import os
import yaml
import logging
from .config_loader import load_config, get_config

log = logging.getLogger("ainventory")

class ConfigManager:
    """Manages backend.yaml configuration file updates."""

    @staticmethod
    def get_config_path():
        """Returns the absolute path to backend.yaml."""
        base_dir = os.path.dirname(os.path.abspath(__file__))
        project_root = os.path.dirname(base_dir)
        return os.path.join(project_root, "config", "backend.yaml")

    @staticmethod
    def read_config() -> dict:
        """Read backend.yaml and return current config."""
        path = ConfigManager.get_config_path()
        if not os.path.exists(path):
            log.warning(f"ℹ️ {path} not found. Returning empty dict.")
            return {}
        
        try:
            with open(path, 'r', encoding='utf-8') as f:
                return yaml.safe_load(f) or {}
        except Exception as e:
            log.error(f"❌ Failed to read {path}: {e}")
            return {}

    @staticmethod
    def update_config(updates: dict) -> dict:
        """
        Update backend.yaml with new values and return updated config.
        Only updates sections in backend.yaml.
        """
        path = ConfigManager.get_config_path()
        current_yaml = ConfigManager.read_config()
        
        # Merge updates (deep merge for sections)
        for section, values in updates.items():
            if isinstance(values, dict) and section in current_yaml and isinstance(current_yaml[section], dict):
                current_yaml[section].update(values)
            else:
                current_yaml[section] = values

        try:
            with open(path, 'w', encoding='utf-8') as f:
                yaml.safe_dump(current_yaml, f, default_flow_style=False, sort_keys=False)
            log.info(f"✅ Updated {path} with new values.")
            
            # Reload the global config
            load_config()
            return get_config()
        except Exception as e:
            log.error(f"❌ Failed to write {path}: {e}")
            raise

    @staticmethod
    def validate_config_file() -> bool:
        """Validate backend.yaml syntax and required fields."""
        path = ConfigManager.get_config_path()
        if not os.path.exists(path):
            return False
        
        try:
            with open(path, 'r', encoding='utf-8') as f:
                yaml.safe_load(f)
            return True
        except Exception:
            return False

    @staticmethod
    def get_masked_key(key_name: str):
        """Returns a masked version of a configuration value or env var."""
        config = get_config()
        
        # Try to find in config first
        val = None
        if key_name == "JWT_SECRET_KEY":
            val = config.get("auth", {}).get("jwt_secret_key")
        elif key_name == "GEMINI_API_KEY":
            val = config.get("ai", {}).get("gemini_api_key")
        elif key_name == "CLAUDE_API_KEY":
            val = config.get("ai", {}).get("claude_api_key")
        
        # Fallback to env
        if not val:
            val = os.environ.get(key_name)
            
        if not val:
            return None
        
        prefix = ""
        if "GEMINI" in key_name:
            prefix = "G-"
        elif "CLAUDE" in key_name:
            prefix = "sk-"
            
        if len(val) <= 8:
            return f"{prefix}****"
        
        return f"{prefix}****{val[-4:]}"

# Module-level functions for backward compatibility and direct import
def read_config() -> dict:
    """Read backend.yaml and return current config."""
    return ConfigManager.read_config()

def update_config(updates: dict) -> dict:
    """Update backend.yaml with new values and return updated config."""
    return ConfigManager.update_config(updates)

def validate_config_file() -> bool:
    """Validate backend.yaml syntax and required fields."""
    return ConfigManager.validate_config_file()