import { refresh as refreshRequest } from '@/api/auth.js'
import { isAccessTokenExpiring, session, signOut, updateTokenPair, getSessionRevision } from '@/stores/session.js'
import { requireOnline } from '@/utils/network.js'

let refreshPromise = null
let refreshRevision = null
let redirectingToLogin = false

function responseCode(response) {
	return String(response?.data?.code ?? response?.statusCode ?? '')
}

function isUnauthorized(responseOrError) {
	const statusCode = Number(responseOrError?.statusCode ?? responseOrError?.response?.statusCode ?? 0)
	const code = String(responseOrError?.code ?? responseCode(responseOrError))
	return statusCode === 401 || code === '401' || code === 'A0401'
}

function sessionExpiredError(source) {
	const error = new Error('登录已过期，请重新登录')
	error.code = source?.code || 'A0401'
	error.statusCode = source?.statusCode || 401
	return error
}

function redirectAfterSessionExpiry() {
	if (redirectingToLogin) return
	redirectingToLogin = true
	if (typeof uni !== 'undefined' && typeof uni.showToast === 'function') {
		uni.showToast({ title: '登录已过期，请重新登录', icon: 'none', duration: 2200 })
	}
	if (typeof uni !== 'undefined' && typeof uni.reLaunch === 'function') {
		uni.reLaunch({
			url: '/pages/login/login',
			complete() { setTimeout(() => { redirectingToLogin = false }, 1000) }
		})
	}
}

function expireSession(source, observedRefreshToken = session.refreshToken) {
	if (observedRefreshToken && session.refreshToken && observedRefreshToken !== session.refreshToken) return session.token
	const hadSession = Boolean(session.currentUser || session.token || session.refreshToken)
	signOut()
	if (hadSession) redirectAfterSessionExpiry()
	throw sessionExpiredError(source)
}

function networkError(error, fallback = '网络连接失败') {
	const next = new Error(error?.errMsg || fallback)
	next.network = true
	return next
}

function rawRequest(options, accessToken) {
	const baseUrl = session.apiBase || '/api/platform/v1'
	const headers = { ...(options.header || {}) }
	if (accessToken) headers.Authorization = `Bearer ${accessToken}`
	if (session.requestId) headers['X-Request-Id'] = session.requestId
	return new Promise((resolve, reject) => {
		uni.request({
			...options,
			url: `${baseUrl}${options.url}`,
			header: headers,
			success: resolve,
			fail: (error) => reject(networkError(error))
		})
	})
}

function requireSameSession(revision) {
	if (getSessionRevision() !== revision) throw new Error('登录会话已变更，请重新操作')
}

async function refreshAccessToken() {
	const revision = getSessionRevision()
	const observedRefreshToken = session.refreshToken
	if (!observedRefreshToken) return expireSession(null, observedRefreshToken)
	if (!refreshPromise || refreshRevision !== revision) {
		refreshRevision = revision
		refreshPromise = (async () => {
			if (session.refreshToken !== observedRefreshToken && session.token) return session.token
			try {
				const tokens = await refreshRequest(observedRefreshToken)
				requireSameSession(revision)
				if (session.refreshToken !== observedRefreshToken) {
					if (session.token) return session.token
					throw sessionExpiredError()
				}
				updateTokenPair(tokens)
				redirectingToLogin = false
				return session.token
			} catch (error) {
				requireSameSession(revision)
				if (isUnauthorized(error)) return expireSession(error, observedRefreshToken)
				throw error
			}
		})()
		const pending = refreshPromise
		const release = () => { if (refreshPromise === pending) { refreshPromise = null; refreshRevision = null } }
		pending.then(release, release) // Original pending promise still propagates failures to callers.
	}
	return refreshPromise
}

async function validAccessToken() {
	if (!session.token || isAccessTokenExpiring(session.token)) return refreshAccessToken()
	return session.token
}

export function ensureAccessToken() {
	return validAccessToken()
}

async function runAuthenticated(execute) {
	requireOnline()
	const revision = getSessionRevision()
	let accessToken = await validAccessToken()
	requireSameSession(revision)
	let response = await execute(accessToken)
	requireSameSession(revision)
	if (!isUnauthorized(response)) return response
	accessToken = session.token && session.token !== accessToken ? session.token : await refreshAccessToken()
	requireSameSession(revision)
	const activeRefreshToken = session.refreshToken
	response = await execute(accessToken)
	requireSameSession(revision)
	if (isUnauthorized(response)) expireSession(response, activeRefreshToken)
	return response
}

export function apiRequest(options) {
	return runAuthenticated((accessToken) => rawRequest(options, accessToken)).then((response) => {
		const body = response.data || {}
		const code = responseCode(response)
		if (code !== '200') {
			const error = new Error(body.message || '服务端请求失败')
			error.code = body.code || response.statusCode
			error.statusCode = response.statusCode
			error.requestId = body.requestId || response.header?.['X-Request-Id'] || response.header?.['x-request-id']
			error.traceId = body.traceId || response.header?.['X-Trace-Id'] || response.header?.['x-trace-id']
			throw error
		}
		return body.data
	})
}

export function apiDownload(options) {
	return runAuthenticated((accessToken) => new Promise((resolve, reject) => {
		const headers = { ...(options.header || {}) }
		if (accessToken) headers.Authorization = `Bearer ${accessToken}`
		if (session.requestId) headers['X-Request-Id'] = session.requestId
		uni.downloadFile({ ...options, header: headers, success: resolve, fail: (error) => reject(networkError(error, '文件下载失败')) })
	}))
}

export function apiUpload(options, onProgress) {
	return runAuthenticated((accessToken) => new Promise((resolve, reject) => {
		const headers = { ...(options.header || {}) }
		if (accessToken) headers.Authorization = `Bearer ${accessToken}`
		if (session.requestId) headers['X-Request-Id'] = session.requestId
		const task = uni.uploadFile({ ...options, header: headers, success: resolve, fail: (error) => reject(networkError(error)) })
		if (task && typeof task.onProgressUpdate === 'function' && typeof onProgress === 'function') task.onProgressUpdate(({ progress }) => onProgress(progress))
	}))
}

export { isUnauthorized }