from PIL import Image
from io import BytesIO
import requests
import base64
from typing import Union, Tuple

def resize_image(image_input: Union[str, BytesIO], target_size: Tuple[int, int], return_format: str = "base64") -> str:
    """
    Resize an image to the target size while maintaining aspect ratio.
    
    Args:
        image_input: URL, file path, base64 string, or BytesIO object
        target_size: Tuple (width, height) for the target size
        return_format: Format to return the image in ("base64" or "pil")
        
    Returns:
        Base64 encoded string of the resized image or PIL Image object
    """
    # Convert input to PIL Image
    if isinstance(image_input, str):
        if image_input.startswith(('http://', 'https://')):
            # It's a URL
            response = requests.get(image_input, timeout=10)
            response.raise_for_status()
            image = Image.open(BytesIO(response.content))
        elif image_input.startswith('data:image'):
            # It's a base64 data URI
            base64_data = image_input.split(',')[1]
            image = Image.open(BytesIO(base64.b64decode(base64_data)))
        elif ';base64,' not in image_input and len(image_input) > 500:
            # Likely a raw base64 string
            image = Image.open(BytesIO(base64.b64decode(image_input)))
        else:
            # Assume it's a file path
            image = Image.open(image_input)
    elif isinstance(image_input, BytesIO):
        image = Image.open(image_input)
    else:
        raise ValueError("Unsupported image input type")

    # Calculate the aspect ratio
    aspect_ratio = min(target_size[0] / image.width, target_size[1] / image.height)
    
    # Calculate new size
    new_size = (int(image.width * aspect_ratio), int(image.height * aspect_ratio))
    
    # Resize the image using the proper resampling filter
    resized_image = image.resize(new_size, Image.LANCZOS)
    
    # Return in requested format
    if return_format.lower() == "base64":
        buffer = BytesIO()
        resized_image.save(buffer, format="PNG")
        return base64.b64encode(buffer.getvalue()).decode('utf-8')
    else:
        return resized_image