import { afterEach, describe, expect, it, vi } from 'vitest';

import {
  requestPlainTextCompletion,
  streamPlainTextCompletion,
} from './llmClient';

function createSseResponse(body: string) {
  const encoder = new TextEncoder();
  const stream = new ReadableStream<Uint8Array>({
    start(controller) {
      controller.enqueue(encoder.encode(body));
      controller.close();
    },
  });

  return new Response(stream, {
    headers: {
      'Content-Type': 'text/event-stream; charset=utf-8',
    },
  });
}

describe('llmClient streamPlainTextCompletion', () => {
  afterEach(() => {
    vi.unstubAllGlobals();
    vi.restoreAllMocks();
  });

  it('reads OpenAI compatible SSE through the shared stream reader', async () => {
    const onUpdate = vi.fn();
    const fetchMock = vi.fn().mockResolvedValue(
      createSseResponse(
        [
          'data: {"choices":[{"delta":{"content":"溪上"}}]}\r\n\r\n',
          'data: not-json\r\n\r\n',
          'data: {"choices":[{"delta":{"content":"春风"}}]}\r\n\r\n',
          'data: [DONE]\r\n\r\n',
          'data: {"choices":[{"delta":{"content":"不应读取"}}]}\r\n\r\n',
        ].join(''),
      ),
    );
    vi.stubGlobal('fetch', fetchMock);

    const result = await streamPlainTextCompletion('system', 'user', {
      onUpdate,
    });

    expect(result).toBe('溪上春风');
    expect(onUpdate).toHaveBeenNthCalledWith(1, '溪上');
    expect(onUpdate).toHaveBeenNthCalledWith(2, '溪上春风');
    expect(onUpdate).toHaveBeenCalledTimes(2);
  });

  it('reads api-server SSE delta events', async () => {
    const onUpdate = vi.fn();
    const fetchMock = vi.fn().mockResolvedValue(
      createSseResponse(
        [
          'event: delta\r\n',
          'data: {"delta":"你","content":"你","finishReason":null}\r\n\r\n',
          'event: delta\r\n',
          'data: {"delta":"好","content":"你好","finishReason":null}\r\n\r\n',
          'event: complete\r\n',
          'data: {"id":"resp_01","model":"gpt-5.4-mini","content":"你好","finishReason":"stop"}\r\n\r\n',
          'data: [DONE]\r\n\r\n',
        ].join(''),
      ),
    );
    vi.stubGlobal('fetch', fetchMock);

    const result = await streamPlainTextCompletion('system', 'user', {
      onUpdate,
    });

    expect(result).toBe('你好');
    expect(onUpdate).toHaveBeenNthCalledWith(1, '你');
    expect(onUpdate).toHaveBeenNthCalledWith(2, '你好');
    expect(onUpdate).toHaveBeenCalledTimes(2);
  });
});

describe('llmClient requestPlainTextCompletion', () => {
  afterEach(() => {
    vi.unstubAllGlobals();
    vi.restoreAllMocks();
  });

  it('reads api-server response envelope content', async () => {
    const fetchMock = vi.fn().mockResolvedValue(
      new Response(
        JSON.stringify({
          ok: true,
          data: {
            id: 'resp_01',
            model: 'gpt-5.4-mini',
            content: '代理成功',
            finishReason: 'stop',
          },
          error: null,
          meta: {requestId: 'req_01'},
        }),
      ),
    );
    vi.stubGlobal('fetch', fetchMock);

    const result = await requestPlainTextCompletion('system', 'user');

    expect(result).toBe('代理成功');
  });
});