Create flowconfig mapping from jspm

generate-jspm-flowconfig.js

#!/usr/bin/env node
"use strict";
const _ = require("lodash");
const fs = require("fs");
const path = require("path");
const jspm = require("jspm");
const build = new jspm.Builder();
const System = build.loader;

// Generate the path to the root of the project... We can use this to
// remove it from paths later.
const appRootPath = System.normalizeSync("").replace("file://", "");

const dependencyPaths = Object.keys(System.map)
	.reduce((deps, importName) => {
		const dep = System.normalizeSync(importName);

		if (dep.indexOf("@") === -1) {
			return deps;
		}

		let mappedFiles = [];
		if (System.packages[dep]) {
			mappedFiles = Object.keys(System.packages[dep].map)
				.reduce((mapPackages, mapPackage) => {
					return mapPackages.concat([
						[mapPackage, System.normalizeSync(mapPackage, dep).replace("file://", "")]
					]);
				}, []);
		}

		return deps.concat([
				[importName, dep.replace("file://", "")]
			]).concat(mappedFiles)
	}, []);

let output = [];

for (let i = 0; i < dependencyPaths.length; i++) {
	const dependency = dependencyPaths[i][0];
	const fullPath = dependencyPaths[i][1];
	const pkg = require(`${fullPath}.json`);

	// Generate the root directory for the dependency (minus the filesystem path)
	const basePath = fullPath.slice(appRootPath.length - 1);
	// If there is a main path, generate it here (using the json file each jspm package comes with)
	let mainPath = pkg.main ? path.resolve(fullPath, pkg.main).slice(appRootPath.length - 1) : null;
	// Sometimes the path does not include the .js extension... so make sure it does.
	if (mainPath && mainPath.indexOf(".js") === -1) {
		mainPath += ".js";
	}

	output.push(`module.name_mapper='^${dependency}\\/\\(.*\\)$' -> '<PROJECT_ROOT>${basePath}/\\1'`);
	if (mainPath) {
		output.push(`module.name_mapper='^${dependency}$' -> '<PROJECT_ROOT>${mainPath}'`);
	}
}

// HACK: It's possible to get lots of projects with the same third party dependency, so
// let's remove it here.
output = _.uniq(output);

const warningMessage = "## AUTOMATICALLY GENERATED -- DO NOT MODIFY";
const flowConfig = fs.readFileSync(path.resolve(".flowconfig"), "utf8");
const flowConfigLines = flowConfig.split("\n");
const warningLine = flowConfigLines.indexOf(warningMessage);

let newConfig = flowConfigLines;
if (warningLine > -1) {
	newConfig = flowConfigLines.slice(0, warningLine + 1).concat(output);
} else {
	newConfig = flowConfigLines.concat([warningMessage]).concat(output);
}

fs.writeFileSync(".flowconfig", newConfig.join("\n"));