'use strict';

const config = require('wild-config');
const fs = require('fs');
const tls = require('tls');
const db = require('./db');
const tlsOptions = require('../imap-core/lib/tls-options');
const CertHandler = require('./cert-handler');

const certs = new Map();
const servers = [];
const ctxCache = new Map();

let certHandler;

module.exports.reload = () => {
    // load certificate files
    [false, 'imap', 'lmtp', 'pop3', 'api', 'api.mobileconfig'].forEach(type => {
        let tlsconf = config.tls;

        if (type) {
            let path = (type + '.tls').split('.');
            tlsconf = config;
            for (let i = 0; i < path.length; i++) {
                let key = path[i];
                if (!tlsconf[key]) {
                    tlsconf = false;
                    break;
                }
                tlsconf = tlsconf[key];
            }
            if (!tlsconf || !tlsconf.key) {
                tlsconf = config.tls;
            }
        }

        if (!tlsconf) {
            return;
        }

        let key, cert, ca, dhparam;

        if (tlsconf.key) {
            key = fs.readFileSync(tlsconf.key, 'ascii');
        }

        if (!key) {
            return;
        }

        if (tlsconf.cert) {
            cert = fs.readFileSync(tlsconf.cert, 'ascii');
        }

        if (tlsconf.dhparam) {
            dhparam = fs.readFileSync(tlsconf.dhparam, 'ascii');
        }

        if (tlsconf.ca) {
            ca = [].concat(tlsconf.ca || []).map(ca => fs.readFileSync(ca, 'ascii'));
            if (!ca.length) {
                ca = false;
            }
        }

        certs.set(type || 'default', {
            key,
            cert,
            ca,
            dhparam
        });
    });

    if (!certs.has('default')) {
        certs.set('default', {
            key: fs.readFileSync(__dirname + '/../certs/example.key', 'ascii'),
            cert: fs.readFileSync(__dirname + '/../certs/example.cert', 'ascii'),
            ca: false
        });
    }
};

module.exports.reload();

module.exports.get = type => (certs.has(type) ? certs.get(type) : certs.get('default')) || false;

module.exports.loadTLSOptions = (serverOptions, name) => {
    Object.keys(config[name].tls || {}).forEach(key => {
        if (!['key', 'cert', 'ca', 'dhparam'].includes(key)) {
            serverOptions[key] = config[name].tls[key];
        }
    });

    let serverCerts = module.exports.get(name);

    if (serverCerts) {
        serverOptions.key = serverCerts.key;

        if (serverCerts.ca) {
            serverOptions.ca = serverCerts.ca;
        }

        serverOptions.cert = serverCerts.cert;

        if (serverCerts.dhparam) {
            serverOptions.dhparam = serverCerts.dhparam;
        }
    }
};

module.exports.registerReload = (server, name) => {
    servers.push({ server, name });
};

module.exports.getContextForServername = async (servername, serverOptions) => {
    const query = { servername };
    let cachedContext = false;
    if (ctxCache.has(servername)) {
        cachedContext = ctxCache.get(servername);
        if (cachedContext.entry && cachedContext.entry.v) {
            // check for updates
            query.v = { $ne: cachedContext.entry.v };
        }
    }

    const certData = await db.database.collection('certs').findOne(query);
    if (!certData) {
        return (cachedContext && cachedContext.context) || false;
    }

    if (!certHandler) {
        certHandler = new CertHandler({
            cipher: config.certs && config.certs.cipher,
            secret: config.certs && config.certs.secret,
            database: db.database,
            redis: db.redis
        });
    }

    // key might be encrypted
    let privateKey = certHandler.decodeKey(certData.privateKey);

    let serviceCtxOpts = { key: privateKey, cert: certData.cert };
    for (let key of ['dhparam']) {
        if (serverOptions[key]) {
            serviceCtxOpts[key] = serverOptions[key];
        }
    }

    let ctxOptions = tlsOptions(serviceCtxOpts);

    let context = tls.createSecureContext(ctxOptions);

    ctxCache.set(servername, { entry: certData, context });

    return context;
};

config.on('reload', () => {
    module.exports.reload();
    servers.forEach(entry => {
        let serverCerts = certs.get(entry.name);
        let certOptions = {};
        if (serverCerts) {
            certOptions.key = serverCerts.key;
            if (serverCerts.ca) {
                certOptions.ca = serverCerts.ca;
            }
            certOptions.cert = serverCerts.cert;
            if (serverCerts.dhparam) {
                certOptions.dhparam = serverCerts.dhparam;
            }
            entry.server.updateSecureContext(certOptions);
        }
    });
});