"""Port scanner implementation."""

import socket
import asyncio
from typing import List, Dict, Set, Optional, Callable
from concurrent.futures import ThreadPoolExecutor
import logging

from app.config import settings

logger = logging.getLogger(__name__)


class PortScanner:
    """Scanner for detecting open ports on hosts."""
    
    # Predefined port ranges for different scan types
    PORT_RANGES = {
        'quick': [21, 22, 23, 25, 53, 80, 110, 143, 443, 445, 3306, 3389, 5432, 8080, 8443],
        'standard': list(range(1, 1001)),
        'deep': list(range(1, 65536)),
    }
    
    def __init__(
        self,
        timeout: int = None,
        max_workers: int = None,
        progress_callback: Optional[Callable[[str, int, float], None]] = None
    ):
        """
        Initialize port scanner.
        
        Args:
            timeout: Socket connection timeout in seconds
            max_workers: Maximum number of concurrent workers
            progress_callback: Optional callback for progress updates (host, port, progress)
        """
        self.timeout = timeout or settings.default_scan_timeout
        self.max_workers = max_workers or settings.max_concurrent_scans
        self.progress_callback = progress_callback
    
    async def scan_host_ports(
        self,
        host: str,
        scan_type: str = 'quick',
        custom_ports: Optional[List[int]] = None
    ) -> List[Dict[str, any]]:
        """
        Scan ports on a single host.
        
        Args:
            host: IP address or hostname
            scan_type: Type of scan ('quick', 'standard', 'deep', or 'custom')
            custom_ports: Custom port list (required if scan_type is 'custom')
            
        Returns:
            List of dictionaries with port information
        """
        logger.info(f"Starting port scan on {host} (type: {scan_type})")
        
        # Determine ports to scan
        if scan_type == 'custom' and custom_ports:
            ports = custom_ports
        elif scan_type in self.PORT_RANGES:
            ports = self.PORT_RANGES[scan_type]
        else:
            ports = self.PORT_RANGES['quick']
        
        # Scan ports
        open_ports = await self._scan_ports_async(host, ports)
        
        logger.info(f"Scan completed on {host}. Found {len(open_ports)} open ports")
        return open_ports
    
    async def _scan_ports_async(self, host: str, ports: List[int]) -> List[Dict[str, any]]:
        """
        Scan multiple ports asynchronously.
        
        Args:
            host: Host to scan
            ports: List of ports to scan
            
        Returns:
            List of open port information
        """
        open_ports = []
        total = len(ports)
        completed = 0
        
        loop = asyncio.get_event_loop()
        
        with ThreadPoolExecutor(max_workers=self.max_workers) as executor:
            futures = []
            
            for port in ports:
                future = loop.run_in_executor(executor, self._check_port, host, port)
                futures.append((port, future))
            
            # Process results
            for port, future in futures:
                try:
                    result = await future
                    if result:
                        open_ports.append(result)
                        logger.debug(f"Found open port {port} on {host}")
                except Exception as e:
                    logger.debug(f"Error checking port {port} on {host}: {e}")
                finally:
                    completed += 1
                    if self.progress_callback:
                        progress = completed / total
                        self.progress_callback(host, port, progress)
        
        return sorted(open_ports, key=lambda x: x['port'])
    
    def _check_port(self, host: str, port: int) -> Optional[Dict[str, any]]:
        """
        Check if a port is open on a host.
        
        Args:
            host: Host to check
            port: Port number
            
        Returns:
            Dictionary with port info if open, None otherwise
        """
        try:
            sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            sock.settimeout(self.timeout)
            result = sock.connect_ex((host, port))
            sock.close()
            
            if result == 0:
                return {
                    'port': port,
                    'protocol': 'tcp',
                    'state': 'open',
                    'service_name': self._guess_service_name(port)
                }
            
            return None
            
        except socket.error as e:
            logger.debug(f"Socket error checking {host}:{port}: {e}")
            return None
        except Exception as e:
            logger.debug(f"Error checking {host}:{port}: {e}")
            return None
    
    def _guess_service_name(self, port: int) -> Optional[str]:
        """
        Guess service name based on well-known ports.
        
        Args:
            port: Port number
            
        Returns:
            Service name or None
        """
        common_services = {
            20: 'ftp-data',
            21: 'ftp',
            22: 'ssh',
            23: 'telnet',
            25: 'smtp',
            53: 'dns',
            80: 'http',
            110: 'pop3',
            143: 'imap',
            443: 'https',
            445: 'smb',
            3306: 'mysql',
            3389: 'rdp',
            5432: 'postgresql',
            5900: 'vnc',
            8080: 'http-alt',
            8443: 'https-alt',
        }
        
        return common_services.get(port)
    
    def parse_port_range(self, port_range: str) -> List[int]:
        """
        Parse port range string to list of ports.
        
        Args:
            port_range: String like "80,443,8000-8100"
            
        Returns:
            List of port numbers
        """
        ports = set()
        
        try:
            for part in port_range.split(','):
                part = part.strip()
                
                if '-' in part:
                    # Range like "8000-8100"
                    start, end = map(int, part.split('-'))
                    if 1 <= start <= end <= 65535:
                        ports.update(range(start, end + 1))
                else:
                    # Single port
                    port = int(part)
                    if 1 <= port <= 65535:
                        ports.add(port)
            
            return sorted(list(ports))
            
        except ValueError as e:
            logger.error(f"Error parsing port range '{port_range}': {e}")
            return []