# coding: utf-8
import numpy as np
import torch
from torch import nn

from TTS.tts.utils.measures import alignment_diagonal_score
from TTS.tts.utils.visual import plot_alignment, plot_spectrogram
from TTS.tts.layers.tacotron.gst_layers import GST
from TTS.tts.layers.tacotron.tacotron2 import Decoder, Encoder, Postnet
from TTS.tts.models.tacotron_abstract import TacotronAbstract


class Tacotron2(TacotronAbstract):
    """Tacotron2 as in https://arxiv.org/abs/1712.05884

    It's an autoregressive encoder-attention-decoder-postnet architecture.

    Args:
        num_chars (int): number of input characters to define the size of embedding layer.
        num_speakers (int): number of speakers in the dataset. >1 enables multi-speaker training and model learns speaker embeddings.
        r (int): initial model reduction rate.
        postnet_output_dim (int, optional): postnet output channels. Defaults to 80.
        decoder_output_dim (int, optional): decoder output channels. Defaults to 80.
        attn_type (str, optional): attention type. Check ```TTS.tts.layers.tacotron.common_layers.init_attn```. Defaults to 'original'.
        attn_win (bool, optional): enable/disable attention windowing.
            It especially useful at inference to keep attention alignment diagonal. Defaults to False.
        attn_norm (str, optional): Attention normalization method. "sigmoid" or "softmax". Defaults to "softmax".
        prenet_type (str, optional): prenet type for the decoder. Defaults to "original".
        prenet_dropout (bool, optional): prenet dropout rate. Defaults to True.
        prenet_dropout_at_inference (bool, optional): use dropout at inference time. This leads to a better quality for
            some models. Defaults to False.
        forward_attn (bool, optional): enable/disable forward attention.
            It is only valid if ```attn_type``` is ```original```.  Defaults to False.
        trans_agent (bool, optional): enable/disable transition agent in forward attention. Defaults to False.
        forward_attn_mask (bool, optional): enable/disable extra masking over forward attention. Defaults to False.
        location_attn (bool, optional): enable/disable location sensitive attention.
            It is only valid if ```attn_type``` is ```original```. Defaults to True.
        attn_K (int, optional): Number of attention heads for GMM attention. Defaults to 5.
        separate_stopnet (bool, optional): enable/disable separate stopnet training without only gradient
            flow from stopnet to the rest of the model.  Defaults to True.
        bidirectional_decoder (bool, optional): enable/disable bidirectional decoding. Defaults to False.
        double_decoder_consistency (bool, optional): enable/disable double decoder consistency. Defaults to False.
        ddc_r (int, optional): reduction rate for the coarse decoder of double decoder consistency. Defaults to None.
        encoder_in_features (int, optional): input channels for the encoder. Defaults to 512.
        decoder_in_features (int, optional): input channels for the decoder. Defaults to 512.
        speaker_embedding_dim (int, optional): external speaker conditioning vector channels. Defaults to None.
        use_gst (bool, optional): enable/disable Global style token module.
        gst (Coqpit, optional): Coqpit to initialize the GST module. If `None`, GST is disabled. Defaults to None.
        gradual_trainin (List): Gradual training schedule. If None or `[]`, no gradual training is used.
            Defaults to `[]`.
    """
    def __init__(self,
                 num_chars,
                 num_speakers,
                 r,
                 postnet_output_dim=80,
                 decoder_output_dim=80,
                 attn_type="original",
                 attn_win=False,
                 attn_norm="softmax",
                 prenet_type="original",
                 prenet_dropout=True,
                 prenet_dropout_at_inference=False,
                 forward_attn=False,
                 trans_agent=False,
                 forward_attn_mask=False,
                 location_attn=True,
                 attn_K=5,
                 separate_stopnet=True,
                 bidirectional_decoder=False,
                 double_decoder_consistency=False,
                 ddc_r=None,
                 encoder_in_features=512,
                 decoder_in_features=512,
                 speaker_embedding_dim=None,
                 use_gst=False,
                 gst=None,
                 gradual_training=[]):
        super().__init__(num_chars, num_speakers, r, postnet_output_dim,
                         decoder_output_dim, attn_type, attn_win, attn_norm,
                         prenet_type, prenet_dropout,
                         prenet_dropout_at_inference, forward_attn,
                         trans_agent, forward_attn_mask, location_attn, attn_K,
                         separate_stopnet, bidirectional_decoder,
                         double_decoder_consistency, ddc_r,
                         encoder_in_features, decoder_in_features,
                         speaker_embedding_dim, use_gst, gst, gradual_training)

        # speaker embedding layer
        if self.num_speakers > 1:
            if not self.embeddings_per_sample:
                speaker_embedding_dim = 512
                self.speaker_embedding = nn.Embedding(self.num_speakers,
                                                      speaker_embedding_dim)
                self.speaker_embedding.weight.data.normal_(0, 0.3)

        # speaker and gst embeddings is concat in decoder input
        if self.num_speakers > 1:
            self.decoder_in_features += speaker_embedding_dim  # add speaker embedding dim

        # embedding layer
        self.embedding = nn.Embedding(num_chars, 512, padding_idx=0)

        # base model layers
        self.encoder = Encoder(self.encoder_in_features)
        self.decoder = Decoder(
            self.decoder_in_features,
            self.decoder_output_dim,
            r,
            attn_type,
            attn_win,
            attn_norm,
            prenet_type,
            prenet_dropout,
            forward_attn,
            trans_agent,
            forward_attn_mask,
            location_attn,
            attn_K,
            separate_stopnet,
        )
        self.postnet = Postnet(self.postnet_output_dim)

        # setup prenet dropout
        self.decoder.prenet.dropout_at_inference = prenet_dropout_at_inference

        # global style token layers
        if self.gst and use_gst:
            self.gst_layer = GST(
                num_mel=decoder_output_dim,
                speaker_embedding_dim=speaker_embedding_dim,
                num_heads=gst.gst_num_heads,
                num_style_tokens=gst.gst_num_style_tokens,
                gst_embedding_dim=gst.gst_embedding_dim,
            )

        # backward pass decoder
        if self.bidirectional_decoder:
            self._init_backward_decoder()
        # setup DDC
        if self.double_decoder_consistency:
            self.coarse_decoder = Decoder(
                self.decoder_in_features,
                self.decoder_output_dim,
                ddc_r,
                attn_type,
                attn_win,
                attn_norm,
                prenet_type,
                prenet_dropout,
                forward_attn,
                trans_agent,
                forward_attn_mask,
                location_attn,
                attn_K,
                separate_stopnet,
            )

    @staticmethod
    def shape_outputs(mel_outputs, mel_outputs_postnet, alignments):
        mel_outputs = mel_outputs.transpose(1, 2)
        mel_outputs_postnet = mel_outputs_postnet.transpose(1, 2)
        return mel_outputs, mel_outputs_postnet, alignments

    def forward(self,
                text,
                text_lengths,
                mel_specs=None,
                mel_lengths=None,
                cond_input=None):
        """
        Shapes:
            text: [B, T_in]
            text_lengths: [B]
            mel_specs: [B, T_out, C]
            mel_lengths: [B]
            cond_input: 'speaker_ids': [B, 1] and  'x_vectors':[B, C]
        """
        outputs = {
            'alignments_backward': None,
            'decoder_outputs_backward': None
        }
        # compute mask for padding
        # B x T_in_max (boolean)
        input_mask, output_mask = self.compute_masks(text_lengths, mel_lengths)
        # B x D_embed x T_in_max
        embedded_inputs = self.embedding(text).transpose(1, 2)
        # B x T_in_max x D_en
        encoder_outputs = self.encoder(embedded_inputs, text_lengths)
        if self.gst and self.use_gst:
            # B x gst_dim
            encoder_outputs = self.compute_gst(encoder_outputs, mel_specs,
                                               cond_input['x_vectors'])
        if self.num_speakers > 1:
            if not self.embeddings_per_sample:
                # B x 1 x speaker_embed_dim
                speaker_embeddings = self.speaker_embedding(cond_input['speaker_ids'])[:,
                                                                        None]
            else:
                # B x 1 x speaker_embed_dim
                speaker_embeddings = torch.unsqueeze(cond_input['x_vectors'], 1)
            encoder_outputs = self._concat_speaker_embedding(
                encoder_outputs, speaker_embeddings)

        encoder_outputs = encoder_outputs * input_mask.unsqueeze(2).expand_as(
            encoder_outputs)

        # B x mel_dim x T_out -- B x T_out//r x T_in -- B x T_out//r
        decoder_outputs, alignments, stop_tokens = self.decoder(
            encoder_outputs, mel_specs, input_mask)
        # sequence masking
        if mel_lengths is not None:
            decoder_outputs = decoder_outputs * output_mask.unsqueeze(
                1).expand_as(decoder_outputs)
        # B x mel_dim x T_out
        postnet_outputs = self.postnet(decoder_outputs)
        postnet_outputs = decoder_outputs + postnet_outputs
        # sequence masking
        if output_mask is not None:
            postnet_outputs = postnet_outputs * output_mask.unsqueeze(
                1).expand_as(postnet_outputs)
        # B x T_out x mel_dim -- B x T_out x mel_dim -- B x T_out//r x T_in
        decoder_outputs, postnet_outputs, alignments = self.shape_outputs(
            decoder_outputs, postnet_outputs, alignments)
        if self.bidirectional_decoder:
            decoder_outputs_backward, alignments_backward = self._backward_pass(
                mel_specs, encoder_outputs, input_mask)
            outputs['alignments_backward'] = alignments_backward
            outputs['decoder_outputs_backward'] = decoder_outputs_backward
        if self.double_decoder_consistency:
            decoder_outputs_backward, alignments_backward = self._coarse_decoder_pass(
                mel_specs, encoder_outputs, alignments, input_mask)
            outputs['alignments_backward'] = alignments_backward
            outputs['decoder_outputs_backward'] = decoder_outputs_backward
        outputs.update({
            'postnet_outputs': postnet_outputs,
            'decoder_outputs': decoder_outputs,
            'alignments': alignments,
            'stop_tokens': stop_tokens
        })
        return outputs

    @torch.no_grad()
    def inference(self, text, cond_input=None):
        embedded_inputs = self.embedding(text).transpose(1, 2)
        encoder_outputs = self.encoder.inference(embedded_inputs)

        if self.gst and self.use_gst:
            # B x gst_dim
            encoder_outputs = self.compute_gst(encoder_outputs, cond_input['style_mel'],
                                               cond_input['x_vectors'])
        if self.num_speakers > 1:
            if not self.embeddings_per_sample:
                x_vector = self.speaker_embedding(cond_input['speaker_ids'])[:, None]
                x_vector = torch.unsqueeze(x_vector, 0).transpose(1, 2)
            else:
                x_vector = cond_input

            encoder_outputs = self._concat_speaker_embedding(
                encoder_outputs, x_vector)

        decoder_outputs, alignments, stop_tokens = self.decoder.inference(
            encoder_outputs)
        postnet_outputs = self.postnet(decoder_outputs)
        postnet_outputs = decoder_outputs + postnet_outputs
        decoder_outputs, postnet_outputs, alignments = self.shape_outputs(
            decoder_outputs, postnet_outputs, alignments)
        outputs = {
            'postnet_outputs': postnet_outputs,
            'decoder_outputs': decoder_outputs,
            'alignments': alignments,
            'stop_tokens': stop_tokens
        }
        return outputs

    def train_step(self, batch, criterion):
        """Perform a single training step by fetching the right set if samples from the batch.

        Args:
            batch ([type]): [description]
            criterion ([type]): [description]
        """
        text_input = batch['text_input']
        text_lengths = batch['text_lengths']
        mel_input = batch['mel_input']
        mel_lengths = batch['mel_lengths']
        linear_input = batch['linear_input']
        stop_targets = batch['stop_targets']
        speaker_ids = batch['speaker_ids']
        x_vectors = batch['x_vectors']

        # forward pass model
        outputs = self.forward(text_input,
                               text_lengths,
                               mel_input,
                               mel_lengths,
                               cond_input={
                                   'speaker_ids': speaker_ids,
                                   'x_vectors': x_vectors
                               })

        # set the [alignment] lengths wrt reduction factor for guided attention
        if mel_lengths.max() % self.decoder.r != 0:
            alignment_lengths = (
                mel_lengths +
                (self.decoder.r -
                 (mel_lengths.max() % self.decoder.r))) // self.decoder.r
        else:
            alignment_lengths = mel_lengths // self.decoder.r

        cond_input = {'speaker_ids': speaker_ids, 'x_vectors': x_vectors}
        outputs = self.forward(text_input, text_lengths, mel_input,
                               mel_lengths, cond_input)

        # compute loss
        loss_dict = criterion(
            outputs['model_outputs'],
            outputs['decoder_outputs'],
            mel_input,
            linear_input,
            outputs['stop_tokens'],
            stop_targets,
            mel_lengths,
            outputs['decoder_outputs_backward'],
            outputs['alignments'],
            alignment_lengths,
            outputs['alignments_backward'],
            text_lengths,
        )

        # compute alignment error (the lower the better )
        align_error = 1 - alignment_diagonal_score(outputs['alignments'])
        loss_dict["align_error"] = align_error
        return outputs, loss_dict

    def train_log(self, ap, batch, outputs):
        postnet_outputs = outputs['model_outputs']
        alignments = outputs['alignments']
        alignments_backward = outputs['alignments_backward']
        mel_input = batch['mel_input']

        pred_spec = postnet_outputs[0].data.cpu().numpy()
        gt_spec = mel_input[0].data.cpu().numpy()
        align_img = alignments[0].data.cpu().numpy()

        figures = {
            "prediction": plot_spectrogram(pred_spec, ap, output_fig=False),
            "ground_truth": plot_spectrogram(gt_spec, ap, output_fig=False),
            "alignment": plot_alignment(align_img, output_fig=False),
        }

        if self.bidirectional_decoder or self.double_decoder_consistency:
            figures["alignment_backward"] = plot_alignment(
                alignments_backward[0].data.cpu().numpy(), output_fig=False)

        # Sample audio
        train_audio = ap.inv_melspectrogram(pred_spec.T)
        return figures, train_audio

    def eval_step(self, batch, criterion):
        return self.train_step(batch, criterion)

    def eval_log(self, ap, batch, outputs):
        return self.train_log(ap, batch, outputs)