helpers.js

const path = require("path");
const fs = require("fs");

const LOG = require("@sap/cds").log("dev-approuter") || console;

/**
 * Parses the approuter configuration from an `xs-dev.json` file.
 * If that file doesn't exist, it looks for an `xs-app.json` file.
 * Also scans the routes of the config file and checks for the `dependency` property
 * and stores those in `config.dependencyRoutes`, which is where the dev approuter will do its magic.
 * @returns {Object} the approuter configuration including all `dependencyRoutes`.
 */
const parseConfig = () => {
	let config;
	let configFile;
	let configFiles = ["xs-dev.json", "xs-app.json"];
	for (const file of configFiles) {
		if (fs.existsSync(path.join(process.cwd(), file))) {
			config = JSON.parse(fs.readFileSync(path.join(process.cwd(), file), { encoding: "utf8" }));
			configFile = file;
			LOG.info(`Using configuration from ${path.join(process.cwd(), configFile)}`);
			break;
		}
	}
	config.dependencyRoutes = {};
	config.routes?.forEach((route) => {
		if (route.dependency) {
			if (config.dependencyRoutes[`${route.dependency}`]) {
				throw new Error(`Duplicate dependency "${route.dependency}" found in file ${path.join(process.cwd(), configFile)}.`);
			} else {
				config.dependencyRoutes[`${route.dependency}`] = {};
				Object.assign(config.dependencyRoutes[`${route.dependency}`], route);
			}
		}
	});
	return config;
};

/**
 * Applies the `config.dependencyRoutes` to the `config.routes` and removes them.
 * @param {Object} config - the approuter configuration including all `dependencyRoutes`.
 * @returns {Object} config - the approuter configuration that can be used to start the approuter.
 */
const applyDependencyConfig = (config) => {
	config.routes?.forEach((route) => {
		if (route.dependency) {
			Object.assign(route, config.dependencyRoutes[route.dependency]);
			delete route.dependency;
			delete route.options;
		}
	});
	delete config.dependencyRoutes;
	LOG.info("running these routes:", config.routes);
	return config;
};

/**
 * Adds a destination to `process.env.destinations` for a given module.
 * If a destination with this `name === moduleId` already exists, no new destination will be created.
 * @param {String} moduleId - the id of the module that a destination is created for.
 * @param {Number} port - the port of the localhost that the destination should point to.
 * @param {String} mountPath - the path the module was mounted to and the destination should point to.
 */
const addDestination = (moduleId, port, mountPath) => {
	let destinations = [];
	if (process.env.destinations) {
		destinations = JSON.parse(process.env.destinations);
	}

	let url = `http://localhost${port ? `:${port}` : ""}${mountPath || ""}`;

	// only add new destination if it's not already provided
	const destinationAlreadyExists = destinations.some((destination) => {
		const lowerCaseDestination = {};
		Object.keys(destination).forEach((key) => {
			lowerCaseDestination[key.toLowerCase()] = destination[key];
		});
		return lowerCaseDestination.name === moduleId;
	});
	if (!destinationAlreadyExists) {
		destinations.push({
			Name: moduleId,
			Authentication: "NoAuthentication",
			ProxyType: "Internet",
			Type: "HTTP",
			URL: url,
		});
		process.env.destinations = JSON.stringify(destinations);
	}
	LOG.info("running these destinations:", JSON.parse(process.env.destinations));
};

/**
 * Configures the route for a given CDS module.
 * @param {String} moduleId - the id of the module that the route should be configured for.
 * @param {String[]} servicesPaths - an array of service paths that the CDS module serves.
 * @param {Object} route - the route that is to be configured.
 * @returns {Object} the configured route.
 */
const configureCDSRoute = (moduleId, servicesPaths, route) => {
	if (!route.source) {
		route.source = servicesPaths
			.map((path) => {
				return `${path}(/.*)`;
			})
			.join("|");
	}
	route.destination = moduleId;
	delete route.dependency;

	return route;
};

/**
 * Configures the route for a given UI5 module.
 * @param {String} moduleId - the id of the module that the route should be configured for.
 * @param {String} sourcePath - the path the approuter should handle the module at.
 * @param {Object} route - the route that is to be configured.
 * @returns {Object} the configured route.
 */
const configureUI5Route = (moduleId, sourcePath, route) => {
	if (sourcePath === "/") {
		// special regex to avoid endless loop
		route.source = `^(?!.*(/_${sourcePath}))`;
	} else {
		route.source = `^${sourcePath}(/.*)$`;
		route.target = "$1";
	}
	route.destination = moduleId;
	delete route.dependency;

	return route;
};

module.exports = {
	parseConfig,
	applyDependencyConfig,
	addDestination,
	configureCDSRoute,
	configureUI5Route,
};