import torch
import numpy as np
import torch.nn as nn
import torch.nn.functional as F

import matplotlib.pyplot as plt
from utilities3 import *

import operator
from functools import reduce
from functools import partial

from timeit import default_timer
import scipy.io

torch.manual_seed(0)
np.random.seed(0)

activation = F.relu

################################################################
# lowrank layers
################################################################
class LowRank2d(nn.Module):
    def __init__(self, in_channels, out_channels, s, ker_width, rank):
        super(LowRank2d, self).__init__()
        self.in_channels = in_channels
        self.out_channels = out_channels
        self.s = s
        self.n = s*s
        self.rank = rank

        self.phi = DenseNet([in_channels, ker_width, in_channels*out_channels*rank], torch.nn.ReLU)
        self.psi = DenseNet([in_channels, ker_width, in_channels*out_channels*rank], torch.nn.ReLU)


    def forward(self, v):
        batch_size = v.shape[0]

        phi_eval = self.phi(v).reshape(batch_size, self.n, self.out_channels, self.in_channels, self.rank)
        psi_eval = self.psi(v).reshape(batch_size, self.n, self.out_channels, self.in_channels, self.rank)

        # print(psi_eval.shape, v.shape, phi_eval.shape)
        v = torch.einsum('bnoir,bni,bmoir->bmo',psi_eval, v, phi_eval)

        return v



class MyNet(torch.nn.Module):
    def __init__(self, s, width=16, ker_width=256, rank=16):
        super(MyNet, self).__init__()
        self.s = s
        self.width = width
        self.ker_width = ker_width
        self.rank = rank

        self.fc0 = nn.Linear(12, self.width)

        self.conv0 = LowRank2d(width, width, s, ker_width, rank)
        self.conv1 = LowRank2d(width, width, s, ker_width, rank)
        self.conv2 = LowRank2d(width, width, s, ker_width, rank)
        self.conv3 = LowRank2d(width, width, s, ker_width, rank)

        self.w0 = nn.Linear(self.width, self.width)
        self.w1 = nn.Linear(self.width, self.width)
        self.w2 = nn.Linear(self.width, self.width)
        self.w3 = nn.Linear(self.width, self.width)
        self.bn0 = torch.nn.BatchNorm1d(self.width)
        self.bn1 = torch.nn.BatchNorm1d(self.width)
        self.bn2 = torch.nn.BatchNorm1d(self.width)
        self.bn3 = torch.nn.BatchNorm1d(self.width)

        self.fc1 = nn.Linear(self.width, 128)
        self.fc2 = nn.Linear(128, 1)


    def forward(self, x):
        batch_size = x.shape[0]
        size_x, size_y = x.shape[1], x.shape[2]
        x = x.view(batch_size, size_x*size_y, -1)

        x = self.fc0(x)

        x1 = self.conv0(x)
        x2 = self.w0(x)
        x = x1 + x2
        x = self.bn0(x.reshape(-1, self.width)).view(batch_size, size_x*size_y, self.width)
        x = F.relu(x)
        x1 = self.conv1(x)
        x2 = self.w1(x)
        x = x1 + x2
        x = self.bn1(x.reshape(-1, self.width)).view(batch_size, size_x*size_y, self.width)
        x = F.relu(x)
        x1 = self.conv2(x)
        x2 = self.w2(x)
        x = x1 + x2
        x = self.bn2(x.reshape(-1, self.width)).view(batch_size, size_x*size_y, self.width)
        x = F.relu(x)
        x1 = self.conv3(x)
        x2 = self.w3(x)
        x = x1 + x2
        x = self.bn3(x.reshape(-1, self.width)).view(batch_size, size_x*size_y, self.width)

        x = self.fc1(x)
        x = F.relu(x)
        x = self.fc2(x)
        x = x.view(batch_size, size_x, size_y, -1)
        return x

class Net2d(nn.Module):
    def __init__(self, width=12, ker_width=128, rank=4):
        super(Net2d, self).__init__()

        self.conv1 = MyNet(s=64, width=width, ker_width=ker_width, rank=rank)


    def forward(self, x):
        x = self.conv1(x)
        return x


    def count_params(self):
        c = 0
        for p in self.parameters():
            c += reduce(operator.mul, list(p.size()))

        return c

################################################################
# configs
################################################################
# TRAIN_PATH = 'data/ns_data_V10000_N1200_T20.mat'
# TEST_PATH = 'data/ns_data_V10000_N1200_T20.mat'
# TRAIN_PATH = 'data/ns_data_V1000_N1000_train.mat'
# TEST_PATH = 'data/ns_data_V1000_N1000_train_2.mat'
# TRAIN_PATH = 'data/ns_data_V1000_N5000.mat'
# TEST_PATH = 'data/ns_data_V1000_N5000.mat'
TRAIN_PATH = 'data/ns_data_V100_N1000_T50_1.mat'
TEST_PATH = 'data/ns_data_V100_N1000_T50_2.mat'

ntrain = 1000
ntest = 200

batch_size = 5
batch_size2 = batch_size

epochs = 500
learning_rate = 0.0025
scheduler_step = 100
scheduler_gamma = 0.5

print(epochs, learning_rate, scheduler_step, scheduler_gamma)

path = 'ns_lowrank_rnn_V100_T40_N'+str(ntrain)+'_ep' + str(epochs) + '_m'
path_model = 'model/'+path
path_train_err = 'results/'+path+'train.txt'
path_test_err = 'results/'+path+'test.txt'
path_image = 'image/'+path


runtime = np.zeros(2, )
t1 = default_timer()


sub = 1
S = 64
T_in = 10
T = 40
step = 1


################################################################
# load dataset
################################################################
reader = MatReader(TRAIN_PATH)
train_a = reader.read_field('u')[:ntrain,::sub,::sub,:T_in]
train_u = reader.read_field('u')[:ntrain,::sub,::sub,T_in:T+T_in]

reader = MatReader(TEST_PATH)
test_a = reader.read_field('u')[-ntest:,::sub,::sub,:T_in]
test_u = reader.read_field('u')[-ntest:,::sub,::sub,T_in:T+T_in]

print(train_u.shape)
print(test_u.shape)
assert (S == train_u.shape[-2])
assert (T == train_u.shape[-1])


train_a = train_a.reshape(ntrain,S,S,T_in)
test_a = test_a.reshape(ntest,S,S,T_in)

gridx = torch.tensor(np.linspace(0, 1, S), dtype=torch.float)
gridx = gridx.reshape(1, S, 1, 1).repeat([1, 1, S, 1])
gridy = torch.tensor(np.linspace(0, 1, S), dtype=torch.float)
gridy = gridy.reshape(1, 1, S, 1).repeat([1, S, 1, 1])

train_a = torch.cat((train_a, gridx.repeat([ntrain,1,1,1]), gridy.repeat([ntrain,1,1,1])), dim=-1)
test_a = torch.cat((test_a, gridx.repeat([ntest,1,1,1]), gridy.repeat([ntest,1,1,1])), dim=-1)

train_loader = torch.utils.data.DataLoader(torch.utils.data.TensorDataset(train_a, train_u), batch_size=batch_size, shuffle=True)
test_loader = torch.utils.data.DataLoader(torch.utils.data.TensorDataset(test_a, test_u), batch_size=batch_size, shuffle=False)

t2 = default_timer()

print('preprocessing finished, time used:', t2-t1)
device = torch.device('cuda')

################################################################
# training and evaluation
################################################################
model = Net2d().cuda()
# model = torch.load('model/ns_fourier_V100_N1000_ep100_m8_w20')

print(model.count_params())
optimizer = torch.optim.Adam(model.parameters(), lr=learning_rate, weight_decay=1e-4)
scheduler = torch.optim.lr_scheduler.StepLR(optimizer, step_size=scheduler_step, gamma=scheduler_gamma)


myloss = LpLoss(size_average=False)
gridx = gridx.to(device)
gridy = gridy.to(device)

for ep in range(epochs):
    model.train()
    t1 = default_timer()
    train_l2_step = 0
    train_l2_full = 0
    for xx, yy in train_loader:
        loss = 0
        xx = xx.to(device)
        yy = yy.to(device)

        for t in range(0, T, step):
            y = yy[..., t:t + step]
            im = model(xx)
            loss += myloss(im.reshape(batch_size, -1), y.reshape(batch_size, -1))

            if t == 0:
                pred = im
            else:
                pred = torch.cat((pred, im), -1)

            xx = torch.cat((xx[..., step:-2], im,
                            gridx.repeat([batch_size, 1, 1, 1]), gridy.repeat([batch_size, 1, 1, 1])), dim=-1)

        train_l2_step += loss.item()
        l2_full = myloss(pred.reshape(batch_size, -1), yy.reshape(batch_size, -1))
        train_l2_full += l2_full.item()

        optimizer.zero_grad()
        loss.backward()
        # l2_full.backward()
        optimizer.step()

    test_l2_step = 0
    test_l2_full = 0
    with torch.no_grad():
        for xx, yy in test_loader:
            loss = 0
            xx = xx.to(device)
            yy = yy.to(device)

            for t in range(0, T, step):
                y = yy[..., t:t + step]
                im = model(xx)
                loss += myloss(im.reshape(batch_size, -1), y.reshape(batch_size, -1))

                if t == 0:
                    pred = im
                else:
                    pred = torch.cat((pred, im), -1)

                xx = torch.cat((xx[..., step:-2], im,
                                gridx.repeat([batch_size, 1, 1, 1]), gridy.repeat([batch_size, 1, 1, 1])), dim=-1)


            test_l2_step += loss.item()
            test_l2_full += myloss(pred.reshape(batch_size, -1), yy.reshape(batch_size, -1)).item()

    t2 = default_timer()
    scheduler.step()
    print(ep, t2 - t1, train_l2_step / ntrain / (T / step), train_l2_full / ntrain, test_l2_step / ntest / (T / step),
          test_l2_full / ntest)
# torch.save(model, path_model)


# pred = torch.zeros(test_u.shape)
# index = 0
# test_loader = torch.utils.data.DataLoader(torch.utils.data.TensorDataset(test_a, test_u), batch_size=1, shuffle=False)
# with torch.no_grad():
#     for x, y in test_loader:
#         test_l2 = 0;
#         x, y = x.cuda(), y.cuda()
#
#         out = model(x)
#         out = y_normalizer.decode(out)
#         pred[index] = out
#
#         test_l2 += myloss(out.view(1, -1), y.view(1, -1)).item()
#         print(index, test_l2)
#         index = index + 1

# scipy.io.savemat('pred/'+path+'.mat', mdict={'pred': pred.cpu().numpy()})

