const OPENROUTER_BASE = 'https://openrouter.ai/api/v1';
const DEFAULT_MODEL = 'google/gemini-3.5-flash';

export async function callLLM(
  prompt: string,
  apiKey: string,
  model = DEFAULT_MODEL,
): Promise<string> {
  const res = await fetch(`${OPENROUTER_BASE}/chat/completions`, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      Authorization: `Bearer ${apiKey}`,
      'HTTP-Referer': 'https://tower.insignia.app',
      'X-Title': 'TOWER Community Platform',
    },
    body: JSON.stringify({
      model,
      messages: [{ role: 'user', content: prompt }],
      temperature: 0.1,
    }),
  });

  if (!res.ok) {
    const body = await res.text().catch(() => '');
    throw new Error(`OpenRouter error ${res.status}: ${body}`);
  }

  const data = (await res.json()) as { choices: Array<{ message: { content: string } }> };
  const content = data.choices?.[0]?.message?.content;
  if (!content) throw new Error('OpenRouter returned empty content');
  return content;
}