import argparse

import numpy as np
import mindspore
from mindspore import nn, context, ops
from mindspore.common import dtype as mstype
from mindspore.dataset import MnistDataset
from hcmodel import HCModel

context.set_context(mode=context.GRAPH_MODE, device_target="CPU")


class ImageToDualImage:
    @staticmethod
    def __call__(img):
        return np.concatenate((img, img), axis=0)


def create_dataset(dataset_dir, batch_size, usage=None):
    dataset = MnistDataset(dataset_dir=dataset_dir, usage=usage)
    type_cast_op = mindspore.dataset.transforms.TypeCast(mstype.int32)

    # define map operations
    trans = [mindspore.dataset.vision.Rescale(1.0 / 255.0, 0),
             mindspore.dataset.vision.Normalize(mean=(0.1307,), std=(0.3081,)),
             mindspore.dataset.vision.HWC2CHW(),
             ImageToDualImage()]

    dataset = dataset.map(operations=type_cast_op, input_columns="label")
    dataset = dataset.map(operations=trans, input_columns="image")
    dataset = dataset.batch(batch_size)
    return dataset


def train(model, dataset, loss_fn, optimizer):
    # Define forward function
    def forward_fn(data, label):
        logits = model(data)
        loss = loss_fn(logits, label)
        return loss, logits

    # Get gradient function
    grad_fn = ops.value_and_grad(forward_fn, None, optimizer.parameters, has_aux=True)

    # Define function of one-step training
    def train_step(data, label):
        (loss, _), grads = grad_fn(data, label)
        loss = ops.depend(loss, optimizer(grads))
        return loss

    size = dataset.get_dataset_size()
    model.set_train()
    for batch, (data, label) in enumerate(dataset.create_tuple_iterator()):
        loss = train_step(data, label)

        if batch % 100 == 0:
            loss, current = loss.asnumpy(), batch
            print(f"loss: {loss:>7f}  [{current:>3d}/{size:>3d}]")


def test(model, dataset, loss_fn):
    num_batches = dataset.get_dataset_size()
    model.set_train(False)
    total, test_loss, correct = 0, 0, 0
    for data, label in dataset.create_tuple_iterator():
        pred = model(data)
        total += len(data)
        test_loss += loss_fn(pred, label).asnumpy()
        correct += (pred.argmax(1) == label).asnumpy().sum()
    test_loss /= num_batches
    correct /= total
    print(f"Test: \n Accuracy: {(100*correct):>0.1f}%, Avg loss: {test_loss:>8f} \n")


def main():
    parser = argparse.ArgumentParser(description='MindSpore MNIST Testing')
    parser.add_argument(
        '--dataset', default=None, type=str, metavar='DS', required=True,
        help='Path to the dataset folder'
    )
    parser.add_argument(
        '--bs', default=64, type=int, metavar='N', required=False,
        help='Mini-batch size'
    )
    args = parser.parse_args()

    # Process the MNIST dataset.
    train_dataset = create_dataset(args.dataset, args.bs, "train")
    test_dataset = create_dataset(args.dataset, args.bs, "test")

    for img, lbl in test_dataset.create_tuple_iterator():
        print(f"Shape of image [N, C, H, W]: {img.shape} {img.dtype}")
        print(f"Shape of label: {lbl.shape} {lbl.dtype}")
        break

    # Initialize hypercomplex model
    net = HCModel()

    # Initialize loss function and optimizer
    criterion = nn.CrossEntropyLoss()
    optim = nn.SGD(net.trainable_params(), 1e-2)

    epochs = 10
    for t in range(epochs):
        print(f"Epoch {t+1}\n-------------------------------")
        train(net, train_dataset, criterion, optim)
        test(net, test_dataset, criterion)
    print("Done!")


if __name__ == "__main__":
    main()