import asyncio
import json
from typing import List, Dict, Any
from pathlib import Path

from mcp import ClientSession, StdioServerParameters
from mcp.client.stdio import stdio_client

class MCPToolAdapter:
    def __init__(self, config_path: str = "mcp_server_config.json"):
        self.config_path = config_path
        self.sessions: Dict[str, ClientSession] = {}
        self.exit_stack: Dict[str, Any] = {}
        self.tool_registry: List[Dict[str, Any]] = []

    def _load_config(self) -> Dict[str, Any]:
        """Lädt die Server-Konfiguration aus der JSON-Datei."""
        path = Path(__file__).parent / self.config_path
        if not path.exists():
            print(f"Config file not found: {path}")
            return {}
        
        try:
            with open(path, 'r') as f:
                return json.load(f)
        except json.JSONDecodeError as e:
            print(f"Error decoding JSON config: {e}")
            return {}

    async def initialize_all_sessions(self):
        """Initialisiert alle konfigurierten MCP-Sessions und registriert die Tools."""
        config = self._load_config()
        
        for server_name, params in config.items():
            print(f"Initializing session for {server_name}...")
            
            server_params = StdioServerParameters(
                command=params["command"],
                args=params.get("args", []),
                env=params.get("env", None),
            )
            
            try:
                # Verbindung aufbauen
                transport_gen = stdio_client(server_params)
                read, write = await transport_gen.__aenter__()
                session = ClientSession(read, write)
                await session.__aenter__()
                await session.initialize()

                self.sessions[server_name] = session
                # Speichern für den Shutdown
                self.exit_stack[server_name] = (transport_gen, session)

                # Tools abrufen und registrieren
                result = await session.list_tools()
                # result ist oft ein Objekt, wir greifen auf das .tools Attribut zu
                tools = getattr(result, 'tools', [])

                for tool in tools:
                    # 'tool' ist hier meist ein Tool-Objekt vom MCP SDK
                    self.tool_registry.append({
                        "server": server_name,
                        "name": tool.name,
                        "definition": tool
                    })
                
                print(f"Session for {server_name} ready. {len(tools)} tools found.")

            except Exception as e:
                print(f"Failed to initialize {server_name}: {e}")

    def get_all_tools(self) -> List[Dict[str, Any]]:
        """Gibt alle gesammelten Tools zurück."""
        return self.tool_registry

    async def call_tool(self, tool_name: str, arguments: Dict[str, Any]):
        """Findet den richtigen Server für ein Tool und führt es aus."""
        # Suche in der Registry nach dem passenden Server
        tool_entry = next((t for t in self.tool_registry if t["name"] == tool_name), None)
        
        if not tool_entry:
            return f"Error: Tool '{tool_name}' not found in registry."

        server_name = tool_entry["server"]
        session = self.sessions.get(server_name)

        if session:
            try:
                result = await session.call_tool(tool_name, arguments)
                return result
            except Exception as e:
                return f"Error calling tool '{tool_name}' on server '{server_name}': {str(e)}"
        
        return f"Error: Session for server '{server_name}' not active."

    async def shutdown_all_sessions(self):
        """Schließt alle offenen Verbindungen sauber."""
        for server_name, (transport_gen, session) in self.exit_stack.items():
            try:
                await session.__aexit__(None, None, None)
                await transport_gen.__aexit__(None, None, None)
                print(f"Session for {server_name} shut down.")
            except Exception as e:
                print(f"Error during shutdown of {server_name}: {e}")