loggers-factory/src/merge_parameters.js

Javascript package that makes the use of loggers a breath.

const get_default_console_format = require("./get_default_console_format.js");
const get_default_log_format = require("./get_default_log_format.js");

/**
 * Deep merge the given params with the default ones.
 * @see https://stackoverflow.com/a/34749873
 */
function merge_parameters(params) {
	const default_params = requireUncached("./default_params.js");

	// First, we update the format in case a source was given
	// because the mergeDeep function can't do that.
	if ("source" in params) {
		default_params.transport.console.format = get_default_console_format(
			params["source"]
		);
		for (const log_type of ["combined", "errors"]) {
			default_params.transport.logs[log_type].format = get_default_log_format(
				params["source"]
			);
		}
	}
	// We also update the logs paths if a path was given.
	// In params have both a path for all the logs and a
	// special path for one of the logs, there's no problem.
	if ("logs_path" in params) {
		for (const log_type of ["combined", "errors"]) {
			default_params.transport.logs[log_type].logs_path = params["logs_path"];
		}
	}
	return mergeDeep(default_params, params);
}

/**
 * We require the default params at each function call
 * in order to always have the actual default parameters:
 * If we require before the function, the default merge_parameters
 * won't be the same after a function call.
 * @see https://stackoverflow.com/a/16060619
 */
function requireUncached(module_path) {
	delete require.cache[require.resolve(module_path)];
	return require(module_path);
}

/**
 * Simple object check.
 * @param item
 * @returns {Boolean}
 */
function isObject(item) {
	return item && typeof item === "object" && !Array.isArray(item);
}

/**
 * Deep merge two objects.
 * @param target
 * @param ...sources
 */
function mergeDeep(target, ...sources) {
	if (!sources.length) return target;
	const source = sources.shift();

	if (isObject(target) && isObject(source)) {
		for (const key in source) {
			if (isObject(source[key])) {
				if (!target[key]) Object.assign(target, { [key]: {} });
				mergeDeep(target[key], source[key]);
			} else {
				Object.assign(target, { [key]: source[key] });
			}
		}
	}

	return mergeDeep(target, ...sources);
}

module.exports = merge_parameters;