f3lang/cdi

/**
 * The Config Resolver is the central manager for configurations.
 * It offers the functionality to resolve configuration entries based on the injected config path.
 *
 * @author Wolfgang Felbermeier (@f3lang)
 */
class ConfigResolver {

    constructor(configs) {
        this.configs = configs || {};
        this.cache = {};
    }

    /**
     * Adds a new configuration to the collection
     * @param configuration The configuration object
     * @param root The configuration root name
     */
    addConfiguration(configuration, root) {
        this.configs[root] = configuration;
    }

    /**
     * Returns a configuration entry of the available configurations
     * @param root The configuration root to look in
     * @param path The path of the configuration to return
     * @return {*}
     */
    getConfig(root, path) {
        if (root === '' && path === '') {
            return this.configs;
        }
        if (this.cache[root + ":" + path]) {
            return this.cache[root + ":" + path]
        }
        if (!this.configs[root]) {
            throw new Error('Configuration root "' + root + '" does not exist');
        }
        if (path === "" || path === ".") {
            return this.configs[root];
        }
        try {
            let property = this._getProperty(this.configs[root], path.split('.'));
            this.cache[root + ":" + path] = property;
            return property;
        } catch (e) {
            throw new Error('Configuration path "' + path + '" does not exist in configuration root "' + root + '"');
        }
    }

    /**
     * Returns the next available property of obj.
     * e.g.:
     * Your obj:
     * {
     *         banana: {
     *             fruit: {
     *                 price: 1
     *             }
     *         }
     * }
     * and your path will be ['banana', 'fruit', 'price']
     * Then this function will return 1
     *
     * @param obj
     * @param propertyPathArray
     * @private
     */
    _getProperty(obj, propertyPathArray) {
        if (propertyPathArray.length === 1) {
            return obj[propertyPathArray[0]];
        } else {
            return this._getProperty(obj[propertyPathArray.shift()], propertyPathArray);
        }
    }

}

module.exports = ConfigResolver;
module.exports.inject = ['config::'];