read-config-ng/lib/read-config.js

Multi format configuration loader

'use strict';

const merge = require('lodash').merge,
    fs = require('fs'),
    load = require('./load'),
    resolve = require('./resolve'),
    ReadConfigError = require('./read-config-error');

module.exports = sync;
module.exports.sync = sync;
module.exports.async = async;

function async(paths, opts, callback) {
    let err;
    if (typeof opts === 'function' && !callback) {
        callback = opts;
        opts = {};
    }
    opts = defaultOptions(opts);
    err = validateParams(paths, opts, callback);
    if (err) {
        if (typeof callback === 'function') return callback(err);
        throw err;
    }

    load.async(paths, opts, (err, config) => {
        if (err) return callback(err);
        try {
            config = resolve(config, opts);
        } catch (e) {
            return callback(e);
        }
        callback(null, config);
    });
}

function sync(paths, opts) {
    let err, config;
    opts = defaultOptions(opts);
    err = validateParams(paths, opts);
    if (err) throw err;
    config = load.sync(paths, opts);
    config = resolve(config, opts);
    return config;
}

function validateParams(paths, opts, callback) {
    if (opts && typeof opts !== 'object') {
        return new ReadConfigError('Expected parameter with options');
    }
    if (callback && typeof callback !== 'function') {
        return new ReadConfigError('Expected callback parameter');
    }
    if (typeof paths !== 'string' && !Array.isArray(paths)) {
        return new ReadConfigError('Expected a string (or array) with configuration file path');
    }
    if (opts.replaceLocal && opts.replaceLocal && opts.replaceLocal === opts.replaceEnv) {
        return new ReadConfigError('Values opts.replaceLocal and opts.replaceEnv must be different');
    }
    if (opts.basedir && !fs.existsSync(opts.basedir)) {
        return new ReadConfigError(`Base directory not found: ${opts.basedir}`);
    }
}

function defaultOptions(opts) {
    return merge({
        parentField: '__parent',
        basedir: '.',
        replaceEnv: '%',
        replaceLocal: '@',
        skipUnresolved: false,
        freeze: false
    }, opts);
}