import os
os.environ['KMP_DUPLICATE_LIB_OK']='True'
from datasets import load_dataset

# load cifar10 (only small portion for demonstration purposes) 
train_ds, test_ds = load_dataset('cifar10', split=['train[:5000]', 'test[:2000]'])
# split up training into training + validation
splits = train_ds.train_test_split(test_size=0.1)
train_ds = splits['train']
val_ds = splits['test']

id2label = {id:label for id, label in enumerate(train_ds.features['label'].names)}
label2id = {label:id for id,label in id2label.items()}


from transformers import ViTFeatureExtractor

feature_extractor = ViTFeatureExtractor.from_pretrained("google/vit-base-patch16-224-in21k")

from torchvision.transforms import (CenterCrop,
                                    Compose,
                                    Normalize,
                                    RandomHorizontalFlip,
                                    RandomResizedCrop,
                                    Resize,
                                    ToTensor)

normalize = Normalize(mean=feature_extractor.image_mean, std=feature_extractor.image_std)
_train_transforms = Compose(
        [
            RandomResizedCrop(feature_extractor.size),
            RandomHorizontalFlip(),
            ToTensor(),
            normalize,
        ]
    )

_val_transforms = Compose(
        [
            Resize(feature_extractor.size),
            CenterCrop(feature_extractor.size),
            ToTensor(),
            normalize,
        ]
    )

def train_transforms(examples):
    examples['pixel_values'] = [_train_transforms(image.convert("RGB")) for image in examples['img']]
    return examples

def val_transforms(examples):
    examples['pixel_values'] = [_val_transforms(image.convert("RGB")) for image in examples['img']]
    return examples

# Set the transforms
train_ds.set_transform(train_transforms)
val_ds.set_transform(val_transforms)
test_ds.set_transform(val_transforms)


from torch.utils.data import DataLoader
import torch

def collate_fn(examples):
    pixel_values = torch.stack([example["pixel_values"] for example in examples])
    labels = torch.tensor([example["label"] for example in examples])
    return {"pixel_values": pixel_values, "labels": labels}

train_dataloader = DataLoader(train_ds, collate_fn=collate_fn, batch_size=4)


batch = next(iter(train_dataloader))
for k,v in batch.items():
  if isinstance(v, torch.Tensor):
    print(k, v.shape)


from transformers import ViTForImageClassification

model = ViTForImageClassification.from_pretrained('google/vit-base-patch16-224-in21k',
                                                  num_labels=10,
                                                  id2label=id2label,
                                                  label2id=label2id)


from transformers import TrainingArguments, Trainer

metric_name = "accuracy"

args = TrainingArguments(
    f"test-cifar-10",
    save_strategy="epoch",
    evaluation_strategy="epoch",
    learning_rate=2e-5,
    per_device_train_batch_size=10,
    per_device_eval_batch_size=4,
    num_train_epochs=3,
    weight_decay=0.01,
    load_best_model_at_end=True,
    metric_for_best_model=metric_name,
    logging_dir='logs',
    remove_unused_columns=False,
)


from datasets import load_metric
import numpy as np

metric = load_metric("accuracy")

def compute_metrics(eval_pred):
    predictions, labels = eval_pred
    predictions = np.argmax(predictions, axis=1)
    return metric.compute(predictions=predictions, references=labels)


import torch

trainer = Trainer(
    model,
    args,
    train_dataset=train_ds,
    eval_dataset=val_ds,
    data_collator=collate_fn,
    compute_metrics=compute_metrics,
    tokenizer=feature_extractor,
)


trainer.train()