# This file is copied from NNI project
# https://github.com/microsoft/nni/blob/master/examples/trials/mnist-tfv1/mnist.py

"""
A deep MNIST classifier using convolutional layers.

This file is a modification of the official pytorch mnist example:
https://github.com/pytorch/examples/blob/master/mnist/main.py
"""

import os
import argparse
import logging
import nni
import torch
import torch.nn as nn
import torch.nn.functional as F
import torch.optim as optim
from nni.utils import merge_parameter
from torchvision import datasets, transforms

logger = logging.getLogger("mnist_AutoML")


class Net(nn.Module):
    def __init__(self, hidden_size):
        super(Net, self).__init__()
        self.conv1 = nn.Conv2d(1, 20, 5, 1)
        self.conv2 = nn.Conv2d(20, 50, 5, 1)
        self.fc1 = nn.Linear(4 * 4 * 50, hidden_size)
        self.fc2 = nn.Linear(hidden_size, 10)

    def forward(self, x):
        x = F.relu(self.conv1(x))
        x = F.max_pool2d(x, 2, 2)
        x = F.relu(self.conv2(x))
        x = F.max_pool2d(x, 2, 2)
        x = x.view(-1, 4 * 4 * 50)
        x = F.relu(self.fc1(x))
        x = self.fc2(x)
        return F.log_softmax(x, dim=1)


def train(args, model, device, train_loader, optimizer, epoch):
    model.train()
    for batch_idx, (data, target) in enumerate(train_loader):
        if (args["batch_num"] is not None) and batch_idx >= args["batch_num"]:
            break
        data, target = data.to(device), target.to(device)
        optimizer.zero_grad()
        output = model(data)
        loss = F.nll_loss(output, target)
        loss.backward()
        optimizer.step()
        if batch_idx % args["log_interval"] == 0:
            logger.info(
                "Train Epoch: {} [{}/{} ({:.0f}%)]\tLoss: {:.6f}".format(
                    epoch,
                    batch_idx * len(data),
                    len(train_loader.dataset),
                    100.0 * batch_idx / len(train_loader),
                    loss.item(),
                )
            )


def test(args, model, device, test_loader):
    model.eval()
    test_loss = 0
    correct = 0
    with torch.no_grad():
        for data, target in test_loader:
            data, target = data.to(device), target.to(device)
            output = model(data)
            # sum up batch loss
            test_loss += F.nll_loss(output, target, reduction="sum").item()
            # get the index of the max log-probability
            pred = output.argmax(dim=1, keepdim=True)
            correct += pred.eq(target.view_as(pred)).sum().item()

    test_loss /= len(test_loader.dataset)

    accuracy = 100.0 * correct / len(test_loader.dataset)

    logger.info(
        "\nTest set: Average loss: {:.4f}, Accuracy: {}/{} ({:.0f}%)\n".format(
            test_loss, correct, len(test_loader.dataset), accuracy
        )
    )

    return accuracy


def main(args):
    use_cuda = not args["no_cuda"] and torch.cuda.is_available()

    torch.manual_seed(args["seed"])

    device = torch.device("cuda" if use_cuda else "cpu")

    kwargs = {"num_workers": 1, "pin_memory": True} if use_cuda else {}

    data_dir = args["data_dir"]

    train_loader = torch.utils.data.DataLoader(
        datasets.MNIST(
            data_dir,
            train=True,
            download=True,
            transform=transforms.Compose(
                [transforms.ToTensor(), transforms.Normalize((0.1307,), (0.3081,))]
            ),
        ),
        batch_size=args["batch_size"],
        shuffle=True,
        **kwargs
    )
    test_loader = torch.utils.data.DataLoader(
        datasets.MNIST(
            data_dir,
            train=False,
            transform=transforms.Compose(
                [transforms.ToTensor(), transforms.Normalize((0.1307,), (0.3081,))]
            ),
        ),
        batch_size=1000,
        shuffle=True,
        **kwargs
    )

    hidden_size = args["hidden_size"]

    model = Net(hidden_size=hidden_size).to(device)
    optimizer = optim.SGD(model.parameters(), lr=args["lr"], momentum=args["momentum"])

    for epoch in range(1, args["epochs"] + 1):
        train(args, model, device, train_loader, optimizer, epoch)
        test_acc = test(args, model, device, test_loader)

        # report intermediate result
        nni.report_intermediate_result(test_acc)
        logger.debug("test accuracy %g", test_acc)
        logger.debug("Pipe send intermediate result done.")

    # report final result
    nni.report_final_result(test_acc)
    logger.debug("Final result is %g", test_acc)
    logger.debug("Send final result done.")


def get_params():
    # Training settings
    parser = argparse.ArgumentParser(description="PyTorch MNIST Example")
    parser.add_argument("--data_dir", type=str, default="./data", help="data directory")
    parser.add_argument(
        "--batch_size",
        type=int,
        default=64,
        metavar="N",
        help="input batch size for training (default: 64)",
    )
    parser.add_argument("--batch_num", type=int, default=None)
    parser.add_argument(
        "--hidden_size",
        type=int,
        default=512,
        metavar="N",
        help="hidden layer size (default: 512)",
    )
    parser.add_argument(
        "--lr",
        type=float,
        default=0.01,
        metavar="LR",
        help="learning rate (default: 0.01)",
    )
    parser.add_argument(
        "--momentum",
        type=float,
        default=0.5,
        metavar="M",
        help="SGD momentum (default: 0.5)",
    )
    parser.add_argument(
        "--epochs",
        type=int,
        default=10,
        metavar="N",
        help="number of epochs to train (default: 10)",
    )
    parser.add_argument(
        "--seed", type=int, default=1, metavar="S", help="random seed (default: 1)"
    )
    parser.add_argument(
        "--no_cuda", action="store_true", default=False, help="disables CUDA training"
    )
    parser.add_argument(
        "--log_interval",
        type=int,
        default=1000,
        metavar="N",
        help="how many batches to wait before logging training status",
    )

    args, _ = parser.parse_known_args()
    return args


if __name__ == "__main__":
    try:
        # get parameters form tuner
        tuner_params = nni.get_next_parameter()
        logger.debug(tuner_params)
        params = vars(merge_parameter(get_params(), tuner_params))
        print(params)
        main(params)
    except Exception as exception:
        logger.exception(exception)
        raise