from __future__ import annotations

from typing import Any, Dict


class DeltaStore:
    def __init__(self) -> None:
        self.last_full_state: Dict[str, Any] = {}

    def compute_delta(self, current_state: Dict[str, Any], previous_state: Dict[str, Any]) -> Dict[str, Any]:
        delta: Dict[str, Any] = {}
        # naive shallow diff
        keys = set(current_state.keys()) | set(previous_state.keys())
        for k in keys:
            cur = current_state.get(k)
            prev = previous_state.get(k)
            if cur != prev:
                delta[k] = cur
        return delta

    def apply_delta(self, state: Dict[str, Any], delta: Dict[str, Any]) -> Dict[str, Any]:
        new_state = dict(state)
        for k, v in delta.items():
            new_state[k] = v
        return new_state