'use strict';

exports = module.exports = {
    testConfig: testConfig,
    testProviderConfig: testProviderConfig,

    getByIdentifierAndStatePaged,

    get: get,

    startBackupTask: startBackupTask,

    restore: restore,

    backupApp: backupApp,
    downloadApp: downloadApp,

    backupBoxAndApps: backupBoxAndApps,

    upload: upload,

    startCleanupTask: startCleanupTask,
    cleanup: cleanup,
    cleanupCacheFilesSync: cleanupCacheFilesSync,

    injectPrivateFields: injectPrivateFields,
    removePrivateFields: removePrivateFields,

    checkConfiguration: checkConfiguration,

    configureCollectd: configureCollectd,

    generateEncryptionKeysSync: generateEncryptionKeysSync,

    BACKUP_IDENTIFIER_BOX: 'box',

    BACKUP_TYPE_APP: 'app',
    BACKUP_TYPE_BOX: 'box',

    BACKUP_STATE_NORMAL: 'normal', // should rename to created to avoid listing in UI?
    BACKUP_STATE_CREATING: 'creating',
    BACKUP_STATE_ERROR: 'error',

    // for testing
    _getBackupFilePath: getBackupFilePath,
    _restoreFsMetadata: restoreFsMetadata,
    _saveFsMetadata: saveFsMetadata,
    _applyBackupRetentionPolicy: applyBackupRetentionPolicy
};

var addons = require('./addons.js'),
    apps = require('./apps.js'),
    async = require('async'),
    assert = require('assert'),
    backupdb = require('./backupdb.js'),
    BoxError = require('./boxerror.js'),
    collectd = require('./collectd.js'),
    constants = require('./constants.js'),
    CronJob = require('cron').CronJob,
    crypto = require('crypto'),
    database = require('./database.js'),
    DataLayout = require('./datalayout.js'),
    debug = require('debug')('box:backups'),
    ejs = require('ejs'),
    eventlog = require('./eventlog.js'),
    fs = require('fs'),
    locker = require('./locker.js'),
    moment = require('moment'),
    once = require('once'),
    path = require('path'),
    paths = require('./paths.js'),
    progressStream = require('progress-stream'),
    safe = require('safetydance'),
    shell = require('./shell.js'),
    settings = require('./settings.js'),
    syncer = require('./syncer.js'),
    tar = require('tar-fs'),
    tasks = require('./tasks.js'),
    TransformStream = require('stream').Transform,
    util = require('util'),
    zlib = require('zlib'),
    _ = require('underscore');

const BACKUP_UPLOAD_CMD = path.join(__dirname, 'scripts/backupupload.js');
const COLLECTD_CONFIG_EJS = fs.readFileSync(__dirname + '/collectd/cloudron-backup.ejs', { encoding: 'utf8' });

function debugApp(app) {
    assert(typeof app === 'object');

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

// choose which storage backend we use for test purpose we use s3
function api(provider) {
    switch (provider) {
    case 'nfs': return require('./storage/filesystem.js');
    case 'cifs': return require('./storage/filesystem.js');
    case 'sshfs': return require('./storage/filesystem.js');
    case 's3': return require('./storage/s3.js');
    case 'gcs': return require('./storage/gcs.js');
    case 'filesystem': return require('./storage/filesystem.js');
    case 'minio': return require('./storage/s3.js');
    case 's3-v4-compat': return require('./storage/s3.js');
    case 'digitalocean-spaces': return require('./storage/s3.js');
    case 'exoscale-sos': return require('./storage/s3.js');
    case 'wasabi': return require('./storage/s3.js');
    case 'scaleway-objectstorage': return require('./storage/s3.js');
    case 'backblaze-b2': return require('./storage/s3.js');
    case 'linode-objectstorage': return require('./storage/s3.js');
    case 'ovh-objectstorage': return require('./storage/s3.js');
    case 'noop': return require('./storage/noop.js');
    default: return null;
    }
}

function injectPrivateFields(newConfig, currentConfig) {
    if ('password' in newConfig) {
        if (newConfig.password === constants.SECRET_PLACEHOLDER) {
            delete newConfig.password;
        }
        newConfig.encryption = currentConfig.encryption || null;
    } else {
        newConfig.encryption = null;
    }
    if (newConfig.provider === currentConfig.provider) api(newConfig.provider).injectPrivateFields(newConfig, currentConfig);
}

function removePrivateFields(backupConfig) {
    assert.strictEqual(typeof backupConfig, 'object');
    if (backupConfig.encryption) {
        delete backupConfig.encryption;
        backupConfig.password = constants.SECRET_PLACEHOLDER;
    }
    return api(backupConfig.provider).removePrivateFields(backupConfig);
}

function testConfig(backupConfig, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof callback, 'function');

    var func = api(backupConfig.provider);
    if (!func) return callback(new BoxError(BoxError.BAD_FIELD, 'unknown storage provider', { field: 'provider' }));

    if (backupConfig.format !== 'tgz' && backupConfig.format !== 'rsync') return callback(new BoxError(BoxError.BAD_FIELD, 'unknown format', { field: 'format' }));

    const job = safe.safeCall(function () { return new CronJob(backupConfig.schedulePattern); });
    if (!job) return callback(new BoxError(BoxError.BAD_FIELD, 'Invalid schedule pattern', { field: 'schedulePattern' }));

    if ('password' in backupConfig) {
        if (typeof backupConfig.password !== 'string') return callback(new BoxError(BoxError.BAD_FIELD, 'password must be a string', { field: 'password' }));
        if (backupConfig.password.length < 8) return callback(new BoxError(BoxError.BAD_FIELD, 'password must be atleast 8 characters', { field: 'password' }));
    }

    const policy = backupConfig.retentionPolicy;
    if (!policy) return callback(new BoxError(BoxError.BAD_FIELD, 'retentionPolicy is required', { field: 'retentionPolicy' }));
    if (!['keepWithinSecs','keepDaily','keepWeekly','keepMonthly','keepYearly'].find(k => !!policy[k])) return callback(new BoxError(BoxError.BAD_FIELD, 'properties missing', { field: 'retentionPolicy' }));
    if ('keepWithinSecs' in policy && typeof policy.keepWithinSecs !== 'number') return callback(new BoxError(BoxError.BAD_FIELD, 'keepWithinSecs must be a number', { field: 'retentionPolicy' }));
    if ('keepDaily' in policy && typeof policy.keepDaily !== 'number') return callback(new BoxError(BoxError.BAD_FIELD, 'keepDaily must be a number', { field: 'retentionPolicy' }));
    if ('keepWeekly' in policy && typeof policy.keepWeekly !== 'number') return callback(new BoxError(BoxError.BAD_FIELD, 'keepWeekly must be a number', { field: 'retentionPolicy' }));
    if ('keepMonthly' in policy && typeof policy.keepMonthly !== 'number') return callback(new BoxError(BoxError.BAD_FIELD, 'keepMonthly must be a number', { field: 'retentionPolicy' }));
    if ('keepYearly' in policy && typeof policy.keepYearly !== 'number') return callback(new BoxError(BoxError.BAD_FIELD, 'keepYearly must be a number', { field: 'retentionPolicy' }));

    api(backupConfig.provider).testConfig(backupConfig, callback);
}

// this skips password check since that policy is only at creation time
function testProviderConfig(backupConfig, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof callback, 'function');

    var func = api(backupConfig.provider);
    if (!func) return callback(new BoxError(BoxError.BAD_FIELD, 'unknown storage provider', { field: 'provider' }));

    api(backupConfig.provider).testConfig(backupConfig, callback);
}

function generateEncryptionKeysSync(password) {
    assert.strictEqual(typeof password, 'string');

    const aesKeys = crypto.scryptSync(password, Buffer.from('CLOUDRONSCRYPTSALT', 'utf8'), 128);
    return {
        dataKey: aesKeys.slice(0, 32).toString('hex'),
        dataHmacKey: aesKeys.slice(32, 64).toString('hex'),
        filenameKey: aesKeys.slice(64, 96).toString('hex'),
        filenameHmacKey: aesKeys.slice(96).toString('hex')
    };
}

function getByIdentifierAndStatePaged(identifier, state, page, perPage, callback) {
    assert.strictEqual(typeof identifier, 'string');
    assert.strictEqual(typeof state, 'string');
    assert(typeof page === 'number' && page > 0);
    assert(typeof perPage === 'number' && perPage > 0);
    assert.strictEqual(typeof callback, 'function');

    backupdb.getByIdentifierAndStatePaged(identifier, state, page, perPage, function (error, results) {
        if (error) return callback(error);

        callback(null, results);
    });
}

function get(backupId, callback) {
    assert.strictEqual(typeof backupId, 'string');
    assert.strictEqual(typeof callback, 'function');

    backupdb.get(backupId, function (error, result) {
        if (error) return callback(error);

        callback(null, result);
    });
}

// This is not part of the storage api, since we don't want to pull the "format" logistics into that
function getBackupFilePath(backupConfig, backupId, format) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof backupId, 'string');
    assert.strictEqual(typeof format, 'string');

    const backupPath = api(backupConfig.provider).getBackupPath(backupConfig);

    if (format === 'tgz') {
        const fileType = backupConfig.encryption ? '.tar.gz.enc' : '.tar.gz';
        return path.join(backupPath, backupId+fileType);
    } else {
        return path.join(backupPath, backupId);
    }
}

function encryptFilePath(filePath, encryption) {
    assert.strictEqual(typeof filePath, 'string');
    assert.strictEqual(typeof encryption, 'object');

    var encryptedParts = filePath.split('/').map(function (part) {
        let hmac = crypto.createHmac('sha256', Buffer.from(encryption.filenameHmacKey, 'hex'));
        const iv = hmac.update(part).digest().slice(0, 16); // iv has to be deterministic, for our sync (copy) logic to work
        const cipher = crypto.createCipheriv('aes-256-cbc', Buffer.from(encryption.filenameKey, 'hex'), iv);
        let crypt = cipher.update(part);
        crypt = Buffer.concat([ iv, crypt, cipher.final() ]);

        return crypt.toString('base64')     // ensures path is valid
            .replace(/\//g, '-')            // replace '/' of base64 since it conflicts with path separator
            .replace(/=/g,'');              // strip trailing = padding. this is only needed if we concat base64 strings, which we don't
    });

    return encryptedParts.join('/');
}

function decryptFilePath(filePath, encryption) {
    assert.strictEqual(typeof filePath, 'string');
    assert.strictEqual(typeof encryption, 'object');

    let decryptedParts = [];
    for (let part of filePath.split('/')) {
        part = part + Array(part.length % 4).join('='); // add back = padding
        part = part.replace(/-/g, '/');                 // replace with '/'

        try {
            const buffer = Buffer.from(part, 'base64');
            const iv = buffer.slice(0, 16);
            let decrypt = crypto.createDecipheriv('aes-256-cbc', Buffer.from(encryption.filenameKey, 'hex'), iv);
            const plainText = decrypt.update(buffer.slice(16));
            const plainTextString = Buffer.concat([ plainText, decrypt.final() ]).toString('utf8');
            const hmac = crypto.createHmac('sha256', Buffer.from(encryption.filenameHmacKey, 'hex'));
            if (!hmac.update(plainTextString).digest().slice(0, 16).equals(iv)) return { error: new BoxError(BoxError.CRYPTO_ERROR, `mac error decrypting part ${part} of path ${filePath}`) };

            decryptedParts.push(plainTextString);
        } catch (error) {
            debug(`Error decrypting part ${part} of path ${filePath}:`, error);
            return { error: new BoxError(BoxError.CRYPTO_ERROR, `Error decrypting part ${part} of path ${filePath}: ${error.message}`) };
        }
    }

    return { result: decryptedParts.join('/') };
}

class EncryptStream extends TransformStream {
    constructor(encryption) {
        super();
        this._headerPushed = false;
        this._iv = crypto.randomBytes(16);
        this._cipher = crypto.createCipheriv('aes-256-cbc', Buffer.from(encryption.dataKey, 'hex'), this._iv);
        this._hmac = crypto.createHmac('sha256', Buffer.from(encryption.dataHmacKey, 'hex'));
    }

    pushHeaderIfNeeded() {
        if (!this._headerPushed) {
            const magic = Buffer.from('CBV2');
            this.push(magic);
            this._hmac.update(magic);
            this.push(this._iv);
            this._hmac.update(this._iv);
            this._headerPushed = true;
        }
    }

    _transform(chunk, ignoredEncoding, callback) {
        this.pushHeaderIfNeeded();

        try {
            const crypt = this._cipher.update(chunk);
            this._hmac.update(crypt);
            callback(null, crypt);
        } catch (error) {
            callback(error);
        }
    }

    _flush(callback) {
        try {
            this.pushHeaderIfNeeded(); // for 0-length files
            const crypt = this._cipher.final();
            this.push(crypt);
            this._hmac.update(crypt);
            callback(null, this._hmac.digest()); // +32 bytes
        } catch (error) {
            callback(error);
        }
    }
}

class DecryptStream extends TransformStream {
    constructor(encryption) {
        super();
        this._key = Buffer.from(encryption.dataKey, 'hex');
        this._header = Buffer.alloc(0);
        this._decipher = null;
        this._hmac = crypto.createHmac('sha256', Buffer.from(encryption.dataHmacKey, 'hex'));
        this._buffer = Buffer.alloc(0);
    }

    _transform(chunk, ignoredEncoding, callback) {
        const needed = 20 - this._header.length; // 4 for magic, 16 for iv

        if (this._header.length !== 20) { // not gotten header yet
            this._header = Buffer.concat([this._header, chunk.slice(0, needed)]);
            if (this._header.length !== 20) return callback();

            if (!this._header.slice(0, 4).equals(new Buffer.from('CBV2'))) return callback(new BoxError(BoxError.CRYPTO_ERROR, 'Invalid magic in header'));

            const iv = this._header.slice(4);
            this._decipher = crypto.createDecipheriv('aes-256-cbc', this._key, iv);
            this._hmac.update(this._header);
        }

        this._buffer = Buffer.concat([ this._buffer, chunk.slice(needed) ]);
        if (this._buffer.length < 32) return callback(); // hmac trailer length is 32

        try {
            const cipherText = this._buffer.slice(0, -32);
            this._hmac.update(cipherText);
            const plainText = this._decipher.update(cipherText);
            this._buffer = this._buffer.slice(-32);
            callback(null, plainText);
        } catch (error) {
            callback(error);
        }
    }

    _flush (callback) {
        if (this._buffer.length !== 32) return callback(new BoxError(BoxError.CRYPTO_ERROR, 'Invalid password or tampered file (not enough data)'));

        try {
            if (!this._hmac.digest().equals(this._buffer)) return callback(new BoxError(BoxError.CRYPTO_ERROR, 'Invalid password or tampered file (mac mismatch)'));

            const plainText = this._decipher.final();
            callback(null, plainText);
        } catch (error) {
            callback(error);
        }
    }
}

function createReadStream(sourceFile, encryption) {
    assert.strictEqual(typeof sourceFile, 'string');
    assert.strictEqual(typeof encryption, 'object');

    var stream = fs.createReadStream(sourceFile);
    var ps = progressStream({ time: 10000 }); // display a progress every 10 seconds

    stream.on('error', function (error) {
        debug(`createReadStream: read stream error at ${sourceFile}`, error);
        ps.emit('error', new BoxError(BoxError.FS_ERROR, `Error reading ${sourceFile}: ${error.message}`));
    });

    if (encryption) {
        let encryptStream = new EncryptStream(encryption);

        encryptStream.on('error', function (error) {
            debug(`createReadStream: encrypt stream error ${sourceFile}`, error);
            ps.emit('error', new BoxError(BoxError.CRYPTO_ERROR, `Encryption error at ${sourceFile}: ${error.message}`));
        });

        return stream.pipe(encryptStream).pipe(ps);
    } else {
        return stream.pipe(ps);
    }
}

function createWriteStream(destFile, encryption) {
    assert.strictEqual(typeof destFile, 'string');
    assert.strictEqual(typeof encryption, 'object');

    var stream = fs.createWriteStream(destFile);
    var ps = progressStream({ time: 10000 }); // display a progress every 10 seconds

    stream.on('error', function (error) {
        debug(`createWriteStream: write stream error ${destFile}`, error);
        ps.emit('error', new BoxError(BoxError.FS_ERROR, `Write error ${destFile}: ${error.message}`));
    });

    stream.on('finish', function () {
        debug('createWriteStream: done.');
        // we use a separate event because ps is a through2 stream which emits 'finish' event indicating end of inStream and not write
        ps.emit('done');
    });

    if (encryption) {
        let decrypt = new DecryptStream(encryption);
        decrypt.on('error', function (error) {
            debug(`createWriteStream: decrypt stream error ${destFile}`, error);
            ps.emit('error', new BoxError(BoxError.CRYPTO_ERROR, `Decryption error at ${destFile}: ${error.message}`));
        });

        ps.pipe(decrypt).pipe(stream);
    } else {
        ps.pipe(stream);
    }

    return ps;
}

function tarPack(dataLayout, encryption, callback) {
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof encryption, 'object');
    assert.strictEqual(typeof callback, 'function');

    var pack = tar.pack('/', {
        dereference: false, // pack the symlink and not what it points to
        entries: dataLayout.localPaths(),
        ignoreStatError: (path, err) => {
            debug(`tarPack: error stat'ing ${path} - ${err.code}`);
            return err.code === 'ENOENT'; // ignore if file or dir got removed (probably some temporary file)
        },
        map: function(header) {
            header.name = dataLayout.toRemotePath(header.name);
            // the tar pax format allows us to encode filenames > 100 and size > 8GB (see #640)
            // https://www.systutorials.com/docs/linux/man/5-star/
            if (header.size > 8589934590 || header.name > 99) header.pax = { size: header.size };
            return header;
        },
        strict: false // do not error for unknown types (skip fifo, char/block devices)
    });

    var gzip = zlib.createGzip({});
    var ps = progressStream({ time: 10000 }); // emit 'progress' every 10 seconds

    pack.on('error', function (error) {
        debug('tarPack: tar stream error.', error);
        ps.emit('error', new BoxError(BoxError.EXTERNAL_ERROR, error.message));
    });

    gzip.on('error', function (error) {
        debug('tarPack: gzip stream error.', error);
        ps.emit('error', new BoxError(BoxError.EXTERNAL_ERROR, error.message));
    });

    if (encryption) {
        const encryptStream = new EncryptStream(encryption);
        encryptStream.on('error', function (error) {
            debug('tarPack: encrypt stream error.', error);
            ps.emit('error', new BoxError(BoxError.EXTERNAL_ERROR, error.message));
        });

        pack.pipe(gzip).pipe(encryptStream).pipe(ps);
    } else {
        pack.pipe(gzip).pipe(ps);
    }

    return callback(null, ps);
}

function sync(backupConfig, backupId, dataLayout, progressCallback, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof backupId, 'string');
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    // the number here has to take into account the s3.upload partSize (which is 10MB). So 20=200MB
    const concurrency = backupConfig.syncConcurrency || (backupConfig.provider === 's3' ? 20 : 10);

    syncer.sync(dataLayout, function processTask(task, iteratorCallback) {
        debug('sync: processing task: %j', task);
        // the empty task.path is special to signify the directory
        const destPath = task.path && backupConfig.encryption ? encryptFilePath(task.path, backupConfig.encryption) : task.path;
        const backupFilePath = path.join(getBackupFilePath(backupConfig, backupId, backupConfig.format), destPath);

        if (task.operation === 'removedir') {
            debug(`Removing directory ${backupFilePath}`);
            return api(backupConfig.provider).removeDir(backupConfig, backupFilePath)
                .on('progress', (message) => progressCallback({ message }))
                .on('done', iteratorCallback);
        } else if (task.operation === 'remove') {
            debug(`Removing ${backupFilePath}`);
            return api(backupConfig.provider).remove(backupConfig, backupFilePath, iteratorCallback);
        }

        var retryCount = 0;
        async.retry({ times: 5, interval: 20000 }, function (retryCallback) {
            retryCallback = once(retryCallback); // protect again upload() erroring much later after read stream error

            ++retryCount;
            if (task.operation === 'add') {
                progressCallback({ message: `Adding ${task.path}` + (retryCount > 1 ?  ` (Try ${retryCount})` : '') });
                debug(`Adding ${task.path} position ${task.position} try ${retryCount}`);
                var stream = createReadStream(dataLayout.toLocalPath('./' + task.path), backupConfig.encryption);
                stream.on('error', function (error) {
                    debug(`read stream error for ${task.path}: ${error.message}`);
                    retryCallback();
                }); // ignore error if file disappears
                stream.on('progress', function (progress) {
                    const transferred = Math.round(progress.transferred/1024/1024), speed = Math.round(progress.speed/1024/1024);
                    if (!transferred && !speed) return progressCallback({ message: `Uploading ${task.path}` }); // 0M@0MBps looks wrong
                    progressCallback({ message: `Uploading ${task.path}: ${transferred}M@${speed}MBps` }); // 0M@0MBps looks wrong
                });
                api(backupConfig.provider).upload(backupConfig, backupFilePath, stream, function (error) {
                    debug(error ? `Error uploading ${task.path} try ${retryCount}: ${error.message}` : `Uploaded ${task.path}`);
                    retryCallback(error);
                });
            }
        }, iteratorCallback);
    }, concurrency, function (error) {
        if (error) return callback(new BoxError(BoxError.EXTERNAL_ERROR, error.message));

        callback();
    });
}

// this is not part of 'snapshotting' because we need root access to traverse
function saveFsMetadata(dataLayout, metadataFile, callback) {
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof metadataFile, 'string');
    assert.strictEqual(typeof callback, 'function');

    // contains paths prefixed with './'
    let metadata = {
        emptyDirs: [],
        execFiles: []
    };

    for (let lp of dataLayout.localPaths()) {
        var emptyDirs = safe.child_process.execSync(`find ${lp} -type d -empty\n`, { encoding: 'utf8' });
        if (emptyDirs === null) return callback(safe.error);
        if (emptyDirs.length) metadata.emptyDirs = metadata.emptyDirs.concat(emptyDirs.trim().split('\n').map((ed) => dataLayout.toRemotePath(ed)));

        var execFiles = safe.child_process.execSync(`find ${lp} -type f -executable\n`, { encoding: 'utf8' });
        if (execFiles === null) return callback(safe.error);

        if (execFiles.length) metadata.execFiles = metadata.execFiles.concat(execFiles.trim().split('\n').map((ef) => dataLayout.toRemotePath(ef)));
    }

    if (!safe.fs.writeFileSync(metadataFile, JSON.stringify(metadata, null, 4))) return callback(safe.error);

    callback();
}

// this function is called via backupupload (since it needs root to traverse app's directory)
function upload(backupId, format, dataLayoutString, progressCallback, callback) {
    assert.strictEqual(typeof backupId, 'string');
    assert.strictEqual(typeof format, 'string');
    assert.strictEqual(typeof dataLayoutString, 'string');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    debug(`upload: id ${backupId} format ${format} dataLayout ${dataLayoutString}`);

    const dataLayout = DataLayout.fromString(dataLayoutString);

    settings.getBackupConfig(function (error, backupConfig) {
        if (error) return callback(error);

        api(backupConfig.provider).checkPreconditions(backupConfig, dataLayout, function (error) {
            if (error) return callback(error);

            if (format === 'tgz') {
                async.retry({ times: 5, interval: 20000 }, function (retryCallback) {
                    retryCallback = once(retryCallback); // protect again upload() erroring much later after tar stream error

                    tarPack(dataLayout, backupConfig.encryption, function (error, tarStream) {
                        if (error) return retryCallback(error);

                        tarStream.on('progress', function (progress) {
                            const transferred = Math.round(progress.transferred/1024/1024), speed = Math.round(progress.speed/1024/1024);
                            if (!transferred && !speed) return progressCallback({ message: 'Uploading backup' }); // 0M@0MBps looks wrong
                            progressCallback({ message: `Uploading backup ${transferred}M@${speed}MBps` });
                        });
                        tarStream.on('error', retryCallback); // already returns BoxError

                        api(backupConfig.provider).upload(backupConfig, getBackupFilePath(backupConfig, backupId, format), tarStream, retryCallback);
                    });
                }, callback);
            } else {
                async.series([
                    saveFsMetadata.bind(null, dataLayout, `${dataLayout.localRoot()}/fsmetadata.json`),
                    sync.bind(null, backupConfig, backupId, dataLayout, progressCallback)
                ], callback);
            }
        });
    });
}

function tarExtract(inStream, dataLayout, encryption, callback) {
    assert.strictEqual(typeof inStream, 'object');
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof encryption, 'object');
    assert.strictEqual(typeof callback, 'function');

    var gunzip = zlib.createGunzip({});
    var ps = progressStream({ time: 10000 }); // display a progress every 10 seconds
    var extract = tar.extract('/', {
        map: function (header) {
            header.name = dataLayout.toLocalPath(header.name);
            return header;
        },
        dmode: 500 // ensure directory is writable
    });

    const emitError = once((error) => {
        inStream.destroy();
        ps.emit('error', error);
    });

    inStream.on('error', function (error) {
        debug('tarExtract: input stream error.', error);
        emitError(new BoxError(BoxError.EXTERNAL_ERROR, error.message));
    });

    gunzip.on('error', function (error) {
        debug('tarExtract: gunzip stream error.', error);
        emitError(new BoxError(BoxError.EXTERNAL_ERROR, error.message));
    });

    extract.on('error', function (error) {
        debug('tarExtract: extract stream error.', error);
        emitError(new BoxError(BoxError.EXTERNAL_ERROR, error.message));
    });

    extract.on('finish', function () {
        debug('tarExtract: done.');
        // we use a separate event because ps is a through2 stream which emits 'finish' event indicating end of inStream and not extract
        ps.emit('done');
    });

    if (encryption) {
        let decrypt = new DecryptStream(encryption);
        decrypt.on('error', function (error) {
            debug('tarExtract: decrypt stream error.', error);
            emitError(new BoxError(BoxError.EXTERNAL_ERROR, `Failed to decrypt: ${error.message}`));
        });
        inStream.pipe(ps).pipe(decrypt).pipe(gunzip).pipe(extract);
    } else {
        inStream.pipe(ps).pipe(gunzip).pipe(extract);
    }

    callback(null, ps);
}

function restoreFsMetadata(dataLayout, metadataFile, callback) {
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof metadataFile, 'string');
    assert.strictEqual(typeof callback, 'function');

    debug(`Recreating empty directories in ${dataLayout.toString()}`);

    var metadataJson = safe.fs.readFileSync(metadataFile, 'utf8');
    if (metadataJson === null) return callback(new BoxError(BoxError.EXTERNAL_ERROR, 'Error loading fsmetadata.json:' + safe.error.message));
    var metadata = safe.JSON.parse(metadataJson);
    if (metadata === null) return callback(new BoxError(BoxError.EXTERNAL_ERROR, 'Error parsing fsmetadata.json:' + safe.error.message));

    async.eachSeries(metadata.emptyDirs, function createPath(emptyDir, iteratorDone) {
        fs.mkdir(dataLayout.toLocalPath(emptyDir), { recursive: true }, iteratorDone);
    }, function (error) {
        if (error) return callback(new BoxError(BoxError.EXTERNAL_ERROR, `unable to create path: ${error.message}`));

        async.eachSeries(metadata.execFiles, function createPath(execFile, iteratorDone) {
            fs.chmod(dataLayout.toLocalPath(execFile), parseInt('0755', 8), iteratorDone);
        }, function (error) {
            if (error) return callback(new BoxError(BoxError.EXTERNAL_ERROR, `unable to chmod: ${error.message}`));

            callback();
        });
    });
}

function downloadDir(backupConfig, backupFilePath, dataLayout, progressCallback, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof backupFilePath, 'string');
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    debug(`downloadDir: ${backupFilePath} to ${dataLayout.toString()}`);

    function downloadFile(entry, done) {
        let relativePath = path.relative(backupFilePath, entry.fullPath);
        if (backupConfig.encryption) {
            const { error, result } = decryptFilePath(relativePath, backupConfig.encryption);
            if (error) return done(new BoxError(BoxError.CRYPTO_ERROR, 'Unable to decrypt file'));
            relativePath = result;
        }
        const destFilePath = dataLayout.toLocalPath('./' + relativePath);

        fs.mkdir(path.dirname(destFilePath), { recursive: true }, function (error) {
            if (error) return done(new BoxError(BoxError.FS_ERROR, error.message));

            async.retry({ times: 5, interval: 20000 }, function (retryCallback) {
                api(backupConfig.provider).download(backupConfig, entry.fullPath, function (error, sourceStream) {
                    if (error) {
                        progressCallback({ message: `Download ${entry.fullPath} to ${destFilePath} errored: ${error.message}` });
                        return retryCallback(error);
                    }

                    let destStream = createWriteStream(destFilePath, backupConfig.encryption);

                    // protect against multiple errors. must destroy the write stream so that a previous retry does not write
                    let closeAndRetry = once((error) => {
                        if (error) progressCallback({ message: `Download ${entry.fullPath} to ${destFilePath} errored: ${error.message}` });
                        else progressCallback({ message: `Download ${entry.fullPath} to ${destFilePath} finished` });
                        sourceStream.destroy();
                        destStream.destroy();
                        retryCallback(error);
                    });

                    destStream.on('progress', function (progress) {
                        const transferred = Math.round(progress.transferred/1024/1024), speed = Math.round(progress.speed/1024/1024);
                        if (!transferred && !speed) return progressCallback({ message: `Downloading ${entry.fullPath}` }); // 0M@0MBps looks wrong
                        progressCallback({ message: `Downloading ${entry.fullPath}: ${transferred}M@${speed}MBps` });
                    });
                    destStream.on('error', closeAndRetry);

                    sourceStream.on('error', closeAndRetry);

                    progressCallback({ message: `Downloading ${entry.fullPath} to ${destFilePath}` });

                    sourceStream.pipe(destStream, { end: true }).on('done', closeAndRetry);
                });
            }, done);
        });
    }

    api(backupConfig.provider).listDir(backupConfig, backupFilePath, 1000, function (entries, iteratorDone) {
        // https://www.digitalocean.com/community/questions/rate-limiting-on-spaces?answer=40441
        const concurrency = backupConfig.downloadConcurrency || (backupConfig.provider === 's3' ? 30 : 10);

        async.eachLimit(entries, concurrency, downloadFile, iteratorDone);
    }, callback);
}

function download(backupConfig, backupId, format, dataLayout, progressCallback, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof backupId, 'string');
    assert.strictEqual(typeof format, 'string');
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    debug(`download: Downloading ${backupId} of format ${format} to ${dataLayout.toString()}`);

    const backupFilePath = getBackupFilePath(backupConfig, backupId, format);

    if (format === 'tgz') {
        async.retry({ times: 5, interval: 20000 }, function (retryCallback) {
            api(backupConfig.provider).download(backupConfig, backupFilePath, function (error, sourceStream) {
                if (error) return retryCallback(error);

                tarExtract(sourceStream, dataLayout, backupConfig.encryption, function (error, ps) {
                    if (error) return retryCallback(error);

                    ps.on('progress', function (progress) {
                        const transferred = Math.round(progress.transferred/1024/1024), speed = Math.round(progress.speed/1024/1024);
                        if (!transferred && !speed) return progressCallback({ message: 'Downloading backup' }); // 0M@0MBps looks wrong
                        progressCallback({ message: `Downloading ${transferred}M@${speed}MBps` });
                    });
                    ps.on('error', retryCallback);
                    ps.on('done', retryCallback);
                });
            });
        }, callback);
    } else {
        downloadDir(backupConfig, backupFilePath, dataLayout, progressCallback, function (error) {
            if (error) return callback(error);

            restoreFsMetadata(dataLayout, `${dataLayout.localRoot()}/fsmetadata.json`, callback);
        });
    }
}

function restore(backupConfig, backupId, progressCallback, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof backupId, 'string');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    const dataLayout = new DataLayout(paths.BOX_DATA_DIR, []);

    download(backupConfig, backupId, backupConfig.format, dataLayout, progressCallback, function (error) {
        if (error) return callback(error);

        debug('restore: download completed, importing database');

        database.importFromFile(`${dataLayout.localRoot()}/box.mysqldump`, function (error) {
            if (error) return callback(new BoxError(BoxError.DATABASE_ERROR, error));

            debug('restore: database imported');

            settings.initCache(callback);
        });
    });
}

function downloadApp(app, restoreConfig, progressCallback, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof restoreConfig, 'object');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    const appDataDir = safe.fs.realpathSync(path.join(paths.APPS_DATA_DIR, app.id));
    if (!appDataDir) return callback(safe.error);
    const dataLayout = new DataLayout(appDataDir, app.dataDir ? [{ localDir: app.dataDir, remoteDir: 'data' }] : []);

    const startTime = new Date();
    const getBackupConfigFunc = restoreConfig.backupConfig ? (next) => next(null, restoreConfig.backupConfig) : settings.getBackupConfig;

    getBackupConfigFunc(function (error, backupConfig) {
        if (error) return callback(error);

        download(backupConfig, restoreConfig.backupId, restoreConfig.backupFormat, dataLayout, progressCallback, function (error) {
            debug('downloadApp: time: %s', (new Date() - startTime)/1000);

            callback(error);
        });
    });
}

function runBackupUpload(uploadConfig, progressCallback, callback) {
    assert.strictEqual(typeof uploadConfig, 'object');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    const { backupId, format, dataLayout, progressTag } = uploadConfig;
    assert.strictEqual(typeof backupId, 'string');
    assert.strictEqual(typeof format, 'string');
    assert.strictEqual(typeof progressTag, 'string');
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');

    let result = ''; // the script communicates error result as a string

    shell.sudo(`backup-${backupId}`, [ BACKUP_UPLOAD_CMD, backupId, format, dataLayout.toString() ], { preserveEnv: true, ipc: true }, function (error) {
        if (error && (error.code === null /* signal */ || (error.code !== 0 && error.code !== 50))) { // backuptask crashed
            return callback(new BoxError(BoxError.INTERNAL_ERROR, 'Backuptask crashed'));
        } else if (error && error.code === 50) { // exited with error
            return callback(new BoxError(BoxError.EXTERNAL_ERROR, result));
        }

        callback();
    }).on('message', function (progress) { // this is { message } or { result }
        if ('message' in progress) return progressCallback({ message: `${progress.message} (${progressTag})` });
        debug(`runBackupUpload: result - ${JSON.stringify(progress)}`);
        result = progress.result;
    });
}

function getSnapshotInfo(id) {
    assert.strictEqual(typeof id, 'string');

    var contents = safe.fs.readFileSync(paths.SNAPSHOT_INFO_FILE, 'utf8');
    var info = safe.JSON.parse(contents);
    if (!info) return { };
    return info[id] || { };
}

function setSnapshotInfo(id, info, callback) {
    assert.strictEqual(typeof id, 'string');
    assert.strictEqual(typeof info, 'object');
    assert.strictEqual(typeof callback, 'function');

    var contents = safe.fs.readFileSync(paths.SNAPSHOT_INFO_FILE, 'utf8');
    var data = safe.JSON.parse(contents) || { };
    if (info) data[id] = info; else delete data[id];
    if (!safe.fs.writeFileSync(paths.SNAPSHOT_INFO_FILE, JSON.stringify(data, null, 4), 'utf8')) {
        return callback(new BoxError(BoxError.FS_ERROR, safe.error.message));
    }

    callback();
}

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

    progressCallback({ message: 'Snapshotting box' });

    const startTime = new Date();

    database.exportToFile(`${paths.BOX_DATA_DIR}/box.mysqldump`, function (error) {
        if (error) return callback(new BoxError(BoxError.DATABASE_ERROR, error));

        debug(`snapshotBox: took ${(new Date() - startTime)/1000} seconds`);

        return callback();
    });
}

function uploadBoxSnapshot(backupConfig, progressCallback, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    snapshotBox(progressCallback, function (error) {
        if (error) return callback(error);

        const boxDataDir = safe.fs.realpathSync(paths.BOX_DATA_DIR);
        if (!boxDataDir) return callback(safe.error);

        const uploadConfig = {
            backupId: 'snapshot/box',
            format: backupConfig.format,
            dataLayout: new DataLayout(boxDataDir, []),
            progressTag: 'box'
        };

        progressCallback({ message: 'Uploading box snapshot' });

        const startTime = new Date();

        runBackupUpload(uploadConfig, progressCallback, function (error) {
            if (error) return callback(error);

            debug(`uploadBoxSnapshot: took ${(new Date() - startTime)/1000} seconds`);

            setSnapshotInfo('box', { timestamp: new Date().toISOString(), format: backupConfig.format }, callback);
        });
    });
}

function rotateBoxBackup(backupConfig, tag, appBackupIds, progressCallback, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof tag, 'string');
    assert(Array.isArray(appBackupIds));
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    var snapshotInfo = getSnapshotInfo('box');

    const snapshotTime = snapshotInfo.timestamp.replace(/[T.]/g, '-').replace(/[:Z]/g,''); // add this to filename to make it unique, so it's easy to download them
    const backupId = util.format('%s/box_%s_v%s', tag, snapshotTime, constants.VERSION);
    const format = backupConfig.format;

    debug(`Rotating box backup to id ${backupId}`);

    const data = {
        encryptionVersion: backupConfig.encryption ? 2 : null,
        packageVersion: constants.VERSION,
        type: exports.BACKUP_TYPE_BOX,
        state: exports.BACKUP_STATE_CREATING,
        identifier: 'box',
        dependsOn: appBackupIds,
        manifest: null,
        format: format
    };
    backupdb.add(backupId, data, function (error) {
        if (error) return callback(error);

        var copy = api(backupConfig.provider).copy(backupConfig, getBackupFilePath(backupConfig, 'snapshot/box', format), getBackupFilePath(backupConfig, backupId, format));
        copy.on('progress', (message) => progressCallback({ message: `box: ${message}` }));
        copy.on('done', function (copyBackupError) {
            const state = copyBackupError ? exports.BACKUP_STATE_ERROR : exports.BACKUP_STATE_NORMAL;

            backupdb.update(backupId, { state }, function (error) {
                if (copyBackupError) return callback(copyBackupError);
                if (error) return callback(error);

                debug(`Rotated box backup successfully as id ${backupId}`);

                callback(null, backupId);
            });
        });
    });
}

function backupBoxWithAppBackupIds(appBackupIds, tag, progressCallback, callback) {
    assert(Array.isArray(appBackupIds));
    assert.strictEqual(typeof tag, 'string');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    settings.getBackupConfig(function (error, backupConfig) {
        if (error) return callback(error);

        uploadBoxSnapshot(backupConfig, progressCallback, function (error) {
            if (error) return callback(error);

            rotateBoxBackup(backupConfig, tag, appBackupIds, progressCallback, callback);
        });
    });
}

function canBackupApp(app) {
    // only backup apps that are installed or specific pending states

    // stopped apps cannot be backed up because addons might be down (redis)
    if (app.runState === apps.RSTATE_STOPPED) return false;

    // we used to check the health here but that doesn't work for stopped apps. it's better to just fail
    // and inform the user if the backup fails and the app addons have not been setup yet.
    return  app.installationState === apps.ISTATE_INSTALLED ||
            app.installationState === apps.ISTATE_PENDING_CONFIGURE ||
            app.installationState === apps.ISTATE_PENDING_BACKUP ||  // called from apptask
            app.installationState === apps.ISTATE_PENDING_UPDATE; // called from apptask
}

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

    const startTime = new Date();
    progressCallback({ message: `Snapshotting app ${app.fqdn}` });

    if (!safe.fs.writeFileSync(path.join(paths.APPS_DATA_DIR, app.id + '/config.json'), JSON.stringify(app))) {
        return callback(new BoxError(BoxError.FS_ERROR, 'Error creating config.json: ' + safe.error.message));
    }

    addons.backupAddons(app, app.manifest.addons, function (error) {
        if (error) return callback(new BoxError(BoxError.EXTERNAL_ERROR, error.message));

        debugApp(app, `snapshotApp: took ${(new Date() - startTime)/1000} seconds`);

        return callback(null);
    });
}

function rotateAppBackup(backupConfig, app, tag, options, progressCallback, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof tag, 'string');
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    const startTime = new Date();

    var snapshotInfo = getSnapshotInfo(app.id);

    var manifest = snapshotInfo.restoreConfig ? snapshotInfo.restoreConfig.manifest : snapshotInfo.manifest; // compat
    const snapshotTime = snapshotInfo.timestamp.replace(/[T.]/g, '-').replace(/[:Z]/g,''); // add this for unique filename which helps when downloading them
    const backupId = util.format('%s/app_%s_%s_v%s', tag, app.id, snapshotTime, manifest.version);
    const format = backupConfig.format;

    debug(`Rotating app backup of ${app.id} to id ${backupId}`);

    const data = {
        encryptionVersion: backupConfig.encryption ? 2 : null,
        packageVersion: manifest.version,
        type: exports.BACKUP_TYPE_APP,
        state: exports.BACKUP_STATE_CREATING,
        identifier: app.id,
        dependsOn: [ ],
        manifest,
        format: format
    };

    backupdb.add(backupId, data, function (error) {
        if (error) return callback(error);

        var copy = api(backupConfig.provider).copy(backupConfig, getBackupFilePath(backupConfig, `snapshot/app_${app.id}`, format), getBackupFilePath(backupConfig, backupId, format));
        copy.on('progress', (message) => progressCallback({ message: `${message} (${app.fqdn})` }));
        copy.on('done', function (copyBackupError) {
            const state = copyBackupError ? exports.BACKUP_STATE_ERROR : exports.BACKUP_STATE_NORMAL;

            backupdb.update(backupId, { preserveSecs: options.preserveSecs || 0, state }, function (error) {
                if (copyBackupError) return callback(copyBackupError);
                if (error) return callback(error);

                debug(`Rotated app backup of ${app.id} successfully to id ${backupId}. Took ${(new Date() - startTime)/1000} seconds`);

                callback(null, backupId);
            });
        });
    });
}

function uploadAppSnapshot(backupConfig, app, progressCallback, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    snapshotApp(app, progressCallback, function (error) {
        if (error) return callback(error);

        const backupId = util.format('snapshot/app_%s', app.id);
        const appDataDir = safe.fs.realpathSync(path.join(paths.APPS_DATA_DIR, app.id));
        if (!appDataDir) return callback(safe.error);

        const dataLayout = new DataLayout(appDataDir, app.dataDir ? [{ localDir: app.dataDir, remoteDir: 'data' }] : []);

        progressCallback({ message: `Uploading app snapshot ${app.fqdn}`});

        const uploadConfig = {
            backupId,
            format: backupConfig.format,
            dataLayout,
            progressTag: app.fqdn
        };

        const startTime = new Date();

        runBackupUpload(uploadConfig, progressCallback, function (error) {
            if (error) return callback(error);

            debugApp(app, `uploadAppSnapshot: ${backupId} done. ${(new Date() - startTime)/1000} seconds`);

            setSnapshotInfo(app.id, { timestamp: new Date().toISOString(), manifest: app.manifest, format: backupConfig.format }, callback);
        });
    });
}

function backupAppWithTag(app, tag, options, progressCallback, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof tag, 'string');
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    if (!canBackupApp(app)) { // if we cannot backup, reuse it's most recent backup
        getByIdentifierAndStatePaged(app.id, exports.BACKUP_STATE_NORMAL, 1, 1, function (error, results) {
            if (error) return callback(error);
            if (results.length === 0) return callback(null, null); // no backup to re-use

            callback(null, results[0].id);
        });

        return;
    }

    settings.getBackupConfig(function (error, backupConfig) {
        if (error) return callback(error);

        uploadAppSnapshot(backupConfig, app, progressCallback, function (error) {
            if (error) return callback(error);

            rotateAppBackup(backupConfig, app, tag, options, progressCallback, callback);
        });
    });
}

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

    const tag = (new Date()).toISOString().replace(/[T.]/g, '-').replace(/[:Z]/g,'');

    debug(`backupApp - Backing up ${app.fqdn} with tag ${tag}`);

    backupAppWithTag(app, tag, options, progressCallback, callback);
}

// this function expects you to have a lock. Unlike other progressCallback this also has a progress field
function backupBoxAndApps(progressCallback, callback) {
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    const tag = (new Date()).toISOString().replace(/[T.]/g, '-').replace(/[:Z]/g,'');

    apps.getAll(function (error, allApps) {
        if (error) return callback(error);

        let percent = 1;
        let step = 100/(allApps.length+2);

        async.mapSeries(allApps, function iterator(app, iteratorCallback) {
            progressCallback({ percent: percent, message: `Backing up ${app.fqdn}` });
            percent += step;

            if (!app.enableBackup) {
                debug(`Skipped backup ${app.fqdn}`);
                return iteratorCallback(null, null); // nothing to backup
            }

            const startTime = new Date();
            backupAppWithTag(app, tag, { /* options */ }, (progress) => progressCallback({ percent: percent, message: progress.message }), function (error, backupId) {
                if (error) {
                    debugApp(app, 'Unable to backup', error);
                    return iteratorCallback(error);
                }

                debugApp(app, `Backed up. Took ${(new Date() - startTime)/1000} seconds`);

                iteratorCallback(null, backupId || null); // clear backupId if is in BAD_STATE and never backed up
            });
        }, function appsBackedUp(error, backupIds) {
            if (error) return callback(error);

            backupIds = backupIds.filter(function (id) { return id !== null; }); // remove apps in bad state that were never backed up

            progressCallback({ percent: percent, message: 'Backing up system data' });
            percent += step;

            backupBoxWithAppBackupIds(backupIds, tag, (progress) => progressCallback({ percent: percent, message: progress.message }), callback);
        });
    });
}

function startBackupTask(auditSource, callback) {
    let error = locker.lock(locker.OP_FULL_BACKUP);
    if (error) return callback(new BoxError(BoxError.BAD_STATE, `Cannot backup now: ${error.message}`));

    settings.getBackupConfig(function (error, backupConfig) {
        if (error) return callback(error);

        const memoryLimit = 'memoryLimit' in backupConfig ? Math.max(backupConfig.memoryLimit/1024/1024, 400) : 400;

        tasks.add(tasks.TASK_BACKUP, [ ], function (error, taskId) {
            if (error) return callback(error);

            eventlog.add(eventlog.ACTION_BACKUP_START, auditSource, { taskId });

            tasks.startTask(taskId, { timeout: 12 * 60 * 60 * 1000 /* 12 hours */, nice: 15, memoryLimit }, function (error, backupId) {
                locker.unlock(locker.OP_FULL_BACKUP);

                const errorMessage = error ? error.message : '';
                const timedOut = error ? error.code === tasks.ETIMEOUT : false;

                eventlog.add(eventlog.ACTION_BACKUP_FINISH, auditSource, { taskId, errorMessage, timedOut, backupId });
            });

            callback(null, taskId);
        });
    });
}

function applyBackupRetentionPolicy(backups, policy, referencedBackupIds) {
    assert(Array.isArray(backups));
    assert.strictEqual(typeof policy, 'object');
    assert(Array.isArray(referencedBackupIds));

    const now = new Date();

    for (const backup of backups) {
        if (backup.state === exports.BACKUP_STATE_ERROR) {
            backup.discardReason = 'error';
        } else if (backup.state === exports.BACKUP_STATE_CREATING) {
            if ((now - backup.creationTime) < 48*60*60*1000) backup.keepReason = 'creating';
            else backup.discardReason = 'creating-too-long';
        } else if (referencedBackupIds.includes(backup.id)) {
            backup.keepReason = 'reference';
        } else if ((now - backup.creationTime) < (backup.preserveSecs * 1000)) {
            backup.keepReason = 'preserveSecs';
        } else if ((now - backup.creationTime < policy.keepWithinSecs * 1000) || policy.keepWithinSecs < 0) {
            backup.keepReason = 'keepWithinSecs';
        }
    }

    const KEEP_FORMATS = {
        keepDaily: 'Y-M-D',
        keepWeekly: 'Y-W',
        keepMonthly: 'Y-M',
        keepYearly: 'Y'
    };

    for (const format of [ 'keepDaily', 'keepWeekly', 'keepMonthly', 'keepYearly' ]) {
        if (!(format in policy)) continue;

        const n = policy[format]; // we want to keep "n" backups of format
        if (!n) continue; // disabled rule

        let lastPeriod = null, keptSoFar = 0;
        for (const backup of backups) {
            if (backup.discardReason) continue; // already discarded for some reason
            if (backup.keepReason && backup.keepReason !== 'reference') continue; // kept for some other reason
            const period = moment(backup.creationTime).format(KEEP_FORMATS[format]);
            if (period === lastPeriod) continue; // already kept for this period

            lastPeriod = period;
            backup.keepReason = backup.keepReason ? `${backup.keepReason}+${format}` : format;
            if (++keptSoFar === n) break;
        }
    }

    if (policy.keepLatest) {
        let latestNormalBackup = backups.find(b => b.state === exports.BACKUP_STATE_NORMAL);
        if (latestNormalBackup && !latestNormalBackup.keepReason) latestNormalBackup.keepReason = 'latest';
    }

    for (const backup of backups) {
        debug(`applyBackupRetentionPolicy: ${backup.id} ${backup.type} ${backup.keepReason || backup.discardReason || 'unprocessed'}`);
    }
}

function cleanupBackup(backupConfig, backup, progressCallback, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof backup, 'object');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    var backupFilePath = getBackupFilePath(backupConfig, backup.id, backup.format);

    function done(error) {
        if (error) {
            debug('cleanupBackup: error removing backup %j : %s', backup, error.message);
            return callback();
        }

        // prune empty directory if possible
        api(backupConfig.provider).remove(backupConfig, path.dirname(backupFilePath), function (error) {
            if (error) debug('cleanupBackup: unable to prune backup directory %s : %s', path.dirname(backupFilePath), error.message);

            backupdb.del(backup.id, function (error) {
                if (error) debug('cleanupBackup: error removing from database', error);
                else debug('cleanupBackup: removed %s', backup.id);

                callback();
            });
        });
    }

    if (backup.format ==='tgz') {
        progressCallback({ message: `${backup.id}: Removing ${backupFilePath}`});
        api(backupConfig.provider).remove(backupConfig, backupFilePath, done);
    } else {
        var events = api(backupConfig.provider).removeDir(backupConfig, backupFilePath);
        events.on('progress', (message) => progressCallback({ message: `${backup.id}: ${message}` }));
        events.on('done', done);
    }
}

function cleanupAppBackups(backupConfig, referencedAppBackupIds, progressCallback, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert(Array.isArray(referencedAppBackupIds));
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    let removedAppBackupIds = [];

    apps.getAll(function (error, allApps) {
        if (error) return callback(error);

        const allAppIds = allApps.map(a => a.id);

        backupdb.getByTypePaged(exports.BACKUP_TYPE_APP, 1, 1000, function (error, appBackups) {
            if (error) return callback(error);

            // collate the backups by app id. note that the app could already have been uninstalled
            let appBackupsById = {};
            for (const appBackup of appBackups) {
                if (!appBackupsById[appBackup.identifier]) appBackupsById[appBackup.identifier] = [];
                appBackupsById[appBackup.identifier].push(appBackup);
            }

            // apply backup policy per app. keep latest backup only for existing apps
            let appBackupsToRemove = [];
            for (const appId of Object.keys(appBackupsById)) {
                applyBackupRetentionPolicy(appBackupsById[appId], _.extend({ keepLatest: allAppIds.includes(appId) }, backupConfig.retentionPolicy), referencedAppBackupIds);
                appBackupsToRemove = appBackupsToRemove.concat(appBackupsById[appId].filter(b => !b.keepReason));
            }

            async.eachSeries(appBackupsToRemove, function iterator(appBackup, iteratorDone) {
                progressCallback({ message: `Removing app backup (${appBackup.identifier}): ${appBackup.id}`});
                removedAppBackupIds.push(appBackup.id);
                cleanupBackup(backupConfig, appBackup, progressCallback, iteratorDone);
            }, function () {
                debug('cleanupAppBackups: done');

                callback(null, removedAppBackupIds);
            });
        });
    });
}

function cleanupBoxBackups(backupConfig, progressCallback, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    let referencedAppBackupIds = [], removedBoxBackupIds = [];

    backupdb.getByTypePaged(exports.BACKUP_TYPE_BOX, 1, 1000, function (error, boxBackups) {
        if (error) return callback(error);

        applyBackupRetentionPolicy(boxBackups, _.extend({ keepLatest: true }, backupConfig.retentionPolicy), [] /* references */);

        async.eachSeries(boxBackups, function iterator(boxBackup, iteratorNext) {
            if (boxBackup.keepReason) {
                referencedAppBackupIds = referencedAppBackupIds.concat(boxBackup.dependsOn);
                return iteratorNext();
            }

            progressCallback({ message: `Removing box backup ${boxBackup.id}`});

            removedBoxBackupIds.push(boxBackup.id);
            cleanupBackup(backupConfig, boxBackup, progressCallback, iteratorNext);
        }, function () {
            debug('cleanupBoxBackups: done');

            callback(null, { removedBoxBackupIds, referencedAppBackupIds });
        });
    });
}

function cleanupCacheFilesSync() {
    var files = safe.fs.readdirSync(path.join(paths.BACKUP_INFO_DIR));
    if (!files) return;

    files.filter(function (f) { return f.endsWith('.sync.cache'); }).forEach(function (f) {
        safe.fs.unlinkSync(path.join(paths.BACKUP_INFO_DIR, f));
    });
}

// removes the snapshots of apps that have been uninstalled
function cleanupSnapshots(backupConfig, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof callback, 'function');

    var contents = safe.fs.readFileSync(paths.SNAPSHOT_INFO_FILE, 'utf8');
    var info = safe.JSON.parse(contents);
    if (!info) return callback();

    delete info.box;
    async.eachSeries(Object.keys(info), function (appId, iteratorDone) {
        apps.get(appId, function (error /*, app */) {
            if (!error || error.reason !== BoxError.NOT_FOUND) return iteratorDone();

            function done(/* ignoredError */) {
                safe.fs.unlinkSync(path.join(paths.BACKUP_INFO_DIR, `${appId}.sync.cache`));
                safe.fs.unlinkSync(path.join(paths.BACKUP_INFO_DIR, `${appId}.sync.cache.new`));

                setSnapshotInfo(appId, null, function (/* ignoredError */) {
                    debug('cleanupSnapshots: cleaned up snapshot of app id %s', appId);

                    iteratorDone();
                });
            }

            if (info[appId].format ==='tgz') {
                api(backupConfig.provider).remove(backupConfig, getBackupFilePath(backupConfig, `snapshot/app_${appId}`, info[appId].format), done);
            } else {
                var events = api(backupConfig.provider).removeDir(backupConfig, getBackupFilePath(backupConfig, `snapshot/app_${appId}`, info[appId].format));
                events.on('progress', function (detail) { debug(`cleanupSnapshots: ${detail}`); });
                events.on('done', done);
            }
        });
    }, function () {
        debug('cleanupSnapshots: done');

        callback();
    });
}

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

    settings.getBackupConfig(function (error, backupConfig) {
        if (error) return callback(error);

        if (backupConfig.retentionPolicy.keepWithinSecs < 0) {
            debug('cleanup: keeping all backups');
            return callback(null, {});
        }

        progressCallback({ percent: 10, message: 'Cleaning box backups' });

        cleanupBoxBackups(backupConfig, progressCallback, function (error, { removedBoxBackupIds, referencedAppBackupIds }) {
            if (error) return callback(error);

            progressCallback({ percent: 40, message: 'Cleaning app backups' });

            cleanupAppBackups(backupConfig, referencedAppBackupIds, progressCallback, function (error, removedAppBackupIds) {
                if (error) return callback(error);

                progressCallback({ percent: 90, message: 'Cleaning snapshots' });

                cleanupSnapshots(backupConfig, function (error) {
                    if (error) return callback(error);

                    callback(null, { removedBoxBackupIds, removedAppBackupIds });
                });
            });
        });
    });
}

function startCleanupTask(auditSource, callback) {

    tasks.add(tasks.TASK_CLEAN_BACKUPS, [], function (error, taskId) {
        if (error) return callback(error);

        tasks.startTask(taskId, {}, (error, result) => { // result is { removedBoxBackups, removedAppBackups }
            eventlog.add(eventlog.ACTION_BACKUP_CLEANUP_FINISH, auditSource, {
                taskId,
                errorMessage: error ? error.message : null,
                removedBoxBackups: result ? result.removedBoxBackups : [],
                removedAppBackups: result ? result.removedAppBackups : []
            });
        });

        callback(null, taskId);
    });
}

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

    settings.getBackupConfig(function (error, backupConfig) {
        if (error) return callback(error);

        let message = '';
        if (backupConfig.provider === 'noop') {
            message = 'Cloudron backups are disabled. Please ensure this server is backed up using alternate means. See https://cloudron.io/documentation/backups/#storage-providers for more information.';
        } else if (backupConfig.provider === 'filesystem' && !backupConfig.externalDisk) {
            message = 'Cloudron backups are currently on the same disk as the Cloudron server instance. This is dangerous and can lead to complete data loss if the disk fails. See https://cloudron.io/documentation/backups/#storage-providers for storing backups in an external location.';
        }

        callback(null, message);
    });
}

function configureCollectd(backupConfig, callback) {
    assert.strictEqual(typeof backupConfig, 'object');
    assert.strictEqual(typeof callback, 'function');

    if (backupConfig.provider === 'filesystem') {
        const collectdConf = ejs.render(COLLECTD_CONFIG_EJS, { backupDir: backupConfig.backupFolder });
        collectd.addProfile('cloudron-backup', collectdConf, callback);
    } else {
        collectd.removeProfile('cloudron-backup', callback);
    }
}