module_settings_migrator.js

'use strict';

const DefaultSettings = {
    'presets': [],
};

module.exports = function MigrateSettings(from_ver, to_ver, settings) {
	if (from_ver === undefined) {
		// Migrate legacy config file
		return { ...DefaultSettings, ...settings };
	} else if (from_ver === null) {
		// No config file exists, use default settings
		return DefaultSettings;
	} else {
		// Migrate from older version (using the new system) to latest one
		if (from_ver + 1 < to_ver) {
			// Recursively upgrade in one-version steps
			settings = MigrateSettings(from_ver, from_ver + 1, settings);
			return MigrateSettings(from_ver + 1, to_ver, settings);
		}

		// If we reach this point it's guaranteed that from_ver === to_ver - 1, so we can implement
		// a switch for each version step that upgrades to the next version. This enables us to
		// upgrade from any version to the latest version without additional effort!
		switch (to_ver) {
			default:
				break;
		}

		return settings;
	}
};