import boto3
import os
from urllib.parse import unquote_plus

# This is a dummy script. For a real implementation, you would use a library like Pillow (PIL).
# from PIL import Image

s3_client = boto3.client('s3')

def lambda_handler(event, context):
    """
    A dummy Lambda function that simulates creating a thumbnail for an image
    uploaded to an S3 bucket.
    """
    # Get the destination bucket from environment variables
    dest_bucket = os.environ['DESTINATION_BUCKET']

    for record in event['Records']:
        source_bucket = record['s3']['bucket']['name']
        source_key = unquote_plus(record['s3']['object']['key'])
        
        # Construct the destination key
        dest_key = "thumbnails/" + os.path.basename(source_key)

        print(f"Source Bucket: {source_bucket}")
        print(f"Source Key: {source_key}")
        print(f"Destination Bucket: {dest_bucket}")
        print(f"Destination Key: {dest_key}")

        try:
            # In a real-world scenario, you would:
            # 1. Download the image from the source bucket to /tmp
            #    s3_client.download_file(source_bucket, source_key, '/tmp/image.jpg')
            # 2. Resize the image using a library like Pillow
            #    with Image.open('/tmp/image.jpg') as image:
            #        image.thumbnail((128, 128))
            #        image.save('/tmp/thumbnail.jpg')
            # 3. Upload the thumbnail to the destination bucket
            #    s3_client.upload_file('/tmp/thumbnail.jpg', dest_bucket, dest_key)

            # For this example, we'll just copy the object to simulate the process
            copy_source = {'Bucket': source_bucket, 'Key': source_key}
            s3_client.copy_object(
                CopySource=copy_source,
                Bucket=dest_bucket,
                Key=dest_key
            )
            
            print(f"Successfully created thumbnail for {source_key} in {dest_bucket}")

        except Exception as e:
            print(f"Error processing {source_key}: {e}")
            raise e
            
    return {
        'statusCode': 200,
        'body': 'Thumbnail processing complete.'
    }