import json
import datetime
import logging
from typing import Dict, List, Optional, Any
from pathlib import Path


class ConfigManager:
    """Manages configuration loading, validation, and default values for backtest operations"""
    
    DEFAULT_CONFIG = {
        "start_date": "2025-05-01",
        "stop_date": datetime.datetime.today().strftime('%Y-%m-%d'),
        "initial_usd": 10000,
        "timeframes": ["1D", "6h", "3h", "1h", "30m", "15m", "5m", "1m"],
        "stop_loss_pcts": [0.01, 0.02, 0.03, 0.05],
        "data_dir": "../data",
        "results_dir": "results"
    }

    def __init__(self, logging_instance: Optional[logging.Logger] = None):
        """
        Initialize configuration manager
        
        Args:
            logging_instance: Optional logging instance for output
        """
        self.logging = logging_instance
        self.config = {}

    def load_config(self, config_path: Optional[str] = None) -> Dict[str, Any]:
        """
        Load configuration from file or interactive input
        
        Args:
            config_path: Path to JSON config file, if None prompts for interactive input
            
        Returns:
            Dictionary containing validated configuration
            
        Raises:
            FileNotFoundError: If config file doesn't exist
            json.JSONDecodeError: If config file has invalid JSON
            ValueError: If configuration values are invalid
        """
        if config_path:
            self.config = self._load_from_file(config_path)
        else:
            self.config = self._load_interactive()
            
        self._validate_config()
        return self.config

    def _load_from_file(self, config_path: str) -> Dict[str, Any]:
        """Load configuration from JSON file"""
        try:
            config_file = Path(config_path)
            if not config_file.exists():
                raise FileNotFoundError(f"Configuration file not found: {config_path}")
                
            with open(config_file, 'r') as f:
                config = json.load(f)
                
            if self.logging:
                self.logging.info(f"Configuration loaded from {config_path}")
                
            return config
            
        except json.JSONDecodeError as e:
            error_msg = f"Invalid JSON in configuration file {config_path}: {e}"
            if self.logging:
                self.logging.error(error_msg)
            raise json.JSONDecodeError(error_msg, e.doc, e.pos)

    def _load_interactive(self) -> Dict[str, Any]:
        """Load configuration through interactive prompts"""
        print("No config file provided. Please enter the following values (press Enter to use default):")

        config = {}
        
        # Start date
        start_date = input(f"Start date [{self.DEFAULT_CONFIG['start_date']}]: ") or self.DEFAULT_CONFIG['start_date']
        config['start_date'] = start_date
        
        # Stop date  
        stop_date = input(f"Stop date [{self.DEFAULT_CONFIG['stop_date']}]: ") or self.DEFAULT_CONFIG['stop_date']
        config['stop_date'] = stop_date

        # Initial USD
        initial_usd_str = input(f"Initial USD [{self.DEFAULT_CONFIG['initial_usd']}]: ") or str(self.DEFAULT_CONFIG['initial_usd'])
        try:
            config['initial_usd'] = float(initial_usd_str)
        except ValueError:
            raise ValueError(f"Invalid initial USD value: {initial_usd_str}")

        # Timeframes
        timeframes_str = input(f"Timeframes (comma separated) [{', '.join(self.DEFAULT_CONFIG['timeframes'])}]: ") or ','.join(self.DEFAULT_CONFIG['timeframes'])
        config['timeframes'] = [tf.strip() for tf in timeframes_str.split(',') if tf.strip()]
        
        # Stop loss percentages
        stop_loss_pcts_str = input(f"Stop loss pcts (comma separated) [{', '.join(str(x) for x in self.DEFAULT_CONFIG['stop_loss_pcts'])}]: ") or ','.join(str(x) for x in self.DEFAULT_CONFIG['stop_loss_pcts'])
        try:
            config['stop_loss_pcts'] = [float(x.strip()) for x in stop_loss_pcts_str.split(',') if x.strip()]
        except ValueError:
            raise ValueError(f"Invalid stop loss percentages: {stop_loss_pcts_str}")

        # Add default directories
        config['data_dir'] = self.DEFAULT_CONFIG['data_dir']
        config['results_dir'] = self.DEFAULT_CONFIG['results_dir']
        
        return config

    def _validate_config(self) -> None:
        """
        Validate configuration values
        
        Raises:
            ValueError: If any configuration value is invalid
        """
        # Validate initial USD
        if self.config.get('initial_usd', 0) <= 0:
            raise ValueError("Initial USD must be positive")

        # Validate stop loss percentages
        stop_loss_pcts = self.config.get('stop_loss_pcts', [])
        for pct in stop_loss_pcts:
            if not 0 < pct < 1:
                raise ValueError(f"Stop loss percentage must be between 0 and 1, got: {pct}")

        # Validate dates
        try:
            datetime.datetime.strptime(self.config['start_date'], '%Y-%m-%d')
            datetime.datetime.strptime(self.config['stop_date'], '%Y-%m-%d')
        except ValueError as e:
            raise ValueError(f"Invalid date format (should be YYYY-MM-DD): {e}")

        # Validate timeframes
        timeframes = self.config.get('timeframes', [])
        if not timeframes:
            raise ValueError("At least one timeframe must be specified")

        # Validate directories exist or can be created
        for dir_key in ['data_dir', 'results_dir']:
            dir_path = Path(self.config.get(dir_key, ''))
            try:
                dir_path.mkdir(parents=True, exist_ok=True)
            except Exception as e:
                raise ValueError(f"Cannot create directory {dir_path}: {e}")

        if self.logging:
            self.logging.info("Configuration validation completed successfully")

    def get_config(self) -> Dict[str, Any]:
        """Return the current configuration"""
        return self.config.copy()

    def save_config(self, output_path: str) -> None:
        """
        Save current configuration to file
        
        Args:
            output_path: Path where to save the configuration
        """
        try:
            with open(output_path, 'w') as f:
                json.dump(self.config, f, indent=2)
                
            if self.logging:
                self.logging.info(f"Configuration saved to {output_path}")
                
        except Exception as e:
            error_msg = f"Failed to save configuration to {output_path}: {e}"
            if self.logging:
                self.logging.error(error_msg)
            raise