from PIL import Image, ImageDraw
import io
import logging
from datetime import datetime

logger = logging.getLogger(__name__)

def halftone_effect(img, dot_size=10):
    """
    Apply a halftone effect to the input image.
    """
    grayscale = img.convert('L')
    width, height = grayscale.size

    halftone_image = Image.new('L', (width, height), color=255)
    draw = ImageDraw.Draw(halftone_image)

    for x in range(0, width, dot_size):
        for y in range(0, height, dot_size):
            block_width = min(dot_size, width - x)
            block_height = min(dot_size, height - y)

            region = grayscale.crop((x, y, x + block_width, y + block_height))
            avg_brightness = sum(region.getdata()) / (block_width * block_height)

            max_radius = dot_size // 2
            radius = int((255 - avg_brightness) / 255 * max_radius)
            radius = max(0, min(radius, max_radius))

            center_x = x + dot_size // 2
            center_y = y + dot_size // 2
            draw.ellipse(
                (
                    center_x - radius,
                    center_y - radius,
                    center_x + radius,
                    center_y + radius
                ),
                fill=0
            )

    return halftone_image

def apply_halftone(image_data, dot_size=10):
    start_time = datetime.now()
    logger.info(f"Applying halftone effect - {start_time}")
    
    try:
        input_image = Image.open(io.BytesIO(image_data))
        logger.info(f"Image opened. Mode: {input_image.mode}, Size: {input_image.size}")
        
        dot_size = max(5, min(20, dot_size))
        logger.info(f"Applying halftone effect with dot size: {dot_size}")
        
        output_image = halftone_effect(input_image, dot_size)
        
        img_io = io.BytesIO()
        output_image.save(img_io, 'PNG')
        img_io.seek(0)
        
        duration = (datetime.now() - start_time).total_seconds()
        logger.info(f"Successfully processed. Duration: {duration} seconds")
        return img_io
    except Exception as e:
        logger.error(f"Halftone processing error: {str(e)}", exc_info=True)
        raise