"""NTP-adjusted clock.

Provides a time source that can be adjusted by an offset (e.g. from
NTP or SSU time synchronization).

Ported from net.i2p.util.Clock.
"""

from __future__ import annotations

import threading
import time


class Clock:
    """Clock with adjustable offset (in milliseconds)."""

    def __init__(self) -> None:
        self._lock = threading.Lock()
        self._offset_ms: float = 0.0
        self._updated: bool = False

    def now(self) -> float:
        """Current time in milliseconds, adjusted by offset."""
        return time.time() * 1000.0 + self._offset_ms

    def get_offset(self) -> float:
        """Current offset in milliseconds."""
        with self._lock:
            return self._offset_ms

    def set_offset(self, offset_ms: float) -> None:
        """Set the clock offset in milliseconds."""
        with self._lock:
            self._offset_ms = offset_ms
            self._updated = True

    def was_updated(self) -> bool:
        """Whether set_offset has been called at least once."""
        with self._lock:
            return self._updated