const CONFIG = require('./config.js');
const SESSION_TIME = 2 * 1 * 60 * 60 * 1000; // 2h
const SESSION_COOKIE = "_sessionId";
const crypto = require('crypto');
const ldapjs = require('ldapjs');
const ldap = ldapjs.createClient({
    url: [ CONFIG.ldapUrl, CONFIG.ldapUrl ],
    reconnect: true
    });
const MD5 = require('./md5sum.js').string;

let loggedCache = {};

let ldapReady = new Promise((ok, ko) => {
    ldap.on("error", (err) => { console.error("LDAP Error: " +err) });
    ldap.bind(CONFIG.ldapBindDN, CONFIG.ldapBindPwd, (err) => {
        if (err) {
            console.error(err);
            ko(err);
            throw err;
        }
        console.log("LDAP is ready");
        ok();
    });
});

function getSessionId(cookieObject) {
    return cookieObject?.[SESSION_COOKIE];
}

function getSessionObj(cookieObject) {
    let cookie = getSessionId(cookieObject);
    if (!cookie)
        return null;
    let sessionEntry = loggedCache[cookie];
    const now = (new Date()).getTime();
    if (!sessionEntry || sessionEntry.expire < now)
        return null;
    sessionEntry.expire = now + SESSION_TIME;
    return sessionEntry;
}

function getAccessList(cookieObject) {
    let session = getSessionObj(cookieObject);
    if (!session)
        return null;
    return session.accessList;
}

function getRequestIp(req) {
    return req.headers['x-forwarded-for'] || req.socket.remoteAddress;
}

function sign(msg) {
    return crypto.sign('sha256', Buffer.from(msg), decodeKey(CONFIG.privKey)).toString('base64');
}

function Access() {
}
Access.prototype.id = function() { return ""; }

function LinkAccess(linkId) {
    Access.call(this);
    this.linkId = linkId;
}
LinkAccess.prototype = Object.create(Access.prototype);
LinkAccess.prototype.id = function() { return "LINK_"+this.linkId; }

module.exports = {
    getAccessList: getAccessList,
    getRequestIp: getRequestIp,
    createSession: req => {
        const now = Date.now();
        let sessionInfos = {
            loginDateTime: now,
            expire: now + SESSION_TIME,
            accessList: {},
            random: Math.random(),
            userAgent: req.headers['user-agent'],
            ipAddress: getRequestIp(req)
        };
        let sessionKey = MD5(JSON.stringify(sessionInfos));
        sessionInfos.sessionId = sessionKey;
        loggedCache[sessionKey] = sessionInfos;
        req.cookies[SESSION_COOKIE] = sessionKey;
        return { key: sessionKey, accessList: sessionInfos.accessList };
    },
    addLinkToSession: (req, linkId) => {
        let session = getSessionObj(req.cookies);
        if (!session)
            return;
        let accessList = new LinkAccess(linkId);
        session.accessList[accessList.id()] = accessList;
        return session.accessList;
    },
    removeFromSession: (req, accessId) => {
        let session = getSessionObj(req.cookies);
        if (!session)
            return;
        delete session.accessList[accessId];
        return session.accessList;
    },
    SESSION_COOKIE: SESSION_COOKIE
};