'use strict';

exports = module.exports = {
    getBackupPath: getBackupPath,
    checkPreconditions: checkPreconditions,

    upload: upload,
    download: download,

    copy: copy,

    listDir: listDir,

    remove: remove,
    removeDir: removeDir,

    testConfig: testConfig,
    removePrivateFields: removePrivateFields,
    injectPrivateFields: injectPrivateFields
};

const PROVIDER_FILESYSTEM = 'filesystem';
const PROVIDER_SSHFS = 'sshfs';
const PROVIDER_CIFS = 'cifs';
const PROVIDER_NFS = 'nfs';

var assert = require('assert'),
    BoxError = require('../boxerror.js'),
    DataLayout = require('../datalayout.js'),
    debug = require('debug')('box:storage/filesystem'),
    df = require('@sindresorhus/df'),
    EventEmitter = require('events'),
    fs = require('fs'),
    path = require('path'),
    paths = require('../paths.js'),
    prettyBytes = require('pretty-bytes'),
    readdirp = require('readdirp'),
    safe = require('safetydance'),
    shell = require('../shell.js');

// storage api
function getBackupPath(apiConfig) {
    assert.strictEqual(typeof apiConfig, 'object');

    if (apiConfig.provider === PROVIDER_SSHFS) return path.join(apiConfig.mountPoint, apiConfig.prefix);
    if (apiConfig.provider === PROVIDER_CIFS) return path.join(apiConfig.mountPoint, apiConfig.prefix);
    if (apiConfig.provider === PROVIDER_NFS) return path.join(apiConfig.mountPoint, apiConfig.prefix);

    return apiConfig.backupFolder;
}

// the du call in the function below requires root
function checkPreconditions(apiConfig, dataLayout, callback) {
    assert.strictEqual(typeof apiConfig, 'object');
    assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
    assert.strictEqual(typeof callback, 'function');

    let used = 0;
    for (let localPath of dataLayout.localPaths()) {
        debug(`checkPreconditions: getting disk usage of ${localPath}`);
        let result = safe.child_process.execSync(`du -Dsb ${localPath}`, { encoding: 'utf8' });
        if (!result) return callback(new BoxError(BoxError.FS_ERROR, safe.error));
        used += parseInt(result, 10);
    }

    debug(`checkPreconditions: ${used} bytes`);

    df.file(getBackupPath(apiConfig)).then(function (result) {

        // Check filesystem is mounted so we don't write into the actual folder on disk
        if (apiConfig.provider === PROVIDER_SSHFS || apiConfig.provider === PROVIDER_CIFS || apiConfig.provider === PROVIDER_NFS) {
            if (result.mountpoint !== apiConfig.mountPoint) return callback(new BoxError(BoxError.FS_ERROR, `${apiConfig.mountPoint} is not mounted`));
        } else if (apiConfig.provider === PROVIDER_FILESYSTEM && apiConfig.externalDisk) {
            if (result.mountpoint === '/') return callback(new BoxError(BoxError.FS_ERROR, `${apiConfig.backupFolder} is not mounted`));
        }

        const needed = 0.6 * used + (1024 * 1024 * 1024); // check if there is atleast 1GB left afterwards. aim for 60% because rsync/tgz won't need full 100%
        if (result.available <= needed) return callback(new BoxError(BoxError.FS_ERROR, `Not enough disk space for backup. Needed: ${prettyBytes(needed)} Available: ${prettyBytes(result.available)}`));

        callback(null);
    }).catch(function (error) {
        callback(new BoxError(BoxError.FS_ERROR, error));
    });
}

function upload(apiConfig, backupFilePath, sourceStream, callback) {
    assert.strictEqual(typeof apiConfig, 'object');
    assert.strictEqual(typeof backupFilePath, 'string');
    assert.strictEqual(typeof sourceStream, 'object');
    assert.strictEqual(typeof callback, 'function');

    fs.mkdir(path.dirname(backupFilePath), { recursive: true }, function (error) {
        if (error) return callback(new BoxError(BoxError.EXTERNAL_ERROR, error.message));

        safe.fs.unlinkSync(backupFilePath); // remove any hardlink

        var fileStream = fs.createWriteStream(backupFilePath);

        // this pattern is required to ensure that the file got created before 'finish'
        fileStream.on('open', function () {
            sourceStream.pipe(fileStream);
        });

        fileStream.on('error', function (error) {
            debug('[%s] upload: out stream error.', backupFilePath, error);
            callback(new BoxError(BoxError.EXTERNAL_ERROR, error.message));
        });

        fileStream.on('finish', function () {
            // in test, upload() may or may not be called via sudo script
            const BACKUP_UID = parseInt(process.env.SUDO_UID, 10) || process.getuid();

            // sshfs and cifs handle ownership through the mount args
            if (apiConfig.provider === PROVIDER_FILESYSTEM || apiConfig.provider === PROVIDER_NFS) {
                if (!safe.fs.chownSync(backupFilePath, BACKUP_UID, BACKUP_UID)) return callback(new BoxError(BoxError.EXTERNAL_ERROR, 'Unable to chown:' + safe.error.message));
                if (!safe.fs.chownSync(path.dirname(backupFilePath), BACKUP_UID, BACKUP_UID)) return callback(new BoxError(BoxError.EXTERNAL_ERROR, 'Unable to chown:' + safe.error.message));
            }

            debug('upload %s: done.', backupFilePath);

            callback(null);
        });
    });
}

function download(apiConfig, sourceFilePath, callback) {
    assert.strictEqual(typeof apiConfig, 'object');
    assert.strictEqual(typeof sourceFilePath, 'string');
    assert.strictEqual(typeof callback, 'function');

    debug(`download: ${sourceFilePath}`);

    if (!safe.fs.existsSync(sourceFilePath)) return callback(new BoxError(BoxError.NOT_FOUND, `File not found: ${sourceFilePath}`));

    var fileStream = fs.createReadStream(sourceFilePath);
    callback(null, fileStream);
}

function listDir(apiConfig, dir, batchSize, iteratorCallback, callback) {
    assert.strictEqual(typeof apiConfig, 'object');
    assert.strictEqual(typeof dir, 'string');
    assert.strictEqual(typeof batchSize, 'number');
    assert.strictEqual(typeof iteratorCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    var entries = [];
    var entryStream = readdirp(dir, { type: 'files', alwaysStat: true, lstat: true });
    entryStream.on('data', function (entryInfo) {
        if (entryInfo.stats.isSymbolicLink()) return;

        entries.push({ fullPath: entryInfo.fullPath });
        if (entries.length < batchSize) return;
        entryStream.pause();
        iteratorCallback(entries, function (error) {
            if (error) return callback(error);

            entries = [];
            entryStream.resume();
        });
    });
    entryStream.on('warn', function (error) {
        debug('listDir: warning ', error);
    });
    entryStream.on('end', function () {
        iteratorCallback(entries, callback);
    });
}

function copy(apiConfig, oldFilePath, newFilePath) {
    assert.strictEqual(typeof apiConfig, 'object');
    assert.strictEqual(typeof oldFilePath, 'string');
    assert.strictEqual(typeof newFilePath, 'string');

    var events = new EventEmitter();

    fs.mkdir(path.dirname(newFilePath), { recursive: true }, function (error) {
        if (error) return events.emit('done', new BoxError(BoxError.EXTERNAL_ERROR, error.message));

        events.emit('progress', `Copying ${oldFilePath} to ${newFilePath}`);

        // sshfs and cifs do not allow preserving attributes
        var cpOptions = apiConfig.provider === PROVIDER_FILESYSTEM ? '-a' : '-dR';

        // this will hardlink backups saving space
        cpOptions += apiConfig.noHardlinks ? '' : 'l';

        shell.spawn('copy', '/bin/cp', [ cpOptions, oldFilePath, newFilePath ], { }, function (error) {
            if (error) return events.emit('done', new BoxError(BoxError.EXTERNAL_ERROR, error.message));

            events.emit('done', null);
        });
    });

    return events;
}

function remove(apiConfig, filename, callback) {
    assert.strictEqual(typeof apiConfig, 'object');
    assert.strictEqual(typeof filename, 'string');
    assert.strictEqual(typeof callback, 'function');

    var stat = safe.fs.statSync(filename);
    if (!stat) return callback();

    if (stat.isFile()) {
        if (!safe.fs.unlinkSync(filename)) return callback(new BoxError(BoxError.EXTERNAL_ERROR, safe.error.message));
    } else if (stat.isDirectory()) {
        if (!safe.fs.rmdirSync(filename)) return callback(new BoxError(BoxError.EXTERNAL_ERROR, safe.error.message));
    }

    callback(null);
}

function removeDir(apiConfig, pathPrefix) {
    assert.strictEqual(typeof apiConfig, 'object');
    assert.strictEqual(typeof pathPrefix, 'string');

    var events = new EventEmitter();

    process.nextTick(() => events.emit('progress', `Removing directory ${pathPrefix}`));

    shell.spawn('removeDir', '/bin/rm', [ '-rf', pathPrefix ], { }, function (error) {
        if (error) return events.emit('done', new BoxError(BoxError.EXTERNAL_ERROR, error.message));

        events.emit('done', null);
    });

    return events;
}

function validateBackupTarget(folder) {
    assert.strictEqual(typeof folder, 'string');

    if (path.normalize(folder) !== folder) return new BoxError(BoxError.BAD_FIELD, 'backupFolder must contain a normalized path', { field: 'backupFolder' });
    if (!path.isAbsolute(folder)) return new BoxError(BoxError.BAD_FIELD, 'backupFolder must be an absolute path', { field: 'backupFolder' });

    if (folder === '/') return new BoxError(BoxError.BAD_FIELD, 'backupFolder cannot be /', { field: 'backupFolder' });

    if (!folder.endsWith('/')) folder = folder + '/'; // ensure trailing slash for the prefix matching to work
    const PROTECTED_PREFIXES = [ '/boot/', '/usr/', '/bin/', '/lib/', '/root/', '/var/lib/', paths.baseDir() ];

    if (PROTECTED_PREFIXES.some(p => folder.startsWith(p))) return new BoxError(BoxError.BAD_FIELD, 'backupFolder path is protected', { field: 'backupFolder' });

    return null;
}

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

    if (apiConfig.provider === PROVIDER_FILESYSTEM) {
        if (!apiConfig.backupFolder || typeof apiConfig.backupFolder !== 'string') return callback(new BoxError(BoxError.BAD_FIELD, 'backupFolder must be non-empty string', { field: 'backupFolder' }));
        let error = validateBackupTarget(apiConfig.backupFolder);
        if (error) return callback(error);

        if ('externalDisk' in apiConfig && typeof apiConfig.externalDisk !== 'boolean') return callback(new BoxError(BoxError.BAD_FIELD, 'externalDisk must be boolean', { field: 'externalDisk' }));
    }

    if (apiConfig.provider === PROVIDER_SSHFS || apiConfig.provider === PROVIDER_CIFS || apiConfig.provider === PROVIDER_NFS) {
        if (!apiConfig.mountPoint || typeof apiConfig.mountPoint !== 'string') return callback(new BoxError(BoxError.BAD_FIELD, 'mountPoint must be non-empty string', { field: 'mountPoint' }));
        let error = validateBackupTarget(apiConfig.mountPoint);
        if (error) return callback(error);

        if (typeof apiConfig.prefix !== 'string') return callback(new BoxError(BoxError.BAD_FIELD, 'prefix must be a string', { field: 'prefix' }));
        if (apiConfig.prefix !== '') {
            if (path.isAbsolute(apiConfig.prefix)) return new BoxError(BoxError.BAD_FIELD, 'prefix must be a relative path', { field: 'backupFolder' });
            if (path.normalize(apiConfig.prefix) !== apiConfig.prefix) return callback(new BoxError(BoxError.BAD_FIELD, 'prefix must contain a normalized relative path', { field: 'prefix' }));
        }

        const mounts = safe.fs.readFileSync('/proc/mounts', 'utf8');
        const mountInfo = mounts.split('\n').filter(function (l) { return l.indexOf(apiConfig.mountPoint) !== -1; })[0];
        if (!mountInfo) return callback(new BoxError(BoxError.BAD_FIELD, `${apiConfig.mountPoint} is not mounted`, { field: 'mountPoint' }));

        if (apiConfig.provider === PROVIDER_SSHFS && !mountInfo.split(' ').find(i => i === 'fuse.sshfs')) return callback(new BoxError(BoxError.BAD_FIELD, 'mountPoint must be a "fuse.sshfs" filesystem', { field: 'mountPoint' }));
        if (apiConfig.provider === PROVIDER_CIFS && !mountInfo.split(' ').find(i => i === 'cifs')) return callback(new BoxError(BoxError.BAD_FIELD, 'mountPoint must be a "cifs" filesystem', { field: 'mountPoint' }));
        if (apiConfig.provider === PROVIDER_NFS && !mountInfo.split(' ').find(i => i === 'nfs')) return callback(new BoxError(BoxError.BAD_FIELD, 'mountPoint must be a "nfs" filesystem', { field: 'mountPoint' }));
    }

    // common checks
    const backupPath = getBackupPath(apiConfig);
    const field = apiConfig.provider === PROVIDER_FILESYSTEM ? 'backupFolder' : 'prefix';

    const stat = safe.fs.statSync(backupPath);
    if (!stat) return callback(new BoxError(BoxError.BAD_FIELD, 'Directory does not exist or cannot be accessed: ' + safe.error.message), { field });
    if (!stat.isDirectory()) return callback(new BoxError(BoxError.BAD_FIELD, 'Backup location is not a directory', { field }));

    if (!safe.fs.mkdirSync(path.join(backupPath, 'snapshot')) && safe.error.code !== 'EEXIST') {
        if (safe.error && safe.error.code === 'EACCES') return callback(new BoxError(BoxError.BAD_FIELD, `Access denied. Run "chown yellowtent:yellowtent ${backupPath}" on the server`, { field }));
        return callback(new BoxError(BoxError.BAD_FIELD, safe.error.message, { field }));
    }

    if (!safe.fs.writeFileSync(path.join(backupPath, 'cloudron-testfile'), 'testcontent')) {
        return callback(new BoxError(BoxError.BAD_FIELD, `Unable to create test file as 'yellowtent' user in ${backupPath}: ${safe.error.message}. Check dir/mount permissions`, { field }));
    }

    if (!safe.fs.unlinkSync(path.join(backupPath, 'cloudron-testfile'))) {
        return callback(new BoxError(BoxError.BAD_FIELD, `Unable to remove test file as 'yellowtent' user in ${backupPath}: ${safe.error.message}. Check dir/mount permissions`, { field }));
    }

    if ('noHardlinks' in apiConfig && typeof apiConfig.noHardlinks !== 'boolean') return callback(new BoxError(BoxError.BAD_FIELD, 'noHardlinks must be boolean', { field: 'noHardLinks' }));

    callback(null);
}

function removePrivateFields(apiConfig) {
    return apiConfig;
}

function injectPrivateFields(/* newConfig, currentConfig */) {
}