index.js

#!/usr/bin/env node

const fs = require("fs");
const path = require("path");
const Elm = require("./elm.min.js").Elm;

function getPluginVersion() {
  const file = path.resolve(__dirname, "package.json");
  const nodeJson = JSON.parse(fs.readFileSync(file, "utf8"));
  return nodeJson.version;
}

function getLibraryVersion() {
  let version = "latest";
  try {
    const file = path.resolve(__dirname, "elm.json");
    const elmJson = JSON.parse(fs.readFileSync(file, "utf8"));
    version =
      elmJson.dependencies.direct["eriktim/elm-protocol-buffers"] || version;
  } catch (e) {
    // not fatal
  }
  return version;
}

const pluginVersion = getPluginVersion();
const libraryVersion = getLibraryVersion();
const app = Elm.Main.init({
  flags: {
    plugin: pluginVersion,
    library: libraryVersion,
  },
});

function sendToGenerator(request) {
  return new Promise((resolve) => {
    const responseHandler = (response) => {
      resolve(Buffer.from(response, "base64"));
      app.ports.response.unsubscribe(responseHandler);
    };
    app.ports.response.subscribe(responseHandler);
    app.ports.request.send(request.toString("base64"));
  });
}

const chunks = [];
process.stdin.on("data", (chunk) => {
  chunks.push(chunk);
});
process.stdin.on("end", () => {
  const request = Buffer.concat(chunks);
  sendToGenerator(request).then((response) => process.stdout.write(response));
});