import os

from datetime import datetime

​

def handler(event, context):

    """

    event = {"bucket": "uploads", "key": "cat.jpg"}

    context = {"request_id": "req-1", "deadline_ms": 0}

    """

    src = os.path.join("data", event["bucket"], event["key"])

    dst = os.path.join("data", "thumbnails", event["key"] + ".thumb")

​

    os.makedirs(os.path.dirname(dst), exist_ok=True)

    with open(src, "rb") as f:

        data = f.read()

​

    # "Process": write the first 1024 bytes to simulate a small thumbnail

    with open(dst, "wb") as f:

        f.write(data[:1024])

​

    return {

        "status": "ok",

        "src_bytes": len(data),

        "dst": dst,

        "time": datetime.utcnow().isoformat() + "Z"

    }

​

if __name__ == "__main__":

    os.makedirs("data/uploads", exist_ok=True)

    # Write a fake binary file