import { describe, expect, it } from 'vitest';
import { createLlmClient } from './llm';

function json(body: unknown) {
  return {
    ok: true,
    status: 200,
    json: async () => body,
    text: async () => JSON.stringify(body),
  } as unknown as Response;
}

describe('createLlmClient (injectable transport)', () => {
  it('chat posts model+messages to {base}/chat/completions and returns content', async () => {
    const calls: { url: string; init?: RequestInit }[] = [];
    const transport = async (url: string, init?: RequestInit) => {
      calls.push({ url, init });
      return json({ choices: [{ message: { content: 'hello back' } }] });
    };
    const llm = createLlmClient({ transport, apiBase: 'http://x/v1/', model: 'm1' });
    const out = await llm.chat([{ role: 'user', content: 'hi' }], { maxTokens: 10, temperature: 0.5 });
    expect(out).toBe('hello back');
    expect(calls[0].url).toBe('http://x/v1/chat/completions'); // trailing slash normalized
    const body = JSON.parse(calls[0].init!.body as string);
    expect(body).toEqual({
      model: 'm1',
      messages: [{ role: 'user', content: 'hi' }],
      maxTokens: 10,
      temperature: 0.5,
    });
  });

  it('listModels returns data[].id from GET {base}/models', async () => {
    const transport = async (url: string) => {
      expect(url).toBe('http://x/v1/models');
      return json({ data: [{ id: 'a' }, { id: 'b' }] });
    };
    const llm = createLlmClient({ transport, apiBase: 'http://x/v1', model: 'm' });
    expect(await llm.listModels()).toEqual(['a', 'b']);
  });

  it('chat throws on non-2xx with the HTTP status in the message', async () => {
    const transport = async () =>
      ({
        ok: false,
        status: 503,
        text: async () => 'upstream down',
        json: async () => ({}),
      } as unknown as Response);
    const llm = createLlmClient({ transport, apiBase: 'http://x/v1', model: 'm' });
    await expect(llm.chat([{ role: 'user', content: 'hi' }])).rejects.toThrow(/HTTP 503/);
  });

  it('chat throws when the response has no content', async () => {
    const transport = async () => json({ choices: [] });
    const llm = createLlmClient({ transport, apiBase: 'http://x/v1', model: 'm' });
    await expect(llm.chat([{ role: 'user', content: 'hi' }])).rejects.toThrow(/no choices/);
  });
});