import sys
import time
from dataclasses import dataclass, field
from typing import Dict, List, Tuple

import numpy as np
import torch
import torch.nn.functional as F
from coqpit import Coqpit
from torch import nn
from torch.utils.data import DataLoader
from torch.utils.data.distributed import DistributedSampler

from TTS.tts.utils.visual import plot_spectrogram
from TTS.utils.audio import AudioProcessor
from TTS.utils.io import load_fsspec
from TTS.vocoder.datasets.wavernn_dataset import WaveRNNDataset
from TTS.vocoder.layers.losses import WaveRNNLoss
from TTS.vocoder.models.base_vocoder import BaseVocoder
from TTS.vocoder.utils.distribution import sample_from_discretized_mix_logistic, sample_from_gaussian


def stream(string, variables):
    sys.stdout.write(f"\r{string}" % variables)


# pylint: disable=abstract-method
# relates https://github.com/pytorch/pytorch/issues/42305
class ResBlock(nn.Module):
    def __init__(self, dims):
        super().__init__()
        self.conv1 = nn.Conv1d(dims, dims, kernel_size=1, bias=False)
        self.conv2 = nn.Conv1d(dims, dims, kernel_size=1, bias=False)
        self.batch_norm1 = nn.BatchNorm1d(dims)
        self.batch_norm2 = nn.BatchNorm1d(dims)

    def forward(self, x):
        residual = x
        x = self.conv1(x)
        x = self.batch_norm1(x)
        x = F.relu(x)
        x = self.conv2(x)
        x = self.batch_norm2(x)
        return x + residual


class MelResNet(nn.Module):
    def __init__(self, num_res_blocks, in_dims, compute_dims, res_out_dims, pad):
        super().__init__()
        k_size = pad * 2 + 1
        self.conv_in = nn.Conv1d(in_dims, compute_dims, kernel_size=k_size, bias=False)
        self.batch_norm = nn.BatchNorm1d(compute_dims)
        self.layers = nn.ModuleList()
        for _ in range(num_res_blocks):
            self.layers.append(ResBlock(compute_dims))
        self.conv_out = nn.Conv1d(compute_dims, res_out_dims, kernel_size=1)

    def forward(self, x):
        x = self.conv_in(x)
        x = self.batch_norm(x)
        x = F.relu(x)
        for f in self.layers:
            x = f(x)
        x = self.conv_out(x)
        return x


class Stretch2d(nn.Module):
    def __init__(self, x_scale, y_scale):
        super().__init__()
        self.x_scale = x_scale
        self.y_scale = y_scale

    def forward(self, x):
        b, c, h, w = x.size()
        x = x.unsqueeze(-1).unsqueeze(3)
        x = x.repeat(1, 1, 1, self.y_scale, 1, self.x_scale)
        return x.view(b, c, h * self.y_scale, w * self.x_scale)


class UpsampleNetwork(nn.Module):
    def __init__(
        self,
        feat_dims,
        upsample_scales,
        compute_dims,
        num_res_blocks,
        res_out_dims,
        pad,
        use_aux_net,
    ):
        super().__init__()
        self.total_scale = np.cumproduct(upsample_scales)[-1]
        self.indent = pad * self.total_scale
        self.use_aux_net = use_aux_net
        if use_aux_net:
            self.resnet = MelResNet(num_res_blocks, feat_dims, compute_dims, res_out_dims, pad)
            self.resnet_stretch = Stretch2d(self.total_scale, 1)
        self.up_layers = nn.ModuleList()
        for scale in upsample_scales:
            k_size = (1, scale * 2 + 1)
            padding = (0, scale)
            stretch = Stretch2d(scale, 1)
            conv = nn.Conv2d(1, 1, kernel_size=k_size, padding=padding, bias=False)
            conv.weight.data.fill_(1.0 / k_size[1])
            self.up_layers.append(stretch)
            self.up_layers.append(conv)

    def forward(self, m):
        if self.use_aux_net:
            aux = self.resnet(m).unsqueeze(1)
            aux = self.resnet_stretch(aux)
            aux = aux.squeeze(1)
            aux = aux.transpose(1, 2)
        else:
            aux = None
        m = m.unsqueeze(1)
        for f in self.up_layers:
            m = f(m)
        m = m.squeeze(1)[:, :, self.indent : -self.indent]
        return m.transpose(1, 2), aux


class Upsample(nn.Module):
    def __init__(self, scale, pad, num_res_blocks, feat_dims, compute_dims, res_out_dims, use_aux_net):
        super().__init__()
        self.scale = scale
        self.pad = pad
        self.indent = pad * scale
        self.use_aux_net = use_aux_net
        self.resnet = MelResNet(num_res_blocks, feat_dims, compute_dims, res_out_dims, pad)

    def forward(self, m):
        if self.use_aux_net:
            aux = self.resnet(m)
            aux = torch.nn.functional.interpolate(aux, scale_factor=self.scale, mode="linear", align_corners=True)
            aux = aux.transpose(1, 2)
        else:
            aux = None
        m = torch.nn.functional.interpolate(m, scale_factor=self.scale, mode="linear", align_corners=True)
        m = m[:, :, self.indent : -self.indent]
        m = m * 0.045  # empirically found

        return m.transpose(1, 2), aux


@dataclass
class WavernnArgs(Coqpit):
    """🐸 WaveRNN model arguments.

    rnn_dims (int):
        Number of hidden channels in RNN layers. Defaults to 512.
    fc_dims (int):
        Number of hidden channels in fully-conntected layers. Defaults to 512.
    compute_dims (int):
        Number of hidden channels in the feature ResNet. Defaults to 128.
    res_out_dim (int):
        Number of hidden channels in the feature ResNet output. Defaults to 128.
    num_res_blocks (int):
        Number of residual blocks in the ResNet. Defaults to 10.
    use_aux_net (bool):
        enable/disable the feature ResNet. Defaults to True.
    use_upsample_net (bool):
        enable/ disable the upsampling networl. If False, basic upsampling is used. Defaults to True.
    upsample_factors (list):
        Upsampling factors. The multiply of the values must match the `hop_length`. Defaults to ```[4, 8, 8]```.
    mode (str):
        Output mode of the WaveRNN vocoder. `mold` for Mixture of Logistic Distribution, `gauss` for a single
        Gaussian Distribution and `bits` for quantized bits as the model's output.
    mulaw (bool):
        enable / disable the use of Mulaw quantization for training. Only applicable if `mode == 'bits'`. Defaults
        to `True`.
    pad (int):
            Padding applied to the input feature frames against the convolution layers of the feature network.
            Defaults to 2.
    """

    rnn_dims: int = 512
    fc_dims: int = 512
    compute_dims: int = 128
    res_out_dims: int = 128
    num_res_blocks: int = 10
    use_aux_net: bool = True
    use_upsample_net: bool = True
    upsample_factors: List[int] = field(default_factory=lambda: [4, 8, 8])
    mode: str = "mold"  # mold [string], gauss [string], bits [int]
    mulaw: bool = True  # apply mulaw if mode is bits
    pad: int = 2
    feat_dims: int = 80


class Wavernn(BaseVocoder):
    def __init__(self, config: Coqpit):
        """🐸 WaveRNN model.
        Original paper - https://arxiv.org/abs/1802.08435
        Official implementation - https://github.com/fatchord/WaveRNN

        Args:
            config (Coqpit): [description]

        Raises:
            RuntimeError: [description]

        Examples:
            >>> from TTS.vocoder.configs import WavernnConfig
            >>> config = WavernnConfig()
            >>> model = Wavernn(config)

        Paper Abstract:
            Sequential models achieve state-of-the-art results in audio, visual and textual domains with respect to
            both estimating the data distribution and generating high-quality samples. Efficient sampling for this
            class of models has however remained an elusive problem. With a focus on text-to-speech synthesis, we
            describe a set of general techniques for reducing sampling time while maintaining high output quality.
            We first describe a single-layer recurrent neural network, the WaveRNN, with a dual softmax layer that
            matches the quality of the state-of-the-art WaveNet model. The compact form of the network makes it
            possible to generate 24kHz 16-bit audio 4x faster than real time on a GPU. Second, we apply a weight
            pruning technique to reduce the number of weights in the WaveRNN. We find that, for a constant number of
            parameters, large sparse networks perform better than small dense networks and this relationship holds for
            sparsity levels beyond 96%. The small number of weights in a Sparse WaveRNN makes it possible to sample
            high-fidelity audio on a mobile CPU in real time. Finally, we propose a new generation scheme based on
            subscaling that folds a long sequence into a batch of shorter sequences and allows one to generate multiple
            samples at once. The Subscale WaveRNN produces 16 samples per step without loss of quality and offers an
            orthogonal method for increasing sampling efficiency.
        """
        super().__init__(config)

        if isinstance(self.args.mode, int):
            self.n_classes = 2**self.args.mode
        elif self.args.mode == "mold":
            self.n_classes = 3 * 10
        elif self.args.mode == "gauss":
            self.n_classes = 2
        else:
            raise RuntimeError("Unknown model mode value - ", self.args.mode)

        self.ap = AudioProcessor(**config.audio.to_dict())
        self.aux_dims = self.args.res_out_dims // 4

        if self.args.use_upsample_net:
            assert (
                np.cumproduct(self.args.upsample_factors)[-1] == config.audio.hop_length
            ), " [!] upsample scales needs to be equal to hop_length"
            self.upsample = UpsampleNetwork(
                self.args.feat_dims,
                self.args.upsample_factors,
                self.args.compute_dims,
                self.args.num_res_blocks,
                self.args.res_out_dims,
                self.args.pad,
                self.args.use_aux_net,
            )
        else:
            self.upsample = Upsample(
                config.audio.hop_length,
                self.args.pad,
                self.args.num_res_blocks,
                self.args.feat_dims,
                self.args.compute_dims,
                self.args.res_out_dims,
                self.args.use_aux_net,
            )
        if self.args.use_aux_net:
            self.I = nn.Linear(self.args.feat_dims + self.aux_dims + 1, self.args.rnn_dims)
            self.rnn1 = nn.GRU(self.args.rnn_dims, self.args.rnn_dims, batch_first=True)
            self.rnn2 = nn.GRU(self.args.rnn_dims + self.aux_dims, self.args.rnn_dims, batch_first=True)
            self.fc1 = nn.Linear(self.args.rnn_dims + self.aux_dims, self.args.fc_dims)
            self.fc2 = nn.Linear(self.args.fc_dims + self.aux_dims, self.args.fc_dims)
            self.fc3 = nn.Linear(self.args.fc_dims, self.n_classes)
        else:
            self.I = nn.Linear(self.args.feat_dims + 1, self.args.rnn_dims)
            self.rnn1 = nn.GRU(self.args.rnn_dims, self.args.rnn_dims, batch_first=True)
            self.rnn2 = nn.GRU(self.args.rnn_dims, self.args.rnn_dims, batch_first=True)
            self.fc1 = nn.Linear(self.args.rnn_dims, self.args.fc_dims)
            self.fc2 = nn.Linear(self.args.fc_dims, self.args.fc_dims)
            self.fc3 = nn.Linear(self.args.fc_dims, self.n_classes)

    def forward(self, x, mels):
        bsize = x.size(0)
        h1 = torch.zeros(1, bsize, self.args.rnn_dims).to(x.device)
        h2 = torch.zeros(1, bsize, self.args.rnn_dims).to(x.device)
        mels, aux = self.upsample(mels)

        if self.args.use_aux_net:
            aux_idx = [self.aux_dims * i for i in range(5)]
            a1 = aux[:, :, aux_idx[0] : aux_idx[1]]
            a2 = aux[:, :, aux_idx[1] : aux_idx[2]]
            a3 = aux[:, :, aux_idx[2] : aux_idx[3]]
            a4 = aux[:, :, aux_idx[3] : aux_idx[4]]

        x = (
            torch.cat([x.unsqueeze(-1), mels, a1], dim=2)
            if self.args.use_aux_net
            else torch.cat([x.unsqueeze(-1), mels], dim=2)
        )
        x = self.I(x)
        res = x
        self.rnn1.flatten_parameters()
        x, _ = self.rnn1(x, h1)

        x = x + res
        res = x
        x = torch.cat([x, a2], dim=2) if self.args.use_aux_net else x
        self.rnn2.flatten_parameters()
        x, _ = self.rnn2(x, h2)

        x = x + res
        x = torch.cat([x, a3], dim=2) if self.args.use_aux_net else x
        x = F.relu(self.fc1(x))

        x = torch.cat([x, a4], dim=2) if self.args.use_aux_net else x
        x = F.relu(self.fc2(x))
        return self.fc3(x)

    def inference(self, mels, batched=None, target=None, overlap=None):

        self.eval()
        output = []
        start = time.time()
        rnn1 = self.get_gru_cell(self.rnn1)
        rnn2 = self.get_gru_cell(self.rnn2)

        with torch.no_grad():
            if isinstance(mels, np.ndarray):
                mels = torch.FloatTensor(mels).to(str(next(self.parameters()).device))

            if mels.ndim == 2:
                mels = mels.unsqueeze(0)
            wave_len = (mels.size(-1) - 1) * self.config.audio.hop_length

            mels = self.pad_tensor(mels.transpose(1, 2), pad=self.args.pad, side="both")
            mels, aux = self.upsample(mels.transpose(1, 2))

            if batched:
                mels = self.fold_with_overlap(mels, target, overlap)
                if aux is not None:
                    aux = self.fold_with_overlap(aux, target, overlap)

            b_size, seq_len, _ = mels.size()

            h1 = torch.zeros(b_size, self.args.rnn_dims).type_as(mels)
            h2 = torch.zeros(b_size, self.args.rnn_dims).type_as(mels)
            x = torch.zeros(b_size, 1).type_as(mels)

            if self.args.use_aux_net:
                d = self.aux_dims
                aux_split = [aux[:, :, d * i : d * (i + 1)] for i in range(4)]

            for i in range(seq_len):

                m_t = mels[:, i, :]

                if self.args.use_aux_net:
                    a1_t, a2_t, a3_t, a4_t = (a[:, i, :] for a in aux_split)

                x = torch.cat([x, m_t, a1_t], dim=1) if self.args.use_aux_net else torch.cat([x, m_t], dim=1)
                x = self.I(x)
                h1 = rnn1(x, h1)

                x = x + h1
                inp = torch.cat([x, a2_t], dim=1) if self.args.use_aux_net else x
                h2 = rnn2(inp, h2)

                x = x + h2
                x = torch.cat([x, a3_t], dim=1) if self.args.use_aux_net else x
                x = F.relu(self.fc1(x))

                x = torch.cat([x, a4_t], dim=1) if self.args.use_aux_net else x
                x = F.relu(self.fc2(x))

                logits = self.fc3(x)

                if self.args.mode == "mold":
                    sample = sample_from_discretized_mix_logistic(logits.unsqueeze(0).transpose(1, 2))
                    output.append(sample.view(-1))
                    x = sample.transpose(0, 1).type_as(mels)
                elif self.args.mode == "gauss":
                    sample = sample_from_gaussian(logits.unsqueeze(0).transpose(1, 2))
                    output.append(sample.view(-1))
                    x = sample.transpose(0, 1).type_as(mels)
                elif isinstance(self.args.mode, int):
                    posterior = F.softmax(logits, dim=1)
                    distrib = torch.distributions.Categorical(posterior)

                    sample = 2 * distrib.sample().float() / (self.n_classes - 1.0) - 1.0
                    output.append(sample)
                    x = sample.unsqueeze(-1)
                else:
                    raise RuntimeError("Unknown model mode value - ", self.args.mode)

                if i % 100 == 0:
                    self.gen_display(i, seq_len, b_size, start)

        output = torch.stack(output).transpose(0, 1)
        output = output.cpu()
        if batched:
            output = output.numpy()
            output = output.astype(np.float64)

            output = self.xfade_and_unfold(output, target, overlap)
        else:
            output = output[0]

        if self.args.mulaw and isinstance(self.args.mode, int):
            output = AudioProcessor.mulaw_decode(output, self.args.mode)

        # Fade-out at the end to avoid signal cutting out suddenly
        fade_out = np.linspace(1, 0, 20 * self.config.audio.hop_length)
        output = output[:wave_len]

        if wave_len > len(fade_out):
            output[-20 * self.config.audio.hop_length :] *= fade_out

        self.train()
        return output

    def gen_display(self, i, seq_len, b_size, start):
        gen_rate = (i + 1) / (time.time() - start) * b_size / 1000
        realtime_ratio = gen_rate * 1000 / self.config.audio.sample_rate
        stream(
            "%i/%i -- batch_size: %i -- gen_rate: %.1f kHz -- x_realtime: %.1f  ",
            (i * b_size, seq_len * b_size, b_size, gen_rate, realtime_ratio),
        )

    def fold_with_overlap(self, x, target, overlap):
        """Fold the tensor with overlap for quick batched inference.
            Overlap will be used for crossfading in xfade_and_unfold()
        Args:
            x (tensor)    : Upsampled conditioning features.
                            shape=(1, timesteps, features)
            target (int)  : Target timesteps for each index of batch
            overlap (int) : Timesteps for both xfade and rnn warmup
        Return:
            (tensor) : shape=(num_folds, target + 2 * overlap, features)
        Details:
            x = [[h1, h2, ... hn]]
            Where each h is a vector of conditioning features
            Eg: target=2, overlap=1 with x.size(1)=10
            folded = [[h1, h2, h3, h4],
                      [h4, h5, h6, h7],
                      [h7, h8, h9, h10]]
        """

        _, total_len, features = x.size()

        # Calculate variables needed
        num_folds = (total_len - overlap) // (target + overlap)
        extended_len = num_folds * (overlap + target) + overlap
        remaining = total_len - extended_len

        # Pad if some time steps poking out
        if remaining != 0:
            num_folds += 1
            padding = target + 2 * overlap - remaining
            x = self.pad_tensor(x, padding, side="after")

        folded = torch.zeros(num_folds, target + 2 * overlap, features).to(x.device)

        # Get the values for the folded tensor
        for i in range(num_folds):
            start = i * (target + overlap)
            end = start + target + 2 * overlap
            folded[i] = x[:, start:end, :]

        return folded

    @staticmethod
    def get_gru_cell(gru):
        gru_cell = nn.GRUCell(gru.input_size, gru.hidden_size)
        gru_cell.weight_hh.data = gru.weight_hh_l0.data
        gru_cell.weight_ih.data = gru.weight_ih_l0.data
        gru_cell.bias_hh.data = gru.bias_hh_l0.data
        gru_cell.bias_ih.data = gru.bias_ih_l0.data
        return gru_cell

    @staticmethod
    def pad_tensor(x, pad, side="both"):
        # NB - this is just a quick method i need right now
        # i.e., it won't generalise to other shapes/dims
        b, t, c = x.size()
        total = t + 2 * pad if side == "both" else t + pad
        padded = torch.zeros(b, total, c).to(x.device)
        if side in ("before", "both"):
            padded[:, pad : pad + t, :] = x
        elif side == "after":
            padded[:, :t, :] = x
        return padded

    @staticmethod
    def xfade_and_unfold(y, target, overlap):
        """Applies a crossfade and unfolds into a 1d array.
        Args:
            y (ndarry)    : Batched sequences of audio samples
                            shape=(num_folds, target + 2 * overlap)
                            dtype=np.float64
            overlap (int) : Timesteps for both xfade and rnn warmup
        Return:
            (ndarry) : audio samples in a 1d array
                       shape=(total_len)
                       dtype=np.float64
        Details:
            y = [[seq1],
                 [seq2],
                 [seq3]]
            Apply a gain envelope at both ends of the sequences
            y = [[seq1_in, seq1_target, seq1_out],
                 [seq2_in, seq2_target, seq2_out],
                 [seq3_in, seq3_target, seq3_out]]
            Stagger and add up the groups of samples:
            [seq1_in, seq1_target, (seq1_out + seq2_in), seq2_target, ...]
        """

        num_folds, length = y.shape
        target = length - 2 * overlap
        total_len = num_folds * (target + overlap) + overlap

        # Need some silence for the rnn warmup
        silence_len = overlap // 2
        fade_len = overlap - silence_len
        silence = np.zeros((silence_len), dtype=np.float64)

        # Equal power crossfade
        t = np.linspace(-1, 1, fade_len, dtype=np.float64)
        fade_in = np.sqrt(0.5 * (1 + t))
        fade_out = np.sqrt(0.5 * (1 - t))

        # Concat the silence to the fades
        fade_in = np.concatenate([silence, fade_in])
        fade_out = np.concatenate([fade_out, silence])

        # Apply the gain to the overlap samples
        y[:, :overlap] *= fade_in
        y[:, -overlap:] *= fade_out

        unfolded = np.zeros((total_len), dtype=np.float64)

        # Loop to add up all the samples
        for i in range(num_folds):
            start = i * (target + overlap)
            end = start + target + 2 * overlap
            unfolded[start:end] += y[i]

        return unfolded

    def load_checkpoint(
        self, config, checkpoint_path, eval=False, cache=False
    ):  # pylint: disable=unused-argument, redefined-builtin
        state = load_fsspec(checkpoint_path, map_location=torch.device("cpu"), cache=cache)
        self.load_state_dict(state["model"])
        if eval:
            self.eval()
            assert not self.training

    def train_step(self, batch: Dict, criterion: Dict) -> Tuple[Dict, Dict]:
        mels = batch["input"]
        waveform = batch["waveform"]
        waveform_coarse = batch["waveform_coarse"]

        y_hat = self.forward(waveform, mels)
        if isinstance(self.args.mode, int):
            y_hat = y_hat.transpose(1, 2).unsqueeze(-1)
        else:
            waveform_coarse = waveform_coarse.float()
        waveform_coarse = waveform_coarse.unsqueeze(-1)
        # compute losses
        loss_dict = criterion(y_hat, waveform_coarse)
        return {"model_output": y_hat}, loss_dict

    def eval_step(self, batch: Dict, criterion: Dict) -> Tuple[Dict, Dict]:
        return self.train_step(batch, criterion)

    @torch.no_grad()
    def test(
        self, assets: Dict, test_loader: "DataLoader", output: Dict  # pylint: disable=unused-argument
    ) -> Tuple[Dict, Dict]:
        ap = self.ap
        figures = {}
        audios = {}
        samples = test_loader.dataset.load_test_samples(1)
        for idx, sample in enumerate(samples):
            x = torch.FloatTensor(sample[0])
            x = x.to(next(self.parameters()).device)
            y_hat = self.inference(x, self.config.batched, self.config.target_samples, self.config.overlap_samples)
            x_hat = ap.melspectrogram(y_hat)
            figures.update(
                {
                    f"test_{idx}/ground_truth": plot_spectrogram(x.T),
                    f"test_{idx}/prediction": plot_spectrogram(x_hat.T),
                }
            )
            audios.update({f"test_{idx}/audio": y_hat})
            # audios.update({f"real_{idx}/audio": y_hat})
        return figures, audios

    def test_log(
        self, outputs: Dict, logger: "Logger", assets: Dict, steps: int  # pylint: disable=unused-argument
    ) -> Tuple[Dict, np.ndarray]:
        figures, audios = outputs
        logger.eval_figures(steps, figures)
        logger.eval_audios(steps, audios, self.ap.sample_rate)

    @staticmethod
    def format_batch(batch: Dict) -> Dict:
        waveform = batch[0]
        mels = batch[1]
        waveform_coarse = batch[2]
        return {"input": mels, "waveform": waveform, "waveform_coarse": waveform_coarse}

    def get_data_loader(  # pylint: disable=no-self-use
        self,
        config: Coqpit,
        assets: Dict,
        is_eval: True,
        samples: List,
        verbose: bool,
        num_gpus: int,
    ):
        ap = self.ap
        dataset = WaveRNNDataset(
            ap=ap,
            items=samples,
            seq_len=config.seq_len,
            hop_len=ap.hop_length,
            pad=config.model_args.pad,
            mode=config.model_args.mode,
            mulaw=config.model_args.mulaw,
            is_training=not is_eval,
            verbose=verbose,
        )
        sampler = DistributedSampler(dataset, shuffle=True) if num_gpus > 1 else None
        loader = DataLoader(
            dataset,
            batch_size=1 if is_eval else config.batch_size,
            shuffle=num_gpus == 0,
            collate_fn=dataset.collate,
            sampler=sampler,
            num_workers=config.num_eval_loader_workers if is_eval else config.num_loader_workers,
            pin_memory=True,
        )
        return loader

    def get_criterion(self):
        # define train functions
        return WaveRNNLoss(self.args.mode)

    @staticmethod
    def init_from_config(config: "WavernnConfig"):
        return Wavernn(config)