import { fetchPublicSystemParameters, unwrapSystemSettings, type PublicSystemParameters } from '@/api/ops/systemSettings'

export const SystemParameterCode = {
  DeviceOfflineSeconds: 'device_offline_seconds',
  PageRefreshSeconds: 'page_refresh_seconds',
  AlertRecoveryWaitSeconds: 'alert_recovery_wait_seconds',
  MonitoringRetentionDays: 'monitoring_retention_days',
  OperationLogRetentionDays: 'operation_log_retention_days',
  LoginBackgroundRotationSeconds: 'login_background_rotation_seconds',
} as const

const requiredCodes = Object.values(SystemParameterCode)
let cached: PublicSystemParameters | null = null
let loading: Promise<PublicSystemParameters> | null = null

export async function loadSystemParameters(force = false): Promise<PublicSystemParameters> {
  if (cached && !force) return cached
  if (loading && !force) return loading
  loading = fetchPublicSystemParameters().then((response) => {
    const values = unwrapSystemSettings<PublicSystemParameters>(response)
    if (!values || requiredCodes.some((code) => !Number.isInteger(values[code]))) {
      throw new Error('系统参数未完整初始化')
    }
    cached = values
    return values
  })
  try {
    return await loading
  } finally {
    loading = null
  }
}

export async function getSystemParameter(code: (typeof SystemParameterCode)[keyof typeof SystemParameterCode]): Promise<number> {
  const values = await loadSystemParameters()
  const value = values[code]
  if (!Number.isInteger(value)) throw new Error(`系统参数 ${code} 不存在`)
  return value
}

export function invalidateSystemParameters() {
  cached = null
}