import { describe, expect, test, vi } from 'vitest';
import { buildQaSystemPrompt, runQaAgent, type QaStreamEvent } from '@/lib/qa/agent';
import type { CoursewareKnowledge, RetrievedChunk } from '@/lib/qa/knowledge';

vi.mock('@/lib/ai/llm', () => ({
  streamLLM: (_params: unknown, _source: string) => ({
    textStream: (async function* () {
      yield '你';
      yield '好';
    })(),
  }),
}));

const courseware: CoursewareKnowledge = {
  coursewareId: 'cw-1',
  version: 1,
  language: 'zh-CN',
  title: '示例课件：光合作用',
  knowledge: { coursewareId: 'cw-1', scenes: [] },
  quiz: { scenes: [] },
};

const chunks: RetrievedChunk[] = [
  {
    sceneId: 's1',
    order: 1,
    title: '光合作用概述',
    type: 'slide',
    text: '叶绿体是光合作用的场所。',
    narration: '今天我们来学习光合作用。',
    score: 4,
  },
];

describe('buildQaSystemPrompt', () => {
  test('embeds courseware title, language, chunks and profile', () => {
    const prompt = buildQaSystemPrompt(courseware, chunks, '目标是理解光合作用；初二学生');
    expect(prompt).toContain('示例课件：光合作用');
    expect(prompt).toContain('请使用zh-CN回答');
    expect(prompt).toContain('光合作用概述');
    expect(prompt).toContain('叶绿体是光合作用的场所');
    expect(prompt).toContain('学习者档案');
    expect(prompt).toContain('初二学生');
  });

  test('omits profile section when absent', () => {
    const prompt = buildQaSystemPrompt(courseware, [], undefined);
    expect(prompt).not.toContain('学习者档案');
    expect(prompt).toContain('（本次未检索到相关课件内容）');
  });
});

describe('runQaAgent', () => {
  test('streams text deltas and a done event (no tools)', async () => {
    const events: QaStreamEvent[] = [];
    for await (const event of runQaAgent(
      { model: {} as never, courseware, chunks },
      [{ role: 'user', content: '光合作用发生在哪里？' }],
    )) {
      events.push(event);
    }

    const text = events.filter((e) => e.type === 'text');
    expect(text.map((e) => (e as { delta: string }).delta).join('')).toBe('你好');
    const done = events.find((e) => e.type === 'done') as { type: 'done'; sources: RetrievedChunk[]; toolCalls: number };
    expect(done.sources).toEqual(chunks);
    expect(done.toolCalls).toBe(0);
  });

  test('bounded context: keeps only the last QA_MAX_CONTEXT_TURNS turns', async () => {
    const turns = Array.from({ length: 20 }, (_, i) => ({
      role: 'user' as const,
      content: `消息${i}`,
    }));
    const events: QaStreamEvent[] = [];
    for await (const event of runQaAgent({ model: {} as never, courseware, chunks: [] }, turns)) {
      events.push(event);
    }
    // Stream ran to completion without error; the mock ignores messages.
    expect(events.some((e) => e.type === 'done')).toBe(true);
  });
});