import express from 'express';
import bodyParser from 'body-parser';
import { connectedInstances } from './connected-instances.js';

/**
 * REST request handler for Dispatcher Server. It handles 2 endpoints:
 *
 *  - `POST /json-rpc`: for blocking call from Unified Client to Adapter
 *  - `POST /auth-callback`: for auth callbacks from Adapter to Unified Client
 */
export const restHandler = express();

restHandler.use(bodyParser.json());

restHandler.post('/json-rpc', (req, res) => {
  redirectBlockingCallToAdapter(req.body).then((jsonRPCResponse) => {
    console.log('Blocking response resolved with: %s', JSON.stringify(jsonRPCResponse));
    res.json(jsonRPCResponse);
  });
});

restHandler.post('/auth-callback', (req, res) => {
  redirectAuthCallbackToUnifiedClient(req.body).then((jsonRPCResponse) => {
    console.log('Auth callback resolved with: %s', JSON.stringify(jsonRPCResponse));
    res.json(jsonRPCResponse);
  });
});

/**
 * Dictionary that is used by Dispatcher REST handler. JSON-RPC requests that comes from REST endpoints,
 * add JSON-RPC ID with the promise resolver that will be resolved once associated JSON-RPC response comes through WebSocket.
 */
const jsonRpcIdToResponseResolver: Record<string, (jsonRpcResponse: any) => void> = {};

/**
 * @param jsonRpcId JSON-RPC id for the JSON-RPC response
 *
 * @return `true` if we have REST response resolver waiting for Response with `jsonRpcId`
 */
export const shouldBeIntercepted = (jsonRpcId: string) => {
  return Boolean(jsonRpcIdToResponseResolver[jsonRpcId]);
};

/**
 * @param jsonRpcResponse JSON-RPC response
 *
 * resolve JSON-RPC Response using resolver from `jsonRpcIdToResponseResolver`
 */
export const intercept = (jsonRpcResponse: any) => {
  const resolver = jsonRpcIdToResponseResolver[jsonRpcResponse.id];
  delete jsonRpcIdToResponseResolver[jsonRpcResponse.id];
  resolver(jsonRpcResponse);
};

/**
 * Redirects JSON-RPC request to the Adapter and waits for response
 *
 * @returns Promise that resolves when message from adapter comes back
 */
const redirectBlockingCallToAdapter = (jsonRpc: any) => {
  console.log('Received blocking request: %s', JSON.stringify(jsonRpc));
  return new Promise((resolve) => {
    connectedInstances.adapter?.send(JSON.stringify(jsonRpc));
    jsonRpcIdToResponseResolver[jsonRpc.id] = resolve;
  });
};

/**
 * Redirects JSON-RPC request to the Unified Client and waits for response
 *
 * @returns Promise that resolves when JSON-RPC response from the Adapter comes back
 */
const redirectAuthCallbackToUnifiedClient = (jsonRpc: any) => {
  console.log('Received blocking auth callback request: %s', JSON.stringify(jsonRpc));
  return new Promise((resolve) => {
    connectedInstances.unifiedAblyClient?.send(JSON.stringify(jsonRpc));
    jsonRpcIdToResponseResolver[jsonRpc.id] = resolve;
  });
};