"""Floodfill router tracking for efficient NetDB lookups.

Floodfill routers are peers that participate in the Kademlia-like
distributed hash table, storing and serving NetDB entries.  This manager
tracks known floodfill routers so lookup and store operations can
target them directly.

Ported from net.i2p.router.networkdb.kademlia.FloodfillNetworkDatabaseFacade.
"""

from __future__ import annotations

import random
from typing import Optional


class FloodfillManager:
    """Tracks floodfill routers for efficient NetDB lookups."""

    def __init__(self) -> None:
        self._floodfills: dict[bytes, dict] = {}

    def add_floodfill(self, peer_hash: bytes, info: dict) -> None:
        """Register a peer as a floodfill router."""
        self._floodfills[peer_hash] = info

    def remove_floodfill(self, peer_hash: bytes) -> None:
        """Remove a peer from the floodfill set."""
        self._floodfills.pop(peer_hash, None)

    def select_floodfill(self, exclude: Optional[set[bytes]] = None) -> Optional[bytes]:
        """Select a random floodfill router, optionally excluding some peers.

        Returns None if no eligible floodfill is available.
        """
        exclude = exclude or set()
        candidates = [h for h in self._floodfills if h not in exclude]
        if not candidates:
            return None
        return random.choice(candidates)

    def is_floodfill(self, peer_hash: bytes) -> bool:
        """Check whether a peer is a known floodfill router."""
        return peer_hash in self._floodfills

    def get_all(self) -> list[bytes]:
        """Return a list of all known floodfill peer hashes."""
        return list(self._floodfills.keys())

    @property
    def count(self) -> int:
        """Number of known floodfill routers."""
        return len(self._floodfills)