import { buildA7Packets } from '../core/packet'

/**
 * 校验 WiFi 入参，规则来源于 profile.wifi。
 */
function validateWifi(profile, ssid, password) {
  const errors = []

  if (!ssid || ssid.length > profile.wifi.maxSsidLength) {
    errors.push(`SSID 长度需在 1-${profile.wifi.maxSsidLength} 之间`)
  }

  if (password.length < profile.wifi.minPasswordLength || password.length > profile.wifi.maxPasswordLength) {
    errors.push(`密码长度需在 ${profile.wifi.minPasswordLength}-${profile.wifi.maxPasswordLength} 之间`)
  }

  const invalidChars = profile.wifi.invalidChars || []
  if (invalidChars.some((char) => ssid.includes(char))) {
    errors.push(`SSID 不能包含特殊字符: ${invalidChars.join(' ')}`)
  }

  if (errors.length) {
    throw new Error(errors.join('；'))
  }
}

/**
 * 监听协议状态通知，等待 WiFi 配网状态码返回。
 */
function waitForWifiState(ble, timeout = 8000) {
  return new Promise((resolve, reject) => {
    let timer = null
    let off = null

    const clearAll = () => {
      if (timer) {
        clearTimeout(timer)
      }

      if (off) {
        off()
      }
    }

    timer = setTimeout(() => {
      clearAll()
      reject(new Error('等待 WiFi 状态超时'))
    }, timeout)

    off = ble.on('protocol:state', (payload) => {
      if (![1, 2, 3, 4].includes(payload.stateCode)) {
        return
      }

      clearAll()
      resolve(payload.stateCode)
    })
  })
}

/**
 * WiFi 配网模块：负责打包并发送 ssid|password，随后等待状态通知。
 */
export function createWifiModule(ble) {
  async function configureWifi(ssid, password, options = {}) {
    const profile = ble.getProfile()
    const targetSsid = String(ssid || '')
    const targetPass = String(password || '')

    validateWifi(profile, targetSsid, targetPass)

    const { wifi } = ble.getState().characteristics
    if (!wifi || !wifi.uuid) {
      throw new Error('未发现 UUID_WIFI 特征值')
    }

    const payload = `${targetSsid}|${targetPass}`
    const packets = buildA7Packets(payload, profile.packet)

    // 按分包顺序逐包发送，保持设备端解析一致性。
    for (const packet of packets) {
      await ble.writeCharacteristic(wifi.uuid, packet)
    }

    const stateCode = await waitForWifiState(ble, options.timeout || 8000)

    return {
      success: stateCode === 3,
      stateCode
    }
  }

  return {
    configureWifi
  }
}