/**
 * SLOMonitor + HealthChecker 测试（electron/utils/slo.ts —— 此前零测试）
 *
 * SLOMonitor 契约：
 * 1. 滑动窗口内错误率统计（窗口外记录被清理/忽略）
 * 2. 吞吐量 = 窗口内请求数 / 窗口秒数
 * 3. 延迟分位数 P50/P95/P99（空数据返回 0）
 * 4. 燃烧速率 = 错误率 / 错误预算；>1 触发 violated
 * 5. 低流量语义：窗口内少量请求也按真实比例计算
 * 6. reset / getConfig
 *
 * HealthChecker 契约：database（DB ping / 文件存在）/ free_memory（>200MB）/
 * memory_usage（heap < 512MB）三项检查聚合为 healthy。
 */

import { describe, it, expect, vi, beforeEach, afterEach, beforeAll, afterAll } from 'vitest';
import { mkdtempSync, rmSync } from 'fs';
import { tmpdir } from 'os';
import { join } from 'path';

// electron.app.getPath 指向一个真实存在的临时目录（checkFreeMemory 依赖）
const mockState = vi.hoisted(() => ({ userDataDir: '' }));
vi.mock('electron', async () => {
  const { mkdtempSync } = await import('fs');
  const { tmpdir } = await import('os');
  const { join } = await import('path');
  mockState.userDataDir = mkdtempSync(join(tmpdir(), 'metona-slo-'));
  return { app: { getPath: () => mockState.userDataDir } };
});

import { SLOMonitor, HealthChecker } from '../slo';

describe('SLOMonitor — 基础统计', () => {
  let monitor: SLOMonitor;

  beforeEach(() => {
    vi.useFakeTimers();
    vi.setSystemTime(1_000_000);
    monitor = new SLOMonitor({ windowMs: 60_000 });
  });

  afterEach(() => {
    vi.useRealTimers();
  });

  it('空监控器：errorRate=0、throughput=0、percentile=0、violated=false', () => {
    const status = monitor.getStatus();
    expect(status.errorRate).toBe(0);
    expect(status.throughput).toBe(0);
    expect(status.avgLatencyMs).toBe(0);
    expect(status.percentiles).toEqual({ P50: 0, P95: 0, P99: 0 });
    expect(status.burnRate).toBe(0);
    expect(status.violated).toBe(false);
    expect(status.totalRequests).toBe(0);
    expect(status.errorRequests).toBe(0);
    expect(status.target).toBe(0.999);
  });

  it('全部成功：errorRate=0、violated=false、burnRate=0', () => {
    for (let i = 0; i < 10; i++) monitor.recordRequest(100, true);
    const status = monitor.getStatus();
    expect(status.totalRequests).toBe(10);
    expect(status.errorRequests).toBe(0);
    expect(status.errorRate).toBe(0);
    expect(status.burnRate).toBe(0);
    expect(status.violated).toBe(false);
  });

  it('全部失败：errorRate=1、burnRate=1/errorBudget、violated=true', () => {
    for (let i = 0; i < 5; i++) monitor.recordRequest(10, false);
    const status = monitor.getStatus();
    expect(status.errorRate).toBe(1);
    expect(status.errorRequests).toBe(5);
    // errorBudget = 1 - 0.999 = 0.001
    expect(status.errorBudget).toBeCloseTo(0.001);
    expect(status.burnRate).toBeCloseTo(1000);
    expect(status.violated).toBe(true);
  });

  it('混合请求：errorRate = 错误数/总数', () => {
    monitor.recordRequest(10, true);
    monitor.recordRequest(20, true);
    monitor.recordRequest(30, false);
    monitor.recordRequest(40, true);
    const status = monitor.getStatus();
    expect(status.totalRequests).toBe(4);
    expect(status.errorRate).toBeCloseTo(0.25);
  });

  it('吞吐量 = 窗口内请求数 / 窗口秒数', () => {
    for (let i = 0; i < 30; i++) monitor.recordRequest(5, true);
    const status = monitor.getStatus();
    expect(status.throughput).toBeCloseTo(30 / 60); // 0.5 req/s
  });

  it('平均延迟 = 窗口内延迟总和 / 请求数', () => {
    monitor.recordRequest(100, true);
    monitor.recordRequest(300, true);
    monitor.recordRequest(200, true);
    expect(monitor.getStatus().avgLatencyMs).toBe(200);
  });
});

describe('SLOMonitor — 分位数', () => {
  let monitor: SLOMonitor;
  beforeEach(() => {
    vi.useFakeTimers();
    vi.setSystemTime(1_000_000);
    monitor = new SLOMonitor({ windowMs: 60_000 });
  });
  afterEach(() => {
    vi.useRealTimers();
  });

  it('P50/P95/P99 边界：升序延迟的 ceil 索引取数', () => {
    // [1,2,3,4]：P50=2（idx1），P95=4（idx3），P99=4（idx3）
    for (const lat of [4, 1, 3, 2]) monitor.recordRequest(lat, true);
    const status = monitor.getStatus();
    expect(status.percentiles).toEqual({ P50: 2, P95: 4, P99: 4 });
  });

  it('单元素：所有分位数均为该值', () => {
    monitor.recordRequest(77, true);
    expect(monitor.getStatus().percentiles).toEqual({ P50: 77, P95: 77, P99: 77 });
  });

  it('自定义分位数数组（[0.5,0.9]）生成对应 key', () => {
    const m = new SLOMonitor({ latencyPercentiles: [0.5, 0.9], windowMs: 60_000 });
    m.recordRequest(1, true);
    m.recordRequest(2, true);
    m.recordRequest(3, true);
    m.recordRequest(4, true);
    m.recordRequest(5, true);
    const status = m.getStatus();
    expect(status.percentiles).toEqual({ P50: 3, P90: 5 });
  });
});

describe('SLOMonitor — 滑动窗口', () => {
  let monitor: SLOMonitor;
  beforeEach(() => {
    vi.useFakeTimers();
    vi.setSystemTime(1_000_000);
    monitor = new SLOMonitor({ windowMs: 60_000 });
  });
  afterEach(() => {
    vi.useRealTimers();
  });

  it('窗口外旧记录被 getStatus 忽略（不参与统计）', () => {
    for (let i = 0; i < 3; i++) monitor.recordRequest(10, false); // 全部失败
    // 推进 60 秒以上 —— 旧记录全部过期
    vi.advanceTimersByTime(61_000);
    const status = monitor.getStatus();
    expect(status.totalRequests).toBe(0);
    expect(status.errorRate).toBe(0);
    expect(status.violated).toBe(false);
  });

  it('窗口内保留新记录：混合新旧后只统计新记录', () => {
    monitor.recordRequest(10, false); // 旧失败
    vi.advanceTimersByTime(30_000);
    monitor.recordRequest(20, true); // 新成功（仍在窗口内）
    const status = monitor.getStatus();
    expect(status.totalRequests).toBe(2); // 两条都还在窗口内
    vi.advanceTimersByTime(30_001); // 第一条（30 秒前的）过期
    const status2 = monitor.getStatus();
    expect(status2.totalRequests).toBe(1);
    expect(status2.errorRate).toBe(0);
  });

  it('recordRequest 内部清理：推进时间后旧记录被移除（内存不膨胀）', () => {
    for (let i = 0; i < 5; i++) monitor.recordRequest(1, true);
    vi.advanceTimersByTime(120_000);
    // 再次 recordRequest 触发 cleanup → 旧记录全清
    monitor.recordRequest(2, true);
    expect(monitor.getStatus().totalRequests).toBe(1);
  });

  it('窗口边界：恰在窗口起始点的记录被保留（>= 比较）', () => {
    monitor.recordRequest(1, true);
    vi.advanceTimersByTime(60_000); // 恰满窗口
    const status = monitor.getStatus();
    expect(status.totalRequests).toBe(1);
  });

  it('低流量误报语义：少量请求也按真实比例（单条失败即 100% 错误率 → violated）', () => {
    // target 0.999 预算极低 —— 单条失败即触发 violated（设计语义：低流量不掩盖问题）
    monitor.recordRequest(5, false);
    const status = monitor.getStatus();
    expect(status.errorRate).toBe(1);
    expect(status.violated).toBe(true);
  });

  it('低流量不误报：单条成功请求 errorRate=0 不触发 violated', () => {
    monitor.recordRequest(5, true);
    const status = monitor.getStatus();
    expect(status.errorRate).toBe(0);
    expect(status.violated).toBe(false);
  });
});

describe('SLOMonitor — 配置与重置', () => {
  it('自定义 target 影响错误预算与燃烧速率', () => {
    vi.useFakeTimers();
    const m = new SLOMonitor({ target: 0.9, windowMs: 60_000 });
    m.recordRequest(1, false);
    m.recordRequest(1, true);
    const status = m.getStatus();
    expect(status.errorBudget).toBeCloseTo(0.1);
    expect(status.burnRate).toBeCloseTo(5); // 0.5 / 0.1
    expect(status.violated).toBe(true);
    vi.useRealTimers();
  });

  it('目标 0.5 时 50% 错误率为边界（violated=false）', () => {
    vi.useFakeTimers();
    const m = new SLOMonitor({ target: 0.5, windowMs: 60_000 });
    m.recordRequest(1, true);
    m.recordRequest(1, false);
    const status = m.getStatus();
    expect(status.errorRate).toBeCloseTo(0.5);
    expect(status.burnRate).toBeCloseTo(1);
    expect(status.violated).toBe(false); // burnRate > 1 才触发
    vi.useRealTimers();
  });

  it('reset 清空全部记录', () => {
    vi.useFakeTimers();
    const m = new SLOMonitor({ windowMs: 60_000 });
    m.recordRequest(1, false);
    m.recordRequest(2, false);
    m.reset();
    const status = m.getStatus();
    expect(status.totalRequests).toBe(0);
    expect(status.errorRate).toBe(0);
    vi.useRealTimers();
  });

  it('getConfig 返回默认配置的副本（修改副本不影响实例）', () => {
    const m = new SLOMonitor();
    const config = m.getConfig();
    expect(config.target).toBe(0.999);
    expect(config.windowMs).toBe(5 * 60 * 1000);
    expect(config.latencyPercentiles).toEqual([0.5, 0.95, 0.99]);
    expect(config.latencyThresholdMs).toBe(5000);
    config.target = 0.5;
    expect(m.getConfig().target).toBe(0.999);
  });

  it('getStatus 返回 timestamp 为 Date 实例', () => {
    vi.useFakeTimers();
    vi.setSystemTime(1_234_567);
    const m = new SLOMonitor();
    m.recordRequest(1, true);
    const status = m.getStatus();
    expect(status.timestamp).toBeInstanceOf(Date);
    expect(status.timestamp.getTime()).toBe(1_234_567);
    vi.useRealTimers();
  });
});

describe('HealthChecker — 健康检查聚合', () => {
  let dir: string;
  let db: any;

  // 模块级 ABI 探测（it.skipIf 在注册期求值，不能依赖 beforeAll）
  let dbAvailable = true;
  try {
    // eslint-disable-next-line @typescript-eslint/no-require-imports
    const Probe = require('better-sqlite3');
    new Probe(':memory:').close();
  } catch {
    dbAvailable = false;
  }

  beforeAll(() => {
    if (dbAvailable) {
      // eslint-disable-next-line @typescript-eslint/no-require-imports
      db = new (require('better-sqlite3'))(':memory:');
    }
  });

  afterAll(() => {
    try {
      db?.close();
    } catch {
      /* ignore */
    }
  });

  beforeEach(() => {
    dir = mkdtempSync(join(tmpdir(), 'metona-health-'));
  });

  afterEach(() => {
    try {
      rmSync(dir, { recursive: true, force: true });
    } catch {
      /* ignore */
    }
  });

  it.skipIf(!dbAvailable)('database 检查：注入 DB 成功执行 ping → healthy', async () => {
    const checker = new HealthChecker(() => db);
    const report = await checker.check();
    const dbCheck = report.checks.find((c) => c.name === 'database');
    expect(dbCheck?.healthy).toBe(true);
    expect(typeof dbCheck?.latencyMs).toBe('number');
  });

  it('database 检查：DB ping 抛错 → unhealthy 且带错误信息', async () => {
    const broken = {
      prepare: () => {
        throw new Error('db closed');
      },
    };
    const checker = new HealthChecker(() => broken as never);
    const report = await checker.check();
    const dbCheck = report.checks.find((c) => c.name === 'database');
    expect(dbCheck?.healthy).toBe(false);
    expect(dbCheck?.error).toContain('db closed');
  });

  it('database 检查：无 DB 注入但 dbPath 存在 → healthy（文件存在后备）', async () => {
    const filePath = join(dir, 'agent.db');
    const { writeFileSync } = await import('fs');
    writeFileSync(filePath, 'sqlite', 'utf-8');
    const checker = new HealthChecker(undefined, filePath);
    const report = await checker.check();
    const dbCheck = report.checks.find((c) => c.name === 'database');
    expect(dbCheck?.healthy).toBe(true);
  });

  it('database 检查：无 DB 且 dbPath 不存在 → unhealthy', async () => {
    const checker = new HealthChecker(undefined, join(dir, 'missing.db'));
    const report = await checker.check();
    const dbCheck = report.checks.find((c) => c.name === 'database');
    expect(dbCheck?.healthy).toBe(false);
    expect(dbCheck?.error).toBe('Database not available');
  });

  it('free_memory 检查：userData 存在 → 返回布尔健康态（v0.7.4 降级，不断言 true）', async () => {
    // 回归修复: 原断言 healthy===true 依赖测试机空闲内存 >200MB，低内存 CI 假失败。
    // 降级为断言"检查存在 + healthy 为布尔"。
    const checker = new HealthChecker();
    const report = await checker.check();
    const memCheck = report.checks.find((c) => c.name === 'free_memory');
    expect(memCheck).toBeDefined();
    expect(typeof memCheck?.healthy).toBe('boolean');
  });

  it('memory_usage 检查：返回布尔健康态（v0.7.4 降级，不断言 true）', async () => {
    const checker = new HealthChecker();
    const report = await checker.check();
    const usageCheck = report.checks.find((c) => c.name === 'memory_usage');
    expect(usageCheck).toBeDefined();
    expect(typeof usageCheck?.healthy).toBe('boolean');
  });

  it('check 返回三项检查且 healthy 为聚合结果（全健康 → true）', async () => {
    const checker = new HealthChecker();
    const report = await checker.check();
    expect(report.checks.map((c) => c.name)).toEqual(['database', 'free_memory', 'memory_usage']);
    // 无 DB 无路径 → database 不健康 → 聚合 unhealthy
    expect(report.healthy).toBe(false);
    expect(report.timestamp).toBeInstanceOf(Date);
  });

  it('所有检查健康时聚合 healthy=true', async () => {
    const filePath = join(dir, 'agent.db');
    const { writeFileSync } = await import('fs');
    writeFileSync(filePath, 'sqlite', 'utf-8');
    const checker = new HealthChecker(undefined, filePath);
    const report = await checker.check();
    expect(report.healthy).toBe(true);
  });
});