"""Router maintenance tasks — keepalive, reconnection, broadcast, eviction.

These are long-running async tasks spawned after bootstrap completes.
Each runs in a loop with a configurable interval.
"""

from __future__ import annotations

import asyncio
import logging
import random
import time

from i2p_transport.ntcp2_blocks import padding_block

logger = logging.getLogger(__name__)


async def keepalive_loop(pool, interval: float = 60.0) -> None:
    """Send Padding blocks on idle connections.

    Prevents connections from being closed by the remote peer's idle
    timeout (typically 300s). Sends a small Padding block if no frames
    have been written recently.

    Parameters
    ----------
    pool:
        ConnectionPool instance.
    interval:
        Seconds between keepalive checks.
    """
    logger.info("Keepalive loop started (interval=%ds)", interval)
    while True:
        await asyncio.sleep(interval)
        for peer_hash in list(pool.get_all_peer_hashes()):
            conn = pool.get(peer_hash)
            if conn is None:
                continue
            try:
                idle = conn.seconds_since_last_write()
                if idle >= interval:
                    pad_size = random.randint(0, 15)
                    await conn.send_frame([padding_block(pad_size)])
                    logger.debug(
                        "Sent keepalive padding (%d bytes) to %s...",
                        pad_size, peer_hash[:4].hex(),
                    )
            except Exception:
                logger.info("Keepalive failed for %s..., removing", peer_hash[:4].hex())
                pool.remove(peer_hash)


async def reconnect_loop(
    pool,
    datastore,
    peer_connector,
    target_peers: int = 5,
    interval: float = 30.0,
    connect_timeout: float = 15.0,
) -> None:
    """Maintain target peer count by connecting to new peers from the NetDB.

    Parameters
    ----------
    pool:
        ConnectionPool instance.
    datastore:
        DataStore instance for peer discovery.
    peer_connector:
        PeerConnector instance for NTCP2 handshakes.
    target_peers:
        Desired number of connected peers.
    interval:
        Seconds between reconnection checks.
    connect_timeout:
        Timeout per connection attempt.
    """
    from i2p_netdb.datastore import EntryType
    from i2p_data.router import RouterInfo
    from i2p_router.peer_connector import extract_ntcp2_address

    logger.info("Reconnect loop started (target=%d, interval=%ds)", target_peers, interval)
    while True:
        await asyncio.sleep(interval)
        active = pool.active_count
        if active >= target_peers:
            continue

        needed = target_peers - active
        logger.info("Peer count %d < %d, seeking %d more", active, target_peers, needed)

        # Get candidate peers from NetDB
        all_entries = datastore.get_all()
        random.shuffle(all_entries)
        connected = 0

        for entry in all_entries:
            if connected >= needed:
                break
            if entry.entry_type != EntryType.ROUTER_INFO:
                continue
            if pool.is_connected(entry.key):
                continue

            try:
                ri = RouterInfo.from_bytes(entry.data)
                params = extract_ntcp2_address(ri)
                if params is None:
                    continue

                host, port_num = params[0], params[1]
                logger.info(
                    "Reconnect attempting %s:%d (hash=%s...)",
                    host, port_num, entry.key[:4].hex(),
                )
                conn = await asyncio.wait_for(
                    peer_connector.connect(ri),
                    timeout=connect_timeout,
                )
                if conn is not None:
                    pool.add(entry.key, conn)
                    connected += 1
                    logger.info(
                        "Reconnected to peer %s:%d (hash=%s...)",
                        host, port_num, entry.key[:4].hex(),
                    )
            except asyncio.TimeoutError:
                logger.info(
                    "Reconnect timed out for %s...", entry.key[:4].hex(),
                )
                continue
            except Exception as e:
                logger.info(
                    "Reconnect failed for %s...: %s", entry.key[:4].hex(), e,
                )
                continue

        if connected > 0:
            logger.info("Reconnected to %d peers (total: %d)", connected, pool.active_count)


async def routerinfo_broadcast_loop(
    pool,
    db_store_msg: bytes,
    interval: float = 1800.0,
) -> None:
    """Broadcast our RouterInfo to all connected peers periodically.

    Parameters
    ----------
    pool:
        ConnectionPool instance.
    db_store_msg:
        Pre-built DatabaseStore I2NP message containing our RouterInfo.
    interval:
        Seconds between broadcasts (default 30 min).
    """
    logger.info("RouterInfo broadcast loop started (interval=%ds)", interval)
    while True:
        await asyncio.sleep(interval)
        sent = 0
        for peer_hash in list(pool.get_all_peer_hashes()):
            conn = pool.get(peer_hash)
            if conn is None:
                continue
            try:
                await conn.send_i2np(db_store_msg)
                sent += 1
            except Exception:
                logger.info("Broadcast failed for %s..., removing", peer_hash[:4].hex())
                pool.remove(peer_hash)
        if sent > 0:
            logger.info("Broadcast RouterInfo to %d peers", sent)


async def netdb_eviction_loop(
    datastore,
    sqlite_netdb=None,
    interval: float = 600.0,
    max_age_ms: int = 86_400_000,
) -> None:
    """Evict expired entries from the in-memory DataStore and SQLite cache.

    Parameters
    ----------
    datastore:
        In-memory DataStore instance.
    sqlite_netdb:
        Optional SqliteNetDB instance for disk persistence.
    interval:
        Seconds between eviction runs (default 10 min).
    max_age_ms:
        Maximum entry age in milliseconds (default 24h).
    """
    logger.info("NetDB eviction loop started (interval=%ds, max_age=%dh)", interval, max_age_ms // 3_600_000)
    while True:
        await asyncio.sleep(interval)

        # Evict from in-memory store
        now_ms = int(time.time() * 1000)
        cutoff = now_ms - max_age_ms
        expired_keys = [
            k for k, e in list(zip(datastore.get_all_keys(), datastore.get_all()))
            if e.received_ms < cutoff
        ]
        for k in expired_keys:
            datastore.remove(k)

        # Evict from SQLite
        sqlite_count = 0
        if sqlite_netdb is not None:
            sqlite_count = sqlite_netdb.evict_expired()

        total = len(expired_keys) + sqlite_count
        if total > 0:
            logger.info(
                "Evicted %d expired NetDB entries (%d memory, %d disk)",
                total, len(expired_keys), sqlite_count,
            )