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import sys
from math import sqrt
from os.path import abspath, dirname

import torch
from torch import nn
from torch.nn import functional as F

# enabling modules discovery from global entrypoint
sys.path.append(abspath(dirname(__file__) + "/../"))
from common.layers import ConvNorm, LinearNorm
from common.utils import mask_from_lens, to_gpu


class LocationLayer(nn.Module):
    def __init__(self, attention_n_filters, attention_kernel_size, attention_dim):
        super(LocationLayer, self).__init__()
        padding = int((attention_kernel_size - 1) / 2)
        self.location_conv = ConvNorm(
            2, attention_n_filters, kernel_size=attention_kernel_size, padding=padding, bias=False, stride=1, dilation=1
        )
        self.location_dense = LinearNorm(attention_n_filters, attention_dim, bias=False, w_init_gain="tanh")

    def forward(self, attention_weights_cat):
        processed_attention = self.location_conv(attention_weights_cat)
        processed_attention = processed_attention.transpose(1, 2)
        processed_attention = self.location_dense(processed_attention)
        return processed_attention


class Attention(nn.Module):
    def __init__(
        self,
        attention_rnn_dim,
        embedding_dim,
        attention_dim,
        attention_location_n_filters,
        attention_location_kernel_size,
    ):
        super(Attention, self).__init__()
        self.query_layer = LinearNorm(attention_rnn_dim, attention_dim, bias=False, w_init_gain="tanh")
        self.memory_layer = LinearNorm(embedding_dim, attention_dim, bias=False, w_init_gain="tanh")
        self.v = LinearNorm(attention_dim, 1, bias=False)
        self.location_layer = LocationLayer(attention_location_n_filters, attention_location_kernel_size, attention_dim)
        self.score_mask_value = -float("inf")

    def get_alignment_energies(self, query, processed_memory, attention_weights_cat):
        """
        PARAMS
        ------
        query: decoder output (batch, n_mel_channels * n_frames_per_step)
        processed_memory: processed encoder outputs (B, T_in, attention_dim)
        attention_weights_cat: cumulative and prev. att weights (B, 2, max_time)

        RETURNS
        -------
        alignment (batch, max_time)
        """

        processed_query = self.query_layer(query.unsqueeze(1))
        processed_attention_weights = self.location_layer(attention_weights_cat)
        energies = self.v(torch.tanh(processed_query + processed_attention_weights + processed_memory))

        energies = energies.squeeze(-1)
        return energies

    def forward(self, attention_hidden_state, memory, processed_memory, attention_weights_cat, mask):
        """
        PARAMS
        ------
        attention_hidden_state: attention rnn last output
        memory: encoder outputs
        processed_memory: processed encoder outputs
        attention_weights_cat: previous and cumulative attention weights
        mask: binary mask for padded data
        """
        alignment = self.get_alignment_energies(attention_hidden_state, processed_memory, attention_weights_cat)

        alignment.masked_fill_(mask, self.score_mask_value)

        attention_weights = F.softmax(alignment, dim=1)
        attention_context = torch.bmm(attention_weights.unsqueeze(1), memory)
        attention_context = attention_context.squeeze(1)

        return attention_context, attention_weights


class Prenet(nn.Module):
    def __init__(self, in_dim, sizes):
        super(Prenet, self).__init__()
        in_sizes = [in_dim] + sizes[:-1]
        self.layers = nn.ModuleList(
            [LinearNorm(in_size, out_size, bias=False) for (in_size, out_size) in zip(in_sizes, sizes)]
        )

    def forward(self, x):
        for linear in self.layers:
            x = F.dropout(F.relu(linear(x)), p=0.5, training=True)
        return x


class Postnet(nn.Module):
    """Postnet
    - Five 1-d convolution with 512 channels and kernel size 5
    """

    def __init__(self, n_mel_channels, postnet_embedding_dim, postnet_kernel_size, postnet_n_convolutions):
        super(Postnet, self).__init__()
        self.convolutions = nn.ModuleList()

        self.convolutions.append(
            nn.Sequential(
                ConvNorm(
                    n_mel_channels,
                    postnet_embedding_dim,
                    kernel_size=postnet_kernel_size,
                    stride=1,
                    padding=int((postnet_kernel_size - 1) / 2),
                    dilation=1,
                    w_init_gain="tanh",
                ),
                nn.BatchNorm1d(postnet_embedding_dim),
            )
        )

        for i in range(1, postnet_n_convolutions - 1):
            self.convolutions.append(
                nn.Sequential(
                    ConvNorm(
                        postnet_embedding_dim,
                        postnet_embedding_dim,
                        kernel_size=postnet_kernel_size,
                        stride=1,
                        padding=int((postnet_kernel_size - 1) / 2),
                        dilation=1,
                        w_init_gain="tanh",
                    ),
                    nn.BatchNorm1d(postnet_embedding_dim),
                )
            )

        self.convolutions.append(
            nn.Sequential(
                ConvNorm(
                    postnet_embedding_dim,
                    n_mel_channels,
                    kernel_size=postnet_kernel_size,
                    stride=1,
                    padding=int((postnet_kernel_size - 1) / 2),
                    dilation=1,
                    w_init_gain="linear",
                ),
                nn.BatchNorm1d(n_mel_channels),
            )
        )
        self.n_convs = len(self.convolutions)

    def forward(self, x):
        i = 0
        for conv in self.convolutions:
            if i < self.n_convs - 1:
                x = F.dropout(torch.tanh(conv(x)), 0.5, training=self.training)
            else:
                x = F.dropout(conv(x), 0.5, training=self.training)
            i += 1

        return x


class Encoder(nn.Module):
    """Encoder module:
    - Three 1-d convolution banks
    - Bidirectional LSTM
    """

    def __init__(self, encoder_n_convolutions, encoder_embedding_dim, encoder_kernel_size):
        super(Encoder, self).__init__()

        convolutions = []
        for _ in range(encoder_n_convolutions):
            conv_layer = nn.Sequential(
                ConvNorm(
                    encoder_embedding_dim,
                    encoder_embedding_dim,
                    kernel_size=encoder_kernel_size,
                    stride=1,
                    padding=int((encoder_kernel_size - 1) / 2),
                    dilation=1,
                    w_init_gain="relu",
                ),
                nn.BatchNorm1d(encoder_embedding_dim),
            )
            convolutions.append(conv_layer)
        self.convolutions = nn.ModuleList(convolutions)

        self.lstm = nn.LSTM(
            encoder_embedding_dim, int(encoder_embedding_dim / 2), 1, batch_first=True, bidirectional=True
        )

    @torch.jit.ignore
    def forward(self, x, input_lengths):
        for conv in self.convolutions:
            x = F.dropout(F.relu(conv(x)), 0.5, self.training)

        x = x.transpose(1, 2)

        # pytorch tensor are not reversible, hence the conversion
        input_lengths = input_lengths.cpu().numpy()
        x = nn.utils.rnn.pack_padded_sequence(x, input_lengths, batch_first=True)

        self.lstm.flatten_parameters()
        outputs, _ = self.lstm(x)

        outputs, _ = nn.utils.rnn.pad_packed_sequence(outputs, batch_first=True)

        return outputs

    @torch.jit.export
    def infer(self, x, input_lengths):
        device = x.device
        for conv in self.convolutions:
            x = F.dropout(F.relu(conv(x.to(device))), 0.5, self.training)

        x = x.transpose(1, 2)

        input_lengths = input_lengths.cpu()
        x = nn.utils.rnn.pack_padded_sequence(x, input_lengths, batch_first=True)

        outputs, _ = self.lstm(x)

        outputs, _ = nn.utils.rnn.pad_packed_sequence(outputs, batch_first=True)

        return outputs


class Decoder(nn.Module):
    def __init__(
        self,
        n_mel_channels,
        n_frames_per_step,
        encoder_embedding_dim,
        attention_dim,
        attention_location_n_filters,
        attention_location_kernel_size,
        attention_rnn_dim,
        decoder_rnn_dim,
        prenet_dim,
        max_decoder_steps,
        gate_threshold,
        p_attention_dropout,
        p_decoder_dropout,
        early_stopping,
    ):
        super(Decoder, self).__init__()
        self.n_mel_channels = n_mel_channels
        self.n_frames_per_step = n_frames_per_step
        self.encoder_embedding_dim = encoder_embedding_dim
        self.attention_rnn_dim = attention_rnn_dim
        self.decoder_rnn_dim = decoder_rnn_dim
        self.prenet_dim = prenet_dim
        self.max_decoder_steps = max_decoder_steps
        self.gate_threshold = gate_threshold
        self.p_attention_dropout = p_attention_dropout
        self.p_decoder_dropout = p_decoder_dropout
        self.early_stopping = early_stopping

        self.prenet = Prenet(n_mel_channels * n_frames_per_step, [prenet_dim, prenet_dim])

        self.attention_rnn = nn.LSTMCell(prenet_dim + encoder_embedding_dim, attention_rnn_dim)

        self.attention_layer = Attention(
            attention_rnn_dim,
            encoder_embedding_dim,
            attention_dim,
            attention_location_n_filters,
            attention_location_kernel_size,
        )

        self.decoder_rnn = nn.LSTMCell(attention_rnn_dim + encoder_embedding_dim, decoder_rnn_dim, 1)

        self.linear_projection = LinearNorm(decoder_rnn_dim + encoder_embedding_dim, n_mel_channels * n_frames_per_step)

        self.gate_layer = LinearNorm(decoder_rnn_dim + encoder_embedding_dim, 1, bias=True, w_init_gain="sigmoid")

    def get_go_frame(self, memory):
        """Gets all zeros frames to use as first decoder input
        PARAMS
        ------
        memory: decoder outputs

        RETURNS
        -------
        decoder_input: all zeros frames
        """
        B = memory.size(0)
        dtype = memory.dtype
        device = memory.device
        decoder_input = torch.zeros(B, self.n_mel_channels * self.n_frames_per_step, dtype=dtype, device=device)
        return decoder_input

    def initialize_decoder_states(self, memory):
        """Initializes attention rnn states, decoder rnn states, attention
        weights, attention cumulative weights, attention context, stores memory
        and stores processed memory
        PARAMS
        ------
        memory: Encoder outputs
        mask: Mask for padded data if training, expects None for inference
        """
        B = memory.size(0)
        MAX_TIME = memory.size(1)
        dtype = memory.dtype
        device = memory.device

        attention_hidden = torch.zeros(B, self.attention_rnn_dim, dtype=dtype, device=device)
        attention_cell = torch.zeros(B, self.attention_rnn_dim, dtype=dtype, device=device)

        decoder_hidden = torch.zeros(B, self.decoder_rnn_dim, dtype=dtype, device=device)
        decoder_cell = torch.zeros(B, self.decoder_rnn_dim, dtype=dtype, device=device)

        attention_weights = torch.zeros(B, MAX_TIME, dtype=dtype, device=device)
        attention_weights_cum = torch.zeros(B, MAX_TIME, dtype=dtype, device=device)
        attention_context = torch.zeros(B, self.encoder_embedding_dim, dtype=dtype, device=device)

        processed_memory = self.attention_layer.memory_layer(memory)

        return (
            attention_hidden,
            attention_cell,
            decoder_hidden,
            decoder_cell,
            attention_weights,
            attention_weights_cum,
            attention_context,
            processed_memory,
        )

    def parse_decoder_inputs(self, decoder_inputs):
        """Prepares decoder inputs, i.e. mel outputs
        PARAMS
        ------
        decoder_inputs: inputs used for teacher-forced training, i.e. mel-specs

        RETURNS
        -------
        inputs: processed decoder inputs

        """
        # (B, n_mel_channels, T_out) -> (B, T_out, n_mel_channels)
        decoder_inputs = decoder_inputs.transpose(1, 2)
        decoder_inputs = decoder_inputs.view(
            decoder_inputs.size(0), int(decoder_inputs.size(1) / self.n_frames_per_step), -1
        )
        # (B, T_out, n_mel_channels) -> (T_out, B, n_mel_channels)
        decoder_inputs = decoder_inputs.transpose(0, 1)
        return decoder_inputs

    def parse_decoder_outputs(self, mel_outputs, gate_outputs, alignments):
        """Prepares decoder outputs for output
        PARAMS
        ------
        mel_outputs:
        gate_outputs: gate output energies
        alignments:

        RETURNS
        -------
        mel_outputs:
        gate_outpust: gate output energies
        alignments:
        """
        # (T_out, B) -> (B, T_out)
        alignments = alignments.transpose(0, 1).contiguous()
        # (T_out, B) -> (B, T_out)
        gate_outputs = gate_outputs.transpose(0, 1).contiguous()
        # (T_out, B, n_mel_channels) -> (B, T_out, n_mel_channels)
        mel_outputs = mel_outputs.transpose(0, 1).contiguous()
        # decouple frames per step
        shape = (mel_outputs.shape[0], -1, self.n_mel_channels)
        mel_outputs = mel_outputs.view(*shape)
        # (B, T_out, n_mel_channels) -> (B, n_mel_channels, T_out)
        mel_outputs = mel_outputs.transpose(1, 2)

        return mel_outputs, gate_outputs, alignments

    def decode(
        self,
        decoder_input,
        attention_hidden,
        attention_cell,
        decoder_hidden,
        decoder_cell,
        attention_weights,
        attention_weights_cum,
        attention_context,
        memory,
        processed_memory,
        mask,
    ):
        """Decoder step using stored states, attention and memory
        PARAMS
        ------
        decoder_input: previous mel output

        RETURNS
        -------
        mel_output:
        gate_output: gate output energies
        attention_weights:
        """
        cell_input = torch.cat((decoder_input, attention_context), -1)

        attention_hidden, attention_cell = self.attention_rnn(cell_input, (attention_hidden, attention_cell))
        attention_hidden = F.dropout(attention_hidden, self.p_attention_dropout, self.training)

        attention_weights_cat = torch.cat((attention_weights.unsqueeze(1), attention_weights_cum.unsqueeze(1)), dim=1)
        attention_context, attention_weights = self.attention_layer(
            attention_hidden, memory, processed_memory, attention_weights_cat, mask
        )

        attention_weights_cum += attention_weights
        decoder_input = torch.cat((attention_hidden, attention_context), -1)

        decoder_hidden, decoder_cell = self.decoder_rnn(decoder_input, (decoder_hidden, decoder_cell))
        decoder_hidden = F.dropout(decoder_hidden, self.p_decoder_dropout, self.training)

        decoder_hidden_attention_context = torch.cat((decoder_hidden, attention_context), dim=1)
        decoder_output = self.linear_projection(decoder_hidden_attention_context)

        gate_prediction = self.gate_layer(decoder_hidden_attention_context)

        return (
            decoder_output,
            gate_prediction,
            attention_hidden,
            attention_cell,
            decoder_hidden,
            decoder_cell,
            attention_weights,
            attention_weights_cum,
            attention_context,
        )

    @torch.jit.ignore
    def forward(self, memory, decoder_inputs, memory_lengths):
        """Decoder forward pass for training
        PARAMS
        ------
        memory: Encoder outputs
        decoder_inputs: Decoder inputs for teacher forcing. i.e. mel-specs
        memory_lengths: Encoder output lengths for attention masking.

        RETURNS
        -------
        mel_outputs: mel outputs from the decoder
        gate_outputs: gate outputs from the decoder
        alignments: sequence of attention weights from the decoder
        """

        decoder_input = self.get_go_frame(memory).unsqueeze(0)
        decoder_inputs = self.parse_decoder_inputs(decoder_inputs)
        decoder_inputs = torch.cat((decoder_input, decoder_inputs), dim=0)
        decoder_inputs = self.prenet(decoder_inputs)

        mask = ~mask_from_lens(memory_lengths)
        (
            attention_hidden,
            attention_cell,
            decoder_hidden,
            decoder_cell,
            attention_weights,
            attention_weights_cum,
            attention_context,
            processed_memory,
        ) = self.initialize_decoder_states(memory)

        mel_outputs, gate_outputs, alignments = [], [], []
        while len(mel_outputs) < decoder_inputs.size(0) - 1:
            decoder_input = decoder_inputs[len(mel_outputs)]
            (
                mel_output,
                gate_output,
                attention_hidden,
                attention_cell,
                decoder_hidden,
                decoder_cell,
                attention_weights,
                attention_weights_cum,
                attention_context,
            ) = self.decode(
                decoder_input,
                attention_hidden,
                attention_cell,
                decoder_hidden,
                decoder_cell,
                attention_weights,
                attention_weights_cum,
                attention_context,
                memory,
                processed_memory,
                mask,
            )

            mel_outputs += [mel_output.squeeze(1)]
            gate_outputs += [gate_output.squeeze()]
            alignments += [attention_weights]

        mel_outputs, gate_outputs, alignments = self.parse_decoder_outputs(
            torch.stack(mel_outputs), torch.stack(gate_outputs), torch.stack(alignments)
        )

        return mel_outputs, gate_outputs, alignments

    @torch.jit.export
    def infer(self, memory, memory_lengths):
        """Decoder inference
        PARAMS
        ------
        memory: Encoder outputs

        RETURNS
        -------
        mel_outputs: mel outputs from the decoder
        gate_outputs: gate outputs from the decoder
        alignments: sequence of attention weights from the decoder
        """
        decoder_input = self.get_go_frame(memory)

        mask = ~mask_from_lens(memory_lengths)
        (
            attention_hidden,
            attention_cell,
            decoder_hidden,
            decoder_cell,
            attention_weights,
            attention_weights_cum,
            attention_context,
            processed_memory,
        ) = self.initialize_decoder_states(memory)

        mel_lengths = torch.zeros([memory.size(0)], dtype=torch.int32).cuda()
        not_finished = torch.ones([memory.size(0)], dtype=torch.int32).cuda()

        mel_outputs, gate_outputs, alignments = (torch.zeros(1), torch.zeros(1), torch.zeros(1))
        first_iter = True
        while True:
            decoder_input = self.prenet(decoder_input)
            (
                mel_output,
                gate_output,
                attention_hidden,
                attention_cell,
                decoder_hidden,
                decoder_cell,
                attention_weights,
                attention_weights_cum,
                attention_context,
            ) = self.decode(
                decoder_input,
                attention_hidden,
                attention_cell,
                decoder_hidden,
                decoder_cell,
                attention_weights,
                attention_weights_cum,
                attention_context,
                memory,
                processed_memory,
                mask,
            )

            if first_iter:
                mel_outputs = mel_output.unsqueeze(0)
                gate_outputs = gate_output
                alignments = attention_weights
                first_iter = False
            else:
                mel_outputs = torch.cat((mel_outputs, mel_output.unsqueeze(0)), dim=0)
                gate_outputs = torch.cat((gate_outputs, gate_output), dim=0)
                alignments = torch.cat((alignments, attention_weights), dim=0)

            dec = torch.le(torch.sigmoid(gate_output), self.gate_threshold).to(torch.int32).squeeze(1)

            not_finished = not_finished * dec
            mel_lengths += not_finished

            if self.early_stopping and torch.sum(not_finished) == 0:
                break
            if len(mel_outputs) == self.max_decoder_steps:
                print("Warning! Reached max decoder steps")
                break

            decoder_input = mel_output

        # NOTE(Adrian): This makes it consistent with training-time dims
        # (ML x B) x L --> ML x B x L
        mel_len, bsz, _ = mel_outputs.size()
        alignments = alignments.view(mel_len, bsz, -1)

        mel_outputs, gate_outputs, alignments = self.parse_decoder_outputs(mel_outputs, gate_outputs, alignments)

        return mel_outputs, gate_outputs, alignments, mel_lengths


class Tacotron2(nn.Module):
    def __init__(
        self,
        mask_padding,
        n_mel_channels,
        n_symbols,
        symbols_embedding_dim,
        encoder_kernel_size,
        encoder_n_convolutions,
        encoder_embedding_dim,
        attention_rnn_dim,
        attention_dim,
        attention_location_n_filters,
        attention_location_kernel_size,
        n_frames_per_step,
        decoder_rnn_dim,
        prenet_dim,
        max_decoder_steps,
        gate_threshold,
        p_attention_dropout,
        p_decoder_dropout,
        postnet_embedding_dim,
        postnet_kernel_size,
        postnet_n_convolutions,
        decoder_no_early_stopping,
    ):
        super(Tacotron2, self).__init__()
        self.mask_padding = mask_padding
        self.n_mel_channels = n_mel_channels
        self.n_frames_per_step = n_frames_per_step
        self.embedding = nn.Embedding(n_symbols, symbols_embedding_dim)
        std = sqrt(2.0 / (n_symbols + symbols_embedding_dim))
        val = sqrt(3.0) * std  # uniform bounds for std
        self.embedding.weight.data.uniform_(-val, val)
        self.encoder = Encoder(encoder_n_convolutions, encoder_embedding_dim, encoder_kernel_size)
        self.decoder = Decoder(
            n_mel_channels,
            n_frames_per_step,
            encoder_embedding_dim,
            attention_dim,
            attention_location_n_filters,
            attention_location_kernel_size,
            attention_rnn_dim,
            decoder_rnn_dim,
            prenet_dim,
            max_decoder_steps,
            gate_threshold,
            p_attention_dropout,
            p_decoder_dropout,
            not decoder_no_early_stopping,
        )
        self.postnet = Postnet(n_mel_channels, postnet_embedding_dim, postnet_kernel_size, postnet_n_convolutions)

    def parse_batch(self, batch):
        text_padded, input_lengths, mel_padded, gate_padded, output_lengths = batch
        text_padded = to_gpu(text_padded).long()
        input_lengths = to_gpu(input_lengths).long()
        max_len = torch.max(input_lengths.data).item()
        mel_padded = to_gpu(mel_padded).float()
        gate_padded = to_gpu(gate_padded).float()
        output_lengths = to_gpu(output_lengths).long()

        return ((text_padded, input_lengths, mel_padded, max_len, output_lengths), (mel_padded, gate_padded))

    def parse_output(self, outputs, output_lengths):
        # type: (List[Tensor], Tensor) -> List[Tensor]
        if self.mask_padding and output_lengths is not None:
            mask = ~mask_from_lens(output_lengths)
            mask = mask.expand(self.n_mel_channels, mask.size(0), mask.size(1))
            mask = mask.permute(1, 0, 2)

            outputs[0].masked_fill_(mask, 0.0)
            outputs[1].masked_fill_(mask, 0.0)
            outputs[2].masked_fill_(mask[:, 0, :], 1e3)  # gate energies

        return outputs

    def forward(self, inputs):
        inputs, input_lengths, targets, max_len, output_lengths = inputs
        input_lengths, output_lengths = input_lengths.data, output_lengths.data

        embedded_inputs = self.embedding(inputs).transpose(1, 2)

        encoder_outputs = self.encoder(embedded_inputs, input_lengths)

        mel_outputs, gate_outputs, alignments = self.decoder(encoder_outputs, targets, memory_lengths=input_lengths)

        mel_outputs_postnet = self.postnet(mel_outputs)
        mel_outputs_postnet = mel_outputs + mel_outputs_postnet

        return self.parse_output([mel_outputs, mel_outputs_postnet, gate_outputs, alignments], output_lengths)

    def infer(self, inputs, input_lengths):

        embedded_inputs = self.embedding(inputs).transpose(1, 2)
        encoder_outputs = self.encoder.infer(embedded_inputs, input_lengths)
        mel_outputs, gate_outputs, alignments, mel_lengths = self.decoder.infer(encoder_outputs, input_lengths)

        mel_outputs_postnet = self.postnet(mel_outputs)
        mel_outputs_postnet = mel_outputs + mel_outputs_postnet

        return mel_outputs_postnet, mel_lengths  # XXX , alignments