How to Watch a Folder and Convert New Images in Python

import time
import hashlib
from pathlib import Path
from datetime import datetime

def mock_convert_image(source: Path, dest_dir: Path) -> Path:
    """Mock image conversion: copy bytes and add .converted suffix."""
    dest = dest_dir / f"{source.stem}.converted{source.suffix}"
    dest.write_bytes(source.read_bytes())
    return dest

def watch_folder(source_dir: str = "inbox", dest_dir: str = "outbox", poll_seconds: float = 1.0, max_runs: int = 5):
    """Watch a folder for new files and mock-convert them."""
    src = Path(source_dir)
    dst = Path(dest_dir)
    src.mkdir(exist_ok=True)
    dst.mkdir(exist_ok=True)

    seen = set()
    for run in range(max_runs):
        for file in src.iterdir():
            if file.is_file() and file.name not in seen:
                seen.add(file.name)
                converted = mock_convert_image(file, dst)
                print(f"{datetime.now().isoformat()} | converted '{file.name}' -> '{converted.name}'")
        time.sleep(poll_seconds)

    print(f"Watch complete after {max_runs} poll(s). Total files seen: {len(seen)}")

if __name__ == "__main__":
    # Simulate a new image appearing in the inbox
    Path("inbox").mkdir(exist_ok=True)
    Path("inbox/photo.jpg").write_bytes(b"\xff\xd8mock-image-data")

    watch_folder(max_runs=3, poll_seconds=0.2)