import json, hashlib, os
from pathlib import Path
from typing import Optional
import httpx


class LLMClient:
    def __init__(self, model: str = "gpt-4o-mini", timeout: int = 15,
                 cache_dir: str = ".cache/llm"):
        self.model = model
        self.timeout = timeout
        self.cache_dir = Path(cache_dir)
        self.cache_dir.mkdir(parents=True, exist_ok=True)

    def _cache_key(self, messages: list) -> str:
        return hashlib.sha256(json.dumps(messages, sort_keys=True).encode()).hexdigest()

    def _cache_get(self, key: str) -> Optional[str]:
        path = self.cache_dir / f"{key}.json"
        if path.exists():
            return json.loads(path.read_text()).get("response")
        return None

    def _cache_set(self, key: str, response: str):
        (self.cache_dir / f"{key}.json").write_text(json.dumps({"response": response}))

    def call(self, messages: list, retries: int = 1) -> str:
        key = self._cache_key(messages)
        cached = self._cache_get(key)
        if cached:
            return cached
        api_key = os.environ.get("OPENAI_API_KEY", "")
        for attempt in range(retries + 1):
            try:
                resp = httpx.post(
                    "https://api.openai.com/v1/chat/completions",
                    json={"model": self.model, "messages": messages},
                    headers={"Authorization": f"Bearer {api_key}"},
                    timeout=self.timeout)
                resp.raise_for_status()
                result = resp.json()["choices"][0]["message"]["content"]
                self._cache_set(key, result)
                return result
            except Exception:
                if attempt == retries:
                    raise
        return ""