import json
from openai import OpenAI

class LLMClient:
    def __init__(self, base_url, api_key: str | None = None, model: str = "gpt-4o-mini"):
        self.model = model
        self.client = OpenAI(base_url=base_url, api_key=api_key or "ollama")

    def chat(self, system: str, user: str, json_mode: bool = False, images: list[str] | None = None) -> str | None:
        images = images or []
        if images:
            content = [{"type": "text", "text": user}]
            for b64 in images:
                content.append({
                    "type": "image_url",
                    "image_url": {"url": f"data:image/png;base64,{b64}"},
                })
        else:
            content = user

        kwargs = {
            "model": self.model,
            "messages": [
                {"role": "system", "content": system},
                {"role": "user", "content": content},
            ],
        }
        if json_mode:
            kwargs["response_format"] = {"type": "json_object"}
        resp = self.client.chat.completions.create(**kwargs)
        return resp.choices[0].message.content