import { describe, expect, test } from 'bun:test'
import {
  cpuUsageBetween,
  parseGateway,
  parseMemAvailable,
  parseMemTotal,
  parseNameservers,
} from './host-info.ts'

describe('parseMemTotal', () => {
  test('取 MemTotal 并换算成字节', () => {
    const meminfo = 'MemTotal:  2048000 kB\nMemFree:   100000 kB\nMemAvailable:  512000 kB\n'
    expect(parseMemTotal(meminfo)).toBe(2048000 * 1024)
  })

  test('读不到 /proc/meminfo（非 Linux 平台）返回 null', () => {
    expect(parseMemTotal('')).toBeNull()
  })
})

describe('parseMemAvailable', () => {
  test('取 MemAvailable 并换算成字节', () => {
    const meminfo = 'MemTotal:  2048000 kB\nMemFree:   100000 kB\nMemAvailable:  512000 kB\n'
    expect(parseMemAvailable(meminfo)).toBe(512000 * 1024)
  })

  test('没有这一行（老内核）返回 null', () => {
    expect(parseMemAvailable('MemTotal: 1 kB\nMemFree: 1 kB\n')).toBeNull()
  })
})

describe('parseGateway', () => {
  test('默认路由的网关按小端序倒回来', () => {
    // 0102A8C0 → c0.a8.02.01 → 192.168.2.1
    const table = [
      'Iface\tDestination\tGateway\tFlags\tRefCnt\tUse\tMetric\tMask\t\tMTU\tWindow\tIRTT',
      'eth0\t00000000\t0102A8C0\t0003\t0\t0\t0\t00000000\t0\t0\t0',
      'eth0\t0002A8C0\t00000000\t0001\t0\t0\t0\t00FFFFFF\t0\t0\t0',
    ].join('\n')
    expect(parseGateway(table)).toBe('192.168.2.1')
  })

  test('没有默认路由返回 null', () => {
    const table = 'Iface\tDestination\tGateway\neth0\t0002A8C0\t00000000'
    expect(parseGateway(table)).toBeNull()
  })
})

describe('parseNameservers', () => {
  test('按出现顺序取 nameserver', () => {
    const conf = '# comment\nnameserver 223.5.5.5\nsearch lan\nnameserver 114.114.114.114\n'
    expect(parseNameservers(conf)).toEqual(['223.5.5.5', '114.114.114.114'])
  })
})

describe('cpuUsageBetween', () => {
  test('按两次快照的差值算百分比', () => {
    const usage = cpuUsageBetween({ busy: 100, total: 1000 }, { busy: 350, total: 2000 })
    expect(usage).toBe(25)
  })

  test('时间没有前进时返回 null', () => {
    expect(cpuUsageBetween({ busy: 1, total: 10 }, { busy: 1, total: 10 })).toBeNull()
  })
})