import OpenAI from 'openai';

export interface ChatMessage {
  role: 'system' | 'user' | 'assistant';
  content: string;
}

export interface ChatOptions {
  model: string;
  temperature?: number;
  maxTokens?: number;
}

export interface ChatResult {
  content: string;
  usage?: { promptTokens?: number; completionTokens?: number; totalTokens?: number };
}

export class LlmClient {
  private readonly client: OpenAI;

  constructor(opts: { baseUrl: string; apiKey?: string }) {
    this.client = new OpenAI({ baseURL: opts.baseUrl, apiKey: opts.apiKey || 'not-needed' });
  }

  async chat(messages: ChatMessage[], options: ChatOptions): Promise<ChatResult> {
    const response = await this.client.chat.completions.create({
      model: options.model,
      temperature: options.temperature,
      max_tokens: options.maxTokens,
      messages,
    });

    const choice = response.choices[0];
    if (!choice) {
      throw new Error('LLM returned no choices');
    }

    return {
      content: choice.message?.content ?? '',
      usage: response.usage
        ? {
            promptTokens: response.usage.prompt_tokens,
            completionTokens: response.usage.completion_tokens,
            totalTokens: response.usage.total_tokens,
          }
        : undefined,
    };
  }
}