'use strict';

module.exports = exports = {
    fqdn,
    getName,

    getDnsRecords,
    upsertDnsRecords,
    removeDnsRecords,

    waitForDnsRecord,
    waitForLocations,

    validateHostname,

    makeWildcard,

    registerLocations,
    unregisterLocations,

    checkDnsRecords,
    syncDnsRecords,
    startSyncDnsRecords
};

const apps = require('./apps.js'),
    assert = require('assert'),
    BoxError = require('./boxerror.js'),
    constants = require('./constants.js'),
    dashboard = require('./dashboard.js'),
    debug = require('debug')('box:dns'),
    domains = require('./domains.js'),
    ipaddr = require('ipaddr.js'),
    mail = require('./mail.js'),
    mailServer = require('./mailserver.js'),
    network = require('./network.js'),
    promiseRetry = require('./promise-retry.js'),
    safe = require('safetydance'),
    tasks = require('./tasks.js'),
    tld = require('tldjs');

// choose which subdomain backend we use for test purpose we use route53
function api(provider) {
    assert.strictEqual(typeof provider, 'string');

    switch (provider) {
    case 'bunny': return require('./dns/bunny.js');
    case 'cloudflare': return require('./dns/cloudflare.js');
    case 'desec': return require('./dns/desec.js');
    case 'dnsimple': return require('./dns/dnsimple.js');
    case 'route53': return require('./dns/route53.js');
    case 'gcdns': return require('./dns/gcdns.js');
    case 'digitalocean': return require('./dns/digitalocean.js');
    case 'gandi': return require('./dns/gandi.js');
    case 'godaddy': return require('./dns/godaddy.js');
    case 'inwx': return require('./dns/inwx.js');
    case 'linode': return require('./dns/linode.js');
    case 'vultr': return require('./dns/vultr.js');
    case 'namecom': return require('./dns/namecom.js');
    case 'namecheap': return require('./dns/namecheap.js');
    case 'netcup': return require('./dns/netcup.js');
    case 'hetzner': return require('./dns/hetzner.js');
    case 'noop': return require('./dns/noop.js');
    case 'manual': return require('./dns/manual.js');
    case 'ovh': return require('./dns/ovh.js');
    case 'porkbun': return require('./dns/porkbun.js');
    case 'wildcard': return require('./dns/wildcard.js');
    default: return null;
    }
}

function fqdn(subdomain, domain) {
    assert.strictEqual(typeof subdomain, 'string');
    assert.strictEqual(typeof domain, 'string');

    return subdomain + (subdomain ? '.' : '') + domain;
}

// Hostname validation comes from RFC 1123 (section 2.1)
// Domain name validation comes from RFC 2181 (Name syntax)
// https://en.wikipedia.org/wiki/Hostname#Restrictions_on_valid_host_names
// We are validating the validity of the location-fqdn as host name (and not dns name)
function validateHostname(subdomain, domain) {
    assert.strictEqual(typeof subdomain, 'string');
    assert.strictEqual(typeof domain, 'string');

    const hostname = fqdn(subdomain, domain);

    // workaround https://github.com/oncletom/tld.js/issues/73
    const tmp = hostname.replace('_', '-');
    if (!tld.isValid(tmp)) return new BoxError(BoxError.BAD_FIELD, 'Hostname is not a valid domain name');

    if (hostname.length > 253) return new BoxError(BoxError.BAD_FIELD, 'Hostname length exceeds 253 characters');

    if (subdomain) {
        // label validation
        if (subdomain.split('.').some(function (p) { return p.length > 63 || p.length < 1; })) return new BoxError(BoxError.BAD_FIELD, 'Invalid subdomain length');
        if (subdomain.match(/^[A-Za-z0-9-.]+$/) === null) return new BoxError(BoxError.BAD_FIELD, 'Subdomain can only contain alphanumeric, hyphen and dot');
        if (/^[-.]/.test(subdomain)) return new BoxError(BoxError.BAD_FIELD, 'Subdomain cannot start or end with hyphen or dot');
    }

    return null;
}

// returns the 'name' that needs to be inserted into zone
// eslint-disable-next-line no-unused-vars
function getName(domain, subdomain, type) {
    const part = domain.domain.slice(0, -domain.zoneName.length - 1);

    if (subdomain === '') return part;

    return part ? `${subdomain}.${part}` : subdomain;
}

async function getDnsRecords(subdomain, domain, type) {
    assert.strictEqual(typeof subdomain, 'string');
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof type, 'string');

    const domainObject = await domains.get(domain);
    return await api(domainObject.provider).get(domainObject, subdomain, type);
}

async function checkDnsRecords(subdomain, domain) {
    assert.strictEqual(typeof subdomain, 'string');
    assert.strictEqual(typeof domain, 'string');

    const cnameRecords = await getDnsRecords(subdomain, domain, 'CNAME');
    if (cnameRecords.length !== 0) return { needsOverwrite: true };

    const ipv4 = await network.getIPv4();
    if (ipv4) {
        const ipv4Records = await getDnsRecords(subdomain, domain, 'A');

        // if empty OR exactly one record with the ip, we don't need to overwrite
        if (ipv4Records.length !== 0 && (ipv4Records.length !== 1 || ipv4Records[0] !== ipv4)) return { needsOverwrite: true };
    }

    const ipv6 = await network.getIPv6();
    if (ipv6) {
        const ipv6Records = await getDnsRecords(subdomain, domain, 'AAAA');

        // if empty OR exactly one record with the ip, we don't need to overwrite
        if (ipv6Records.length !== 0 && (ipv6Records.length !== 1 || ipaddr.parse(ipv6Records[0]).toRFC5952String() !== ipv6)) return { needsOverwrite: true };
    }

    return { needsOverwrite: false }; // one record exists and in sync
}

// note: for TXT records the values must be quoted
async function upsertDnsRecords(subdomain, domain, type, values) {
    assert.strictEqual(typeof subdomain, 'string');
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof type, 'string');
    assert(Array.isArray(values));

    debug(`upsertDnsRecords: subdomain:${subdomain} domain:${domain} type:${type} values:${JSON.stringify(values)}`);

    const domainObject = await domains.get(domain);
    await api(domainObject.provider).upsert(domainObject, subdomain, type, values);
}

async function removeDnsRecords(subdomain, domain, type, values) {
    assert.strictEqual(typeof subdomain, 'string');
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof type, 'string');
    assert(Array.isArray(values));

    debug(`removeDnsRecords: subdomain:${subdomain} domain:${domain} type:${type} values:${JSON.stringify(values)}`);

    const domainObject = await domains.get(domain);
    const [error] = await safe(api(domainObject.provider).del(domainObject, subdomain, type, values));
    if (error && error.reason !== BoxError.NOT_FOUND) throw error; // this is never returned afaict
}

async function waitForDnsRecord(subdomain, domain, type, value, options) {
    assert.strictEqual(typeof subdomain, 'string');
    assert.strictEqual(typeof domain, 'string');
    assert(type === 'A' || type === 'AAAA' || type === 'TXT');
    assert.strictEqual(typeof value, 'string');
    assert(options && typeof options === 'object'); // { interval: 5000, times: 50000 }

    const domainObject = await domains.get(domain);

    // linode DNS takes ~15mins
    if (!options.interval) options.interval = domainObject.provider === 'linode' ? 20000 : 5000;

    await api(domainObject.provider).wait(domainObject, subdomain, type, value, options);
}

async function waitForLocations(locations, progressCallback) {
    assert(Array.isArray(locations));
    assert.strictEqual(typeof progressCallback, 'function');

    if (constants.TEST) return;

    const ipv4 = await network.getIPv4();
    const ipv6 = await network.getIPv6();

    for (const location of locations) {
        const { subdomain, domain } = location;
        progressCallback({ message: `Waiting for propagation of ${fqdn(subdomain, domain)}` });

        if (ipv4) {
            const [error] = await safe(waitForDnsRecord(subdomain, domain, 'A', ipv4, { times: 240 }));
            if (error) throw new BoxError(BoxError.DNS_ERROR, `DNS A Record of ${fqdn(subdomain, domain)} is not synced yet: ${error.message}`);
        }

        if (ipv6) {
            const [error] = await safe(waitForDnsRecord(subdomain, domain, 'AAAA', ipv6, { times: 240 }));
            if (error) throw new BoxError(BoxError.DNS_ERROR, `DNS AAAA Record of ${fqdn(subdomain, domain)} is not synced yet: ${error.message}`);
        }
    }
}

function makeWildcard(fqdn) {
    assert.strictEqual(typeof fqdn, 'string');

    // if the fqdn is like *.example.com, this function will do nothing
    const parts = fqdn.split('.');
    parts[0] = '*';
    return parts.join('.');
}

async function registerLocation(location, options, recordType, recordValue) {
    assert.strictEqual(typeof location, 'object');
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof recordType, 'string');
    assert.strictEqual(typeof recordValue, 'string');

    const overwriteDns = options.overwriteDns || false;

    // get the current record before updating it
    const [getError, values] = await safe(getDnsRecords(location.subdomain, location.domain, recordType));
    if (getError) {
        const retryable = getError.reason !== BoxError.ACCESS_DENIED && getError.reason !== BoxError.NOT_FOUND;  // NOT_FOUND is when zone is not found
        debug(`registerLocation: Get error. retryable: ${retryable}. ${getError.message}`);
        throw new BoxError(getError.reason, getError.message, { domain: location, retryable });
    }

    if (values.length === 1 && values[0] === recordValue) return; // up-to-date

    // refuse to update any existing DNS record for custom domains that we did not create
    if (values.length !== 0 && !overwriteDns) throw new BoxError(BoxError.ALREADY_EXISTS, `DNS ${recordType} record already exists`, { domain: location, retryable: false });

    const [upsertError] = await safe(upsertDnsRecords(location.subdomain, location.domain, recordType, [ recordValue ]));
    if (upsertError) {
        const retryable = upsertError.reason === BoxError.BUSY || upsertError.reason === BoxError.EXTERNAL_ERROR;
        debug(`registerLocation: Upsert error. retryable: ${retryable}. ${upsertError.message}`);
        throw new BoxError(BoxError.EXTERNAL_ERROR, upsertError.message, { domain: location, retryable });
    }
}

async function registerLocations(locations, options, progressCallback) {
    assert(Array.isArray(locations));
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof progressCallback, 'function');

    debug(`registerLocations: Will register ${JSON.stringify(locations)} with options ${JSON.stringify(options)}`);

    const ipv4 = await network.getIPv4();
    const ipv6 = await network.getIPv6();

    for (const location of locations) {
        progressCallback({ message: `Registering location ${fqdn(location.subdomain, location.domain)}` });

        await promiseRetry({ times: 200, interval: 5000, debug, retry: (error) => error.retryable }, async function () {
            // cname records cannot co-exist with other records
            const [getError, values] = await safe(getDnsRecords(location.subdomain, location.domain, 'CNAME'));
            if (!getError && values.length === 1) {
                if (!options.overwriteDns) throw new BoxError(BoxError.ALREADY_EXISTS, 'DNS CNAME record already exists', { domain: location, retryable: false });
                debug(`registerLocations: removing CNAME record of ${fqdn(location.subdomain, location.domain)}`);
                await removeDnsRecords(location.subdomain, location.domain, 'CNAME', values);
            }

            if (ipv4) {
                await registerLocation(location, options, 'A', ipv4);
            } else {
                const [error, values] = await safe(getDnsRecords(location.subdomain, location.domain, 'A'));
                if (!error && values.length) await safe(removeDnsRecords(location.subdomain, location.domain, 'A', values), { debug });
            }

            if (ipv6) {
                await registerLocation(location, options, 'AAAA', ipv6);
            } else {
                const [error, values] = await safe(getDnsRecords(location.subdomain, location.domain, 'AAAA'));
                if (!error && values.length) await safe(removeDnsRecords(location.subdomain, location.domain, 'AAAA', values), { debug });
            }
        });
    }
}

async function unregisterLocation(location, recordType, recordValue) {
    assert.strictEqual(typeof location, 'object');
    assert.strictEqual(typeof recordType, 'string');
    assert.strictEqual(typeof recordValue, 'string');

    const [error] = await safe(removeDnsRecords(location.subdomain, location.domain, recordType, [ recordValue ]));
    if (!error || error.reason === BoxError.NOT_FOUND) return;

    const retryable = error.reason === BoxError.BUSY || error.reason === BoxError.EXTERNAL_ERROR;
    debug(`unregisterLocation: Error unregistering location ${recordType}. retryable: ${retryable}. ${error.message}`);

    throw new BoxError(BoxError.EXTERNAL_ERROR, error.message, { domain: location, retryable });
}

async function unregisterLocations(locations, progressCallback) {
    assert(Array.isArray(locations));
    assert.strictEqual(typeof progressCallback, 'function');

    const ipv4 = await network.getIPv4();
    const ipv6 = await network.getIPv6();

    for (const location of locations) {
        progressCallback({ message: `Unregistering location: ${location.subdomain ? (location.subdomain + '.') : ''}${location.domain}` });

        await promiseRetry({ times: 30, interval: 5000, debug, retry: (error) => error.retryable }, async function () {
            if (ipv4) await unregisterLocation(location, 'A', ipv4);
            if (ipv6) await unregisterLocation(location, 'AAAA', ipv6);
        });
    }
}

async function syncDnsRecords(options, progressCallback) {
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof progressCallback, 'function');

    const errors = [];

    if (options.domain && options.type === 'mail') {
        const [error] = await safe(mail.setDnsRecords(options.domain));
        if (error) errors.push({ domain: options.domain, error: error.message });
        return errors;
    }

    let allDomains = await domains.list();

    if (options.domain) allDomains = allDomains.filter(d => d.domain === options.domain);

    const { domain:mailDomain, fqdn:mailFqdn, subdomain:mailSubdomain } = await mailServer.getLocation();
    const dashboardLocation = await dashboard.getLocation();

    const allApps = await apps.list();
    let progress = 1;

    // we sync by domain only to get some nice progress
    for (const domain of allDomains) {
        progressCallback({ percent: progress, message: `Updating DNS of ${domain.domain}`});
        progress += Math.round(100/(1+allDomains.length));

        let locations = [];
        if (domain.domain === dashboardLocation.domain) locations.push({ subdomain: dashboardLocation.subdomain, domain: dashboardLocation.domain });
        if (domain.domain === mailDomain && mailFqdn !== dashboardLocation.fqdn) locations.push({ subdomain: mailSubdomain, domain: mailDomain });

        for (const app of allApps) {
            const appLocations = [{ subdomain: app.subdomain, domain: app.domain }]
                .concat(app.secondaryDomains)
                .concat(app.redirectDomains)
                .concat(app.aliasDomains);
            locations = locations.concat(appLocations.filter(al => al.domain === domain.domain));
        }

        try {
            await registerLocations(locations, { overwriteDns: true }, progressCallback);
            progressCallback({ message: `Updating mail DNS of ${domain.domain}`});
            await mail.setDnsRecords(domain.domain);
        } catch (error) {
            errors.push({ domain: domain.domain, message: error.message });
        }
    }

    return { errors };
}


async function startSyncDnsRecords(options) {
    assert.strictEqual(typeof options, 'object');

    const taskId = await tasks.add(tasks.TASK_SYNC_DNS_RECORDS, [ options ]);
    tasks.startTask(taskId, {});
    return taskId;
}