let online = true
let listening = false
const listeners = new Set()

function notify() {
	for (const listener of listeners) listener(online)
}

function ensureListening() {
	if (listening || typeof uni === 'undefined') return
	listening = true
	if (typeof uni.onNetworkStatusChange === 'function') {
		uni.onNetworkStatusChange((result) => {
			online = Boolean(result.isConnected)
			notify()
		})
	}
	if (typeof uni.getNetworkType === 'function') {
		uni.getNetworkType({
			success: (result) => {
				online = result.networkType !== 'none'
				notify()
			}
		})
	}
}

export function isOnline() {
	ensureListening()
	return online
}

export function requireOnline(message = '当前网络不可用，请联网后刷新重试') {
	if (!isOnline()) {
		const error = new Error(message)
		error.network = true
		throw error
	}
}

export function watchNetwork(listener) {
	ensureListening()
	listeners.add(listener)
	listener(online)
	return () => listeners.delete(listener)
}