const express = require("express");
const bodyParser = require("body-parser");
const { JSONRPCServer } = require("json-rpc-2.0");

const server = new JSONRPCServer();

// First parameter is a method name.
// Second parameter is a method itself.
// A method takes JSON-RPC params and returns a result.
// It can also return a promise of the result.
server.addMethod("echo", ({ text }) => text);
server.addMethod("log", ({ message }) => console.log(message));

const app = express();
app.use(bodyParser.json());

app.post("/json-rpc", (req, res) => {
  const jsonRPCRequest = req.body;
  // server.receive takes a JSON-RPC request and returns a promise of a JSON-RPC response.
  server.receive(jsonRPCRequest).then(jsonRPCResponse => {
    if (jsonRPCResponse) {
      res.json(jsonRPCResponse);
    } else {
      // If response is absent, it was a JSON-RPC notification method.
      // Respond with no content status (204).
      res.sendStatus(204);
    }
  });
});

app.listen(80);

const server = new JSONRPCServer();

// If the method is a higher-order function (a function that returns a function),
// it will pass the custom parameter to the returned function.
// Use this to inject whatever information that method needs outside the regular JSON-RPC request.
server.addMethod("echo", ({ text }) => ({ userID }) => `${userID} said ${text}`);

app.post("/json-rpc", (req, res) => {
  const jsonRPCRequest = req.body;
  const userID = getUserID(req);

  // server.receive takes an optional second parameter.
  // The parameter will be injected to the JSON-RPC method if it was a higher-order function.
  server.receive(jsonRPCRequest, { userID }).then(jsonRPCResponse => {
    if (jsonRPCResponse) {
      res.json(jsonRPCResponse);
    } else {
      res.sendStatus(204);
    }
  });
});

const getUserID = (req) => // Do whatever to get user ID out of the request

import { JSONRPCClient, createJSONRPCErrorResponse } from "json-rpc-2.0";

// JSONRPCClient needs to know how to send a JSON-RPC request.
// Tell it by passing a function to its constructor. The function must take a JSON-RPC request and send it.
const client = new JSONRPCClient(
  (jsonRPCRequest) =>
    fetch("http://localhost/json-rpc", {
      method: "POST",
      headers: {
        "content-type": "application/json"
      },
      body: JSON.stringify(jsonRPCRequest)
    }).then(response => {
      if (response.status === 200) {
        // Use client.receive when you received a JSON-RPC response.
        return response.json().then(jsonRPCResponse => client.receive(jsonRPCResponse));
      } else if (jsonRPCRequest.id !== undefined) {
        client.receive(createJSONRPCErrorResponse(jsonRPCRequest.id, 0, response.statusText));
      }
    })
);

// Use client.request to make a JSON-RPC request call.
// The function returns a promise of the result.
client.request("echo", { text: "Hello, World!" }).then(result => console.log(result));

// Use client.notify to make a JSON-RPC notification call.
// By definition, JSON-RPC notification does not respond.
client.notify("log", { message: "Hello, World!" });

const client = new JSONRPCClient(
  // If it is a higher-order function, it passes the custom params to the returned function.
  (jsonRPCRequest) => ({ token }) =>
    fetch("http://localhost/json-rpc", {
      method: "POST",
      headers: {
        "content-type": "application/json",
        authorization: `Bearer ${token}` // Use the passed token
      },
      body: JSON.stringify(jsonRPCRequest)
    }).then(response => {
      // ...
    })
);

// Pass the custom params as the third argument.
client.request("echo", { text: "Hello, World!" }, { token: "foo's token" });
client.notify("log", { message: "Hello, World!" }, { token: "foo's token" });