"""
Lazy singleton loader for all LLM instances and the CrewAI agents.
Ensures models are initialised once and reused across requests.
"""

import logging
import os
from functools import lru_cache
from typing import Optional

from crewai import LLM
from langchain_openai import ChatOpenAI
from langchain_google_genai import ChatGoogleGenerativeAI

from app.core.config import settings

logger = logging.getLogger(__name__)


# ── LLM singletons ────────────────────────────────────────────────────────────

@lru_cache(maxsize=1)
def get_llm_gemini() -> LLM:
    """Return the cached Gemini CrewAI LLM instance."""
    logger.info("Initialising Gemini LLM (%s)", settings.LLM_GEMINI_MODEL)
    return LLM(
        model=settings.LLM_GEMINI_MODEL,
        temperature=0.2,
        api_key=settings.GOOGLE_API_KEY,
    )


@lru_cache(maxsize=1)
def get_llm_groq() -> LLM:
    """Return the cached Groq CrewAI LLM instance."""
    logger.info("Initialising Groq LLM (%s)", settings.LLM_GROQ_MODEL)
    return LLM(
        model=settings.LLM_GROQ_MODEL,
        temperature=0,
        api_key=settings.GROQ_API_KEY,
    )


@lru_cache(maxsize=1)
def get_llm_open_router() -> LLM:
    """Return the cached OpenRouter CrewAI LLM instance."""
    logger.info("Initialising OpenRouter LLM (%s)", settings.LLM_OPENROUTER_MODEL)
    return LLM(
        api_key=settings.OPENROUTER_API_KEY,
        base_url=settings.LLM_OPENROUTER_BASE_URL,
        model=settings.LLM_OPENROUTER_MODEL,
    )


@lru_cache(maxsize=1)
def get_langchain_llm() -> ChatOpenAI:
    """Return the cached LangChain ChatOpenAI (OpenRouter) instance."""
    logger.info("Initialising LangChain ChatOpenAI via OpenRouter")
    return ChatOpenAI(
        model=settings.LLM_OPENROUTER_MODEL.replace("openrouter/", ""),
        api_key=settings.OPENROUTER_API_KEY,
        base_url=settings.LLM_OPENROUTER_BASE_URL,
    )


@lru_cache(maxsize=1)
def get_gemini_langchain() -> ChatGoogleGenerativeAI:
    """Return the cached LangChain Google Generative AI (Gemini) instance."""
    logger.info("Initialising LangChain Gemini")
    # Strip the crewai prefix for the raw model name
    raw_model = settings.LLM_GEMINI_MODEL.replace("gemini/", "")
    return ChatGoogleGenerativeAI(
        model=raw_model,
        google_api_key=settings.GOOGLE_API_KEY,
        temperature=0,
    )