'use strict';

exports = module.exports = {
    start,
    stop,

    checkCertificate,

    validateConfig,
    applyConfig
};

const assert = require('assert'),
    BoxError = require('./boxerror.js'),
    constants = require('./constants.js'),
    debug = require('debug')('box:directoryserver'),
    eventlog = require('./eventlog.js'),
    groups = require('./groups.js'),
    ldap = require('ldapjs'),
    path = require('path'),
    paths = require('./paths.js'),
    reverseProxy = require('./reverseproxy.js'),
    safe = require('safetydance'),
    settings = require('./settings.js'),
    shell = require('./shell.js'),
    users = require('./users.js'),
    util = require('util'),
    validator = require('validator');

let gServer = null, gCertificate = null;

const NOOP = function () {};

const SET_LDAP_ALLOWLIST_CMD = path.join(__dirname, 'scripts/setldapallowlist.sh');

async function validateConfig(config) {
    const { enabled, secret, allowlist } = config;

    if (!enabled) return;

    if (!secret) throw new BoxError(BoxError.BAD_FIELD, 'secret cannot be empty');

    let gotOne = false;
    for (const line of allowlist.split('\n')) {
        if (!line || line.startsWith('#')) continue;
        const rangeOrIP = line.trim();
        // this checks for IPv4 and IPv6
        if (!validator.isIP(rangeOrIP) && !validator.isIPRange(rangeOrIP)) throw new BoxError(BoxError.BAD_FIELD, `${rangeOrIP} is not a valid IP or range`);
        gotOne = true;
    }

    // only allow if we at least have one allowed IP/range
    if (!gotOne) throw new BoxError(BoxError.BAD_FIELD, 'allowlist must at least contain one IP or range');
}

async function applyConfig(config) {
    assert.strictEqual(typeof config, 'object');

    // this is done only because it's easier for the shell script and the firewall service to get the value
    if (config.enabled) {
        if (!safe.fs.writeFileSync(paths.LDAP_ALLOWLIST_FILE, config.allowlist + '\n', 'utf8')) throw new BoxError(BoxError.FS_ERROR, safe.error.message);
    } else {
        safe.fs.unlinkSync(paths.LDAP_ALLOWLIST_FILE);
    }

    const [error] = await safe(shell.promises.sudo('setLdapAllowlist', [ SET_LDAP_ALLOWLIST_CMD ], {}));
    if (error) throw new BoxError(BoxError.IPTABLES_ERROR, `Error setting ldap allowlist: ${error.message}`);

    if (config.enabled) await start(); else await stop();
}

// helper function to deal with pagination
function finalSend(results, req, res, next) {
    let min = 0;
    let max = results.length;
    let cookie = null;
    let pageSize = 0;

    // check if this is a paging request, if so get the cookie for session info
    req.controls.forEach(function (control) {
        if (control.type === ldap.PagedResultsControl.OID) {
            pageSize = control.value.size;
            cookie = control.value.cookie;
        }
    });

    function sendPagedResults(start, end) {
        start = (start < min) ? min : start;
        end = (end > max || end < min) ? max : end;
        let i;

        for (i = start; i < end; i++) {
            res.send(results[i]);
        }

        return i;
    }

    if (cookie && Buffer.isBuffer(cookie)) {
        // we have pagination
        let first = min;
        if (cookie.length !== 0) {
            first = parseInt(cookie.toString(), 10);
        }
        const last = sendPagedResults(first, first + pageSize);

        let resultCookie;
        if (last < max) {
            resultCookie = Buffer.from(last.toString());
        } else {
            resultCookie = Buffer.from('');
        }

        res.controls.push(new ldap.PagedResultsControl({
            value: {
                size: pageSize, // correctness not required here
                cookie: resultCookie
            }
        }));
    } else {
        // no pagination simply send all
        results.forEach(function (result) {
            res.send(result);
        });
    }

    // all done
    res.end();
    next();
}

async function authorize(req, res, next) {
    debug('authorize: ', req.connection.ldap.bindDN.toString());

    // this is for connection attempts without previous bind
    if (req.connection.ldap.bindDN.equals('cn=anonymous')) return next(new ldap.InsufficientAccessRightsError());

    // we only allow this one DN to pass
    if (!req.connection.ldap.bindDN.equals(constants.USER_DIRECTORY_LDAP_DN)) return next(new ldap.InsufficientAccessRightsError());

    return next();
}

// https://ldapwiki.com/wiki/RootDSE / RFC 4512 - ldapsearch -x -h "${CLOUDRON_LDAP_SERVER}" -p "${CLOUDRON_LDAP_PORT}" -b  "" -s base
// ldapjs seems to call this handler for everything when search === ''
async function maybeRootDSE(req, res, next) {
    debug(`maybeRootDSE: requested with scope:${req.scope} dn:${req.dn.toString()}`);

    if (req.scope !== 'base') return next(new ldap.NoSuchObjectError()); // per the spec, rootDSE search require base scope
    if (!req.dn || req.dn.toString() !== '') return next(new ldap.NoSuchObjectError());

    res.send({
        dn: '',
        attributes: {
            objectclass: [ 'RootDSE', 'top', 'OpenLDAProotDSE' ],
            supportedLDAPVersion: '3',
            vendorName: 'Cloudron LDAP',
            vendorVersion: '1.0.0'
        }
    });
    res.end();
}

async function userSearch(req, res, next) {
    debug('user search: dn %s, scope %s, filter %s (from %s)', req.dn.toString(), req.scope, req.filter.toString(), req.connection.ldap.id);

    const [error, allUsers] = await safe(users.list());
    if (error) return next(new ldap.OperationsError(error.toString()));

    const [groupsError, allGroups] = await safe(groups.listWithMembers());
    if (groupsError) return next(new ldap.OperationsError(error.toString()));

    let results = [];

    // send user objects
    for (const user of allUsers) {
        // skip entries with empty username. Some apps like owncloud can't deal with this
        if (!user.username) continue;

        const dn = ldap.parseDN(`cn=${user.id},ou=users,dc=cloudron`);

        const displayName = user.displayName || user.username || ''; // displayName can be empty and username can be null
        const nameParts = displayName.split(' ');
        const firstName = nameParts[0];
        const lastName = nameParts.length > 1  ? nameParts[nameParts.length - 1] : ''; // choose last part, if it exists

        const obj = {
            dn: dn.toString(),
            attributes: {
                objectclass: ['user', 'inetorgperson', 'person' ],
                objectcategory: 'person',
                cn: displayName,
                uid: user.id,
                entryuuid: user.id, // to support OpenLDAP clients
                mail: user.email,
                mailAlternateAddress: user.fallbackEmail,
                displayname: displayName,
                givenName: firstName,
                username: user.username,
                samaccountname: user.username,      // to support ActiveDirectory clients
                memberof: allGroups.filter(function (g) { return g.userIds.indexOf(user.id) !== -1; }).map(function (g) { return `cn=${g.name},ou=groups,dc=cloudron`; })
            }
        };

        if (user.twoFactorAuthenticationEnabled) obj.attributes.twoFactorAuthenticationEnabled = true;

        // http://www.zytrax.com/books/ldap/ape/core-schema.html#sn has 'name' as SUP which is a DirectoryString
        // which is required to have atleast one character if present
        if (lastName.length !== 0) obj.attributes.sn = lastName;

        // ensure all filter values are also lowercase
        const lowerCaseFilter = safe(function () { return ldap.parseFilter(req.filter.toString().toLowerCase()); }, null);
        if (!lowerCaseFilter) return next(new ldap.OperationsError(safe.error.toString()));

        if ((req.dn.equals(dn) || req.dn.parentOf(dn)) && lowerCaseFilter.matches(obj.attributes)) {
            results.push(obj);
        }
    }

    finalSend(results, req, res, next);
}

async function groupSearch(req, res, next) {
    debug('group search: dn %s, scope %s, filter %s (from %s)', req.dn.toString(), req.scope, req.filter.toString(), req.connection.ldap.id);

    const [error, allUsers] = await safe(users.list());
    if (error) return next(new ldap.OperationsError(error.toString()));

    const results = [];

    let [errorGroups, allGroups] = await safe(groups.listWithMembers());
    if (errorGroups) return next(new ldap.OperationsError(errorGroups.toString()));

    for (const group of allGroups) {
        const dn = ldap.parseDN(`cn=${group.name},ou=groups,dc=cloudron`);
        const members = group.userIds.filter(function (uid) { return allUsers.map(function (u) { return u.id; }).indexOf(uid) !== -1; });

        const obj = {
            dn: dn.toString(),
            attributes: {
                objectclass: ['group'],
                cn: group.name,
                gidnumber: group.id,
                memberuid: members
            }
        };

        // ensure all filter values are also lowercase
        const lowerCaseFilter = safe(function () { return ldap.parseFilter(req.filter.toString().toLowerCase()); }, null);
        if (!lowerCaseFilter) return next(new ldap.OperationsError(safe.error.toString()));

        if ((req.dn.equals(dn) || req.dn.parentOf(dn)) && lowerCaseFilter.matches(obj.attributes)) {
            results.push(obj);
        }
    }

    finalSend(results, req, res, next);
}

// Will attach req.user if successful
async function userAuth(req, res, next) {
    // extract the common name which might have different attribute names
    const cnAttributeName = Object.keys(req.dn.rdns[0].attrs)[0];
    const commonName = req.dn.rdns[0].attrs[cnAttributeName].value;
    if (!commonName) return next(new ldap.NoSuchObjectError(req.dn.toString()));

    const TOTPTOKEN_ATTRIBUTE_NAME = 'totptoken'; // This has to be in-sync with externalldap.js
    const totpToken = req.dn.rdns[0].attrs[TOTPTOKEN_ATTRIBUTE_NAME] ? req.dn.rdns[0].attrs[TOTPTOKEN_ATTRIBUTE_NAME].value : null;

    let verifyFunc;
    if (cnAttributeName === 'mail') {
        verifyFunc = users.verifyWithEmail;
    } else if (commonName.indexOf('@') !== -1) { // if mail is specified, enforce mail check
        verifyFunc = users.verifyWithEmail;
    } else if (commonName.indexOf('uid-') === 0) {
        verifyFunc = users.verify;
    } else {
        verifyFunc = users.verifyWithUsername;
    }

    const [error, user] = await safe(verifyFunc(commonName, req.credentials || '', '', { relaxedTotpCheck: true, totpToken }));
    if (error && error.reason === BoxError.NOT_FOUND) return next(new ldap.NoSuchObjectError(req.dn.toString()));
    if (error && error.reason === BoxError.INVALID_CREDENTIALS) return next(new ldap.InvalidCredentialsError(req.dn.toString()));
    if (error) return next(new ldap.OperationsError(error.message));

    req.user = user;

    next();
}

async function start() {
    if (gServer) return; // already running

    const logger = {
        trace: NOOP,
        debug: NOOP,
        info: debug,
        warn: debug,
        error: debug,
        fatal: debug
    };

    gCertificate = await reverseProxy.getDirectoryServerCertificate();

    gServer = ldap.createServer({
        certificate: gCertificate.cert,
        key: gCertificate.key,
        log: logger
    });

    gServer.on('error', function (error) {
        debug('server startup error: %o', error);
    });

    gServer.bind('ou=system,dc=cloudron', async function(req, res, next) {
        debug('system bind: %s (from %s)', req.dn.toString(), req.connection.ldap.id);

        const tmp = await settings.getDirectoryServerConfig();

        if (!req.dn.equals(constants.USER_DIRECTORY_LDAP_DN)) return next(new ldap.InvalidCredentialsError(req.dn.toString()));
        if (req.credentials !== tmp.secret) return next(new ldap.InvalidCredentialsError(req.dn.toString()));

        req.user = { user: 'directoryServerAdmin' };

        res.end();

        // if we use next in the callback, ldapjs requires this after res.end();
        return next();
    });

    gServer.search('ou=users,dc=cloudron', authorize, userSearch);
    gServer.search('ou=groups,dc=cloudron', authorize, groupSearch);
    gServer.bind('ou=users,dc=cloudron', userAuth, async function (req, res) {
        assert.strictEqual(typeof req.user, 'object');

        await eventlog.upsertLoginEvent(req.user.ghost ? eventlog.ACTION_USER_LOGIN_GHOST : eventlog.ACTION_USER_LOGIN, { authType: 'directoryserver', id: req.connection.ldap.id }, { userId: req.user.id, user: users.removePrivateFields(req.user) });

        res.end();
    });

    gServer.search('', maybeRootDSE); // when '', it seems the callback is called for everything else

    // just log that an attempt was made to unknown route, this helps a lot during app packaging
    gServer.use(function(req, res, next) {
        debug('not handled: dn %s, scope %s, filter %s (from %s)', req.dn ? req.dn.toString() : '-', req.scope, req.filter ? req.filter.toString() : '-', req.connection.ldap.id);
        return next();
    });

    debug(`starting server on port ${constants.USER_DIRECTORY_LDAPS_PORT}`);
    await util.promisify(gServer.listen.bind(gServer))(constants.USER_DIRECTORY_LDAPS_PORT, '::');
}

async function stop() {
    if (!gServer) return;

    debug('stopping server');

    gServer.close();
    gServer = null;
}

async function checkCertificate() {
    const certificate = await reverseProxy.getDirectoryServerCertificate();
    if (certificate.cert === gCertificate.cert) {
        debug('checkCertificate: certificate has not changed');
        return;
    }

    debug('checkCertificate: certificate changed. restarting');
    await stop();
    await start();
}