"""Peer synchronization for RF Mapper multi-scanner deployments"""

import socket
import threading
import time
from datetime import datetime
from typing import Optional

import requests

from .config import Config
from .database import DeviceDatabase


def get_local_ip() -> str:
    """Get the local IP address of this machine."""
    try:
        # Create a socket and connect to an external address
        # This doesn't actually send data, just determines the local IP
        s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        s.connect(("8.8.8.8", 80))
        ip = s.getsockname()[0]
        s.close()
        return ip
    except Exception:
        return "127.0.0.1"


class PeerSync:
    """Manages peer discovery and device metadata synchronization.

    Handles:
    - Registration with peer scanners
    - Background sync thread for pulling/pushing device metadata
    - Conflict resolution using timestamps
    """

    def __init__(self, config: Config, db: DeviceDatabase):
        """Initialize peer sync manager.

        Args:
            config: RF Mapper configuration
            db: Device database instance
        """
        self.config = config
        self.db = db
        self.scanner_identity = config.get_scanner_identity()
        self._running = False
        self._thread: Optional[threading.Thread] = None
        self._last_sync: dict[str, str] = {}  # peer_id -> last sync timestamp

    @property
    def local_url(self) -> str:
        """Get this scanner's URL for peer registration."""
        return f"http://{get_local_ip()}:{self.config.web.port}"

    def start(self):
        """Start the background sync thread."""
        if self._thread and self._thread.is_alive():
            return  # Already running

        self._running = True
        self._thread = threading.Thread(target=self._sync_loop, daemon=True)
        self._thread.start()
        print(f"[Sync] Background sync started (interval: {self.config.scanner.sync_interval_seconds}s)")

    def stop(self):
        """Stop the background sync thread."""
        self._running = False
        if self._thread:
            self._thread.join(timeout=5)
            self._thread = None
        print("[Sync] Background sync stopped")

    def register_with_peer(self, peer_url: str) -> dict:
        """Register this scanner with a peer.

        Args:
            peer_url: Base URL of the peer scanner

        Returns:
            Response from peer containing peer info and known peers

        Raises:
            requests.RequestException on network errors
        """
        payload = {
            "id": self.scanner_identity["id"],
            "name": self.scanner_identity["name"],
            "url": self.local_url,
            "floor": self.scanner_identity["floor"],
            "latitude": self.scanner_identity["latitude"],
            "longitude": self.scanner_identity["longitude"]
        }

        resp = requests.post(
            f"{peer_url.rstrip('/')}/api/peers/register",
            json=payload,
            timeout=10
        )
        resp.raise_for_status()
        return resp.json()

    def sync_devices_from_peer(self, peer_url: str, since: Optional[str] = None) -> int:
        """Pull device updates from a peer.

        Args:
            peer_url: Base URL of the peer scanner
            since: ISO timestamp to get updates since (None = all)

        Returns:
            Number of devices updated locally
        """
        params = {"since": since} if since else {}

        resp = requests.get(
            f"{peer_url.rstrip('/')}/api/sync/devices",
            params=params,
            timeout=15
        )
        resp.raise_for_status()
        data = resp.json()

        devices = data.get("devices", [])
        source_scanner = data.get("scanner_id", "unknown")

        updated = self.db.bulk_update_devices(devices, source_scanner)
        return updated

    def push_devices_to_peer(self, peer_url: str, since: Optional[str] = None) -> dict:
        """Push device updates to a peer.

        Args:
            peer_url: Base URL of the peer scanner
            since: ISO timestamp to send updates since (None = all)

        Returns:
            Response from peer with sync status
        """
        devices = self.db.get_devices_since(since)

        payload = {
            "source_scanner": self.scanner_identity["id"],
            "devices": devices
        }

        resp = requests.post(
            f"{peer_url.rstrip('/')}/api/sync/devices",
            json=payload,
            timeout=15
        )
        resp.raise_for_status()
        return resp.json()

    def _sync_loop(self):
        """Background sync loop - runs every sync_interval_seconds."""
        # Initial delay to let app fully start
        time.sleep(5)

        while self._running:
            peers = self.db.get_peers()

            for peer in peers:
                peer_id = peer["scanner_id"]
                peer_url = peer["url"]

                try:
                    # Pull updates from peer
                    since = self._last_sync.get(peer_id)
                    updated = self.sync_devices_from_peer(peer_url, since)

                    # Push our updates to peer
                    self.push_devices_to_peer(peer_url, since)

                    # Update last sync time and peer last_seen
                    self._last_sync[peer_id] = datetime.now().isoformat()
                    self.db.update_peer_last_seen(peer_id)

                    if updated > 0:
                        print(f"[Sync] Synced with {peer_id}: updated {updated} devices")

                except requests.exceptions.ConnectionError:
                    print(f"[Sync] Peer {peer_id} unreachable at {peer_url}")
                except requests.exceptions.Timeout:
                    print(f"[Sync] Sync with {peer_id} timed out")
                except Exception as e:
                    print(f"[Sync] Error syncing with {peer_id}: {e}")

            # Wait for next sync interval
            for _ in range(self.config.scanner.sync_interval_seconds):
                if not self._running:
                    break
                time.sleep(1)

    def get_status(self) -> dict:
        """Get current sync status.

        Returns:
            Dict with running state, peer count, last sync times
        """
        peers = self.db.get_peers()
        return {
            "running": self._running,
            "sync_interval_seconds": self.config.scanner.sync_interval_seconds,
            "peer_count": len(peers),
            "last_sync": self._last_sync.copy(),
            "local_url": self.local_url
        }