import json
import logging
import os
import sys
from pathlib import Path
from typing import Callable, Optional, TypeVar

T = TypeVar("T")
logger = logging.getLogger(__name__)

PROTECTED_KEYS = [
    "APPNAME",
    "LOG_LEVEL",
    "PATH_EXCLUSION_CONST",
    "MIN_FILES_FOR_PATH",
    "VT_THREAT_TOLERANCE",
    "POLICY_MAP_ENF_AUD"
]

_protected_config = {}

def get_system_config_path() -> Path:
    # Check inside bundled EXE directory first
    bundled_dir = Path(getattr(sys, '_MEIPASS', ''))
    bundled_path = bundled_dir / "system_config.json"
    if bundled_path.exists():
        return bundled_path

    # Fallback to external location
    return Path(__file__).parent.parent / "system_config.json"

def load_protected_config() -> dict:
    global _protected_config
    try:
        with open(get_system_config_path(), "r") as f:
            system_config = json.load(f)
    except FileNotFoundError:
        logging.warning("⚠️ system_config.json not found. Using built-in defaults.")
        system_config = {
            "APPNAME": "AirlockTools",
            "PATH_EXCLUSION_CONST": 4,
            "MIN_FILES_FOR_PATH": 4,
            "VT_THREAT_TOLERANCE": 4,
            "POLICY_MAP_ENF_AUD": {
                "enforced_id": "audit_id"
            }
        }

    _protected_config = {key: system_config[key] for key in PROTECTED_KEYS}
    return _protected_config

def get_protected_value(key: str, cast_type: Callable[[str], T] = str, default: Optional[T] = None) -> Optional[T]:
    value = _protected_config.get(key)
    if value is None:
        logging.warning(f"Protected config key '{key}' not found.")
        return default
    try:
        if isinstance(value, str):
            value = value.strip("'\"")
        return cast_type(value)
    except (ValueError, TypeError):
        logging.warning(f"Invalid value for protected key '{key}': {value}. Expected type {cast_type.__name__}.")
        return default

def get_protected_json(key: str, default: str = "{}") -> dict:
    raw = _protected_config.get(key, default)
    if isinstance(raw, dict):
        return raw
    try:
        return json.loads(raw)
    except json.JSONDecodeError:
        try:
            escaped = raw.encode('unicode_escape').decode('utf-8')
            return json.loads(escaped)
        except Exception as e:
            logging.error(f"Failed to parse protected JSON key '{key}': {e}")
            return json.loads(default)
        



def load_env_json(key: str, default: str):
    raw = os.getenv(key, default)
    try:
        return json.loads(raw)
    except json.JSONDecodeError:
        try:
            escaped = raw.encode('unicode_escape').decode('utf-8')
            return json.loads(escaped)
        except Exception as e:
            logging.error(f"Failed to parse {key}: {e}")
            return json.loads(default)

def load_env(key: str, cast_type: Callable[[str], T] = str, default: Optional[T] = None) -> Optional[T]:
    """
    Safely retrieves an environment variable and casts it to the desired type.

    Parameters:
        key (str): The name of the environment variable.
        cast_type (Callable[[str], T], optional): Function to cast the value. Defaults to str.
        default (Optional[T], optional): Default value if the variable is not set or invalid.

    Returns:
        Optional[T]: The casted value or the default.
    """
    value = os.getenv(key)
    if value is None:
        logger.warning(f"Environment variable '{key}' not set.")
        return default
    try:
        value = value.strip("'\"")  # Strip surrounding quotes
        return cast_type(value)
    except (ValueError, TypeError):
        logger.warning(f"Invalid value for env var '{key}': {value}. Expected type {cast_type.__name__}.")
        return default