require('require-yaml');
const Docker = require('dockerode');
const handlebars = require('handlebars');
const ssh = require('node-ssh');
const fs = require('fs-extra');
const shajs = require('sha.js');
const conf = require('./config.yml');
const package = require('./package.json');

let docker;
let template;
let lastInfoHash;
const appName = package.name;
const isProduction = process.env.NODE_ENV === 'production';
const tmpDir = isProduction ? `/tmp/${appName}` : `${__dirname}/tmp`;
const hashFile = `${tmpDir}/config.hash`;
const confDir = conf.rproxy.confDir;

async function updateProxy(firstRun) {
    console.log('Updating reverse proxy configuration.');

    // Obtaining Docker settings

    let info;

    if (!isProduction) {
        info = require('./test.json');
    } else {
        info = {
            services: await docker.listServices(),
            nodes: await docker.listNodes()
        };
    }

    function sortFn(a, b) {
        return a.name > b.name ? 1 : a.name < b.name ? -1 : 0;
    }

    const nodes = [];
    for (const node of info.nodes) {
        const address = node.ManagerStatus
            ? node.ManagerStatus.Addr.split(':')[0]
            : node.Status.Addr;
        const role = node.Spec && node.Spec.Role

        nodes.push({
            name: node.Description.Hostname,
            address,
            isWorker: role == 'worker'
        });
    }
    nodes.sort(sortFn);

    const services = [];
    for (const service of info.services) {
        const ports = service.Endpoint.Ports;
        if (!Array.isArray(ports) || !ports.length) continue;

        let name = service.Spec.Name;
        const match = name.match(/^(.+)_main$/);
        if (match) name = match[1];

        const port = ports[0];
        const protocol = port.Protocol;

        services.push({
            name,
            port: port.PublishedPort,
            protocol,
            isTcp: protocol == 'tcp'
        });
    }
    services.sort(sortFn);

    const configString = template({
        services,
        nodes,
        info
    });

    // Cheking settings hash

    const infoHash = shajs('sha256')
        .update(configString)
        .digest('hex');
    console.log('Settings hash:', infoHash);

    if (lastInfoHash == infoHash && !firstRun) {
        console.log(`Settings haven't changed, aborting.`);
        return;
    }

    // Creating configuration file

    const tmpConf = `${tmpDir}/config.cfg`;
    fs.writeFileSync(tmpConf, configString);

    if (conf.debug) {
        const delimiter = '#' + '='.repeat(79);
        console.log(delimiter);
        console.log(`# ${confDir}`);
        console.log(delimiter);
        console.log(configString);
        console.log(delimiter);
    }

    // Updating reverse proxies

    const files = {
        local: tmpConf,
        remote: `${confDir}/haproxy.cfg`
    };

    for (const host of conf.rproxy.hosts) {
        console.log(`Updating host: ${host}`);
        if (!isProduction) continue;

        const sshClient = new ssh();
        await sshClient.connect(Object.assign({host}, conf.rproxy.auth));
        await sshClient.putFiles([files]);
        if (firstRun)
            await sshClient.putDirectory(
                `${tmpDir}/maps`,
                `${confDir}/maps`,
                {recursive: true}
            );
        if (conf.rproxy.reloadCmd)
            await sshClient.exec(conf.rproxy.reloadCmd);
        await sshClient.dispose();
    }

    // Saving applied config hash

    lastInfoHash = infoHash;
    fs.writeFileSync(hashFile, infoHash);

    console.log('Configuration updated.');
}

(async() => {
    console.log('Initializing.');
    let timeoutId;
    docker = new Docker(conf.docker);
    template = handlebars.compile(fs.readFileSync('rproxy.handlebars', 'utf8'));

    try {
        fs.mkdirSync(tmpDir);
    } catch (err) {
        if (err.code != 'EEXIST') throw err;
    }

    if (fs.existsSync(hashFile)) {
        lastInfoHash = fs.readFileSync(hashFile, 'utf8');
        console.log('Saved settings hash:', lastInfoHash);
    }

    // Fetch backends

    const hostMap = [];
    const baseMap = [];
    const https = [];
    const zoneMap = [];
    const zones = new Set();

    for (const domain in conf.domains) {
        const domainConf = conf.domains[domain];
        for (const service in domainConf)
            addService(service, domainConf[service], domain);
    }

    function addService(service, serviceConf, mainDomain) {
        let rules;
        if (typeof serviceConf == 'string') {
            rules = serviceConf;
            serviceConf = undefined;
        }

        serviceConf = Object.assign({},
            conf.defaults,
            serviceConf
        );

        if (serviceConf.https)
            https.push(service);
        if (serviceConf.zone) {
            zoneMap.push([service,  serviceConf.zone]);
            zones.add(serviceConf.zone);
        }

        rules = rules || serviceConf.rules;

        if (!rules)
            rules = service;
        if (!Array.isArray(rules))
            rules = [rules];

        for (let rule of rules) {
            if (typeof rule == 'string')
                rule = {domain: rule};

            let domains = rule.domain;
            let paths = rule.path;
            if (!Array.isArray(domains))
                domains = [domains];
            if (!Array.isArray(paths))
                paths = [paths];

            for (const domain of domains) {
            for (const path of paths) {
                const fullDomain = domain && domain !== '$'
                    ? `${domain}.${mainDomain}`
                    : mainDomain;
                if (!path)
                    hostMap.push([fullDomain, service]);
                else
                    baseMap.push([fullDomain + path, service]);
            }}
        }
    }

    // Fetch ACLs

    const aclMap = [];
    const acls = [];

    for (const acl in conf.acls) {
        const aclConf = conf.acls[acl];

        const ips = [];
        for (const ip of aclConf.ips) {
            aclMap.push([ip, acl]);
            ips.push(parseNet(ip));
        }

        acls.push({
            name: acl,
            ips,
            zones: aclConf.zones === 'all'
                ? new Set(zones)
                : new Set(aclConf.zones)
        });
    }

    function parseNet(net) {
        const netSplit = net.split('/');
        const mask = parseInt(netSplit[1]);
        const ip = netSplit[0].split('.')
            .reduce((ipInt, octet) => (ipInt<<8) + parseInt(octet, 10), 0) >>> 0;
        return {ip, mask};
    }

    for (const aAcl of acls) {
    for (const aNet of aAcl.ips) {
    for (const bAcl of acls) {
        if (aAcl === bAcl) continue;
        let match = false;
        for (const bNet of bAcl.ips) {
            match = bNet.mask === 0;
            if (bNet.mask > 0 && bNet.mask <= aNet.mask) {
                const netMask = (~0) << (32 - bNet.mask);
                const aSubnet = aNet.ip & netMask;
                const bSubnet = bNet.ip & netMask;
                match = aSubnet === bSubnet;
            }
            if (match) break;
        }
        if (match) {
            for (const zone of bAcl.zones)
                aAcl.zones.add(zone);
        }
    }}}

    const accessMap = [];
    for (const acl of acls)
    for (const zone of acl.zones)
        accessMap.push(`${acl.name}/${zone}`);

    // Generate maps

    const files = {
        host: hostMap,
        base: baseMap,
        zone: zoneMap,
        acl: aclMap,
        access: accessMap,
        https: https
    };

    function strSortFn(a, b) {
        return a[0] < b[0] ? -1 : a[0] > b[0] ? 1 : 0;
    }
    function netSortFn(a, b) {
        const aMask = parseInt(a[0].split('/')[1], 10);
        const bMask = parseInt(b[0].split('/')[1], 10);
        return bMask - aMask;
    }

    const mapDir = `${tmpDir}/maps`;
    if (await fs.pathExists(mapDir))
        await fs.remove(mapDir, {recursive: true});
    await fs.mkdir(mapDir);

    for (const file in files) {
        files[file].sort(file == 'acl'
            ? netSortFn
            : strSortFn
        );

        const fd = await fs.open(`${mapDir}/${file}.map`, 'w+');
        for (const map of files[file]) {
            if (Array.isArray(map))
                await fs.write(fd, `${map[0]} ${map[1]}\n`);
            else
                await fs.write(fd, `${map}\n`);
        }
        await fs.close(fd);
    }

    // Initalize

    await updateProxy(true);

    console.log('Listening for events.')
    docker.getEvents({}, (err, stream) => {
        if (err || !stream) {
            console.error('Failed to monitor docker host', err);
            return;
        }

        stream.on('data', event => {
            event = JSON.parse(event);
            if (conf.events && conf.events.indexOf(event.Type) == -1) return;
            console.log(`Event: ${event.Type}: ${event.Action}`);

            if (timeoutId) return;
            timeoutId = setTimeout(async () => {
                timeoutId = null;
                await updateProxy();
            }, conf.delay * 1000);
        })
    });
})();