#!/usr/bin/env node

'use strict';

exports = module.exports = {
    initialize: initialize,
    startTask: startTask,

    run: run,

    // exported for testing
    _reserveHttpPort: reserveHttpPort,
    _configureReverseProxy: configureReverseProxy,
    _unconfigureReverseProxy: unconfigureReverseProxy,
    _createAppDir: createAppDir,
    _deleteAppDir: deleteAppDir,
    _verifyManifest: verifyManifest,
    _registerSubdomain: registerSubdomain,
    _unregisterSubdomain: unregisterSubdomain,
    _waitForDnsPropagation: waitForDnsPropagation
};

require('supererror')({ splatchError: true });

var addons = require('./addons.js'),
    appdb = require('./appdb.js'),
    apps = require('./apps.js'),
    assert = require('assert'),
    async = require('async'),
    auditsource = require('./auditsource.js'),
    backups = require('./backups.js'),
    constants = require('./constants.js'),
    database = require('./database.js'),
    DatabaseError = require('./databaseerror.js'),
    debug = require('debug')('box:apptask'),
    df = require('@sindresorhus/df'),
    docker = require('./docker.js'),
    domains = require('./domains.js'),
    DomainsError = domains.DomainsError,
    ejs = require('ejs'),
    eventlog = require('./eventlog.js'),
    fs = require('fs'),
    manifestFormat = require('cloudron-manifestformat'),
    mkdirp = require('mkdirp'),
    net = require('net'),
    os = require('os'),
    path = require('path'),
    paths = require('./paths.js'),
    reverseProxy = require('./reverseproxy.js'),
    rimraf = require('rimraf'),
    safe = require('safetydance'),
    settings = require('./settings.js'),
    shell = require('./shell.js'),
    superagent = require('superagent'),
    sysinfo = require('./sysinfo.js'),
    util = require('util'),
    _ = require('underscore');

var COLLECTD_CONFIG_EJS = fs.readFileSync(__dirname + '/collectd.config.ejs', { encoding: 'utf8' }),
    CONFIGURE_COLLECTD_CMD = path.join(__dirname, 'scripts/configurecollectd.sh'),
    MV_VOLUME_CMD = path.join(__dirname, 'scripts/mvvolume.sh'),
    LOGROTATE_CONFIG_EJS = fs.readFileSync(__dirname + '/logrotate.ejs', { encoding: 'utf8' }),
    CONFIGURE_LOGROTATE_CMD = path.join(__dirname, 'scripts/configurelogrotate.sh');

var NOOP_CALLBACK = function (error) { if (error) debug(error); };

function initialize(callback) {
    assert.strictEqual(typeof callback, 'function');

    async.series([
        database.initialize,
        settings.initCache
    ], callback);
}

function debugApp(app) {
    assert.strictEqual(typeof app, 'object');

    debug(app.fqdn + ' ' + util.format.apply(util, Array.prototype.slice.call(arguments, 1)));
}

// updates the app object and the database
function updateApp(app, values, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof values, 'object');
    assert.strictEqual(typeof callback, 'function');

    debugApp(app, 'updating app with values: %j', values);

    appdb.update(app.id, values, function (error) {
        if (error) return callback(error);

        for (var value in values) {
            app[value] = values[value];
        }

        return callback(null);
    });
}

function reserveHttpPort(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    var server = net.createServer();
    server.listen(0, function () {
        var port = server.address().port;
        updateApp(app, { httpPort: port }, function (error) {
            if (error) {
                server.close();
                return callback(error);
            }

            server.close(callback);
        });
    });
}

function configureReverseProxy(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    reverseProxy.configureApp(app, { userId: null, username: 'apptask' }, callback);
}

function unconfigureReverseProxy(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    // TODO: maybe revoke the cert
    reverseProxy.unconfigureApp(app, callback);
}

function createContainer(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');
    assert(!app.containerId); // otherwise, it will trigger volumeFrom

    debugApp(app, 'creating container');

    docker.createContainer(app, function (error, container) {
        if (error) return callback(new Error('Error creating container: ' + error));

        updateApp(app, { containerId: container.id }, callback);
    });
}

function deleteContainers(app, options, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof callback, 'function');

    debugApp(app, 'deleting app containers (app, scheduler)');

    docker.deleteContainers(app.id, options, function (error) {
        if (error) return callback(new Error('Error deleting container: ' + error));

        updateApp(app, { containerId: null }, callback);
    });
}

function createAppDir(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    mkdirp(path.join(paths.APPS_DATA_DIR, app.id), callback);
}

function deleteAppDir(app, options, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof callback, 'function');

    const appDataDir = path.join(paths.APPS_DATA_DIR, app.id);

    // resolve any symlinked data dir
    const stat = safe.fs.lstatSync(appDataDir);
    if (!stat) return callback(null);

    const resolvedAppDataDir = stat.isSymbolicLink() ? safe.fs.readlinkSync(appDataDir) : appDataDir;

    if (safe.fs.existsSync(resolvedAppDataDir)) {
        const entries = safe.fs.readdirSync(resolvedAppDataDir);
        if (!entries) return callback(`Error listing ${resolvedAppDataDir}: ${safe.error.message}`);

        // remove only files. directories inside app dir are currently volumes managed by the addons
        // we cannot delete those dirs anyway because of perms
        entries.forEach(function (entry) {
            let stat = safe.fs.statSync(path.join(resolvedAppDataDir, entry));
            if (stat && !stat.isDirectory()) safe.fs.unlinkSync(path.join(resolvedAppDataDir, entry));
        });
    }

    // if this fails, it's probably because the localstorage/redis addons have not cleaned up properly
    if (options.removeDirectory) {
        if (stat.isSymbolicLink()) {
            if (!safe.fs.unlinkSync(appDataDir)) return callback(safe.error.code === 'ENOENT' ? null : safe.error);
        } else {
            if (!safe.fs.rmdirSync(appDataDir)) return callback(safe.error.code === 'ENOENT' ? null : safe.error);
        }
    }

    callback(null);
}

function addCollectdProfile(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    var collectdConf = ejs.render(COLLECTD_CONFIG_EJS, { appId: app.id, containerId: app.containerId, appDataDir: apps.getDataDir(app, app.dataDir) });
    fs.writeFile(path.join(paths.COLLECTD_APPCONFIG_DIR, app.id + '.conf'), collectdConf, function (error) {
        if (error) return callback(error);
        shell.sudo('addCollectdProfile', [ CONFIGURE_COLLECTD_CMD, 'add', app.id ], {}, callback);
    });
}

function removeCollectdProfile(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    fs.unlink(path.join(paths.COLLECTD_APPCONFIG_DIR, app.id + '.conf'), function (error) {
        if (error && error.code !== 'ENOENT') debugApp(app, 'Error removing collectd profile', error);
        shell.sudo('removeCollectdProfile', [ CONFIGURE_COLLECTD_CMD, 'remove', app.id ], {}, callback);
    });
}

function addLogrotateConfig(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    docker.inspect(app.containerId, function (error, result) {
        if (error) return callback(error);

        var runVolume = result.Mounts.find(function (mount) { return mount.Destination === '/run'; });
        if (!runVolume) return callback(new Error('App does not have /run mounted'));

        // logrotate configs can have arbitrary commands, so the config files must be owned by root
        var logrotateConf = ejs.render(LOGROTATE_CONFIG_EJS, { volumePath: runVolume.Source, appId: app.id });
        var tmpFilePath = path.join(os.tmpdir(), app.id + '.logrotate');
        fs.writeFile(tmpFilePath, logrotateConf, function (error) {
            if (error) return callback(error);
            shell.sudo('addLogrotateConfig', [ CONFIGURE_LOGROTATE_CMD, 'add', app.id, tmpFilePath ], {}, callback);
        });
    });
}

function removeLogrotateConfig(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    shell.sudo('removeLogrotateConfig', [ CONFIGURE_LOGROTATE_CMD, 'remove', app.id ], {}, callback);
}

function verifyManifest(manifest, callback) {
    assert.strictEqual(typeof manifest, 'object');
    assert.strictEqual(typeof callback, 'function');

    var error = manifestFormat.parse(manifest);
    if (error) return callback(new Error(util.format('Manifest error: %s', error.message)));

    error = apps.checkManifestConstraints(manifest);
    if (error) return callback(error);

    return callback(null);
}

function downloadIcon(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    // nothing to download if we dont have an appStoreId
    if (!app.appStoreId) return callback(null);

    debugApp(app, 'Downloading icon of %s@%s', app.appStoreId, app.manifest.version);

    var iconUrl = settings.apiServerOrigin() + '/api/v1/apps/' + app.appStoreId + '/versions/' + app.manifest.version + '/icon';

    async.retry({ times: 10, interval: 5000 }, function (retryCallback) {
        superagent
            .get(iconUrl)
            .buffer(true)
            .timeout(30 * 1000)
            .end(function (error, res) {
                if (error && !error.response) return retryCallback(new Error('Network error downloading icon:' + error.message));
                if (res.statusCode !== 200) return retryCallback(null); // ignore error. this can also happen for apps installed with cloudron-cli

                if (!safe.fs.writeFileSync(path.join(paths.APP_ICONS_DIR, app.id + '.png'), res.body)) return retryCallback(new Error('Error saving icon:' + safe.error.message));

                retryCallback(null);
            });
    }, callback);
}

function registerSubdomain(app, overwrite, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof overwrite, 'boolean');
    assert.strictEqual(typeof callback, 'function');

    sysinfo.getPublicIp(function (error, ip) {
        if (error) return callback(error);

        async.retry({ times: 200, interval: 5000 }, function (retryCallback) {
            debugApp(app, 'Registering subdomain location [%s] overwrite: %s', app.fqdn, overwrite);

            // get the current record before updating it
            domains.getDnsRecords(app.location, app.domain, 'A', function (error, values) {
                if (error && error.reason === DomainsError.EXTERNAL_ERROR) return retryCallback(error); // try again
                if (error) return retryCallback(null, error); // give up for access and other errors

                // refuse to update any existing DNS record for custom domains that we did not create
                if (values.length !== 0 && !overwrite) return retryCallback(null, new Error('DNS Record already exists'));

                domains.upsertDnsRecords(app.location, app.domain, 'A', [ ip ], function (error) {
                    if (error && (error.reason === DomainsError.STILL_BUSY || error.reason === DomainsError.EXTERNAL_ERROR)) {
                        debug('Upsert error. Will retry.', error.message);
                        return retryCallback(error); // try again
                    }

                    retryCallback(null, error);
                });
            });
        }, function (error, result) {
            if (error || result instanceof Error) return callback(error || result);
            callback(null);
        });
    });
}

function unregisterSubdomain(app, location, domain, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof location, 'string');
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof callback, 'function');

    sysinfo.getPublicIp(function (error, ip) {
        if (error) return callback(error);

        async.retry({ times: 30, interval: 5000 }, function (retryCallback) {
            debugApp(app, 'Unregistering subdomain: %s', app.fqdn);

            domains.removeDnsRecords(location, domain, 'A', [ ip ], function (error) {
                if (error && error.reason === DomainsError.NOT_FOUND) return retryCallback(null, null); // domain can be not found if oldConfig.domain or restoreConfig.domain was removed
                if (error && (error.reason === DomainsError.STILL_BUSY || error.reason === DomainsError.EXTERNAL_ERROR)) return retryCallback(error); // try again

                retryCallback(null, error);
            });
        }, function (error, result) {
            if (error || result instanceof Error) return callback(error || result);
            callback(null);
        });
    });
}

function registerAlternateDomains(app, overwrite, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof overwrite, 'boolean');
    assert.strictEqual(typeof callback, 'function');

    sysinfo.getPublicIp(function (error, ip) {
        if (error) return callback(error);

        async.eachSeries(app.alternateDomains, function (domain, callback) {
            async.retry({ times: 200, interval: 5000 }, function (retryCallback) {
                debugApp(app, 'Registering alternate subdomain [%s] overwrite: %s', (domain.subdomain ? (domain.subdomain + '.') : '') + domain.domain, overwrite);

                // get the current record before updating it
                domains.getDnsRecords(domain.subdomain, domain.domain, 'A', function (error, values) {
                    if (error) return retryCallback(error);

                    // refuse to update any existing DNS record for custom domains that we did not create
                    if (values.length !== 0 && !overwrite) return retryCallback(null, new Error('DNS Record already exists'));

                    domains.upsertDnsRecords(domain.subdomain, domain.domain, 'A', [ ip ], function (error) {
                        if (error && (error.reason === DomainsError.STILL_BUSY || error.reason === DomainsError.EXTERNAL_ERROR)) {
                            debug('Upsert error. Will retry.', error.message);
                            return retryCallback(error); // try again
                        }
                        retryCallback(null, error);
                    });
                });
            }, function (error, result) {
                if (error || result instanceof Error) return callback(error || result);
                callback();
            });
        }, callback);
    });
}

function unregisterAlternateDomains(app, all, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof all, 'boolean');
    assert.strictEqual(typeof callback, 'function');

    let obsoleteDomains = [];
    if (all) {
        obsoleteDomains = app.alternateDomains;
    } else if (app.oldConfig) { // oldConfig can be null during an infra update
        obsoleteDomains = app.oldConfig.alternateDomains.filter(function (o) {
            return !app.alternateDomains.some(function (n) { return n.subdomain === o.subdomain && n.domain === o.domain; });
        });
    }

    if (obsoleteDomains.length === 0) return callback();

    sysinfo.getPublicIp(function (error, ip) {
        if (error) return callback(error);

        async.eachSeries(obsoleteDomains, function (domain, callback) {
            async.retry({ times: 30, interval: 5000 }, function (retryCallback) {
                debugApp(app, 'Unregistering subdomain: %s%s', domain.subdomain ? (domain.subdomain + '.') : '', domain.domain);

                domains.removeDnsRecords(domain.subdomain, domain.domain, 'A', [ ip ], function (error) {
                    if (error && error.reason === DomainsError.NOT_FOUND) return retryCallback(null, null);
                    if (error && (error.reason === DomainsError.STILL_BUSY || error.reason === DomainsError.EXTERNAL_ERROR)) return retryCallback(error); // try again

                    retryCallback(null, error);
                });
            }, function (error, result) {
                if (error || result instanceof Error) return callback(error || result);
                callback();
            });
        }, callback);
    });
}

function removeIcon(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    if (!safe.fs.unlinkSync(path.join(paths.APP_ICONS_DIR, app.id + '.png'))) {
        if (safe.error.code !== 'ENOENT') debugApp(app, 'cannot remove icon : %s', safe.error);
    }

    if (!safe.fs.unlinkSync(path.join(paths.APP_ICONS_DIR, app.id + '.user.png'))) {
        if (safe.error.code !== 'ENOENT') debugApp(app, 'cannot remove user icon : %s', safe.error);
    }

    callback(null);
}

function cleanupLogs(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    // note that redis container logs are cleaned up by the addon
    rimraf(path.join(paths.LOG_DIR, app.id), function (error) {
        if (error) debugApp(app, 'cannot cleanup logs: %s', error);

        callback(null);
    });
}

function waitForDnsPropagation(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    if (!constants.CLOUDRON) {
        debugApp(app, 'Skipping dns propagation check for development');
        return callback(null);
    }

    sysinfo.getPublicIp(function (error, ip) {
        if (error) return callback(error);

        domains.waitForDnsRecord(app.location, app.domain, 'A', ip, { interval: 5000, times: 240 }, function (error) {
            if (error) return callback(error);

            // now wait for alternateDomains, if any
            async.eachSeries(app.alternateDomains, function (domain, iteratorCallback) {
                domains.waitForDnsRecord(domain.subdomain, domain.domain, 'A', ip, { interval: 5000, times: 240 }, iteratorCallback);
            }, callback);
        });
    });
}

function migrateDataDir(app, sourceDir, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof sourceDir, 'string');
    assert.strictEqual(typeof callback, 'function');

    let resolvedSourceDir = apps.getDataDir(app, sourceDir);
    let resolvedTargetDir = apps.getDataDir(app, app.dataDir);

    debug(`migrateDataDir: migrating data from ${resolvedSourceDir} to ${resolvedTargetDir}`);

    shell.sudo('migrateDataDir', [ MV_VOLUME_CMD, resolvedSourceDir, resolvedTargetDir ], {}, callback);
}

function downloadImage(manifest, callback) {
    assert.strictEqual(typeof manifest, 'object');
    assert.strictEqual(typeof callback, 'function');

    docker.info(function (error, info) {
        if (error) return callback(error);

        const dfAsync = util.callbackify(df.file);
        dfAsync(info.DockerRootDir, function (error, diskUsage) {
            if (error) return callback(error);
            if (diskUsage.available < (1024*1024*1024)) return callback(new Error('Not enough disk space to pull docker image. See https://cloudron.io/documentation/storage/#docker-image-location'));

            docker.downloadImage(manifest, callback);
        });
    });
}

// Ordering is based on the following rationale:
//   - configure nginx, icon, oauth
//   - register subdomain.
//          at this point, the user can visit the site and the above nginx config can show some install screen.
//          the icon can be displayed in this nginx page and oauth proxy means the page can be protected
//   - download image
//   - setup volumes
//   - setup addons (requires the above volume)
//   - setup the container (requires image, volumes, addons)
//   - setup collectd (requires container id)
// restore is also handled here since restore is just an install with some oldConfig to clean up
function install(app, progressCallback, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    const restoreConfig = app.restoreConfig, isRestoring = app.installationState === appdb.ISTATE_PENDING_RESTORE;

    async.series([
        // this protects against the theoretical possibility of an app being marked for install/restore from
        // a previous version of box code
        verifyManifest.bind(null, app.manifest),

        // teardown for re-installs
        progressCallback.bind(null, { percent: 10, message: 'Cleaning up old install' }),
        unconfigureReverseProxy.bind(null, app),
        removeCollectdProfile.bind(null, app),
        removeLogrotateConfig.bind(null, app),
        stopApp.bind(null, app),
        deleteContainers.bind(null, app, { managedOnly: true }),
        function teardownAddons(next) {
            // when restoring, app does not require these addons anymore. remove carefully to preserve the db passwords
            var addonsToRemove = !isRestoring ? app.manifest.addons : _.omit(app.oldConfig.manifest.addons, Object.keys(app.manifest.addons));

            addons.teardownAddons(app, addonsToRemove, next);
        },
        deleteAppDir.bind(null, app, { removeDirectory: false }), // do not remove any symlinked appdata dir

        // for restore case
        function deleteImageIfChanged(done) {
            if (!app.oldConfig || (app.oldConfig.manifest.dockerImage === app.manifest.dockerImage)) return done();

            docker.deleteImage(app.oldConfig.manifest, done);
        },

        reserveHttpPort.bind(null, app),

        progressCallback.bind(null, { percent: 20, message: 'Downloading icon' }),
        downloadIcon.bind(null, app),

        progressCallback.bind(null, { percent: 30, message: 'Registering subdomain' }),
        registerSubdomain.bind(null, app, isRestoring /* overwrite */),

        progressCallback.bind(null, { percent: 35, message: 'Registering alternate domains' }),
        registerAlternateDomains.bind(null, app, isRestoring /* overwrite */),

        progressCallback.bind(null, { percent: 40, message: 'Downloading image' }),
        downloadImage.bind(null, app.manifest),

        progressCallback.bind(null, { percent: 50, message: 'Creating app data directory' }),
        createAppDir.bind(null, app),

        function restoreFromBackup(next) {
            if (!restoreConfig) {
                async.series([
                    progressCallback.bind(null, { percent: 60, message: 'Setting up addons' }),
                    addons.setupAddons.bind(null, app, app.manifest.addons),
                ], next);
            } else {
                async.series([
                    progressCallback.bind(null, { percent: 65, message: 'Download backup and restoring addons' }),
                    addons.setupAddons.bind(null, app, app.manifest.addons),
                    addons.clearAddons.bind(null, app, app.manifest.addons),
                    backups.restoreApp.bind(null, app, app.manifest.addons, restoreConfig, (progress) => updateApp(app, { installationProgress: `65, Restore - ${progress.message}` }, NOOP_CALLBACK))
                ], next);
            }
        },

        progressCallback.bind(null, { percent: 70, message: 'Creating container' }),
        createContainer.bind(null, app),

        progressCallback.bind(null, { percent: 75, message: 'Setting up logrotate config' }),
        addLogrotateConfig.bind(null, app),

        progressCallback.bind(null, { percent: 80, message: 'Setting up collectd profile' }),
        addCollectdProfile.bind(null, app),

        runApp.bind(null, app),

        progressCallback.bind(null, { percent: 85, message: 'Waiting for DNS propagation' }),
        exports._waitForDnsPropagation.bind(null, app),

        progressCallback.bind(null, { percent: 95, message: 'Configuring reverse proxy' }),
        configureReverseProxy.bind(null, app),

        progressCallback.bind(null, { percent: 100, message: 'Done' }),
        updateApp.bind(null, app, { installationState: appdb.ISTATE_INSTALLED, health: null, taskId: null })
    ], function seriesDone(error) {
        if (error) {
            debugApp(app, 'error installing app: %s', error);
            return updateApp(app, { installationState: appdb.ISTATE_ERROR, installationProgress: error.message }, callback.bind(null, error));
        }
        callback(null);
    });
}

function backup(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    async.series([
        updateApp.bind(null, app, { installationProgress: '10, Backing up' }),
        backups.backupApp.bind(null, app, { /* options */ }, (progress) => updateApp(app, { installationProgress: `30, ${progress.message}` }, NOOP_CALLBACK)),

        // done!
        function (callback) {
            debugApp(app, 'installed');
            updateApp(app, { installationState: appdb.ISTATE_INSTALLED, installationProgress: '' }, callback);
        }
    ], function seriesDone(error) {
        if (error) {
            debugApp(app, 'error backing up app: %s', error);
            return updateApp(app, { installationState: appdb.ISTATE_INSTALLED, installationProgress: error.message }, callback.bind(null, error)); // return to installed state intentionally
        }
        callback(null);
    });
}

// note that configure is called after an infra update as well
function configure(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    // oldConfig can be null during an infra update
    const locationChanged = app.oldConfig && (app.oldConfig.fqdn !== app.fqdn);
    const dataDirChanged = app.oldConfig && (app.oldConfig.dataDir !== app.dataDir);

    async.series([
        updateApp.bind(null, app, { installationProgress: '10, Cleaning up old install' }),
        unconfigureReverseProxy.bind(null, app),
        removeCollectdProfile.bind(null, app),
        removeLogrotateConfig.bind(null, app),
        stopApp.bind(null, app),
        deleteContainers.bind(null, app, { managedOnly: true }),
        unregisterAlternateDomains.bind(null, app, false /* all */),
        function (next) {
            if (!locationChanged) return next();

            unregisterSubdomain(app, app.oldConfig.location, app.oldConfig.domain, next);
        },

        reserveHttpPort.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '20, Downloading icon' }),
        downloadIcon.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '30, Registering subdomain' }),
        registerSubdomain.bind(null, app, !locationChanged /* overwrite */), // if location changed, do not overwrite to detect conflicts

        updateApp.bind(null, app, { installationProgress: '35, Registering alternate domains'}),
        registerAlternateDomains.bind(null, app, true /* overwrite */), // figure out when to overwrite

        updateApp.bind(null, app, { installationProgress: '40, Downloading image' }),
        downloadImage.bind(null, app.manifest),

        updateApp.bind(null, app, { installationProgress: '45, Ensuring app data directory' }),
        createAppDir.bind(null, app),

        // re-setup addons since they rely on the app's fqdn (e.g oauth)
        updateApp.bind(null, app, { installationProgress: '50, Setting up addons' }),
        addons.setupAddons.bind(null, app, app.manifest.addons),

        // migrate dataDir
        function (next) {
            if (!dataDirChanged) return next();

            migrateDataDir(app, app.oldConfig.dataDir, next);
        },

        updateApp.bind(null, app, { installationProgress: '60, Creating container' }),
        createContainer.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '65, Setting up logrotate config' }),
        addLogrotateConfig.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '70, Add collectd profile' }),
        addCollectdProfile.bind(null, app),

        runApp.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '80, Waiting for DNS propagation' }),
        exports._waitForDnsPropagation.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '90, Configuring reverse proxy' }),
        configureReverseProxy.bind(null, app),

        // done!
        function (callback) {
            debugApp(app, 'configured');
            updateApp(app, { installationState: appdb.ISTATE_INSTALLED, installationProgress: '', health: null }, callback);
        }
    ], function seriesDone(error) {
        if (error) {
            debugApp(app, 'error reconfiguring : %s', error);
            return updateApp(app, { installationState: appdb.ISTATE_ERROR, installationProgress: error.message }, callback.bind(null, error));
        }
        callback(null);
    });
}

// nginx configuration is skipped because app.httpPort is expected to be available
function update(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    debugApp(app, `Updating to ${app.updateConfig.manifest.version}`);

    // app does not want these addons anymore
    // FIXME: this does not handle option changes (like multipleDatabases)
    var unusedAddons = _.omit(app.manifest.addons, Object.keys(app.updateConfig.manifest.addons));

    const FORCED_UPDATE = (app.installationState === appdb.ISTATE_PENDING_FORCE_UPDATE);

    async.series([
        // this protects against the theoretical possibility of an app being marked for update from
        // a previous version of box code
        updateApp.bind(null, app, { installationProgress: '0, Verify manifest' }),
        verifyManifest.bind(null, app.updateConfig.manifest),

        function (next) {
            if (FORCED_UPDATE) return next(null);

            async.series([
                updateApp.bind(null, app, { installationProgress: '15, Backing up app' }),
                // preserve update backups for 3 weeks
                backups.backupApp.bind(null, app, { preserveSecs: 3*7*24*60*60 }, (progress) => updateApp(app, { installationProgress: `15, Backup - ${progress.message}` }, NOOP_CALLBACK))
            ], function (error) {
                if (error) error.backupError = true;
                next(error);
            });
        },

        // download new image before app is stopped. this is so we can reduce downtime
        // and also not remove the 'common' layers when the old image is deleted
        updateApp.bind(null, app, { installationProgress: '25, Downloading image' }),
        downloadImage.bind(null, app.updateConfig.manifest),

        // note: we cleanup first and then backup. this is done so that the app is not running should backup fail
        // we cannot easily 'recover' from backup failures because we have to revert manfest and portBindings
        updateApp.bind(null, app, { installationProgress: '35, Cleaning up old install' }),
        removeCollectdProfile.bind(null, app),
        removeLogrotateConfig.bind(null, app),
        stopApp.bind(null, app),
        deleteContainers.bind(null, app, { managedOnly: true }),
        function deleteImageIfChanged(done) {
            if (app.manifest.dockerImage === app.updateConfig.manifest.dockerImage) return done();

            docker.deleteImage(app.manifest, done);
        },

        // only delete unused addons after backup
        addons.teardownAddons.bind(null, app, unusedAddons),

        // free unused ports
        function (next) {
            const currentPorts = app.portBindings || {};
            const newTcpPorts = app.updateConfig.manifest.tcpPorts || {};
            const newUdpPorts = app.updateConfig.manifest.udpPorts || {};

            async.each(Object.keys(currentPorts), function (portName, callback) {
                if (newTcpPorts[portName] || newUdpPorts[portName]) return callback(); // port still in use

                appdb.delPortBinding(currentPorts[portName], apps.PORT_TYPE_TCP, function (error) {
                    if (error && error.reason === DatabaseError.NOT_FOUND) console.error('Portbinding does not exist in database.');
                    else if (error) return next(error);

                    // also delete from app object for further processing (the db is updated in the next step)
                    delete app.portBindings[portName];

                    callback();
                });
            }, next);
        },

        // switch over to the new config. manifest, memoryLimit, portBindings, appstoreId are updated here
        updateApp.bind(null, app, app.updateConfig),

        updateApp.bind(null, app, { installationProgress: '45, Downloading icon' }),
        downloadIcon.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '70, Updating addons' }),
        addons.setupAddons.bind(null, app, app.updateConfig.manifest.addons),

        updateApp.bind(null, app, { installationProgress: '80, Creating container' }),
        createContainer.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '85, Setting up logrotate config' }),
        addLogrotateConfig.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '90, Add collectd profile' }),
        addCollectdProfile.bind(null, app),

        runApp.bind(null, app),

        // done!
        function (callback) {
            debugApp(app, 'updated');
            updateApp(app, { installationState: appdb.ISTATE_INSTALLED, installationProgress: '', health: null, updateConfig: null, updateTime: new Date() }, callback);
        }
    ], function seriesDone(error) {
        if (error && error.backupError) {
            debugApp(app, 'update aborted because backup failed', error);
            updateApp(app, { installationState: appdb.ISTATE_INSTALLED, installationProgress: '', health: null, updateConfig: null }, callback.bind(null, error));
        } else if (error) {
            debugApp(app, 'Error updating app: %s', error);
            updateApp(app, { installationState: appdb.ISTATE_ERROR, installationProgress: error.message, updateTime: new Date() }, callback.bind(null, error));
        } else {
            // do not spam the notifcation view
            if (FORCED_UPDATE) return callback();

            eventlog.add(eventlog.ACTION_APP_UPDATE_FINISH, auditsource.APP_TASK, { app: app, success: true }, callback);
        }
    });
}

function uninstall(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    debugApp(app, 'uninstalling');

    async.series([
        updateApp.bind(null, app, { installationProgress: '0, Remove collectd profile' }),
        removeCollectdProfile.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '5, Remove logrotate config' }),
        removeLogrotateConfig.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '10, Stopping app' }),
        stopApp.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '20, Deleting container' }),
        deleteContainers.bind(null, app, {}),

        updateApp.bind(null, app, { installationProgress: '30, Teardown addons' }),
        addons.teardownAddons.bind(null, app, app.manifest.addons),

        updateApp.bind(null, app, { installationProgress: '40, Deleting app data directory' }),
        deleteAppDir.bind(null, app, { removeDirectory: true }),

        updateApp.bind(null, app, { installationProgress: '50, Deleting image' }),
        docker.deleteImage.bind(null, app.manifest),

        updateApp.bind(null, app, { installationProgress: '60, Unregistering domains' }),
        unregisterAlternateDomains.bind(null, app, true /* all */),
        unregisterSubdomain.bind(null, app, app.location, app.domain),

        updateApp.bind(null, app, { installationProgress: '70, Cleanup icon' }),
        removeIcon.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '80, Unconfiguring reverse proxy' }),
        unconfigureReverseProxy.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '90, Cleanup logs' }),
        cleanupLogs.bind(null, app),

        updateApp.bind(null, app, { installationProgress: '95, Remove app from database' }),
        appdb.del.bind(null, app.id)
    ], function seriesDone(error) {
        if (error) {
            debugApp(app, 'error uninstalling app: %s', error);
            return updateApp(app, { installationState: appdb.ISTATE_ERROR, installationProgress: error.message }, callback.bind(null, error));
        }
        callback(null);
    });
}

function runApp(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    docker.startContainer(app.containerId, function (error) {
        if (error) return callback(error);

        updateApp(app, { runState: appdb.RSTATE_RUNNING }, callback);
    });
}

function stopApp(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    docker.stopContainers(app.id, function (error) {
        if (error) return callback(error);

        updateApp(app, { runState: appdb.RSTATE_STOPPED, health: null }, callback);
    });
}

function handleRunCommand(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    if (app.runState === appdb.RSTATE_PENDING_STOP) {
        return stopApp(app, callback);
    }

    if (app.runState === appdb.RSTATE_PENDING_START || app.runState === appdb.RSTATE_RUNNING) {
        debugApp(app, 'Resuming app with state : %s', app.runState);
        return runApp(app, callback);
    }

    debugApp(app, 'handleRunCommand - doing nothing: %s', app.runState);

    return callback(null);
}

function startTask(appId, callback) {
    assert.strictEqual(typeof appId, 'string');
    assert.strictEqual(typeof callback, 'function');

    // determine what to do
    apps.get(appId, function (error, app) {
        if (error) return callback(error);

        debugApp(app, 'startTask installationState: %s runState: %s', app.installationState, app.runState);

        switch (app.installationState) {
        case appdb.ISTATE_PENDING_UNINSTALL: return uninstall(app, callback);
        case appdb.ISTATE_PENDING_CONFIGURE: return configure(app, callback);

        case appdb.ISTATE_PENDING_UPDATE: return update(app, callback);
        case appdb.ISTATE_PENDING_FORCE_UPDATE: return update(app, callback);

        case appdb.ISTATE_PENDING_INSTALL: return install(app, callback);
        case appdb.ISTATE_PENDING_CLONE: return install(app, callback);
        case appdb.ISTATE_PENDING_RESTORE: return install(app, callback);

        case appdb.ISTATE_PENDING_BACKUP: return backup(app, callback);
        case appdb.ISTATE_INSTALLED: return handleRunCommand(app, callback);

        case appdb.ISTATE_ERROR:
            debugApp(app, 'Internal error. apptask launched with error status.');
            return callback(null);
        default:
            debugApp(app, 'apptask launched with invalid command');
            return callback(new Error('Unknown command in apptask:' + app.installationState));
        }
    });
}

function run(appId, progressCallback, callback) {
    assert.strictEqual(typeof appId, 'string');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    // determine what to do
    apps.get(appId, function (error, app) {
        if (error) return callback(error);

        debugApp(app, 'startTask installationState: %s runState: %s', app.installationState, app.runState);

        switch (app.installationState) {
        case appdb.ISTATE_PENDING_INSTALL: return install(app, progressCallback, callback);

        default:
            debugApp(app, 'apptask launched with invalid command');
            return callback(new Error('Unknown command in apptask:' + app.installationState));
        }
    });
}

if (require.main === module) {
    assert.strictEqual(process.argv.length, 3, 'Pass the appid as argument');

    // add a separator for the log file
    debug('------------------------------------------------------------');
    debug('Apptask for %s', process.argv[2]);

    process.on('SIGTERM', function () {
        debug('taskmanager sent SIGTERM since it got a new task for this app');
        process.exit(0);
    });

    initialize(function (error) {
        if (error) throw error;

        startTask(process.argv[2], function (error) {
            if (error) debug('Apptask completed with error', error);

            debug('Apptask completed for %s', process.argv[2]);
            // https://nodejs.org/api/process.html are exit codes used by node. apps.js uses the value below
            // to check apptask crashes
            process.exit(error ? 50 : 0);
        });
    });
}