from typing import Dict, List, Any
import PIL
import torch
import base64
import os
import io
from transformers import ViTImageProcessor, VisionEncoderDecoderModel

device = torch.device('cuda' if torch.cuda.is_available() else 'cpu')


class PreTrainedPipeline():
    def __init__(self, path=""):
        self.model = VisionEncoderDecoderModel.from_pretrained(
            pretrained_model_name_or_path=path,
            config=os.path.join(path, 'config.json')
        )
        self.model.eval()
        self.model = self.model.to(device)

        self.processor = ViTImageProcessor.from_pretrained(
            pretrained_model_name_or_path=os.path.join(
                path, 'preprocessor_config.json')
        )

    def __call__(self, data: Any) -> Dict[str, List[float]]:
        """
        Args:
            data (:str:):
                Inputs should be an image encoded in base 64.
        Return:
            A :obj:`dict`:. The object returned should be a dict like
                {"feature_vector": [0.6331314444541931,...,-0.7866355180740356,]} containing :
                - "feature_vector": A list of floats corresponding to the image embedding.
        """
        # decode base64 image to PIL
        image = PIL.Image.open(io.BytesIO(base64.b64decode(data)))

        inputs = self.processor(images=image, return_tensors="pt")
        outputs = self.model.encoder(**inputs)
        feature_vector = outputs.last_hidden_state[0, 0, :].tolist()
        # postprocess the prediction
        return {"feature_vector": feature_vector}