import threading
from typing import Any, List, Optional

from tools.prompts import build_chat_system_prompt
from tools.text import normalize_message


class ChatHandler:
    def __init__(self, llm: Any, startup_error: Optional[str] = None):
        self._llm = llm
        self._startup_error = startup_error
        self._lock = threading.Lock()
        self._system_prompt = build_chat_system_prompt()

    def send(self, message: str, history: Optional[List[Any]]) -> tuple[str, List[Any]]:
        safe_history = history or []
        clean = normalize_message(message)
        if not clean:
            return "", safe_history

        if self._startup_error:
            return "", safe_history + [
                {"role": "user", "content": clean},
                {"role": "assistant", "content": f"startup_error: {self._startup_error}"},
            ]

        if self._llm is None:
            return "", safe_history + [
                {"role": "user", "content": clean},
                {"role": "assistant", "content": "startup_error: agent unavailable"},
            ]

        with self._lock:
            reply = self._llm.chat(self._system_prompt, safe_history, clean)

        return "", safe_history + [
            {"role": "user", "content": clean},
            {"role": "assistant", "content": reply},
        ]