocast
else:
    # Nothing to do if torch<1.6.0
    @contextmanager
    def autocast(enabled=True):
        yield


class ESPnetSVModel(FunASRModel):
    """CTC-attention hybrid Encoder-Decoder model"""

    def __init__(
        self,
        vocab_size: int,
        token_list: Union[Tuple[str, ...], List[str]],
        frontend: Optional[AbsFrontend],
        specaug: Optional[AbsSpecAug],
        normalize: Optional[AbsNormalize],
        preencoder: Optional[AbsPreEncoder],
        encoder: AbsEncoder,
        postencoder: Optional[AbsPostEncoder],
        pooling_layer: torch.nn.Module,
        decoder: AbsDecoder,
    ):

        super().__init__()
        # note that eos is the same as sos (equivalent ID)
        self.vocab_size = vocab_size
        self.token_list = token_list.copy()

        self.frontend = frontend
        self.specaug = specaug
        self.normalize = normalize
        self.preencoder = preencoder
        self.postencoder = postencoder
        self.encoder = encoder
        self.pooling_layer = pooling_layer
        self.decoder = decoder

    def forward(
        self,
        speech: torch.Tensor,
        speech_lengths: torch.Tensor,
        text: torch.Tensor,
        text_lengths: torch.Tensor,
    ) -> Tuple[torch.Tensor, Dict[str, torch.Tensor], torch.Tensor]:
        """Frontend + Encoder + Decoder + Calc loss
        Args:
            speech: (Batch, Length, ...)
            speech_lengths: (Batch, )
            text: (Batch, Length)
            text_lengths: (Batch,)
        """
        assert text_lengths.dim() == 1, text_lengths.shape
        # Check that batch_size is unified
        assert (
            speech.shape[0]
            == speech_lengths.shape[0]
            == text.shape[0]
            == text_lengths.shape[0]
        ), (speech.shape, speech_lengths.shape, text.shape, text_lengths.shape)
        batch_size = speech.shape[0]

        # for data-parallel
        text = text[:, : text_lengths.max()]

        # 1. Encoder
        encoder_out, encoder_out_lens = self.encode(speech, speech_lengths)
        intermediate_outs = None
        if isinstance(encoder_out, tuple):
            intermediate_outs = encoder_out[1]
            encoder_out = encoder_out[0]

        loss_att, acc_att, cer_att, wer_att = None, None, None, None
        loss_ctc, cer_ctc = None, None
        loss_transducer, cer_transducer, wer_transducer = None, None, None
        stats = dict()

        # 1. CTC branch
        if self.ctc_weight != 0.0:
            loss_ctc, cer_ctc = self._calc_ctc_loss(
                encoder_out, encoder_out_lens, text, text_lengths
            )

            # Collect CTC branch stats
            stats["loss_ctc"] = loss_ctc.detach() if loss_ctc is not None else None
            stats["cer_ctc"] = cer_ctc

        # Intermediate CTC (optional)
        loss_interctc = 0.0
        if self.interctc_weight != 0.0 and intermediate_outs is not None:
            for layer_idx, intermediate_out in intermediate_outs:
                # we assume intermediate_out has the same length & padding
                # as those of encoder_out
                loss_ic, cer_ic = self._calc_ctc_loss(
                    intermediate_out, encoder_out_lens, text, text_lengths
                )
                loss_interctc = loss_interctc + loss_ic

                # Collect Intermedaite CTC stats
                stats["loss_interctc_layer{}".format(layer_idx)] = (
                    loss_ic.detach() if loss_ic is not None else None
                )
                stats["cer_interctc_layer{}".format(layer_idx)] = cer_ic

            loss_interctc = loss_interctc / len(intermediate_outs)

            # calculate whole encoder loss
            loss_ctc = (
                1 - self.interctc_weight
            ) * loss_ctc + self.interctc_weight * loss_interctc

        if self.use_transducer_decoder:
            # 2a. Transducer decoder branch
            (
                loss_transducer,
                cer_transducer,
                wer_transducer,
            ) = self._calc_transducer_loss(
                encoder_out,
                encoder_out_lens,
                text,
            )

            if loss_ctc is not None:
                loss = loss_transducer + (self.ctc_weight * loss_ctc)
            else:
                loss = loss_transducer

            # Collect Transducer branch stats
            stats["loss_transducer"] = (
                loss_transducer.detach() if loss_transducer is not None else None
            )
            stats["cer_transducer"] = cer_transducer
            stats["wer_transducer"] = wer_transducer

        else:
            # 2b. Attention decoder branch
            if self.ctc_weight != 1.0:
                loss_att, acc_att, cer_att, wer_att = self._calc_att_loss(
                    encoder_out, encoder_out_lens, text, text_lengths
                )

            # 3. CTC-Att loss definition
            if self.ctc_weight == 0.0:
                loss = loss_att
            elif self.ctc_weight == 1.0:
                loss = loss_ctc
            else:
                loss = self.ctc_weight * loss_ctc + (1 - self.ctc_weight) * loss_att

            # Collect Attn branch stats
            stats["loss_att"] = loss_att.detach() if loss_att is not None else None
            stats["acc"] = acc_att
            stats["cer"] = cer_att
            stats["wer"] = wer_att

        # Collect total loss stats
        stats["loss"] = torch.clone(loss.detach())

        # force_gatherable: to-device and to-tensor if scalar for DataParallel
        loss, stats, weight = force_gatherable((loss, stats, batch_size), loss.device)
        return loss, stats, weight

    def collect_feats(
        self,
        speech: torch.Tensor,
        speech_lengths: torch.Tensor,
        text: torch.Tensor,
        text_lengths: torch.Tensor,
    ) -> Dict[str, torch.Tensor]:
        if self.extract_feats_in_collect_stats:
            feats, feats_lengths = self._extract_feats(speech, speech_lengths)
        else:
            # Generate dummy stats if extract_feats_in_collect_stats is False
            logging.warning(
                "Generating dummy stats for feats and feats_lengths, "
                "because encoder_conf.extract_feats_in_collect_stats is "
                f"{self.extract_feats_in_collect_stats}"
            )
            feats, feats_lengths = speech, speech_lengths
        return {"feats": feats, "feats_lengths": feats_lengths}

    def encode(
        self, speech: torch.Tensor, speech_lengths: torch.Tensor
    ) -> Tuple[torch.Tensor, torch.Tensor]:
        """Frontend + Encoder. Note that this method is used by asr_inference.py
        Args:
            speech: (Batch, Length, ...)
            speech_lengths: (Batch, )
        """
        with autocast(False):
            # 1. Extract feats
            feats, feats_lengths = self._extract_feats(speech, speech_lengths)

            # 2. Data augmentation
            if self.specaug is not None and self.training:
                feats, feats_lengths = self.specaug(feats, feats_lengths)

            # 3. Normalization for feature: e.g. Global-CMVN, Utterance-CMVN
            if self.normalize is not None:
                feats, feats_lengths = self.normalize(feats, feats_lengths)

        # Pre-encoder, e.g. used for raw input data
        if self.preencoder is not None:
            feats, feats_lengths = self.preencoder(feats, feats_lengths)

        # 4. Forward encoder
        # feats: (Batch, Length, Dim) -> (Batch, Channel, Length2, Dim2)
        encoder_out, encoder_out_lens = self.encoder(feats, feats_lengths)

        # Post-encoder, e.g. NLU
        if self.postencoder is not None:
            encoder_out, encoder_out_lens = self.postencoder(
                encoder_out, encoder_out_lens
            )

        return encoder_out, encoder_out_lens

    def _extract_feats(
        self, speech: torch.Tensor, speech_lengths: torch.Tensor
    ) -> Tuple[torch.Tensor, torch.Tensor]:
        assert speech_lengths.dim() == 1, speech_lengths.shape

        # for data-parallel
        speech = speech[:, : speech_lengths.max()]

        if self.frontend is not None:
            # Frontend
            #  e.g. STFT and Feature extract
            #       data_loader may send time-domain signal in this case
            # speech (Batch, NSamples) -> feats: (Batch, NFrames, Dim)
            feats, feats_lengths = self.frontend(speech, speech_lengths)
        else:
            # No frontend and no feature extract
            feats, feats_lengths = speech, speech_lengths
        return feats, feats_lengths
