from __future__ import annotations

import atexit
import logging
import signal
import subprocess
import re
import threading
import time
from typing import Any, Callable

from .dependencies import check_tool

logger = logging.getLogger('intercept.process')

# Track all spawned processes for cleanup
_spawned_processes: list[subprocess.Popen] = []
_process_lock = threading.Lock()


def register_process(process: subprocess.Popen) -> None:
    """Register a spawned process for cleanup on exit."""
    with _process_lock:
        _spawned_processes.append(process)


def unregister_process(process: subprocess.Popen) -> None:
    """Unregister a process from cleanup list."""
    with _process_lock:
        if process in _spawned_processes:
            _spawned_processes.remove(process)


def cleanup_all_processes() -> None:
    """Clean up all registered processes on exit."""
    logger.info("Cleaning up all spawned processes...")
    with _process_lock:
        for process in _spawned_processes:
            if process and process.poll() is None:
                try:
                    process.terminate()
                    process.wait(timeout=2)
                except subprocess.TimeoutExpired:
                    process.kill()
                except Exception as e:
                    logger.warning(f"Error cleaning up process: {e}")
        _spawned_processes.clear()


def safe_terminate(process: subprocess.Popen | None, timeout: float = 2.0) -> bool:
    """
    Safely terminate a process.

    Args:
        process: Process to terminate
        timeout: Seconds to wait before killing

    Returns:
        True if process was terminated, False if already dead or None
    """
    if not process:
        return False

    if process.poll() is not None:
        # Already dead
        unregister_process(process)
        return False

    try:
        process.terminate()
        process.wait(timeout=timeout)
        unregister_process(process)
        return True
    except subprocess.TimeoutExpired:
        process.kill()
        unregister_process(process)
        return True
    except Exception as e:
        logger.warning(f"Error terminating process: {e}")
        return False


# Register cleanup handlers
atexit.register(cleanup_all_processes)

# Handle signals for graceful shutdown
def _signal_handler(signum, frame):
    """Handle termination signals.

    Keep this minimal — logging and lock acquisition in signal handlers
    can deadlock when another thread holds the logging or process lock.
    Process cleanup is handled by the atexit handler registered above.
    """
    import sys
    if signum == signal.SIGINT:
        raise KeyboardInterrupt()
    sys.exit(0)


# Only register signal handlers if we're not in a thread
try:
    signal.signal(signal.SIGTERM, _signal_handler)
    signal.signal(signal.SIGINT, _signal_handler)
except ValueError:
    # Can't set signal handlers from a thread
    pass


def cleanup_stale_processes() -> None:
    """Kill any stale processes from previous runs (but not system services)."""
    # Note: dump1090 is NOT included here as users may run it as a system service
    processes_to_kill = ['rtl_adsb', 'rtl_433', 'multimon-ng', 'rtl_fm']
    for proc_name in processes_to_kill:
        try:
            subprocess.run(['pkill', '-9', proc_name], capture_output=True)
        except (subprocess.SubprocessError, OSError):
            pass


def is_valid_mac(mac: str | None) -> bool:
    """Validate MAC address format."""
    if not mac:
        return False
    return bool(re.match(r'^([0-9A-Fa-f]{2}:){5}[0-9A-Fa-f]{2}$', mac))


def is_valid_channel(channel: str | int | None) -> bool:
    """Validate WiFi channel number."""
    try:
        ch = int(channel)  # type: ignore[arg-type]
        return 1 <= ch <= 200
    except (ValueError, TypeError):
        return False


def detect_devices() -> list[dict[str, Any]]:
    """Detect RTL-SDR devices."""
    devices: list[dict[str, Any]] = []

    if not check_tool('rtl_test'):
        return devices

    try:
        result = subprocess.run(
            ['rtl_test', '-t'],
            capture_output=True,
            text=True,
            timeout=5
        )
        output = result.stderr + result.stdout

        # Parse device info
        device_pattern = r'(\d+):\s+(.+?)(?:,\s*SN:\s*(\S+))?$'

        for line in output.split('\n'):
            line = line.strip()
            match = re.match(device_pattern, line)
            if match:
                devices.append({
                    'index': int(match.group(1)),
                    'name': match.group(2).strip().rstrip(','),
                    'serial': match.group(3) or 'N/A'
                })

        if not devices:
            found_match = re.search(r'Found (\d+) device', output)
            if found_match:
                count = int(found_match.group(1))
                for i in range(count):
                    devices.append({
                        'index': i,
                        'name': f'RTL-SDR Device {i}',
                        'serial': 'Unknown'
                    })

    except Exception:
        pass

    return devices