feat: more useful error messages

Author: krystxf

src/data/stop-ids.ts

@@ -0,0 +1,119 @@
+export const stopIDs = [
+  "U1040Z101P",
+  "U1040Z102P",
+  "U157Z101P",
+  "U157Z102P",
+  "U50Z101P",
+  "U50Z102P",
+  "U897Z101P",
+  "U510Z101P",
+  "U510Z102P",
+  "U321Z101P",
+  "U321Z102P",
+  "U1071Z101P",
+  "U1071Z102P",
+  "U118Z101P",
+  "U118Z102P",
+  "U689Z101P",
+  "U689Z102P",
+  "U689Z121P",
+  "U689Z122P",
+  "U286Z101P",
+  "U142Z101P",
+  "U142Z102P",
+  "U135Z101P",
+  "U135Z102P",
+  "U163Z101P",
+  "U163Z102P",
+  "U1154Z101P",
+  "U1154Z102P",
+  "U52Z102P",
+  "U52Z101P",
+  "U190Z101P",
+  "U190Z102P",
+  "U655Z101P",
+  "U655Z102P",
+  "U685Z101P",
+  "U685Z102P",
+  "U209Z101P",
+  "U209Z102P",
+  "U228Z101P",
+  "U228Z102P",
+  "U237Z101P",
+  "U237Z102P",
+  "U675Z101P",
+  "U675Z102P",
+  "U75Z101P",
+  "U75Z102P",
+  "U758Z101P",
+  "U758Z102P",
+  "U78Z101P",
+  "U78Z102P",
+  "U1000Z102P",
+  "U1007Z101P",
+  "U1007Z102P",
+  "U258Z101P",
+  "U258Z102P",
+  "U360Z101P",
+  "U360Z102P",
+  "U1072Z101P",
+  "U1072Z102P",
+  "U1072Z121P",
+  "U1072Z122P",
+  "U400Z101P",
+  "U400Z102P",
+  "U400Z121P",
+  "U400Z122P",
+  "U115Z101P",
+  "U115Z102P",
+  "U462Z101P",
+  "U462Z102P",
+  "U476Z101P",
+  "U476Z102P",
+  "U480Z101P",
+  "U480Z102P",
+  "U539Z101P",
+  "U539Z102P",
+  "U306Z101P",
+  "U602Z101P",
+  "U602Z102P",
+  "U106Z101P",
+  "U106Z102P",
+  "U529Z101P",
+  "U529Z102P",
+  "U385Z101P",
+  "U385Z102P",
+  "U507Z101P",
+  "U507Z102P",
+  "U597Z101P",
+  "U597Z102P",
+  "U603Z101P",
+  "U603Z102P",
+  "U957Z101P",
+  "U957Z102P",
+  "U818Z101P",
+  "U818Z102P",
+  "U601Z101P",
+  "U601Z102P",
+  "U953Z101P",
+  "U953Z102P",
+  "U458Z101P",
+  "U458Z102P",
+  "U703Z101P",
+  "U703Z102P",
+  "U1140Z101P",
+  "U1140Z102P",
+  "U713Z101P",
+  "U713Z102P",
+  "U332Z101P",
+  "U332Z102P",
+  "U100Z101P",
+  "U100Z102P",
+  "U474Z101P",
+  "U474Z102P",
+  "U527Z101P",
+  "U527Z102P",
+  "U1141Z102P",
+  "U921Z101P",
+  "U921Z102P",
+] as const satisfies `U${number}Z${number}P`[];

src/fetch-metro/fetch-metro.ts

@@ -22,7 +22,11 @@ export const fetchApiData = async (stopIDs: string[]) => {
   }
 
   const body = await res.json();
-  const parsed = ApiResponseSchema.parse(body);
+  const parsed = ApiResponseSchema.safeParse(body);
+  if (!parsed.success) {
+    console.error("Golemio API response:", body);
+    throw new Error("Golemio API response is in unexpected format");
+  }
 
-  return parsed;
+  return parsed.data;
 };

src/schemas.ts

@@ -1,7 +1,8 @@
 import { z } from "zod";
 import { MetroLine } from "./types";
+import { stopIDs } from "./data/stop-ids";
 
-export const StopIDsSchema = z.array(z.string()).nonempty().max(10);
+export const StopIDsSchema = z.array(z.enum(stopIDs)).nonempty().max(10);
 
 export const SubscribeSchema = z.object({
   subscribe: StopIDsSchema,

src/server.ts

@@ -7,10 +7,10 @@ import { group } from "radash";
 import { STOP_IDS_HEADER, INTERVAL } from "./server/server.const";
 import { fetchApiData } from "./fetch-metro/fetch-metro";
 import { StopIDsSchema, SubscribeSchema, type ApiResponse } from "./schemas";
-import { getParsedDeparture } from "./server/server.utils";
+import { getErrorResponse, getParsedDeparture } from "./server/server.utils";
 
 if (!process.env.GOLEMIO_API_KEY) {
-  throw new Error("GOLEMIO_API_KEY is not set");
+  throw new Error("GOLEMIO_API_KEY is not set in .env");
 }
 
 let intervalId: number | null = null;
@@ -99,17 +99,27 @@ const fetchData = async (clientID?: string) => {
 const server = Bun.serve<ClientData>({
   fetch(req, server) {
     const stopIDsHeaderRaw = req.headers.get(STOP_IDS_HEADER);
-    const StopIDsHeaderParsed = JSON.parse(stopIDsHeaderRaw ?? "");
-    const res = StopIDsSchema.safeParse(StopIDsHeaderParsed);
+    if (!stopIDsHeaderRaw)
+      return getErrorResponse(`"${STOP_IDS_HEADER}" header is missing`);
+
+    let StopIDsHeaderParsed: unknown;
+    try {
+      StopIDsHeaderParsed = JSON.parse(stopIDsHeaderRaw);
+    } catch (error) {
+      return getErrorResponse(`"${STOP_IDS_HEADER}" header ${error}`);
+    }
 
-    if (!res.success) return new Response("Invalid request", { status: 400 });
+    const res = StopIDsSchema.safeParse(StopIDsHeaderParsed);
+    if (!res.success)
+      return getErrorResponse(
+        `"${STOP_IDS_HEADER}" error: ${res.error.errors[0].message}`
+      );
 
     const clientID = uuid();
     subscribedStopIDsByClientID.set(clientID, res.data);
     const success = server.upgrade(req, { data: { clientID } });
 
-    if (!success)
-      return new Response("Failed to upgrade connection", { status: 500 });
+    if (!success) return getErrorResponse("Failed to upgrade connection");
   },
   websocket: {
     open(ws) {
@@ -125,8 +135,24 @@ const server = Bun.serve<ClientData>({
       intervalId = intervalObj[Symbol.toPrimitive]();
     },
     message(ws, message) {
-      const res = SubscribeSchema.safeParse(message);
-      if (!res.success) return;
+      if (typeof message !== "string") {
+        ws.close(1011, "Message has to be string");
+        return;
+      }
+
+      let StopIDsHeaderParsed: unknown;
+      try {
+        StopIDsHeaderParsed = JSON.parse(message);
+      } catch (error) {
+        ws.close(1011, String(error));
+        return;
+      }
+
+      const res = SubscribeSchema.safeParse(StopIDsHeaderParsed);
+      if (!res.success) {
+        ws.close(1011, res.error.errors[0].message);
+        return;
+      }
 
       subscribedStopIDsByClientID.set(ws.data.clientID, res.data.subscribe);
     },

src/server/server.utils.ts

@@ -1,6 +1,13 @@
 import type { Departure } from "../types";
 import type { ApiResponse } from "../schemas";
 
+export const getErrorResponse = (message: string): Response => {
+  return new Response(message, {
+    status: 500,
+    headers: [["error", message]], // Postman doesn't show response body when testing websocket
+  });
+};
+
 export const getParsedDeparture = (
   departure: ApiResponse["departures"][0]
 ): Departure => {