Idempotent Consumer: Store Processed IDs in Python

import json
from pathlib import Path


class IdempotentStore:
    def __init__(self, storage_path: str = "processed_ids.json"):
        self.storage_path = Path(storage_path)
        self.processed_ids = self._load()

    def _load(self) -> set:
        if self.storage_path.exists():
            with self.storage_path.open() as f:
                return set(json.load(f))
        return set()

    def _save(self) -> None:
        with self.storage_path.open("w") as f:
            json.dump(sorted(self.processed_ids), f)

    def is_processed(self, message_id: str) -> bool:
        return message_id in self.processed_ids

    def mark_processed(self, message_id: str) -> None:
        self.processed_ids.add(message_id)
        self._save()


if __name__ == "__main__":
    store = IdempotentStore()
    sample_id = "msg-2024-001"

    if store.is_processed(sample_id):
        print(f"Duplicate skipped: {sample_id}")
    else:
        store.mark_processed(sample_id)
        print(f"Processed and stored: {sample_id}")