"""
Train EiV model using different seeds
"""
import random
import importlib
import os
import argparse
import json

import numpy as np
import torch
import torch.backends.cudnn
from torch.utils.data import DataLoader
from torch.utils.tensorboard.writer import SummaryWriter

from EIVArchitectures import Networks, initialize_weights
from EIVTrainingRoutines import train_and_store, loss_functions


# read in data via --data option
parser = argparse.ArgumentParser()
parser.add_argument("--data", help="Loads data", default='california')
parser.add_argument("--no-autoindent", help="",
        action="store_true") # to avoid conflics in IPython
args = parser.parse_args()
data = args.data

# load hyperparameters from JSON file
with open(os.path.join('configurations',f'eiv_{data}.json'),'r') as conf_file:
    conf_dict = json.load(conf_file)

long_dataname = conf_dict["long_dataname"]
short_dataname = conf_dict["short_dataname"]
lr = conf_dict["lr"]
batch_size = conf_dict["batch_size"]
test_batch_size = conf_dict["test_batch_size"]
number_of_epochs = conf_dict["number_of_epochs"]
unscaled_reg = conf_dict["unscaled_reg"]
report_point = conf_dict["report_point"]
p = conf_dict["p"]
lr_update = conf_dict["lr_update"]
# offset before updating sigma_y after each epoch
std_y_update_points = conf_dict["std_y_update_points"]
# will be used to predict the RMSE and update sigma_y accordingly
eiv_prediction_number_of_draws = conf_dict["eiv_prediction_number_of_draws"]
eiv_prediction_number_of_batches = \
        conf_dict["eiv_prediction_number_of_batches"]
init_std_y_list = conf_dict["init_std_y_list"]
fixed_std_x = conf_dict['fixed_std_x']
gamma = conf_dict["gamma"]
hidden_layers = conf_dict["hidden_layers"]
seed_range = conf_dict['seed_range']

print(f"Training on {long_dataname} data")

try:
    gpu_number = conf_dict["gpu_number"]
    device = torch.device(f'cuda:{gpu_number}' if torch.cuda.is_available()
            else 'cpu')
except KeyError:
    device = torch.device('cpu')

load_data = importlib.import_module(f'EIVData.{long_dataname}').load_data

# reproducability
seed_list = range(seed_range[0], seed_range[1])

def set_seeds(seed):
    torch.backends.cudnn.benchmark = False
    np.random.seed(seed)
    random.seed(seed) 
    torch.manual_seed(seed)

# to store the RMSE
rmse_chain = []

class UpdatedTrainEpoch(train_and_store.TrainEpoch):
    def pre_epoch_update(self, net, epoch):
        """
        Overwrites the corresponding method
        """
        if epoch == 0:
            self.lr = self.initial_lr
            self.optimizer = torch.optim.Adam(net.parameters(), lr=self.lr)
            self.lr_scheduler = torch.optim.lr_scheduler.StepLR(
            self.optimizer, lr_update, gamma)

    def update_std_y(self, net):
        """
        Update the std_y of `net` via the RMSE of the prediction.
        """
        net_train_state = net.training
        net_noise_state = net.noise_is_on
        net.train()
        net.noise_on()
        pred_collection = []
        y_collection = []
        for i, (x,y) in  enumerate(self.train_dataloader):
            if i >= eiv_prediction_number_of_batches:
                break
            if len(y.shape) <= 1:
                y = y.view((-1,1))
            x,y = x.to(device), y.to(device)
            pred, _ = net.predict(x,
                    number_of_draws=eiv_prediction_number_of_draws,
                    remove_graph = True,
                    take_average_of_prediction=True)
            pred_collection.append(pred)
            y_collection.append(y)
        pred_collection = torch.cat(pred_collection, dim=0)
        y_collection = torch.cat(y_collection, dim=0)
        assert pred_collection.shape == y_collection.shape
        rmse = torch.sqrt(torch.mean((pred_collection - y_collection)**2))
        net.change_std_y(rmse)
        if not net_train_state:
            net.eval()
        if not net_noise_state:
            net.noise_off()

    def check_if_update_std_y(self, epoch):
        """
        Check whether to update std_y according to `epoch_number` and
        `std_y_update_points`. If the later is an integer, after all epochs
        greater than this number an update will be made (i.e. `True` will
        be returned). If it is a list, only `epoch_number` greater than
        `std_y_update_points[0]` that divide `std_y_update_points[1]` will
        result in a True.
        """
        if type(std_y_update_points) is int:
            return epoch >= std_y_update_points
        else:
            assert type(std_y_update_points) is list
            return epoch >= std_y_update_points[0]\
                        and epoch % std_y_update_points[1] == 0

    def post_epoch_update(self, net, epoch):
        """
        Overwrites the corresponding method
        """
        if self.check_if_update_std_y(epoch):
            self.update_std_y(net)
        self.lr_scheduler.step()

    def post_train_update(self, net, epoch):
        """
        Overwrites the corresponding method. If std_y of `net` was not updated
        in the last training step, update it when finished with training.
        `epoch` should be the number of the last training epoch.
        """
        if not self.check_if_update_std_y(epoch):
            self.update_std_y(net)

    def extra_report(self, net, i):
        """
        Overwrites the corresponding method
        and fed after initialization of this class
        """
        rmse = self.rmse(net).item()
        rmse_chain.append(rmse)
        writer.add_scalar('RMSE', rmse, self.total_count)
        writer.add_scalar('std_y', self.last_std_y, self.total_count)
        writer.add_scalar('train loss', self.last_train_loss, self.total_count)
        writer.add_scalar('test loss', self.last_test_loss, self.total_count)
        print(f'RMSE {rmse:.3f}')

    def rmse(self, net):
        """
        Compute the root mean squared error for `net`
        """
        net_train_state = net.training
        net_noise_state = net.noise_is_on
        net.eval()
        net.noise_off()
        x, y = next(iter(self.test_dataloader))
        if len(y.shape) <= 1:
            y = y.view((-1,1))
        out = net(x.to(device))[0].detach().cpu()
        assert out.shape == y.shape
        if net_train_state:
            net.train()
        if net_noise_state:
            net.noise_on()
        return torch.sqrt(torch.mean((out-y)**2))

def train_on_data(init_std_y, seed):
    """
    Sets `seed`, loads data and trains an Bernoulli Modell, starting with
    `init_std_y`.
    """
    # set seed
    set_seeds(seed)
    # load Datasets
    train_data, test_data = load_data(seed=seed, splitting_part=0.8,
            normalize=True)
    # make dataloaders
    train_dataloader = DataLoader(train_data, batch_size=batch_size, 
            shuffle=True)
    test_dataloader = DataLoader(test_data, batch_size=test_batch_size,
            shuffle=True)
    # create a net
    input_dim = train_data[0][0].numel()
    output_dim = train_data[0][1].numel()
    net = Networks.FNNEIV(p=p,
            init_std_y=init_std_y,
            h=[input_dim, *hidden_layers, output_dim],
            fixed_std_x=fixed_std_x)
    net.apply(initialize_weights.glorot_init)
    net = net.to(device)
    net.std_y_par.requires_grad = False
    std_x_map = lambda: net.get_std_x().detach().cpu().item()
    std_y_map = lambda: net.get_std_y().detach().cpu().item()
    # regularization
    reg = unscaled_reg/len(train_data)
    # create epoch_map
    criterion = loss_functions.nll_eiv
    epoch_map = UpdatedTrainEpoch(train_dataloader=train_dataloader,
            test_dataloader=test_dataloader,
            criterion=criterion, std_y_map=std_y_map, std_x_map=std_x_map,
            lr=lr, reg=reg, report_point=report_point, device=device)
    # run and save
    save_file = os.path.join('saved_networks',
            f'eiv_{short_dataname}'\
                    f'_init_std_y_{init_std_y:.3f}_ureg_{unscaled_reg:.1f}'\
                    f'_p_{p:.2f}_fixed_std_x_{fixed_std_x:.3f}'\
                    f'_seed_{seed}.pkl')
    train_and_store.train_and_store(net=net, 
            epoch_map=epoch_map,
            number_of_epochs=number_of_epochs,
            save_file=save_file)
    

if __name__ == '__main__':
    for seed in seed_list:
        # Tensorboard monitoring
        writer = SummaryWriter(log_dir=f'/home/martin09/tmp/tensorboard/'\
                f'run_eiv_{short_dataname}_lr_{lr:.4f}_seed'\
                f'_{seed}_uregu_{unscaled_reg:.1f}_p_{p:.2f}'\
                f'_fixed_std_x_{fixed_std_x:.3f}')
        print(f'>>>>SEED: {seed}')
        for init_std_y in init_std_y_list:
            print(f'Using init_std_y={init_std_y:.3f}')
            train_on_data(init_std_y, seed)