import os
import sys
import torch

from typing import Optional

from torch.nn.utils import remove_weight_norm
from torch.nn.utils.parametrizations import weight_norm

now_dir = os.getcwd()
sys.path.append(now_dir)

from .modules import WaveNet
from .commons import get_padding, init_weights


LRELU_SLOPE = 0.1

def create_conv1d_layer(channels, kernel_size, dilation):
    return weight_norm(torch.nn.Conv1d(channels, channels, kernel_size, 1, dilation=dilation, padding=get_padding(kernel_size, dilation)))

def apply_mask(tensor, mask):
    return tensor * mask if mask is not None else tensor

class ResBlockBase(torch.nn.Module):
    def __init__(self, channels, kernel_size, dilations):
        super(ResBlockBase, self).__init__()
        
        self.convs1 = torch.nn.ModuleList([create_conv1d_layer(channels, kernel_size, d) for d in dilations])
        self.convs1.apply(init_weights)

        self.convs2 = torch.nn.ModuleList([create_conv1d_layer(channels, kernel_size, 1) for _ in dilations])
        self.convs2.apply(init_weights)

    def forward(self, x, x_mask=None):
        for c1, c2 in zip(self.convs1, self.convs2):
            xt = torch.nn.functional.leaky_relu(x, LRELU_SLOPE)
            xt = apply_mask(xt, x_mask)
            xt = torch.nn.functional.leaky_relu(c1(xt), LRELU_SLOPE)
            xt = apply_mask(xt, x_mask)
            xt = c2(xt)
            x = xt + x
        return apply_mask(x, x_mask)

    def remove_weight_norm(self):
        for conv in self.convs1 + self.convs2:
            remove_weight_norm(conv)

class ResBlock1(ResBlockBase):
    def __init__(self, channels, kernel_size=3, dilation=(1, 3, 5)):
        super(ResBlock1, self).__init__(channels, kernel_size, dilation)

class ResBlock2(ResBlockBase):
    def __init__(self, channels, kernel_size=3, dilation=(1, 3)):
        super(ResBlock2, self).__init__(channels, kernel_size, dilation)

class Log(torch.nn.Module):
    def forward(self, x, x_mask, reverse=False, **kwargs):
        if not reverse:
            y = torch.log(torch.clamp_min(x, 1e-5)) * x_mask
            logdet = torch.sum(-y, [1, 2])
            return y, logdet
        else:
            x = torch.exp(x) * x_mask
            return x

class Flip(torch.nn.Module):
    def forward(self, x, *args, reverse=False, **kwargs):
        x = torch.flip(x, [1])
        if not reverse:
            logdet = torch.zeros(x.size(0)).to(dtype=x.dtype, device=x.device)
            return x, logdet
        else: return x

class ElementwiseAffine(torch.nn.Module):
    def __init__(self, channels):
        super().__init__()
        self.channels = channels
        self.m = torch.nn.Parameter(torch.zeros(channels, 1))
        self.logs = torch.nn.Parameter(torch.zeros(channels, 1))

    def forward(self, x, x_mask, reverse=False, **kwargs):
        if not reverse:
            y = self.m + torch.exp(self.logs) * x
            y = y * x_mask
            logdet = torch.sum(self.logs * x_mask, [1, 2])
            return y, logdet
        else:
            x = (x - self.m) * torch.exp(-self.logs) * x_mask
            return x


class ResidualCouplingBlock(torch.nn.Module):
    def __init__(self, channels, hidden_channels, kernel_size, dilation_rate, n_layers, n_flows=4, gin_channels=0):
        super(ResidualCouplingBlock, self).__init__()
        self.channels = channels
        self.hidden_channels = hidden_channels
        self.kernel_size = kernel_size
        self.dilation_rate = dilation_rate
        self.n_layers = n_layers
        self.n_flows = n_flows
        self.gin_channels = gin_channels

        self.flows = torch.nn.ModuleList()
        for i in range(n_flows):
            self.flows.append(ResidualCouplingLayer(channels, hidden_channels, kernel_size, dilation_rate, n_layers, gin_channels=gin_channels, mean_only=True))
            self.flows.append(Flip())

    def forward(self, x: torch.Tensor, x_mask: torch.Tensor, g: Optional[torch.Tensor] = None, reverse = False):
        if not reverse:
            for flow in self.flows:
                x, _ = flow(x, x_mask, g=g, reverse=reverse)
        else:
            for flow in reversed(self.flows):
                x = flow.forward(x, x_mask, g=g, reverse=reverse)

        return x

    def remove_weight_norm(self):
        for i in range(self.n_flows):
            self.flows[i * 2].remove_weight_norm()

    def __prepare_scriptable__(self):
        for i in range(self.n_flows):
            for hook in self.flows[i * 2]._forward_pre_hooks.values():
                if (hook.__module__ == "torch.nn.utils.parametrizations.weight_norm" and hook.__class__.__name__ == "WeightNorm"): torch.nn.utils.remove_weight_norm(self.flows[i * 2])
        return self


class ResidualCouplingLayer(torch.nn.Module):
    def __init__(self, channels, hidden_channels, kernel_size, dilation_rate, n_layers, p_dropout=0, gin_channels=0, mean_only=False):
        assert channels % 2 == 0, "Channels/2"
        super().__init__()
        self.channels = channels
        self.hidden_channels = hidden_channels
        self.kernel_size = kernel_size
        self.dilation_rate = dilation_rate
        self.n_layers = n_layers
        self.half_channels = channels // 2
        self.mean_only = mean_only

        self.pre = torch.nn.Conv1d(self.half_channels, hidden_channels, 1)
        self.enc = WaveNet(hidden_channels, kernel_size, dilation_rate, n_layers, p_dropout=p_dropout, gin_channels=gin_channels)
        self.post = torch.nn.Conv1d(hidden_channels, self.half_channels * (2 - mean_only), 1)
        self.post.weight.data.zero_()
        self.post.bias.data.zero_()

    def forward(self, x, x_mask, g=None, reverse=False):
        x0, x1 = torch.split(x, [self.half_channels] * 2, 1)
        h = self.pre(x0) * x_mask
        h = self.enc(h, x_mask, g=g)
        stats = self.post(h) * x_mask

        if not self.mean_only: m, logs = torch.split(stats, [self.half_channels] * 2, 1)
        else:
            m = stats
            logs = torch.zeros_like(m)

        if not reverse:
            x1 = m + x1 * torch.exp(logs) * x_mask
            x = torch.cat([x0, x1], 1)
            logdet = torch.sum(logs, [1, 2])
            return x, logdet
        else:
            x1 = (x1 - m) * torch.exp(-logs) * x_mask
            x = torch.cat([x0, x1], 1)
            return x

    def remove_weight_norm(self):
        self.enc.remove_weight_norm()