"""LLM 调用封装。"""

from __future__ import annotations

import os
import re
import time
from pathlib import Path
from typing import Any

import requests
from dotenv import load_dotenv


class LLMError(RuntimeError):
    """LLM 请求失败。"""


def strip_thinking(text: str) -> str:
    """移除模型返回中的 think 块。"""
    if not text:
        return ""
    cleaned = re.sub(r"<think(?:ing)?>.*?</think(?:ing)?>", "", text, flags=re.DOTALL | re.IGNORECASE).strip()
    unclosed = re.search(r"<think(?:ing)?>", cleaned, flags=re.IGNORECASE)
    if not unclosed:
        return cleaned

    before = cleaned[: unclosed.start()].strip()
    after = cleaned[unclosed.end():]
    json_fence = re.search(r"```(?:json)?\s*\{.*", after, flags=re.DOTALL | re.IGNORECASE)
    if json_fence:
        return (before + "\n" + json_fence.group(0).strip()).strip()
    json_start = after.find("{")
    if json_start >= 0:
        return (before + "\n" + after[json_start:].strip()).strip()
    return before


class LLMClient:
    def __init__(
        self,
        api_key: str | None = None,
        base_url: str | None = None,
        model: str | None = None,
        retry_attempts: int = 3,
        retry_delay_seconds: float = 2,
        timeout: int = 120,
    ) -> None:
        self._load_project_env()
        self.api_key = api_key or os.environ.get("OPENAI_API_KEY", "")
        self.base_url = (base_url or os.environ.get("OPENAI_BASE_URL") or "https://api.openai.com/v1").rstrip("/")
        self.model = model or os.environ.get("OPENAI_MODEL", "gpt-4o-mini")
        self.retry_attempts = retry_attempts
        self.retry_delay_seconds = retry_delay_seconds
        self.timeout = timeout

    def _load_project_env(self) -> None:
        env_path = Path(os.getcwd()) / ".env"
        if env_path.exists():
            load_dotenv(dotenv_path=env_path, override=False)

    def chat(self, messages: list[dict[str, str]], **kwargs: Any) -> str:
        url = f"{self.base_url}/chat/completions"
        payload = {"model": self.model, "messages": messages, **kwargs}
        headers = {"Content-Type": "application/json"}
        if self.api_key:
            headers["Authorization"] = f"Bearer {self.api_key}"

        last_error: Exception | None = None
        for attempt in range(self.retry_attempts):
            try:
                response = requests.post(url, json=payload, headers=headers, timeout=self.timeout)
                response.raise_for_status()
                content = response.json()["choices"][0]["message"]["content"]
                return strip_thinking(content)
            except requests.exceptions.HTTPError as exc:
                last_error = exc
                status = getattr(getattr(exc, "response", None), "status_code", None)
                if status in {429, 529, 500, 502, 503, 504} and attempt < self.retry_attempts - 1:
                    time.sleep(self.retry_delay_seconds)
                    continue
                break
            except Exception as exc:
                last_error = exc
                if attempt < self.retry_attempts - 1:
                    time.sleep(self.retry_delay_seconds)
                    continue
                break

        raise LLMError(f"LLM 请求失败: {last_error}")