'use strict';

exports = module.exports = {
    get,
    getByIdentifierAndStatePaged,
    getByTypePaged,
    add,
    update,
    setState,
    list,
    del,

    startBackupTask,

    startCleanupTask,
    cleanupCacheFilesSync,

    removePrivateFields,

    generateEncryptionKeysSync,

    getSnapshotInfo,
    setSnapshotInfo,

    validatePolicy,
    validateEncryptionPassword,
    testStorage,
    validateFormat,

    getPolicy,
    setPolicy,

    getConfig,
    setConfig,
    setStorage,
    setLimits,

    getRootPath,
    setupStorage,

    remount,
    getMountStatus,

    BACKUP_IDENTIFIER_BOX: 'box',
    BACKUP_IDENTIFIER_MAIL: 'mail',

    BACKUP_TYPE_APP: 'app',
    BACKUP_TYPE_BOX: 'box',
    BACKUP_TYPE_MAIL: 'mail',

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

const assert = require('assert'),
    BoxError = require('./boxerror.js'),
    constants = require('./constants.js'),
    cron = require('./cron.js'),
    CronJob = require('cron').CronJob,
    crypto = require('crypto'),
    database = require('./database.js'),
    debug = require('debug')('box:backups'),
    eventlog = require('./eventlog.js'),
    hat = require('./hat.js'),
    locker = require('./locker.js'),
    mounts = require('./mounts.js'),
    path = require('path'),
    paths = require('./paths.js'),
    safe = require('safetydance'),
    settings = require('./settings.js'),
    storage = require('./storage.js'),
    tasks = require('./tasks.js'),
    _ = require('underscore');

const BACKUPS_FIELDS = [ 'id', 'remotePath', 'label', 'identifier', 'creationTime', 'packageVersion', 'type', 'dependsOnJson', 'state', 'manifestJson', 'format', 'preserveSecs', 'encryptionVersion' ];

function postProcess(result) {
    assert.strictEqual(typeof result, 'object');

    result.dependsOn = result.dependsOnJson ? safe.JSON.parse(result.dependsOnJson) : [];
    delete result.dependsOnJson;

    result.manifest = result.manifestJson ? safe.JSON.parse(result.manifestJson) : null;
    delete result.manifestJson;

    return result;
}

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

// this function is used in migrations - 20200512172301-settings-backup-encryption.js
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')
    };
}

async function add(data) {
    assert(data && typeof data === 'object');
    assert.strictEqual(typeof data.remotePath, 'string');
    assert(data.encryptionVersion === null || typeof data.encryptionVersion === 'number');
    assert.strictEqual(typeof data.packageVersion, 'string');
    assert.strictEqual(typeof data.type, 'string');
    assert.strictEqual(typeof data.identifier, 'string');
    assert.strictEqual(typeof data.state, 'string');
    assert(Array.isArray(data.dependsOn));
    assert.strictEqual(typeof data.manifest, 'object');
    assert.strictEqual(typeof data.format, 'string');
    assert.strictEqual(typeof data.preserveSecs, 'number');

    const creationTime = data.creationTime || new Date(); // allow tests to set the time
    const manifestJson = JSON.stringify(data.manifest);
    const prefixId = data.type === exports.BACKUP_TYPE_APP ? `${data.type}_${data.identifier}` : data.type; // type and identifier are same for other types
    const id = `${prefixId}_v${data.packageVersion}_${hat(32)}`; // id is used by the UI to derive dependent packages. making this a UUID will require a lot of db querying

    const [error] = await safe(database.query('INSERT INTO backups (id, remotePath, identifier, encryptionVersion, packageVersion, type, creationTime, state, dependsOnJson, manifestJson, format, preserveSecs) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)',
        [ id, data.remotePath, data.identifier, data.encryptionVersion, data.packageVersion, data.type, creationTime, data.state, JSON.stringify(data.dependsOn), manifestJson, data.format, data.preserveSecs ]));

    if (error && error.code === 'ER_DUP_ENTRY') throw new BoxError(BoxError.ALREADY_EXISTS, 'Backup already exists');
    if (error) throw error;

    return id;
}

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

    const results = await database.query(`SELECT ${BACKUPS_FIELDS} FROM backups WHERE identifier = ? AND state = ? ORDER BY creationTime DESC LIMIT ?,?`, [ identifier, state, (page-1)*perPage, perPage ]);

    results.forEach(function (result) { postProcess(result); });

    return results;
}

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

    const result = await database.query('SELECT ' + BACKUPS_FIELDS + ' FROM backups WHERE id = ? ORDER BY creationTime DESC', [ id ]);
    if (result.length === 0) return null;

    return postProcess(result[0]);
}

async function getByTypePaged(type, page, perPage) {
    assert.strictEqual(typeof type, 'string');
    assert(typeof page === 'number' && page > 0);
    assert(typeof perPage === 'number' && perPage > 0);

    const results = await database.query(`SELECT ${BACKUPS_FIELDS} FROM backups WHERE type = ? ORDER BY creationTime DESC LIMIT ?,?`, [ type, (page-1)*perPage, perPage ]);

    results.forEach(function (result) { postProcess(result); });

    return results;
}

function validateLabel(label) {
    assert.strictEqual(typeof label, 'string');

    if (label.length >= 200) return new BoxError(BoxError.BAD_FIELD, 'label too long');
    if (/[^a-zA-Z0-9._() -]/.test(label)) return new BoxError(BoxError.BAD_FIELD, 'label can only contain alphanumerals, space, dot, hyphen, brackets or underscore');

    return null;
}

async function validatePolicy(policy) {
    assert.strictEqual(typeof policy, 'object');

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

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

// this is called by REST API
async function update(id, data) {
    assert.strictEqual(typeof id, 'string');
    assert.strictEqual(typeof data, 'object');

    let error;
    if ('label' in data) {
        error = validateLabel(data.label);
        if (error) throw error;
    }

    const fields = [], values = [];
    for (const p in data) {
        if (p === 'label' || p === 'preserveSecs') {
            fields.push(p + ' = ?');
            values.push(data[p]);
        }
    }
    values.push(id);

    const backup = await get(id);
    if (backup === null) throw new BoxError(BoxError.NOT_FOUND, 'Backup not found');

    const result = await database.query('UPDATE backups SET ' + fields.join(', ') + ' WHERE id = ?', values);
    if (result.affectedRows !== 1) throw new BoxError(BoxError.NOT_FOUND, 'Backup not found');

    if ('preserveSecs' in data) {
        // update the dependancies
        for (const depId of backup.dependsOn) {
            await database.query('UPDATE backups SET preserveSecs=? WHERE id = ?', [ data.preserveSecs, depId]);
        }
    }
}

async function setState(id, state) {
    assert.strictEqual(typeof id, 'string');
    assert.strictEqual(typeof state, 'string');

    const result = await database.query('UPDATE backups SET state = ? WHERE id = ?', [state, id]);
    if (result.affectedRows !== 1) throw new BoxError(BoxError.NOT_FOUND, 'Backup not found');
}

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

    const backupConfig = await getConfig();

    const memoryLimit = backupConfig.limits?.memoryLimit ? Math.max(backupConfig.limits.memoryLimit/1024/1024, 1024) : 1024;

    const taskId = await tasks.add(tasks.TASK_BACKUP, [ { /* options */ } ]);

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

    tasks.startTask(taskId, { timeout: 24 * 60 * 60 * 1000 /* 24 hours */, nice: 15, memoryLimit }, async function (error, backupId) {
        locker.unlock(locker.OP_FULL_BACKUP);

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

        const backup = backupId ? await get(backupId) : null;
        await safe(eventlog.add(eventlog.ACTION_BACKUP_FINISH, auditSource, { taskId, errorMessage, timedOut, backupId, remotePath: backup?.remotePath }), { debug });
    });

    return taskId;
}

async function list(page, perPage) {
    assert(typeof page === 'number' && page > 0);
    assert(typeof perPage === 'number' && perPage > 0);

    const results = await database.query('SELECT ' + BACKUPS_FIELDS + ' FROM backups ORDER BY creationTime DESC LIMIT ?,?', [ (page-1)*perPage, perPage ]);

    results.forEach(function (result) { postProcess(result); });

    return results;
}

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

    const result = await database.query('DELETE FROM backups WHERE id=?', [ id ]);
    if (result.affectedRows !== 1) throw new BoxError(BoxError.NOT_FOUND, 'Backup not found');
}

// this function is used in migrations - 20200512172301-settings-backup-encryption.js
function cleanupCacheFilesSync() {
    const 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));
        });
}

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

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

// keeps track of contents of the snapshot directory. this provides a way to clean up backups of uninstalled apps
async function setSnapshotInfo(id, info) {
    assert.strictEqual(typeof id, 'string');
    assert.strictEqual(typeof info, 'object');

    const contents = safe.fs.readFileSync(paths.SNAPSHOT_INFO_FILE, 'utf8');
    const 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')) {
        throw new BoxError(BoxError.FS_ERROR, safe.error.message);
    }
}

async function startCleanupTask(auditSource) {
    assert.strictEqual(typeof auditSource, 'object');

    const taskId = await tasks.add(tasks.TASK_CLEAN_BACKUPS, []);

    tasks.startTask(taskId, {}, async (error, result) => { // result is { removedBoxBackupPaths, removedAppBackupPaths, removedMailBackupPaths, missingBackupPaths }
        await safe(eventlog.add(eventlog.ACTION_BACKUP_CLEANUP_FINISH, auditSource, {
            taskId,
            errorMessage: error ? error.message : null,
            removedBoxBackupPaths: result ? result.removedBoxBackupPaths : [],
            removedMailBackupPaths: result ? result.removedMailBackupPaths : [],
            removedAppBackupPaths: result ? result.removedAppBackupPaths : [],
            missingBackupPaths: result ? result.missingBackupPaths : []
        }), { debug });
    });

    return taskId;
}

async function testStorage(storageConfig) {
    assert.strictEqual(typeof storageConfig, 'object');

    const func = storage.api(storageConfig.provider);
    if (!func) return new BoxError(BoxError.BAD_FIELD, 'unknown storage provider');

    await storage.api(storageConfig.provider).testConfig(storageConfig);
}

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

    if (password.length < 8) return new BoxError(BoxError.BAD_FIELD, 'password must be atleast 8 characters');
}

function managedBackupMountObject(backupConfig) {
    assert(mounts.isManagedProvider(backupConfig.provider));

    return {
        name: 'backup',
        hostPath: paths.MANAGED_BACKUP_MOUNT_DIR,
        mountType: backupConfig.provider,
        mountOptions: backupConfig.mountOptions
    };
}

async function remount(auditSource) {
    assert.strictEqual(typeof auditSource, 'object');

    const backupConfig = await getConfig();

    if (mounts.isManagedProvider(backupConfig.provider)) {
        await mounts.remount(managedBackupMountObject(backupConfig));
    }
}

async function getMountStatus() {
    const backupConfig = await getConfig();

    let hostPath;
    if (mounts.isManagedProvider(backupConfig.provider)) {
        hostPath = paths.MANAGED_BACKUP_MOUNT_DIR;
    } else if (backupConfig.provider === 'mountpoint') {
        hostPath = backupConfig.mountPoint;
    } else if (backupConfig.provider === 'filesystem') {
        hostPath = backupConfig.backupFolder;
    } else {
        throw new BoxError(BoxError.BAD_STATE, 'Backup location is not a mount');
    }

    return await mounts.getStatus(backupConfig.provider, hostPath); // { state, message }
}

async function getPolicy() {
    const result = await settings.getJson(settings.BACKUP_POLICY_KEY);
    return result || {
        retention: { keepWithinSecs: 2 * 24 * 60 * 60 }, // 2 days
        schedule: '00 00 23 * * *' // every day at 11pm
    };
}

async function setPolicy(policy) {
    assert.strictEqual(typeof policy, 'object');

    const error = await validatePolicy(policy);
    if (error) throw error;

    await settings.setJson(settings.BACKUP_POLICY_KEY, policy);
    await cron.handleBackupPolicyChanged(policy);
}

function getRootPath(storageConfig, mountPath) {
    assert.strictEqual(typeof storageConfig, 'object');
    assert.strictEqual(typeof mountPath, 'string');

    if (mounts.isManagedProvider(storageConfig.provider)) {
        return path.join(mountPath, storageConfig.prefix);
    } else if (storageConfig.provider === 'mountpoint') {
        return path.join(storageConfig.mountPoint, storageConfig.prefix);
    } else if (storageConfig.provider === 'filesystem') {
        return storageConfig.backupFolder;
    } else {
        return storageConfig.prefix;
    }
}

async function getConfig() {
    const result = await settings.getJson(settings.BACKUP_STORAGE_KEY) || { provider: 'filesystem', backupFolder: paths.DEFAULT_BACKUP_DIR, format: 'tgz', encryption: null };
    const limits = await settings.getJson(settings.BACKUP_LIMITS_KEY);
    if (limits) result.limits = limits;
    result.rootPath = getRootPath(result, paths.MANAGED_BACKUP_MOUNT_DIR); // note: rootPath will be dynamic for managed mount providers during app import
    return result;
}

async function setConfig(backupConfig) {
    assert.strictEqual(typeof backupConfig, 'object');

    await settings.setJson(settings.BACKUP_STORAGE_KEY, _.omit(backupConfig, 'limits'));
    await settings.setJson(settings.BACKUP_LIMITS_KEY, backupConfig.limits || null);
}

async function setLimits(limits) {
    assert.strictEqual(typeof limits, 'object');

    await settings.setJson(settings.BACKUP_LIMITS_KEY, limits);
}

function validateFormat(format) {
    assert.strictEqual(typeof format, 'string');

    if (format === 'tgz' || format == 'rsync') return null;

    return new BoxError(BoxError.BAD_FIELD, 'Invalid backup format');
}

async function setupStorage(storageConfig, hostPath) {
    assert.strictEqual(typeof storageConfig, 'object');
    assert.strictEqual(typeof hostPath, 'string');

    if (!mounts.isManagedProvider(storageConfig.provider)) return null;

    const error = mounts.validateMountOptions(storageConfig.provider, storageConfig.mountOptions);
    if (error) throw error;

    debug(`setupStorage: setting up mount at ${hostPath} with ${storageConfig.provider}`);

    const newMount = {
        name: path.basename(hostPath),
        hostPath: hostPath,
        mountType: storageConfig.provider,
        mountOptions: storageConfig.mountOptions
    };

    await mounts.tryAddMount(newMount, { timeout: 10 }); // 10 seconds

    return newMount;
}

async function setStorage(storageConfig) {
    assert.strictEqual(typeof storageConfig, 'object');

    const oldConfig = await getConfig();

    if (storageConfig.provider === oldConfig.provider) storage.api(storageConfig.provider).injectPrivateFields(storageConfig, oldConfig);

    const foratmError = validateFormat(storageConfig.format);
    if (foratmError) throw foratmError;

    debug('setStorage: validating new storage configuration');
    const rootPath = getRootPath(storageConfig, '/mnt/backup-storage-validation');
    const testStorageConfig = Object.assign({ rootPath }, storageConfig);
    const testMountObject = await setupStorage(testStorageConfig, '/mnt/backup-storage-validation');
    const testStorageError = await testStorage(testStorageConfig);
    if (testMountObject) await mounts.removeMount(testMountObject);
    if (testStorageError) throw testStorageError;

    debug('setStorage: removing old storage configuration');
    if (mounts.isManagedProvider(oldConfig.provider)) await safe(mounts.removeMount(managedBackupMountObject(oldConfig)));

    debug('setStorage: setting up new storage configuration');
    await setupStorage(storageConfig, paths.MANAGED_BACKUP_MOUNT_DIR);

    storageConfig.encryption = null;
    if ('password' in storageConfig) { // user set password
        if (storageConfig.password === constants.SECRET_PLACEHOLDER) {
            storageConfig.encryption = oldConfig.encryption || null;
        } else {
            const encryptionPasswordError = await validateEncryptionPassword(storageConfig.password);
            if (encryptionPasswordError) throw encryptionPasswordError;

            storageConfig.encryption = generateEncryptionKeysSync(storageConfig.password);
        }
        delete storageConfig.password;
    }

    debug('setBackupConfig: clearing backup cache');
    cleanupCacheFilesSync();

    await settings.setJson(settings.BACKUP_STORAGE_KEY, storageConfig);
}