"""
Tool Service

Handles tool management and execution for LangGraph agents.

Usage:
    from apps.chatbot.services import ToolService
    
    # Get enabled tools for user
    tools = ToolService.get_user_tools(user)
    
    # Enable a tool
    ToolService.enable_tool(user, "web_search")
"""

from typing import List, Dict, Any, Optional
from uuid import UUID

from langchain_core.tools import BaseTool
from apps.chatbot.models import UserTool, AvailableTool
from apps.accounts.models import CustomUser


class ToolService:
    """Service for managing user tools."""
    
    @staticmethod
    def get_user_tools(
        user: CustomUser,
        enabled_only: bool = True
    ) -> List[UserTool]:
        """
        Get user's tools.
        
        Args:
            user: The user
            enabled_only: Only return enabled tools
        
        Returns:
            List of UserTool instances
        """
        query = UserTool.objects.filter(user=user)
        
        if enabled_only:
            query = query.filter(is_enabled=True)
        
        return list(query.select_related('available_tool'))
    
    @staticmethod
    def enable_tool(
        user: CustomUser,
        tool_name: str,
        configuration: Optional[Dict[str, Any]] = None
    ) -> UserTool:
        """
        Enable a tool for user.
        
        Args:
            user: The user
            tool_name: Tool internal name
            configuration: Tool configuration
        
        Returns:
            Created/updated UserTool instance
        """
        available_tool = AvailableTool.objects.get(
            tool_name=tool_name,
            is_active=True
        )
        
        user_tool, created = UserTool.objects.get_or_create(
            user=user,
            available_tool=available_tool,
            defaults={
                'tool_name': tool_name,
                'tool_display_name': available_tool.display_name,
                'is_enabled': True,
                'configuration': configuration or {}
            }
        )
        
        if not created:
            user_tool.is_enabled = True
            if configuration:
                user_tool.configuration = configuration
            user_tool.save()
        
        return user_tool
    
    @staticmethod
    def disable_tool(user: CustomUser, tool_name: str) -> None:
        """
        Disable a tool for user.
        
        Args:
            user: The user
            tool_name: Tool internal name
        """
        UserTool.objects.filter(
            user=user,
            tool_name=tool_name
        ).update(is_enabled=False)
    
    @staticmethod
    def get_tool_instances(
        user: CustomUser
    ) -> List[BaseTool]:
        """
        Get LangChain tool instances for user.
        
        Args:
            user: The user
        
        Returns:
            List of LangChain BaseTool instances
        
        Example:
            tools = ToolService.get_tool_instances(user)
            
            # Use with agent
            agent = create_react_agent(
                model=model,
                tools=tools,
                checkpointer=checkpointer
            )
        """
        user_tools = ToolService.get_user_tools(user, enabled_only=True)
        
        # TODO: Implement tool loading logic
        # This would load actual LangChain tools based on tool_name
        # For now, return empty list
        return []
    
    @staticmethod
    def check_rate_limit(
        user: CustomUser,
        tool_name: str
    ) -> Dict[str, Any]:
        """
        Check if user has exceeded tool rate limit.
        
        Args:
            user: The user
            tool_name: Tool to check
        
        Returns:
            Dict with allowed status
        """
        try:
            user_tool = UserTool.objects.get(
                user=user,
                tool_name=tool_name,
                is_enabled=True
            )
            return user_tool.check_rate_limit()
        except UserTool.DoesNotExist:
            return {
                'allowed': False,
                'reason': 'Tool not enabled'
            }
    
    @staticmethod
    def increment_tool_usage(
        user: CustomUser,
        tool_name: str
    ) -> None:
        """
        Increment tool usage counter.
        
        Args:
            user: The user
            tool_name: Tool that was used
        """
        UserTool.objects.filter(
            user=user,
            tool_name=tool_name
        ).update(
            usage_count=models.F('usage_count') + 1,
            last_used_at=timezone.now()
        )