"""
Utility for loading prompts and instructions from external JSON files.
"""

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

logger = logging.getLogger(__name__)

class PromptLoader:
    """Loads prompts and instructions from external JSON files."""
    
    def __init__(self, base_dir: Optional[Path] = None):
        """Initialize with base directory."""
        if base_dir is None:
            # Default to the project root directory
            self.base_dir = Path(__file__).parent.parent
        else:
            self.base_dir = Path(base_dir)
            
        self.prompts_dir = self.base_dir / "prompts"
        self.instructions_dir = self.base_dir / "instructions"
        
        # Cache for loaded files
        self._cache: Dict[str, Dict[str, Any]] = {}
        
    def load_prompt(self, prompt_name: str, **kwargs) -> str:
        """
        Load a prompt from the prompts directory.
        Supports both .txt (plain text) and .json formats.
        
        Args:
            prompt_name: Name of the prompt file (without extension)
            **kwargs: Variables to substitute in the prompt
            
        Returns:
            The loaded prompt with variables substituted
        """
        # Try .txt format first (preferred), then fall back to .json
        txt_path = self.prompts_dir / f"{prompt_name}.txt"
        json_path = self.prompts_dir / f"{prompt_name}.json"
        
        if txt_path.exists():
            # Load plain text file
            logger.debug(f"Loading prompt from .txt file: {txt_path}")
            with open(txt_path, 'r', encoding='utf-8') as f:
                prompt_text = f.read().strip()
        elif json_path.exists():
            # Load JSON file (legacy format)
            logger.debug(f"Loading prompt from .json file: {json_path}")
            data = self._load_json_file(json_path)
            prompt_data = data.get("prompt", "")
            
            # Handle both string and list formats
            if isinstance(prompt_data, list):
                # Join list elements with newlines to create a single string
                prompt_text = "\n".join(prompt_data)
            else:
                prompt_text = prompt_data
        else:
            raise FileNotFoundError(f"Prompt file not found: {prompt_name} (checked .txt and .json)")
        
        # Substitute variables if provided
        if kwargs:
            try:
                logger.debug(f"Formatting prompt {prompt_name} with variables: {list(kwargs.keys())}")
                prompt_text = prompt_text.format(**kwargs)
                logger.debug(f"Successfully formatted prompt {prompt_name}")
            except KeyError as e:
                logger.warning(f"Missing variable {e} in prompt {prompt_name}")
            except Exception as e:
                logger.error(f"Error formatting prompt {prompt_name}: {e}")
                logger.error(f"Available variables: {list(kwargs.keys())}")
                
        return prompt_text
        
    def load_instruction(self, instruction_name: str) -> str:
        """
        Load instructions from the instructions directory as a single string.
        
        Args:
            instruction_name: Name of the instruction file (without .json extension)
            
        Returns:
            The loaded instructions as a joined string
        """
        instructions_list = self.load_instructions_as_list(instruction_name)
        return "\n".join(instructions_list)
        
    def load_instructions_as_list(self, instruction_name: str) -> List[str]:
        """
        Load instructions and return as a list of strings.
        
        Args:
            instruction_name: Name of the instruction file (without .json extension)
            
        Returns:
            List of instruction strings
        """
        instruction_path = self.instructions_dir / f"{instruction_name}.json"
        data = self._load_json_file(instruction_path)
        
        instructions = data.get("instructions", [])
        
        # Filter out empty strings
        return [instruction for instruction in instructions if instruction.strip()]
        
    def _load_json_file(self, file_path: Path) -> Dict[str, Any]:
        """Load JSON file content with caching."""
        cache_key = str(file_path)
        
        # Check cache first
        if cache_key in self._cache:
            return self._cache[cache_key]
            
        try:
            if not file_path.exists():
                raise FileNotFoundError(f"File not found: {file_path}")
                
            with open(file_path, 'r', encoding='utf-8') as f:
                data = json.load(f)
                
            # Cache the data
            self._cache[cache_key] = data
            logger.debug(f"Loaded {file_path.name}: {type(data)} with {len(data)} keys")
            
            return data
            
        except json.JSONDecodeError as e:
            logger.error(f"Invalid JSON in file {file_path}: {e}")
            raise
        except Exception as e:
            logger.error(f"Error loading file {file_path}: {e}")
            raise
            
    def clear_cache(self):
        """Clear the file cache."""
        self._cache.clear()
        logger.debug("Prompt loader cache cleared")
        
    def list_prompts(self) -> List[str]:
        """List all available prompt files."""
        if not self.prompts_dir.exists():
            return []
            
        prompts = []
        for file_path in self.prompts_dir.rglob("*.json"):
            # Get relative path from prompts dir
            rel_path = file_path.relative_to(self.prompts_dir)
            # Remove .json extension and convert to forward slashes
            prompt_name = str(rel_path.with_suffix(''))
            prompts.append(prompt_name)
            
        return sorted(prompts)
        
    def list_instructions(self) -> List[str]:
        """List all available instruction files."""
        if not self.instructions_dir.exists():
            return []
            
        instructions = []
        for file_path in self.instructions_dir.rglob("*.json"):
            # Get relative path from instructions dir
            rel_path = file_path.relative_to(self.instructions_dir)
            # Remove .json extension and convert to forward slashes
            instruction_name = str(rel_path.with_suffix(''))
            instructions.append(instruction_name)
            
        return sorted(instructions)
        
    def get_info(self) -> dict:
        """Get information about the prompt loader."""
        return {
            "base_dir": str(self.base_dir),
            "prompts_dir": str(self.prompts_dir),
            "instructions_dir": str(self.instructions_dir),
            "prompts_dir_exists": self.prompts_dir.exists(),
            "instructions_dir_exists": self.instructions_dir.exists(),
            "available_prompts": self.list_prompts(),
            "available_instructions": self.list_instructions(),
            "cache_size": len(self._cache)
        }

# Global instance
prompt_loader = PromptLoader()