import torch
import torch.nn as nn
import numpy as np
import time
import math
import random
from torch.nn.utils.rnn import pack_padded_sequence, pad_packed_sequence
# from networks.layers import *


def init_weight(m):
    if isinstance(m, nn.Conv1d) or isinstance(m, nn.Linear) or isinstance(m, nn.ConvTranspose1d):
        nn.init.xavier_normal_(m.weight)
        # m.bias.data.fill_(0.01)
        if m.bias is not None:
            nn.init.constant_(m.bias, 0)


# batch_size, dimension and position
# output: (batch_size, dim)
def positional_encoding(batch_size, dim, pos):
    assert batch_size == pos.shape[0]
    positions_enc = np.array([
        [pos[j] / np.power(10000, (i-i%2)/dim) for i in range(dim)]
        for j in range(batch_size)
    ], dtype=np.float32)
    positions_enc[:, 0::2] = np.sin(positions_enc[:, 0::2])
    positions_enc[:, 1::2] = np.cos(positions_enc[:, 1::2])
    return torch.from_numpy(positions_enc).float()


def get_padding_mask(batch_size, seq_len, cap_lens):
    cap_lens = cap_lens.data.tolist()
    mask_2d = torch.ones((batch_size, seq_len, seq_len), dtype=torch.float32)
    for i, cap_len in enumerate(cap_lens):
        mask_2d[i, :, :cap_len] = 0
    return mask_2d.bool(), 1 - mask_2d[:, :, 0].clone()


def top_k_logits(logits, k):
    v, ix = torch.topk(logits, k)
    out = logits.clone()
    out[out < v[:, [-1]]] = -float('Inf')
    return out


class PositionalEncoding(nn.Module):

    def __init__(self, d_model, max_len=300):
        super(PositionalEncoding, self).__init__()

        pe = torch.zeros(max_len, d_model)
        position = torch.arange(0, max_len, dtype=torch.float).unsqueeze(1)
        div_term = torch.exp(torch.arange(0, d_model, 2).float() * (-math.log(10000.0) / d_model))
        pe[:, 0::2] = torch.sin(position * div_term)
        pe[:, 1::2] = torch.cos(position * div_term)
        # pe = pe.unsqueeze(0).transpose(0, 1)
        self.register_buffer('pe', pe)

    def forward(self, pos):
        return self.pe[pos]


class MovementConvEncoder(nn.Module):
    def __init__(self, input_size, hidden_size, output_size):
        super(MovementConvEncoder, self).__init__()
        self.main = nn.Sequential(
            nn.Conv1d(input_size, hidden_size, 4, 2, 1),
            nn.Dropout(0.2, inplace=True),
            nn.LeakyReLU(0.2, inplace=True),
            nn.Conv1d(hidden_size, output_size, 4, 2, 1),
            nn.Dropout(0.2, inplace=True),
            nn.LeakyReLU(0.2, inplace=True),
        )
        self.out_net = nn.Linear(output_size, output_size)
        self.main.apply(init_weight)
        self.out_net.apply(init_weight)

    def forward(self, inputs):
        inputs = inputs.permute(0, 2, 1)
        outputs = self.main(inputs).permute(0, 2, 1)
        # print(outputs.shape)
        return self.out_net(outputs)


class MovementConvDecoder(nn.Module):
    def __init__(self, input_size, hidden_size, output_size):
        super(MovementConvDecoder, self).__init__()
        self.main = nn.Sequential(
            nn.ConvTranspose1d(input_size, hidden_size, 4, 2, 1),
            # nn.Dropout(0.2, inplace=True),
            nn.LeakyReLU(0.2, inplace=True),
            nn.ConvTranspose1d(hidden_size, output_size, 4, 2, 1),
            # nn.Dropout(0.2, inplace=True),
            nn.LeakyReLU(0.2, inplace=True),
        )
        self.out_net = nn.Linear(output_size, output_size)

        self.main.apply(init_weight)
        self.out_net.apply(init_weight)

    def forward(self, inputs):
        inputs = inputs.permute(0, 2, 1)
        outputs = self.main(inputs).permute(0, 2, 1)
        return self.out_net(outputs)

class TextEncoderBiGRUCo(nn.Module):
    def __init__(self, word_size, pos_size, hidden_size, output_size, device):
        super(TextEncoderBiGRUCo, self).__init__()
        self.device = device

        self.pos_emb = nn.Linear(pos_size, word_size)
        self.input_emb = nn.Linear(word_size, hidden_size)
        self.gru = nn.GRU(hidden_size, hidden_size, batch_first=True, bidirectional=True)
        self.output_net = nn.Sequential(
            nn.Linear(hidden_size * 2, hidden_size),
            nn.LayerNorm(hidden_size),
            nn.LeakyReLU(0.2, inplace=True),
            nn.Linear(hidden_size, output_size)
        )

        self.input_emb.apply(init_weight)
        self.pos_emb.apply(init_weight)
        self.output_net.apply(init_weight)
        # self.linear2.apply(init_weight)
        # self.batch_size = batch_size
        self.hidden_size = hidden_size
        self.hidden = nn.Parameter(torch.randn((2, 1, self.hidden_size), requires_grad=True))

    # input(batch_size, seq_len, dim)
    def forward(self, word_embs, pos_onehot, cap_lens):
        num_samples = word_embs.shape[0]

        pos_embs = self.pos_emb(pos_onehot)
        inputs = word_embs + pos_embs
        input_embs = self.input_emb(inputs)
        hidden = self.hidden.repeat(1, num_samples, 1)

        cap_lens = cap_lens.data.tolist()
        emb = pack_padded_sequence(input_embs, cap_lens, batch_first=True)

        gru_seq, gru_last = self.gru(emb, hidden)

        gru_last = torch.cat([gru_last[0], gru_last[1]], dim=-1)

        return self.output_net(gru_last)


class MotionEncoderBiGRUCo(nn.Module):
    def __init__(self, input_size, hidden_size, output_size, device):
        super(MotionEncoderBiGRUCo, self).__init__()
        self.device = device

        self.input_emb = nn.Linear(input_size, hidden_size)
        self.gru = nn.GRU(hidden_size, hidden_size, batch_first=True, bidirectional=True)
        self.output_net = nn.Sequential(
            nn.Linear(hidden_size*2, hidden_size),
            nn.LayerNorm(hidden_size),
            nn.LeakyReLU(0.2, inplace=True),
            nn.Linear(hidden_size, output_size)
        )

        self.input_emb.apply(init_weight)
        self.output_net.apply(init_weight)
        self.hidden_size = hidden_size
        self.hidden = nn.Parameter(torch.randn((2, 1, self.hidden_size), requires_grad=True))

    # input(batch_size, seq_len, dim)
    def forward(self, inputs, m_lens):
        num_samples = inputs.shape[0]

        input_embs = self.input_emb(inputs)
        hidden = self.hidden.repeat(1, num_samples, 1)

        cap_lens = m_lens.data.tolist()
        emb = pack_padded_sequence(input_embs, cap_lens, batch_first=True)

        gru_seq, gru_last = self.gru(emb, hidden)

        gru_last = torch.cat([gru_last[0], gru_last[1]], dim=-1)

        return self.output_net(gru_last)