intercept/utils/bluetooth/scanner.py

"""
Main Bluetooth scanner coordinator.

Coordinates DBus and fallback scanners, manages device aggregation and heuristics.
"""

from __future__ import annotations

import logging
import queue
import threading
import time
from datetime import datetime
from typing import Callable, Generator, Optional

from .aggregator import DeviceAggregator
from .capability_check import check_capabilities
from .constants import (
    DEFAULT_SCAN_DURATION,
    DEVICE_STALE_TIMEOUT,
    PROTOCOL_AUTO,
    PROTOCOL_BLE,
    PROTOCOL_CLASSIC,
)
from .dbus_scanner import DBusScanner
from .fallback_scanner import FallbackScanner
from .heuristics import HeuristicsEngine
from .models import BTDeviceAggregate, BTObservation, ScanStatus, SystemCapabilities

logger = logging.getLogger(__name__)

# Global scanner instance
_scanner_instance: Optional['BluetoothScanner'] = None
_scanner_lock = threading.Lock()


class BluetoothScanner:
    """
    Main Bluetooth scanner coordinating DBus and fallback scanners.

    Provides unified API for scanning, device aggregation, and heuristics.
    """

    def __init__(self, adapter_id: Optional[str] = None):
        """
        Initialize Bluetooth scanner.

        Args:
            adapter_id: Adapter path/name (e.g., '/org/bluez/hci0' or 'hci0').
        """
        self._adapter_id = adapter_id
        self._aggregator = DeviceAggregator()
        self._heuristics = HeuristicsEngine()
        self._status = ScanStatus()
        self._lock = threading.Lock()

        # Scanner backends
        self._dbus_scanner: Optional[DBusScanner] = None
        self._fallback_scanner: Optional[FallbackScanner] = None
        self._active_backend: Optional[str] = None

        # Event queue for SSE streaming
        self._event_queue: queue.Queue = queue.Queue(maxsize=1000)

        # Duration-based scanning
        self._scan_timer: Optional[threading.Timer] = None

        # Callbacks
        self._on_device_updated_callbacks: list[Callable[[BTDeviceAggregate], None]] = []

        # Capability check result
        self._capabilities: Optional[SystemCapabilities] = None

    def start_scan(
        self,
        mode: str = 'auto',
        duration_s: Optional[int] = None,
        transport: str = 'auto',
        rssi_threshold: int = -100,
    ) -> bool:
        """
        Start Bluetooth scanning.

        Args:
            mode: Scanner mode ('dbus', 'bleak', 'hcitool', 'bluetoothctl', 'auto').
            duration_s: Scan duration in seconds (None for indefinite).
            transport: BLE transport filter ('bredr', 'le', 'auto').
            rssi_threshold: Minimum RSSI for device discovery.

        Returns:
            True if scan started successfully.
        """
        with self._lock:
            if self._status.is_scanning:
                return True

            # Check capabilities
            self._capabilities = check_capabilities()

            # Determine adapter
            adapter = self._adapter_id or self._capabilities.default_adapter
            if not adapter and mode == 'dbus':
                self._status.error = "No Bluetooth adapter found"
                return False

            # Select and start backend
            started = False
            backend_used = None
            original_mode = mode

            if mode == 'auto':
                mode = self._capabilities.recommended_backend or 'bleak'

            if mode == 'dbus':
                started, backend_used = self._start_dbus(adapter, transport, rssi_threshold)

            # Fallback: try non-DBus methods if DBus failed or wasn't requested
            if not started and (original_mode == 'auto' or mode in ('bleak', 'hcitool', 'bluetoothctl')):
                started, backend_used = self._start_fallback(adapter, original_mode)

            if not started:
                self._status.error = f"Failed to start scanner with mode '{mode}'"
                return False

            # Update status
            self._active_backend = backend_used
            self._status = ScanStatus(
                is_scanning=True,
                mode=mode,
                backend=backend_used,
                adapter_id=adapter,
                started_at=datetime.now(),
                duration_s=duration_s,
            )

            # Queue status event
            self._queue_event({
                'type': 'status',
                'status': 'started',
                'backend': backend_used,
                'mode': mode,
            })

            # Set up timer for duration-based scanning
            if duration_s:
                self._scan_timer = threading.Timer(duration_s, self.stop_scan)
                self._scan_timer.daemon = True
                self._scan_timer.start()

            logger.info(f"Bluetooth scan started: mode={mode}, backend={backend_used}")
            return True

    def _start_dbus(
        self,
        adapter: str,
        transport: str,
        rssi_threshold: int
    ) -> tuple[bool, Optional[str]]:
        """Start DBus scanner."""
        try:
            self._dbus_scanner = DBusScanner(
                adapter_path=adapter,
                on_observation=self._handle_observation,
            )
            if self._dbus_scanner.start(transport=transport, rssi_threshold=rssi_threshold):
                return True, 'dbus'
        except Exception as e:
            logger.warning(f"DBus scanner failed: {e}")
        return False, None

    def _start_fallback(self, adapter: str, preferred: str) -> tuple[bool, Optional[str]]:
        """Start fallback scanner."""
        try:
            # Extract adapter name from path if needed
            adapter_name = adapter.split('/')[-1] if adapter else 'hci0'

            self._fallback_scanner = FallbackScanner(
                adapter=adapter_name,
                on_observation=self._handle_observation,
            )
            if self._fallback_scanner.start():
                return True, self._fallback_scanner.backend
        except Exception as e:
            logger.warning(f"Fallback scanner failed: {e}")
        return False, None

    def stop_scan(self) -> None:
        """Stop Bluetooth scanning."""
        with self._lock:
            if not self._status.is_scanning:
                return

            # Cancel timer if running
            if self._scan_timer:
                self._scan_timer.cancel()
                self._scan_timer = None

            # Stop active scanner
            if self._dbus_scanner:
                self._dbus_scanner.stop()
                self._dbus_scanner = None

            if self._fallback_scanner:
                self._fallback_scanner.stop()
                self._fallback_scanner = None

            # Update status
            self._status.is_scanning = False
            self._active_backend = None

            # Queue status event
            self._queue_event({
                'type': 'status',
                'status': 'stopped',
            })

            logger.info("Bluetooth scan stopped")

    def _handle_observation(self, observation: BTObservation) -> None:
        """Handle incoming observation from scanner backend."""
        try:
            # Ingest into aggregator
            device = self._aggregator.ingest(observation)

            # Evaluate heuristics
            self._heuristics.evaluate(device)

            # Update device count
            with self._lock:
                self._status.devices_found = self._aggregator.device_count

            # Queue event
            self._queue_event({
                'type': 'device',
                'action': 'update',
                'device': device.to_summary_dict(),
            })

            # Callbacks
            for cb in self._on_device_updated_callbacks:
                try:
                    cb(device)
                except Exception as cb_err:
                    logger.error(f"Device callback error: {cb_err}")

        except Exception as e:
            logger.error(f"Error handling observation: {e}")

    def _queue_event(self, event: dict) -> None:
        """Add event to queue for SSE streaming."""
        try:
            self._event_queue.put_nowait(event)
        except queue.Full:
            # Drop oldest event
            try:
                self._event_queue.get_nowait()
                self._event_queue.put_nowait(event)
            except queue.Empty:
                pass

    def get_status(self) -> ScanStatus:
        """Get current scan status."""
        with self._lock:
            self._status.devices_found = self._aggregator.device_count
            return self._status

    def get_devices(
        self,
        sort_by: str = 'last_seen',
        sort_desc: bool = True,
        min_rssi: Optional[int] = None,
        protocol: Optional[str] = None,
        max_age_seconds: float = DEVICE_STALE_TIMEOUT,
    ) -> list[BTDeviceAggregate]:
        """
        Get list of discovered devices with optional filtering.

        Args:
            sort_by: Field to sort by ('last_seen', 'rssi_current', 'name', 'seen_count').
            sort_desc: Sort descending if True.
            min_rssi: Minimum RSSI filter.
            protocol: Protocol filter ('ble', 'classic', None for all).
            max_age_seconds: Maximum age for devices.

        Returns:
            List of BTDeviceAggregate instances.
        """
        devices = self._aggregator.get_active_devices(max_age_seconds)

        # Filter by RSSI
        if min_rssi is not None:
            devices = [d for d in devices if d.rssi_current and d.rssi_current >= min_rssi]

        # Filter by protocol
        if protocol:
            devices = [d for d in devices if d.protocol == protocol]

        # Sort
        sort_key = {
            'last_seen': lambda d: d.last_seen,
            'rssi_current': lambda d: d.rssi_current or -999,
            'name': lambda d: (d.name or '').lower(),
            'seen_count': lambda d: d.seen_count,
            'first_seen': lambda d: d.first_seen,
        }.get(sort_by, lambda d: d.last_seen)

        devices.sort(key=sort_key, reverse=sort_desc)

        return devices

    def get_device(self, device_id: str) -> Optional[BTDeviceAggregate]:
        """Get a specific device by ID."""
        return self._aggregator.get_device(device_id)

    def get_snapshot(self) -> list[dict]:
        """Get current device snapshot for TSCM integration."""
        devices = self.get_devices()
        return [d.to_dict() for d in devices]

    def stream_events(self, timeout: float = 1.0) -> Generator[dict, None, None]:
        """
        Generator for SSE event streaming.

        Args:
            timeout: Queue get timeout in seconds.

        Yields:
            Event dictionaries.
        """
        while True:
            try:
                event = self._event_queue.get(timeout=timeout)
                yield event
            except queue.Empty:
                yield {'type': 'ping'}

    def set_baseline(self) -> int:
        """Set current devices as baseline."""
        count = self._aggregator.set_baseline()
        self._queue_event({
            'type': 'baseline',
            'action': 'set',
            'device_count': count,
        })
        return count

    def clear_baseline(self) -> None:
        """Clear the baseline."""
        self._aggregator.clear_baseline()
        self._queue_event({
            'type': 'baseline',
            'action': 'cleared',
        })

    def clear_devices(self) -> None:
        """Clear all tracked devices."""
        self._aggregator.clear()
        self._queue_event({
            'type': 'devices',
            'action': 'cleared',
        })

    def prune_stale(self, max_age_seconds: float = DEVICE_STALE_TIMEOUT) -> int:
        """Prune stale devices."""
        return self._aggregator.prune_stale_devices(max_age_seconds)

    def get_capabilities(self) -> SystemCapabilities:
        """Get system capabilities."""
        if not self._capabilities:
            self._capabilities = check_capabilities()
        return self._capabilities

    def set_on_device_updated(self, callback: Callable[[BTDeviceAggregate], None]) -> None:
        """Set callback for device updates (legacy, adds to callback list)."""
        self.add_device_callback(callback)

    def add_device_callback(self, callback: Callable[[BTDeviceAggregate], None]) -> None:
        """Add a callback for device updates."""
        if callback not in self._on_device_updated_callbacks:
            self._on_device_updated_callbacks.append(callback)

    def remove_device_callback(self, callback: Callable[[BTDeviceAggregate], None]) -> None:
        """Remove a device update callback."""
        if callback in self._on_device_updated_callbacks:
            self._on_device_updated_callbacks.remove(callback)

    @property
    def is_scanning(self) -> bool:
        """Check if scanning is active.

        Cross-checks the backend scanner state, since bleak scans can
        expire silently without calling stop_scan().
        """
        if not self._status.is_scanning:
            return False

        # Detect backends that finished on their own (e.g. bleak timeout)
        backend_alive = (
            (self._dbus_scanner and self._dbus_scanner.is_scanning)
            or (self._fallback_scanner and self._fallback_scanner.is_scanning)
        )
        if not backend_alive:
            self._status.is_scanning = False
            return False

        return True

    @property
    def device_count(self) -> int:
        """Number of tracked devices."""
        return self._aggregator.device_count

    @property
    def has_baseline(self) -> bool:
        """Whether baseline is set."""
        return self._aggregator.has_baseline


def get_bluetooth_scanner(adapter_id: Optional[str] = None) -> BluetoothScanner:
    """
    Get or create the global Bluetooth scanner instance.

    Args:
        adapter_id: Adapter path/name (only used on first call).

    Returns:
        BluetoothScanner instance.
    """
    global _scanner_instance

    with _scanner_lock:
        if _scanner_instance is None:
            _scanner_instance = BluetoothScanner(adapter_id)
        return _scanner_instance


def reset_bluetooth_scanner() -> None:
    """Reset the global scanner instance (for testing)."""
    global _scanner_instance

    with _scanner_lock:
        if _scanner_instance:
            _scanner_instance.stop_scan()
        _scanner_instance = None