Source code for src.config.loader

"""Configuration loader with validation."""

import os
from pathlib import Path
from typing import Optional
import yaml
from dotenv import load_dotenv

from .schema import Config
from ..utils.errors import InvalidConfigError, MissingAPIKeyError
from ..utils.logging import get_logger

logger = get_logger(__name__)




class ConfigLoader:
    """Load and validate configuration from YAML file."""
    
    def __init__(self, config_path: Optional[Path] = None):
        """
        Initialize configuration loader.
        
        Args:
            config_path: Path to config.yaml file. Defaults to ./config.yaml
        """
        self.config_path = config_path or Path("config.yaml")
        


    def load(self) -> Config:
        """
        Load and validate configuration.
        
        Returns:
            Validated Config object
            
        Raises:
            InvalidConfigError: If configuration is invalid
            MissingAPIKeyError: If required API key not found
        """
        # Load environment variables
        load_dotenv()
        
        # Check if config file exists
        if not self.config_path.exists():
            raise InvalidConfigError(
                f"Configuration file not found: {self.config_path}\n"
                f"Please create a config.yaml file. See examples/ for templates."
            )
        
        # Load YAML
        try:
            with open(self.config_path, 'r', encoding='utf-8') as f:
                config_data = yaml.safe_load(f)
        except yaml.YAMLError as e:
            raise InvalidConfigError(f"Invalid YAML syntax: {e}")
        except Exception as e:
            raise InvalidConfigError(f"Failed to load config file: {e}")
        
        # Validate with Pydantic
        try:
            config = Config(**config_data)
        except Exception as e:
            raise InvalidConfigError(f"Configuration validation failed: {e}")
        
        # Validate API key
        self._validate_api_key(config)
        
        logger.info(f"Configuration loaded: {config.project.name}")
        logger.debug(f"Loaded {len(config.queries)} queries for analysis")
        
        return config

    
    def _validate_api_key(self, config: Config) -> None:
        """
        Validate that required API key is available.
        
        Args:
            config: Configuration object
            
        Raises:
            MissingAPIKeyError: If API key not found in environment
        """
        api_key_env = config.data_source.api_key_env
        api_key = os.getenv(api_key_env)
        
        if not api_key:
            raise MissingAPIKeyError(
                f"API key not found in environment variable: {api_key_env}\n"
                f"Please set this variable in your .env file or environment.\n"
                f"Example: export {api_key_env}='your_key_here'"
            )
        
        logger.debug(f"API key validated from {api_key_env}")





def load_config(config_path: Optional[Path] = None) -> Config:
    """
    Convenience function to load configuration.
    
    Args:
        config_path: Path to config.yaml file
        
    Returns:
        Validated Config object
    """
    loader = ConfigLoader(config_path)
    return loader.load()