/**
 * Replay Buffer 单元测试（v0.8.1 P0-3 模块化收口）
 *
 * 锁定有界缓冲契约：条数/字节双上限溢出丢最旧、truncated 标记、runId 记录、
 * TERMINATED 保留 + 新内容兜底重置、终态清除（会话删除联动）。
 */

import { describe, it, expect, beforeEach } from 'vitest';
import {
  appendReplay,
  resetReplayBuffer,
  markReplayTerminated,
  clearReplayBuffer,
  getReplayBufferData,
} from '../replay-buffer';

describe('replay-buffer — 有界回放缓冲（v0.8.1 P0-3）', () => {
  beforeEach(() => {
    clearReplayBuffer('s1');
  });

  it('append + get：按序返回事件与 runId', () => {
    appendReplay('s1', { channel: 'stateChange', payload: { runId: 'run_a' }, ts: 1 });
    appendReplay('s1', { channel: 'streamEvent', payload: { type: 'text_delta' }, ts: 2 });
    const data = getReplayBufferData('s1');
    expect(data.events).toHaveLength(2);
    expect(data.events[0].channel).toBe('stateChange');
    expect(data.runId).toBe('run_a');
    expect(data.truncated).toBe(false);
  });

  it('条数上限：超过 2000 条丢弃最旧并置 truncated', () => {
    for (let i = 0; i < 2005; i++) {
      appendReplay('s1', { channel: 'streamEvent', payload: { i }, ts: i });
    }
    const data = getReplayBufferData('s1');
    expect(data.events.length).toBeLessThanOrEqual(2000);
    expect(data.truncated).toBe(true);
    // 最旧的已被丢弃
    expect((data.events[0].payload as { i: number }).i).toBeGreaterThan(0);
  });

  it('字节上限：单条 1MB 的超大 payload 被丢弃并置 truncated', () => {
    const big = 'x'.repeat(1024 * 1024);
    for (let i = 0; i < 6; i++) {
      appendReplay('s1', { channel: 'streamEvent', payload: { big }, ts: i });
    }
    const data = getReplayBufferData('s1');
    expect(data.truncated).toBe(true);
    // 缓冲字节被控制在 4MB 上限附近（至少留最后一条）
    expect(data.events.length).toBeGreaterThanOrEqual(1);
    expect(data.events.length).toBeLessThan(6);
  });

  it('TERMINATED 保留缓冲；新内容到达兜底重置', () => {
    appendReplay('s1', { channel: 'stateChange', payload: { state: 'TERMINATED' }, ts: 1 });
    markReplayTerminated('s1');
    // 完成后仍可回放最终内容
    expect(getReplayBufferData('s1').events).toHaveLength(1);
    // 下一次 run 的新内容 → 缓冲重置
    appendReplay('s1', { channel: 'streamEvent', payload: { type: 'text_delta' }, ts: 2 });
    const data = getReplayBufferData('s1');
    expect(data.events).toHaveLength(1);
    expect(data.truncated).toBe(false);
  });

  it('INIT 重置：清除上一 run 的缓冲', () => {
    appendReplay('s1', { channel: 'streamEvent', payload: { a: 1 }, ts: 1 });
    resetReplayBuffer('s1');
    expect(getReplayBufferData('s1').events).toHaveLength(0);
  });

  it('clearReplayBuffer：终态清除（会话删除联动）', () => {
    appendReplay('s1', { channel: 'streamEvent', payload: { a: 1 }, ts: 1 });
    clearReplayBuffer('s1');
    const data = getReplayBufferData('s1');
    expect(data.events).toHaveLength(0);
    expect(data.runId).toBeNull();
  });
});