"""
Config Service - Business logic for config file management

This service handles all operations related to scan configuration files,
including creation, validation, listing, and deletion.
"""

import os
import re
import yaml
import ipaddress
from typing import Dict, List, Tuple, Any, Optional
from datetime import datetime
from pathlib import Path
from werkzeug.utils import secure_filename


class ConfigService:
    """Business logic for config management"""

    def __init__(self, configs_dir: str = '/app/configs'):
        """
        Initialize the config service.

        Args:
            configs_dir: Directory where config files are stored
        """
        self.configs_dir = configs_dir

        # Ensure configs directory exists
        os.makedirs(self.configs_dir, exist_ok=True)

    def list_configs(self) -> List[Dict[str, Any]]:
        """
        List all config files with metadata.

        Returns:
            List of config metadata dictionaries:
            [
                {
                    "filename": "prod-scan.yaml",
                    "title": "Prod Scan",
                    "path": "/app/configs/prod-scan.yaml",
                    "created_at": "2025-11-15T10:30:00Z",
                    "size_bytes": 1234,
                    "used_by_schedules": ["Daily Scan", "Weekly Audit"]
                }
            ]
        """
        configs = []

        # Get all YAML files in configs directory
        if not os.path.exists(self.configs_dir):
            return configs

        for filename in os.listdir(self.configs_dir):
            if not filename.endswith(('.yaml', '.yml')):
                continue

            filepath = os.path.join(self.configs_dir, filename)

            if not os.path.isfile(filepath):
                continue

            try:
                # Get file metadata
                stat_info = os.stat(filepath)
                created_at = datetime.fromtimestamp(stat_info.st_mtime).isoformat() + 'Z'
                size_bytes = stat_info.st_size

                # Parse YAML to get title
                title = None
                try:
                    with open(filepath, 'r') as f:
                        data = yaml.safe_load(f)
                        if isinstance(data, dict):
                            title = data.get('title', filename)
                except Exception:
                    title = filename  # Fallback to filename if parsing fails

                # Get schedules using this config
                used_by_schedules = self.get_schedules_using_config(filename)

                configs.append({
                    'filename': filename,
                    'title': title,
                    'path': filepath,
                    'created_at': created_at,
                    'size_bytes': size_bytes,
                    'used_by_schedules': used_by_schedules
                })
            except Exception as e:
                # Skip files that can't be read
                continue

        # Sort by created_at (most recent first)
        configs.sort(key=lambda x: x['created_at'], reverse=True)

        return configs

    def get_config(self, filename: str) -> Dict[str, Any]:
        """
        Get config file content and parsed data.

        Args:
            filename: Config filename

        Returns:
            {
                "filename": "prod-scan.yaml",
                "content": "title: Prod Scan\n...",
                "parsed": {"title": "Prod Scan", "sites": [...]}
            }

        Raises:
            FileNotFoundError: If config doesn't exist
            ValueError: If config content is invalid
        """
        filepath = os.path.join(self.configs_dir, filename)

        if not os.path.exists(filepath):
            raise FileNotFoundError(f"Config file '{filename}' not found")

        # Read file content
        with open(filepath, 'r') as f:
            content = f.read()

        # Parse YAML
        try:
            parsed = yaml.safe_load(content)
        except yaml.YAMLError as e:
            raise ValueError(f"Invalid YAML syntax: {str(e)}")

        return {
            'filename': filename,
            'content': content,
            'parsed': parsed
        }

    def create_from_yaml(self, filename: str, content: str) -> str:
        """
        Create config from YAML content.

        Args:
            filename: Desired filename (will be sanitized)
            content: YAML content string

        Returns:
            Final filename (sanitized)

        Raises:
            ValueError: If content invalid or filename conflict
        """
        # Sanitize filename
        filename = secure_filename(filename)

        # Ensure .yaml extension
        if not filename.endswith(('.yaml', '.yml')):
            filename += '.yaml'

        filepath = os.path.join(self.configs_dir, filename)

        # Check for conflicts
        if os.path.exists(filepath):
            raise ValueError(f"Config file '{filename}' already exists")

        # Parse and validate YAML
        try:
            parsed = yaml.safe_load(content)
        except yaml.YAMLError as e:
            raise ValueError(f"Invalid YAML syntax: {str(e)}")

        # Validate config structure
        is_valid, error_msg = self.validate_config_content(parsed)
        if not is_valid:
            raise ValueError(f"Invalid config structure: {error_msg}")

        # Write file
        with open(filepath, 'w') as f:
            f.write(content)

        return filename

    def create_from_cidr(
        self,
        title: str,
        cidr: str,
        site_name: Optional[str] = None,
        ping_default: bool = False
    ) -> Tuple[str, str]:
        """
        Create config from CIDR range.

        Args:
            title: Scan configuration title
            cidr: CIDR range (e.g., "10.0.0.0/24")
            site_name: Optional site name (defaults to "Site 1")
            ping_default: Default ping expectation for all IPs

        Returns:
            Tuple of (final_filename, yaml_content)

        Raises:
            ValueError: If CIDR invalid or other validation errors
        """
        # Validate and parse CIDR
        try:
            network = ipaddress.ip_network(cidr, strict=False)
        except ValueError as e:
            raise ValueError(f"Invalid CIDR range: {str(e)}")

        # Check if network is too large (prevent expansion of huge ranges)
        if network.num_addresses > 10000:
            raise ValueError(f"CIDR range too large: {network.num_addresses} addresses. Maximum is 10,000.")

        # Expand CIDR to list of IP addresses
        ip_list = [str(ip) for ip in network.hosts()]

        # If network has only 1 address (like /32 or /128), hosts() returns empty
        # In that case, use the network address itself
        if not ip_list:
            ip_list = [str(network.network_address)]

        # Build site name
        if not site_name or not site_name.strip():
            site_name = "Site 1"

        # Build IP configurations
        ips = []
        for ip_address in ip_list:
            ips.append({
                'address': ip_address,
                'expected': {
                    'ping': ping_default,
                    'tcp_ports': [],
                    'udp_ports': []
                }
            })

        # Build YAML structure
        config_data = {
            'title': title.strip(),
            'sites': [
                {
                    'name': site_name.strip(),
                    'ips': ips
                }
            ]
        }

        # Convert to YAML string
        yaml_content = yaml.dump(config_data, sort_keys=False, default_flow_style=False)

        # Generate filename from title
        filename = self.generate_filename_from_title(title)

        filepath = os.path.join(self.configs_dir, filename)

        # Check for conflicts
        if os.path.exists(filepath):
            raise ValueError(f"Config file '{filename}' already exists")

        # Write file
        with open(filepath, 'w') as f:
            f.write(yaml_content)

        return filename, yaml_content

    def update_config(self, filename: str, yaml_content: str) -> None:
        """
        Update existing config file with new YAML content.

        Args:
            filename: Config filename to update
            yaml_content: New YAML content string

        Raises:
            FileNotFoundError: If config doesn't exist
            ValueError: If YAML content is invalid
        """
        filepath = os.path.join(self.configs_dir, filename)

        # Check if file exists
        if not os.path.exists(filepath):
            raise FileNotFoundError(f"Config file '{filename}' not found")

        # Parse and validate YAML
        try:
            parsed = yaml.safe_load(yaml_content)
        except yaml.YAMLError as e:
            raise ValueError(f"Invalid YAML syntax: {str(e)}")

        # Validate config structure
        is_valid, error_msg = self.validate_config_content(parsed)
        if not is_valid:
            raise ValueError(f"Invalid config structure: {error_msg}")

        # Write updated content
        with open(filepath, 'w') as f:
            f.write(yaml_content)

    def delete_config(self, filename: str) -> None:
        """
        Delete config file if not used by schedules.

        Args:
            filename: Config filename to delete

        Raises:
            FileNotFoundError: If config doesn't exist
            ValueError: If config used by active schedules
        """
        filepath = os.path.join(self.configs_dir, filename)

        if not os.path.exists(filepath):
            raise FileNotFoundError(f"Config file '{filename}' not found")

        # Check if used by schedules
        schedules = self.get_schedules_using_config(filename)
        if schedules:
            schedule_list = ', '.join(schedules)
            raise ValueError(
                f"Cannot delete config '{filename}' because it is used by the following schedules: {schedule_list}"
            )

        # Delete file
        os.remove(filepath)

    def validate_config_content(self, content: Dict) -> Tuple[bool, str]:
        """
        Validate parsed YAML config structure.

        Args:
            content: Parsed YAML config as dict

        Returns:
            Tuple of (is_valid, error_message)
        """
        if not isinstance(content, dict):
            return False, "Config must be a dictionary/object"

        # Check required fields
        if 'title' not in content:
            return False, "Missing required field: 'title'"

        if 'sites' not in content:
            return False, "Missing required field: 'sites'"

        # Validate title
        if not isinstance(content['title'], str) or not content['title'].strip():
            return False, "Field 'title' must be a non-empty string"

        # Validate sites
        sites = content['sites']
        if not isinstance(sites, list):
            return False, "Field 'sites' must be a list"

        if len(sites) == 0:
            return False, "Must have at least one site defined"

        # Validate each site
        for i, site in enumerate(sites):
            if not isinstance(site, dict):
                return False, f"Site {i+1} must be a dictionary/object"

            if 'name' not in site:
                return False, f"Site {i+1} missing required field: 'name'"

            if 'ips' not in site:
                return False, f"Site {i+1} missing required field: 'ips'"

            if not isinstance(site['ips'], list):
                return False, f"Site {i+1} field 'ips' must be a list"

            if len(site['ips']) == 0:
                return False, f"Site {i+1} must have at least one IP"

            # Validate each IP
            for j, ip_config in enumerate(site['ips']):
                if not isinstance(ip_config, dict):
                    return False, f"Site {i+1} IP {j+1} must be a dictionary/object"

                if 'address' not in ip_config:
                    return False, f"Site {i+1} IP {j+1} missing required field: 'address'"

                if 'expected' not in ip_config:
                    return False, f"Site {i+1} IP {j+1} missing required field: 'expected'"

                if not isinstance(ip_config['expected'], dict):
                    return False, f"Site {i+1} IP {j+1} field 'expected' must be a dictionary/object"

        return True, ""

    def get_schedules_using_config(self, filename: str) -> List[str]:
        """
        Get list of schedule names using this config.

        Args:
            filename: Config filename

        Returns:
            List of schedule names (e.g., ["Daily Scan", "Weekly Audit"])
        """
        # Import here to avoid circular dependency
        try:
            from web.services.schedule_service import ScheduleService
            schedule_service = ScheduleService()

            # Get all schedules
            schedules = schedule_service.list_schedules()

            # Build full path for comparison
            config_path = os.path.join(self.configs_dir, filename)

            # Find schedules using this config
            using_schedules = []
            for schedule in schedules:
                schedule_config = schedule.get('config_file', '')

                # Handle both absolute paths and just filenames
                if schedule_config == filename or schedule_config == config_path:
                    using_schedules.append(schedule.get('name', 'Unknown'))

            return using_schedules

        except ImportError:
            # If ScheduleService doesn't exist yet, return empty list
            return []
        except Exception:
            # If any error occurs, return empty list (safer than failing)
            return []

    def generate_filename_from_title(self, title: str) -> str:
        """
        Generate safe filename from scan title.

        Args:
            title: Scan title string

        Returns:
            Safe filename (e.g., "Prod Scan 2025" -> "prod-scan-2025.yaml")
        """
        # Convert to lowercase
        filename = title.lower()

        # Replace spaces with hyphens
        filename = filename.replace(' ', '-')

        # Remove special characters (keep only alphanumeric, hyphens, underscores)
        filename = re.sub(r'[^a-z0-9\-_]', '', filename)

        # Remove consecutive hyphens
        filename = re.sub(r'-+', '-', filename)

        # Remove leading/trailing hyphens
        filename = filename.strip('-')

        # Limit length (max 200 chars, reserve 5 for .yaml)
        max_length = 195
        if len(filename) > max_length:
            filename = filename[:max_length]

        # Ensure not empty
        if not filename:
            filename = 'config'

        # Add .yaml extension
        filename += '.yaml'

        return filename

    def get_config_path(self, filename: str) -> str:
        """
        Get absolute path for a config file.

        Args:
            filename: Config filename

        Returns:
            Absolute path to config file
        """
        return os.path.join(self.configs_dir, filename)

    def config_exists(self, filename: str) -> bool:
        """
        Check if a config file exists.

        Args:
            filename: Config filename

        Returns:
            True if file exists, False otherwise
        """
        filepath = os.path.join(self.configs_dir, filename)
        return os.path.exists(filepath) and os.path.isfile(filepath)