/**
 * WebVPN 会话 Cookie：调用 ic-ctbu-backend-py /webvpnlogin，并可 Redis 缓存。
 */
const crypto = require('crypto')
const axios = require('axios')
const config = require('../../config.json')
const db = require('../../plugin/DataBase/db')
const Redis = require('../../plugin/DataBase/Redis')

const CACHE_PREFIX = 'webvpn_cookie:'
const CACHE_TTL_SEC = 10 * 60

class WebVpnLoginError extends Error {
    constructor(message, { pyCode, pyMsg } = {}) {
        super(message)
        this.name = 'WebVpnLoginError'
        this.pyCode = pyCode
        this.pyMsg = pyMsg
    }
}

function webvpnLoginBaseUrl() {
    const u = config.webvpnLoginBaseUrl || config.url3
    return (u && String(u).replace(/\/$/, '')) || ''
}

function isProbablyVpnLoginHtml(body) {
    if (typeof body !== 'string') return false
    return (
        body.includes('lyuapServer') ||
        body.includes('ivpn') ||
        body.includes('统一身份认证') ||
        body.includes('rump_frontend/login')
    )
}

/**
 * @param {string} createUserUuid
 * @param {string} lepaoStudentNum
 * @returns {Promise<string>}
 */
async function resolveUserAgentFromLepaoAccount(createUserUuid, lepaoStudentNum) {
    if (!createUserUuid || !lepaoStudentNum) return ''
    const rows = await db.query(
        'SELECT userAgent FROM lepao_account WHERE create_user = ? AND student_num = ? LIMIT 1',
        [createUserUuid, lepaoStudentNum]
    )
    const ua = rows?.[0]?.userAgent
    return ua && String(ua).trim() ? String(ua).trim() : ''
}

/**
 * @param {string} ua
 * @returns {string} 拼在 Redis key 后的后缀（含前导冒号）
 */
function cacheKeySuffixForUa(ua) {
    if (!ua) return ':default'
    const h = crypto.createHash('sha256').update(ua, 'utf8').digest('hex').slice(0, 16)
    return `:${h}`
}

/**
 * @param {unknown} err
 * @returns {boolean} 是否应将乐跑账号标为 state=3（统一认证凭证类失败）
 */
function isWebVpnUnifiedAuthCredentialFailure(err) {
    const code = err && typeof err.pyCode === 'number' ? err.pyCode : null
    const msg = String((err && err.pyMsg) || (err && err.message) || '')
    if (code === 401) return true
    if (code === 500) {
        const patterns = ['密码错误', '用户名或密码错误', '用户不存在', '账号或密码', '用户名错误', '帐号或密码']
        return patterns.some((p) => msg.includes(p))
    }
    return false
}

/**
 * @param {string} studentNum
 * @param {string} [createUserUuid]
 * @param {string} [jwUsername]
 */
async function markLepaoUnifiedAuthFailed(studentNum, createUserUuid, jwUsername) {
    const t = Date.now()
    await db.query('UPDATE lepao_account SET state = 3, update_time = ? WHERE student_num = ?', [
        t,
        studentNum
    ])
    if (createUserUuid && jwUsername) {
        try {
            await db.query(
                'UPDATE jw_account SET state = 0, update_time = ? WHERE create_user = ? AND username = ?',
                [t, createUserUuid, jwUsername]
            )
        } catch (_) {
            /* ignore */
        }
        try {
            await invalidateWebVpnCookie(createUserUuid, jwUsername)
        } catch (_) {
            /* ignore */
        }
    }
}

/**
 * WebVPN 凭证校验成功：将教务绑定标为已启用（与教务「激活」同属 state=1）。
 * @param {string} createUserUuid
 * @param {string} jwUsername 学号（教务登录名）
 */
async function markJwUnifiedAuthSucceeded(createUserUuid, jwUsername) {
    const t = Date.now()
    await db.query(
        'UPDATE jw_account SET state = 1, update_time = ? WHERE create_user = ? AND username = ?',
        [t, createUserUuid, jwUsername]
    )
}

/**
 * @param {string} username
 * @param {string} password
 * @param {{ userAgent?: string, createUserUuid?: string, lepaoStudentNum?: string }} [opts]
 */
async function fetchWebVpnCookieFromPy(username, password, opts = {}) {
    const base = webvpnLoginBaseUrl()
    if (!base) {
        throw new Error('未配置 webvpnLoginBaseUrl')
    }
    let ua = ''
    if (opts.userAgent && String(opts.userAgent).trim()) {
        ua = String(opts.userAgent).trim()
    } else if (opts.createUserUuid && opts.lepaoStudentNum) {
        ua = await resolveUserAgentFromLepaoAccount(opts.createUserUuid, opts.lepaoStudentNum)
    }
    const url = `${base}/webvpnlogin`
    const body = { username, password }
    if (ua) body.user_agent = ua
    const res = await axios.post(url, body, { timeout: 120000, proxy: false, validateStatus: () => true })
    const data = res.data
    if (!data || data.code !== 0 || !data.webvpn_cookie) {
        const pyMsg = data?.msg || '统一身份认证登录失败'
        const pyCode = typeof data?.code === 'number' ? data.code : undefined
        throw new WebVpnLoginError(pyMsg, { pyCode, pyMsg })
    }
    return String(data.webvpn_cookie)
}

/**
 * @returns {Promise<{ error: string|null, password?: string }>}
 */
async function resolveJwCredentialForLepao(uuid, jwUsername) {
    const rows = await db.query(
        'SELECT password, state FROM jw_account WHERE create_user = ? AND username = ?',
        [uuid, jwUsername]
    )
    if (!rows || rows.length !== 1 || !rows[0].password) {
        return {
            error: '未绑定统一认证账号，请先在乐跑绑定中填写统一认证密码'
        }
    }
    if (Number(rows[0].state) === 2) {
        return {
            error: '统一认证账号已标记为失效，请重新绑定教务密码'
        }
    }
    return { error: null, password: rows[0].password }
}

/**
 * WebVPN 登录用：仅需已存密码；state 可为 0（待同步）或 1，排除 2（失效）。
 */
async function getJwPasswordForWebVpn(uuid, jwUsername) {
    const rows = await db.query(
        'SELECT password, state FROM jw_account WHERE create_user = ? AND username = ?',
        [uuid, jwUsername]
    )
    if (!rows || rows.length !== 1 || !rows[0].password) {
        throw new Error('未绑定统一认证账号，请先在乐跑绑定中填写统一认证密码')
    }
    if (Number(rows[0].state) === 2) {
        throw new Error('统一认证账号已标记为失效，请重新绑定教务密码')
    }
    return rows[0].password
}

async function assertLepaoJwBindingOrThrow(uuid, jwUsername) {
    const r = await resolveJwCredentialForLepao(uuid, jwUsername)
    if (r.error) throw new Error(r.error)
}

async function getJwPasswordForUser(uuid, jwUsername) {
    const r = await resolveJwCredentialForLepao(uuid, jwUsername)
    if (r.error) throw new Error(r.error)
    return r.password
}

const { syncLepaoStateViaBeforeRun } = require('./lepaoBeforeRunStateSync')

/**
 * @param {string} createUserUuid
 * @param {string} jwUsername 教务登录名
 * @param {{ skipCache?: boolean, skipPostWebVpnLepaoSync?: boolean, logger?: object }} [opts]
 */
async function getWebVpnCookieHeader(createUserUuid, jwUsername, opts = {}) {
    const skipCache = opts.skipCache === true
    const skipPost = opts.skipPostWebVpnLepaoSync === true
    const ua = await resolveUserAgentFromLepaoAccount(createUserUuid, jwUsername)
    const suffix = cacheKeySuffixForUa(ua)
    const key = `${CACHE_PREFIX}${createUserUuid}:${jwUsername}${suffix}`
    if (!skipCache) {
        const cached = await Redis.get(key)
        if (cached) return cached
    }
    const pwd = await getJwPasswordForWebVpn(createUserUuid, jwUsername)
    const cookie = await fetchWebVpnCookieFromPy(jwUsername, pwd, ua ? { userAgent: ua } : {})
    await Redis.set(key, cookie, { EX: CACHE_TTL_SEC })

    await markJwUnifiedAuthSucceeded(createUserUuid, jwUsername)

    if (!skipPost) {
        const accRows = await db.query(
            'SELECT uid, token, school_id, userAgent FROM lepao_account WHERE student_num = ? AND create_user = ? LIMIT 1',
            [jwUsername, createUserUuid]
        )
        const conditionSql = 'student_num = ? AND create_user = ?'
        const queryParams = [jwUsername, createUserUuid]
        try {
            await syncLepaoStateViaBeforeRun({
                studentNum: jwUsername,
                ownerUuid: createUserUuid,
                webvpnCookie: cookie,
                account: accRows?.[0],
                conditionSql,
                queryParams,
                invalidateWebVpn: () => invalidateWebVpnCookie(createUserUuid, jwUsername),
                refreshWebVpnCookie: async () => {
                    try {
                        return await getWebVpnCookieHeader(createUserUuid, jwUsername, {
                            skipCache: true,
                            skipPostWebVpnLepaoSync: true,
                            logger: opts.logger
                        })
                    } catch (e) {
                        if (isWebVpnUnifiedAuthCredentialFailure(e)) {
                            await markLepaoUnifiedAuthFailed(jwUsername, createUserUuid, jwUsername)
                        }
                        throw e
                    }
                },
                logger: opts.logger
            })
        } catch (syncErr) {
            opts.logger?.warn?.(`[WebVPN] 乐跑 token 同步异常 ${jwUsername}: ${syncErr.stack || syncErr}`)
        }
    }

    return cookie
}

/**
 * 清除该用户下该教务账号的 WebVPN Cookie 缓存（含历史无 UA 后缀的 key 与当前 UA 派生 key）。
 * @param {string} createUserUuid
 * @param {string} jwUsername
 */
async function invalidateWebVpnCookie(createUserUuid, jwUsername) {
    const legacyKey = `${CACHE_PREFIX}${createUserUuid}:${jwUsername}`
    await Redis.del(legacyKey)
    const ua = await resolveUserAgentFromLepaoAccount(createUserUuid, jwUsername)
    const suffix = cacheKeySuffixForUa(ua)
    await Redis.del(`${CACHE_PREFIX}${createUserUuid}:${jwUsername}${suffix}`)
    await Redis.del(`${CACHE_PREFIX}${createUserUuid}:${jwUsername}:default`)
}

module.exports = {
    webvpnLoginBaseUrl,
    isProbablyVpnLoginHtml,
    WebVpnLoginError,
    fetchWebVpnCookieFromPy,
    resolveJwCredentialForLepao,
    assertLepaoJwBindingOrThrow,
    getJwPasswordForUser,
    getJwPasswordForWebVpn,
    getWebVpnCookieHeader,
    invalidateWebVpnCookie,
    isWebVpnUnifiedAuthCredentialFailure,
    markLepaoUnifiedAuthFailed,
    markJwUnifiedAuthSucceeded,
    resolveUserAgentFromLepaoAccount,
    CACHE_TTL_SEC
}