"""Клиент внешней LLM (OpenAI-совместимый API платформы ИИ)."""

from __future__ import annotations

import logging
from dataclasses import dataclass

import httpx

from app.config import settings

logger = logging.getLogger(__name__)


@dataclass
class LlmTestResult:
    ok: bool
    configured: bool
    model: str
    endpoint: str
    message: str
    sample: str | None = None
    status_code: int | None = None
    error: str | None = None


class LlmClient:
    def __init__(self) -> None:
        self._system_prompt = self._load_system_prompt()

    def is_configured(self) -> bool:
        return settings.llm_enabled and bool(settings.llm_api_key or settings.llm_jwt_token)

    def _load_system_prompt(self) -> str:
        path = settings.system_prompt_path
        if path.exists():
            try:
                content = path.read_text(encoding="utf-8")
                return content[:6000]
            except OSError:
                pass
        return settings.system_prompt_fallback

    def _headers(self) -> dict[str, str]:
        headers = {"Content-Type": "application/json"}
        if settings.llm_api_key:
            headers["Authorization"] = f"Bearer {settings.llm_api_key}"
        if settings.llm_jwt_token:
            headers["X-JWT-Token"] = settings.llm_jwt_token
        # OpenRouter рекомендует указать referer
        if "openrouter.ai" in settings.llm_chat_url:
            headers["HTTP-Referer"] = "http://localhost:5173"
            headers["X-Title"] = "VKUS IT Assistant"
        return headers

    def test_connection(self) -> LlmTestResult:
        endpoint = settings.llm_chat_url
        model = settings.llm_model

        if not settings.llm_enabled:
            return LlmTestResult(
                ok=False,
                configured=False,
                model=model,
                endpoint=endpoint,
                message="LLM отключена (VKUS_LLM_ENABLED=false)",
            )

        if not settings.llm_api_key and not settings.llm_jwt_token:
            return LlmTestResult(
                ok=False,
                configured=False,
                model=model,
                endpoint=endpoint,
                message="API-ключ не задан (VKUS_LLM_API_KEY)",
            )

        payload = {
            "model": model,
            "messages": [
                {"role": "user", "content": "Ответь одним словом: работает"},
            ],
            "max_tokens": 16,
            "temperature": 0,
        }

        try:
            with httpx.Client(timeout=settings.llm_timeout, verify=settings.llm_verify_ssl) as client:
                response = client.post(endpoint, json=payload, headers=self._headers())
                if response.status_code >= 400:
                    return LlmTestResult(
                        ok=False,
                        configured=True,
                        model=model,
                        endpoint=endpoint,
                        message="Ошибка HTTP при обращении к LLM",
                        status_code=response.status_code,
                        error=response.text[:500],
                    )
                data = response.json()
                sample = data["choices"][0]["message"]["content"].strip()
                return LlmTestResult(
                    ok=True,
                    configured=True,
                    model=model,
                    endpoint=endpoint,
                    message="Соединение с LLM установлено",
                    sample=sample,
                    status_code=response.status_code,
                )
        except httpx.TimeoutException:
            return LlmTestResult(
                ok=False,
                configured=True,
                model=model,
                endpoint=endpoint,
                message=f"Таймаут ({settings.llm_timeout} сек)",
                error="timeout",
            )
        except Exception as exc:
            logger.exception("LLM connection test failed")
            return LlmTestResult(
                ok=False,
                configured=True,
                model=model,
                endpoint=endpoint,
                message="Не удалось подключиться к LLM",
                error=str(exc)[:500],
            )

    def generate_with_context(self, query: str, context: str) -> str | None:
        if not self.is_configured():
            return None

        user_content = (
            "Используй только предоставленный контекст из корпоративных инструкций.\n"
            "Если контекста недостаточно — честно скажи об этом.\n"
            "Ответ должен быть кратким, структурированным, на русском языке.\n\n"
            f"### Контекст\n{context}\n\n"
            f"### Вопрос сотрудника\n{query}"
        )

        payload = {
            "model": settings.llm_model,
            "messages": [
                {"role": "system", "content": self._system_prompt},
                {"role": "user", "content": user_content},
            ],
            "temperature": settings.llm_temperature,
            "max_tokens": settings.llm_max_tokens,
        }

        try:
            with httpx.Client(timeout=settings.llm_timeout, verify=settings.llm_verify_ssl) as client:
                response = client.post(settings.llm_chat_url, json=payload, headers=self._headers())
                response.raise_for_status()
                data = response.json()
                return data["choices"][0]["message"]["content"].strip()
        except Exception as exc:
            if settings.use_template_on_llm_failure:
                logger.warning("LLM request failed, fallback to template: %s", exc)
            else:
                logger.error("LLM request failed: %s", exc)
            return None


_llm_client: LlmClient | None = None


def get_llm_client() -> LlmClient:
    global _llm_client
    if _llm_client is None:
        _llm_client = LlmClient()
    return _llm_client