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 logging
import torch

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


import pdb
import random
import math


class MFCCA(FunASRModel):
    """
    Author: Audio, Speech and Language Processing Group (ASLP@NPU), Northwestern Polytechnical University
    MFCCA:Multi-Frame Cross-Channel attention for multi-speaker ASR in Multi-party meeting scenario
    https://arxiv.org/abs/2210.05265
    """

    def __init__(
        self,
        vocab_size: int,
        token_list: Union[Tuple[str, ...], List[str]],
        frontend: Optional[AbsFrontend],
        specaug: Optional[AbsSpecAug],
        normalize: Optional[AbsNormalize],
        encoder: AbsEncoder,
        decoder: AbsDecoder,
        ctc: CTC,
        rnnt_decoder: None = None,
        ctc_weight: float = 0.5,
        ignore_id: int = -1,
        lsm_weight: float = 0.0,
        mask_ratio: float = 0.0,
        length_normalized_loss: bool = False,
        report_cer: bool = True,
        report_wer: bool = True,
        sym_space: str = "<space>",
        sym_blank: str = "<blank>",
        preencoder: Optional[AbsPreEncoder] = None,
    ):
        assert 0.0 <= ctc_weight <= 1.0, ctc_weight
        assert rnnt_decoder is None, "Not implemented"

        super().__init__()
        # note that eos is the same as sos (equivalent ID)
        self.sos = vocab_size - 1
        self.eos = vocab_size - 1
        self.vocab_size = vocab_size
        self.ignore_id = ignore_id
        self.ctc_weight = ctc_weight
        self.token_list = token_list.copy()

        self.mask_ratio = mask_ratio

        self.frontend = frontend
        self.specaug = specaug
        self.normalize = normalize
        self.preencoder = preencoder
        self.encoder = encoder
        # we set self.decoder = None in the CTC mode since
        # self.decoder parameters were never used and PyTorch complained
        # and threw an Exception in the multi-GPU experiment.
        # thanks Jeff Farris for pointing out the issue.
        if ctc_weight == 1.0:
            self.decoder = None
        else:
            self.decoder = decoder
        if ctc_weight == 0.0:
            self.ctc = None
        else:
            self.ctc = ctc
        self.rnnt_decoder = rnnt_decoder
        self.criterion_att = LabelSmoothingLoss(
            size=vocab_size,
            padding_idx=ignore_id,
            smoothing=lsm_weight,
            normalize_length=length_normalized_loss,
        )

        if report_cer or report_wer:
            self.error_calculator = ErrorCalculator(
                token_list, sym_space, sym_blank, report_cer, report_wer
            )
        else:
            self.error_calculator = None

    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)
        # pdb.set_trace()
        if speech.dim() == 3 and speech.size(2) == 8 and self.mask_ratio != 0:
            rate_num = random.random()
            # rate_num = 0.1
            if rate_num <= self.mask_ratio:
                retain_channel = math.ceil(random.random() * 8)
                if retain_channel > 1:
                    speech = speech[:, :, torch.randperm(8)[0:retain_channel].sort().values]
                else:
                    speech = speech[:, :, torch.randperm(8)[0]]
        # pdb.set_trace()
        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)

        # 2a. Attention-decoder branch
        if self.ctc_weight == 1.0:
            loss_att, acc_att, cer_att, wer_att = None, None, None, None
        else:
            loss_att, acc_att, cer_att, wer_att = self._calc_att_loss(
                encoder_out, encoder_out_lens, text, text_lengths
            )

        # 2b. CTC branch
        if self.ctc_weight == 0.0:
            loss_ctc, cer_ctc = None, None
        else:
            loss_ctc, cer_ctc = self._calc_ctc_loss(
                encoder_out, encoder_out_lens, text, text_lengths
            )

        # 2c. RNN-T branch
        if self.rnnt_decoder is not None:
            _ = self._calc_rnnt_loss(encoder_out, encoder_out_lens, text, text_lengths)

        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

        stats = dict(
            loss=loss.detach(),
            loss_att=loss_att.detach() if loss_att is not None else None,
            loss_ctc=loss_ctc.detach() if loss_ctc is not None else None,
            acc=acc_att,
            cer=cer_att,
            wer=wer_att,
            cer_ctc=cer_ctc,
        )

        # 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]:
        feats, feats_lengths, channel_size = self._extract_feats(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, channel_size = 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)
        # pdb.set_trace()
        encoder_out, encoder_out_lens, _ = self.encoder(feats, feats_lengths, channel_size)

        assert encoder_out.size(0) == speech.size(0), (
            encoder_out.size(),
            speech.size(0),
        )
        if encoder_out.dim() == 4:
            assert encoder_out.size(2) <= encoder_out_lens.max(), (
                encoder_out.size(),
                encoder_out_lens.max(),
            )
        else:
            assert encoder_out.size(1) <= encoder_out_lens.max(), (
                encoder_out.size(),
                encoder_out_lens.max(),
            )

        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, channel_size = self.frontend(speech, speech_lengths)
        else:
            # No frontend and no feature extract
            feats, feats_lengths = speech, speech_lengths
            channel_size = 1
        return feats, feats_lengths, channel_size

    def _calc_att_loss(
        self,
        encoder_out: torch.Tensor,
        encoder_out_lens: torch.Tensor,
        ys_pad: torch.Tensor,
        ys_pad_lens: torch.Tensor,
    ):
        ys_in_pad, ys_out_pad = add_sos_eos(ys_pad, self.sos, self.eos, self.ignore_id)
        ys_in_lens = ys_pad_lens + 1

        # 1. Forward decoder
        decoder_out, _ = self.decoder(encoder_out, encoder_out_lens, ys_in_pad, ys_in_lens)

        # 2. Compute attention loss
        loss_att = self.criterion_att(decoder_out, ys_out_pad)
        acc_att = th_accuracy(
            decoder_out.view(-1, self.vocab_size),
            ys_out_pad,
            ignore_label=self.ignore_id,
        )

        # Compute cer/wer using attention-decoder
        if self.training or self.error_calculator is None:
            cer_att, wer_att = None, None
        else:
            ys_hat = decoder_out.argmax(dim=-1)
            cer_att, wer_att = self.error_calculator(ys_hat.cpu(), ys_pad.cpu())

        return loss_att, acc_att, cer_att, wer_att

    def _calc_ctc_loss(
        self,
        encoder_out: torch.Tensor,
        encoder_out_lens: torch.Tensor,
        ys_pad: torch.Tensor,
        ys_pad_lens: torch.Tensor,
    ):
        # Calc CTC loss
        if encoder_out.dim() == 4:
            encoder_out = encoder_out.mean(1)
        loss_ctc = self.ctc(encoder_out, encoder_out_lens, ys_pad, ys_pad_lens)

        # Calc CER using CTC
        cer_ctc = None
        if not self.training and self.error_calculator is not None:
            ys_hat = self.ctc.argmax(encoder_out).data
            cer_ctc = self.error_calculator(ys_hat.cpu(), ys_pad.cpu(), is_ctc=True)
        return loss_ctc, cer_ctc

    def _calc_rnnt_loss(
        self,
        encoder_out: torch.Tensor,
        encoder_out_lens: torch.Tensor,
        ys_pad: torch.Tensor,
        ys_pad_lens: torch.Tensor,
    ):
        raise NotImplementedError