// src/ai.mjs: an answer from an AI model under the plan's AI allowance, with
// no key of your own, as the guide Call an AI model under the allowance shows.
import { AllowanceRefusal, AllowanceUpstreamError, generateText } from '@turnzero/ai_allowance';

// The live transport, which only the process entry opens: the platform's
// origin and this copy's credential, from the settings it receives. A local
// run receives the development credential, so the same transport works there.
// Where the credential is not set, it sends nothing and says which line writes it.
export function liveTransport() {
  const origin = process.env.TURNZERO_CLOUD_GATEWAY_URL ?? process.env.TURNZERO_CLOUD_API;
  return (path, init = {}) => {
    const credential = process.env.TURNZERO_CLOUD_APP_TOKEN;
    if (!credential) throw new Error('TURNZERO_CLOUD_APP_TOKEN is not set, so no request was sent. Run the provision line again, then start the app again.');
    return fetch(origin + path, { ...init, headers: { ...init.headers, authorization: `Bearer ${credential}` } });
  };
}

// The asker over any transport: the live one, or a test double's. It answers
// { answer } for one question, or { unanswered } naming why the model gave
// none: allowance_drawn, the month's units are drawn (the refusal
// allowance_exhausted); allowance_unavailable, the platform's key is not in
// place; or upstream_quota, the provider is out of capacity.
export function createAsker(transport) {
  return async (question) => {
    try {
      const answer = await generateText(transport, {
        system: 'Answer the question in a few sentences.',
        messages: [{ role: 'user', content: question }],
        maxOutputTokens: 400,
      });
      const { used, quota } = answer.allowance;
      if (typeof used === 'number' && typeof quota === 'number') console.log(`AI allowance: ${quota - used} of ${quota} units left before this call`);
      return { answer: answer.text };
    } catch (error) {
      // Choose the fallback by the refusal's name, never by its message.
      const refusal = error instanceof AllowanceRefusal ? error.refusal : null;
      if (refusal === 'allowance_exhausted') return { unanswered: 'allowance_drawn' };
      if (refusal === 'allowance_unavailable') return { unanswered: 'allowance_unavailable' };
      const providerFull = error instanceof AllowanceUpstreamError && error.quota;
      if (providerFull) return { unanswered: 'upstream_quota' };
      throw error;
    }
  };
}