import torch
from torch import nn
from torch.utils.data import DataLoader
from torchvision import datasets
from torchvision.transforms import ToTensor
import torch.nn.functional as F
import time
import matplotlib.pyplot as plt
from torch.profiler import profile, record_function, ProfilerActivity

torch.set_flush_denormal(True)

training_data = datasets.MNIST(
    root="data",
    train=True,
    download=True,
    transform=ToTensor(),
)

test_data = datasets.MNIST(
    root="data",
    train=False,
    download=True,
    transform=ToTensor(),
)

batch_size = 64

train_dataloader = DataLoader(training_data, batch_size=batch_size, shuffle=True, num_workers=4)
test_dataloader = DataLoader(test_data, batch_size=batch_size, num_workers=4)

for input_data, labels in test_dataloader:
    print(f"Shape of input_data [N, C, H, W]: {input_data.shape}")
    print(f"Shape of labels: {labels.shape} (type: {labels.dtype})")
    break

device = (
    "cuda"
    if torch.cuda.is_available()
    else "mps"
    if torch.backends.mps.is_available()
    else "cpu"
)

# device = "cpu"
print(f"Using {device} device")


class ConvNetwork(nn.Module):
    def __init__(self):
        super().__init__()
        self.flatten = nn.Flatten()
        # self.conv_stack = nn.Sequential(
        #     nn.Conv2d(1, 1, 3, 1, padding=0),
        #     nn.GELU(),
        #     # nn.MaxPool2d(2, 1),
        #     # nn.GELU(),
        #     nn.Conv2d(1, 1, 3, 1, padding=0),
        #     nn.GELU(),
        #     # nn.Conv2d(1, 1, 3, 1, padding=0, device=device),
        #     # nn.GELU(),
        #     # nn.Conv2d(1, 1, 3, 1, padding=0, device=device),
        #     # nn.GELU(),
        #     # nn.Conv2d(1, 1, 3, 1, padding=0, device=device),
        #     # nn.GELU(),
        #     # nn.Conv2d(1, 1, 3, 1, padding=0, device=device),
        #     # nn.GELU(),
        #     # nn.MaxPool2d(),
        # )
        #
        # self.linear_stack = nn.Sequential(
        #     nn.Linear(24 * 24, 64),
        #     nn.GELU(),
        #     # nn.Dropout(0.1),
        #     nn.Linear(64, 32),
        #     nn.GELU(),
        #     # nn.Linear(256, 128),
        #     # nn.GELU(),
        #     # nn.Dropout(0.2),
        #     # nn.Linear(128, 64),
        #     # nn.GELU(),
        #     # nn.Dropout(0.2),
        #     nn.Linear(32, 10),
        #     # nn.GELU(),
        #     # nn.Linear(512, 10),
        # )

        self.conv_stack = nn.Sequential(
            nn.Conv2d(1, 32, 3, 1),
            nn.GELU(),
            nn.Conv2d(32, 64, 3, 1),
            nn.GELU(),
            nn.MaxPool2d(2),
            nn.Conv2d(64, 128, 3, 1),
            nn.GELU(),
            nn.Conv2d(128, 128, 3, 1),
            nn.GELU(),
            nn.MaxPool2d(2)
        )
        self.linear_stack = nn.Sequential(
            nn.Linear(128 * 4 * 4, 128),
            nn.GELU(),
            nn.Linear(128, 10)
        )

    def forward(self, x):
        x = self.conv_stack(x)
        # x = self.flatten(x)
        x = x.view(x.size(0), -1)
        logits = self.linear_stack(x)
        return logits


feed_forward_model = ConvNetwork().to(device)
print(feed_forward_model)

loss_fn = nn.MSELoss()
loss_fn = nn.CrossEntropyLoss()
sgd_optimizer = torch.optim.SGD(feed_forward_model.parameters(), lr=1e-3, momentum=0.9)
adam = torch.optim.AdamW(feed_forward_model.parameters(), lr=1e-3)

def train(dataloader, model, loss_fn, optimizer):
    size = len(dataloader.dataset)
    model.train()
    for batch, (X, y) in enumerate(dataloader):
        X, y = X.to(device), y.to(device)

        # with profile(activities=[
        #     ProfilerActivity.CPU, ProfilerActivity.CUDA], record_shapes=True) as prof:
        #     with record_function("model_inference"):
        pred = model(X)
        # print(prof.key_averages().table(sort_by="cuda_time_total", row_limit=10))

        loss = loss_fn(pred, y)  #loss_fn(pred, F.one_hot(y, num_classes=10).float())

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

        if batch % 100 == 0:
            loss = loss.item()
            current = (batch + 1) * len(X)
            print(f"loss: {loss:>7f}  [{current:>5d}/{size:>5d}]")


def test(dataloader, model, loss_fn):
    size = len(dataloader.dataset)
    num_batches = len(dataloader)
    model.eval()
    test_loss, correct = 0, 0
    misclassified_images = []
    with torch.no_grad():
        for X, y in dataloader:
            X, y = X.to(device), y.to(device)

            pred = model(X)

            test_loss += loss_fn(pred, y).item()
            correct += (pred.argmax(1) == y).type(torch.float).sum().item()
            # Collect misclassified images
            misclassified_images.extend(
                [(img, true_label, pred_label) for img, true_label, pred_label in zip(X, y, pred.argmax(1)) if
                 true_label != pred_label])
    test_loss /= num_batches
    correct /= size
    print(f"Test Error: \n Accuracy: {(100 * correct):>0.1f}%, Avg loss: {test_loss:>8f} \n")
    return misclassified_images



epochs = 20
start_time = time.time()
for t in range(epochs):
    print(
        f"Epoch {t + 1} (lr: {sgd_optimizer.state_dict()['param_groups'][0]['lr']})\n-------------------------------")
    train(train_dataloader,
          feed_forward_model,
          loss_fn,
          adam)
    test(test_dataloader,
         feed_forward_model,
         loss_fn)
print("Done!")
end_time = time.time()
duration = end_time - start_time
print(f"Training took {duration:.2f} seconds")

misclassified_images = test(test_dataloader, feed_forward_model, loss_fn)
print(len(misclassified_images))

# # Visualizing misclassified images
# plt.figure(figsize=(10, 10))
# for i, (image, true_label, pred_label) in enumerate(misclassified_images):
#     # plt.subplot(5, 5, i + 1)
#     plt.imshow(image.cpu().squeeze(), cmap='gray')
#     plt.title(f'True: {true_label.item()}\nPredicted: {pred_label.item()}')
#     plt.axis('off')
#     plt.show()