gen-clients.js

import Handlebars from "handlebars";
import pbjs from "protobufjs";

// Load Protocol Buffer from specified .proto file
const pb = pbjs.loadSync("api/vendor/protocoltypes.proto");

// Function to decapitalize the first letter of a string
const uncap = (str) => str.charAt(0).toLowerCase() + str.slice(1);

const getInterface = (typ) => {
  const parts = typ.split(".");
  const ilast = `I${parts.pop()}`;
  parts.push(ilast);
  return parts.join(".");
};

// Define an array of services
const services = ["weshnet.protocol.v1.ProtocolService"];

// Prepare Handlebars templates
const serviceClientTemplate = Handlebars.compile(`
import api from './api/index.d'
import { Unary, ResponseStream, RequestStream } from './types'

export type ServiceClientType<S> = {{#each services}} {{this}} {{/each}}never;
`);

const ClientTemplate = Handlebars.compile(`
export interface {{name}}Client {
  {{#each methods}}
    {{this.name}}: {{this.type}}<api.{{this.svcName}}.{{this.request}}, api.{{this.svcName}}.{{this.reply}}>,
  {{/each}}
}
`);

// Gather data for ServiceClientType
let serviceData = {
  services: services.map((svcType) => {
    const svc = pb.lookup(svcType);
    return `S extends typeof api.${svc.parent.parent.name}.${svc.name} ? ${svc.name}Client :`;
  }),
};

// Generate and output ServiceClientType
console.log(serviceClientTemplate(serviceData));

// Gather data for each Client and output
for (const svcType of services) {
  const svc = pb.lookup(svcType);
  const methodsData = Object.entries(svc.methods).map(([key, method]) => {
    let rpcType = "";
    if (!method.requestStream && !method.responseStream) {
      // Unary
      rpcType = "Unary";
    } else if (method.requestStream && !method.responseStream) {
      // Request Stream
      rpcType = "RequestStream";
    } else if (!method.requestStream && method.responseStream) {
      // Response Stream
      rpcType = "ResponseStream";
    } else {
      // Dubplex
      rpcType = "never";
    }

    const name = uncap(key);
    return {
      name: name,
      request: getInterface(method.requestType),
      reply: method.responseType,
      type: rpcType,
      svcName: `${svc.parent.parent.name}`,
    };
  });

  let ClientData = {
    name: svc.name,
    methods: methodsData,
  };

  console.log(ClientTemplate(ClientData));
}