Implement If-Match Precondition Update in Python

from dataclasses import dataclass
from typing import Optional


@dataclass
class Resource:
    id: str
    version: int = 1
    data: str = ""
    etag: str = "etag-1"


class MockResourceStore:
    def __init__(self):
        self.resources = {}

    def update(self, resource_id: str, new_data: str, if_match: Optional[str] = None) -> bool:
        resource = self.resources.get(resource_id)
        if not resource:
            return False

        if if_match and if_match != resource.etag:
            return False

        resource.data = new_data
        resource.version += 1
        resource.etag = f"etag-{resource.version}"
        return True


def main():
    store = MockResourceStore()
    store.resources["item-1"] = Resource(id="item-1")

    # Successful update with matching precondition
    success = store.update("item-1", "new data", if_match="etag-1")
    print(f"Success with matching etag: {success}")

    # Failed update with stale etag
    stale = store.update("item-1", "other data", if_match="etag-1")
    print(f"Success with stale etag: {stale}")

    # Correct new etag works
    correct = store.update("item-1", "latest data", if_match="etag-2")
    print(f"Success with current etag: {correct}")

    print(f"Final resource: {store.resources['item-1']}")


if __name__ == "__main__":
    main()