# Copyright ESPnet (https://github.com/espnet/espnet). All Rights Reserved.
#  Apache 2.0  (http://www.apache.org/licenses/LICENSE-2.0)

from contextlib import contextmanager
from distutils.version import LooseVersion
from typing import Dict
from typing import Tuple

import numpy as np
import torch
import torch.nn as  nn
from typeguard import check_argument_types

from funasr.models.frontend.wav_frontend import WavFrontendMel23
from funasr.modules.eend_ola.encoder import EENDOLATransformerEncoder
from funasr.modules.eend_ola.encoder_decoder_attractor import EncoderDecoderAttractor
from funasr.modules.eend_ola.utils.power import generate_mapping_dict
from funasr.torch_utils.device_funcs import force_gatherable
from funasr.models.base_model import FunASRModel

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


def pad_attractor(att, max_n_speakers):
    C, D = att.shape
    if C < max_n_speakers:
        att = torch.cat([att, torch.zeros(max_n_speakers - C, D).to(torch.float32).to(att.device)], dim=0)
    return att


class DiarEENDOLAModel(FunASRModel):
    """EEND-OLA diarization model"""

    def __init__(
            self,
            frontend: WavFrontendMel23,
            encoder: EENDOLATransformerEncoder,
            encoder_decoder_attractor: EncoderDecoderAttractor,
            n_units: int = 256,
            max_n_speaker: int = 8,
            attractor_loss_weight: float = 1.0,
            mapping_dict=None,
            **kwargs,
    ):
        assert check_argument_types()

        super().__init__()
        self.frontend = frontend
        self.enc = encoder
        self.eda = encoder_decoder_attractor
        self.attractor_loss_weight = attractor_loss_weight
        self.max_n_speaker = max_n_speaker
        if mapping_dict is None:
            mapping_dict = generate_mapping_dict(max_speaker_num=self.max_n_speaker)
            self.mapping_dict = mapping_dict
        # PostNet
        self.postnet = nn.LSTM(self.max_n_speaker, n_units, 1, batch_first=True)
        self.output_layer = nn.Linear(n_units, mapping_dict['oov'] + 1)

    def forward_encoder(self, xs, ilens):
        xs = nn.utils.rnn.pad_sequence(xs, batch_first=True, padding_value=-1)
        pad_shape = xs.shape
        xs_mask = [torch.ones(ilen).to(xs.device) for ilen in ilens]
        xs_mask = torch.nn.utils.rnn.pad_sequence(xs_mask, batch_first=True, padding_value=0).unsqueeze(-2)
        emb = self.enc(xs, xs_mask)
        emb = torch.split(emb.view(pad_shape[0], pad_shape[1], -1), 1, dim=0)
        emb = [e[0][:ilen] for e, ilen in zip(emb, ilens)]
        return emb

    def forward_post_net(self, logits, ilens):
        maxlen = torch.max(ilens).to(torch.int).item()
        logits = nn.utils.rnn.pad_sequence(logits, batch_first=True, padding_value=-1)
        logits = nn.utils.rnn.pack_padded_sequence(logits, ilens.cpu().to(torch.int64), batch_first=True, enforce_sorted=False)
        outputs, (_, _) = self.postnet(logits)
        outputs = nn.utils.rnn.pad_packed_sequence(outputs, batch_first=True, padding_value=-1, total_length=maxlen)[0]
        outputs = [output[:ilens[i].to(torch.int).item()] for i, output in enumerate(outputs)]
        outputs = [self.output_layer(output) for output in outputs]
        return outputs

    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.enc(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
        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

        # 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 estimate_sequential(self,
                            speech: torch.Tensor,
                            speech_lengths: torch.Tensor,
                            n_speakers: int = None,
                            shuffle: bool = True,
                            threshold: float = 0.5,
                            **kwargs):
        speech = [s[:s_len] for s, s_len in zip(speech, speech_lengths)]
        emb = self.forward_encoder(speech, speech_lengths)
        if shuffle:
            orders = [np.arange(e.shape[0]) for e in emb]
            for order in orders:
                np.random.shuffle(order)
            attractors, probs = self.eda.estimate(
                [e[torch.from_numpy(order).to(torch.long).to(speech[0].device)] for e, order in zip(emb, orders)])
        else:
            attractors, probs = self.eda.estimate(emb)
        attractors_active = []
        for p, att, e in zip(probs, attractors, emb):
            if n_speakers and n_speakers >= 0:
                att = att[:n_speakers, ]
                attractors_active.append(att)
            elif threshold is not None:
                silence = torch.nonzero(p < threshold)[0]
                n_spk = silence[0] if silence.size else None
                att = att[:n_spk, ]
                attractors_active.append(att)
            else:
                NotImplementedError('n_speakers or threshold has to be given.')
        raw_n_speakers = [att.shape[0] for att in attractors_active]
        attractors = [
            pad_attractor(att, self.max_n_speaker) if att.shape[0] <= self.max_n_speaker else att[:self.max_n_speaker]
            for att in attractors_active]
        ys = [torch.matmul(e, att.permute(1, 0)) for e, att in zip(emb, attractors)]
        logits = self.forward_post_net(ys, speech_lengths)
        ys = [self.recover_y_from_powerlabel(logit, raw_n_speaker) for logit, raw_n_speaker in
              zip(logits, raw_n_speakers)]

        return ys, emb, attractors, raw_n_speakers

    def recover_y_from_powerlabel(self, logit, n_speaker):
        pred = torch.argmax(torch.softmax(logit, dim=-1), dim=-1)
        oov_index = torch.where(pred == self.mapping_dict['oov'])[0]
        for i in oov_index:
            if i > 0:
                pred[i] = pred[i - 1]
            else:
                pred[i] = 0
        pred = [self.inv_mapping_func(i) for i in pred]
        decisions = [bin(num)[2:].zfill(self.max_n_speaker)[::-1] for num in pred]
        decisions = torch.from_numpy(
            np.stack([np.array([int(i) for i in dec]) for dec in decisions], axis=0)).to(logit.device).to(
            torch.float32)
        decisions = decisions[:, :n_speaker]
        return decisions

    def inv_mapping_func(self, label):

        if not isinstance(label, int):
            label = int(label)
        if label in self.mapping_dict['label2dec'].keys():
            num = self.mapping_dict['label2dec'][label]
        else:
            num = -1
        return num

    def collect_feats(self, **batch: torch.Tensor) -> Dict[str, torch.Tensor]:
        pass