fix(botCodeStore): ensure user cannot create a second bot even if they are inactive (#199)

## How does this PR impact the user?

User won't be able to have multiple bots in the game. Currently, we
create them a second bot if they submit code while they are inactive.

## Description

- [x] ensure that we check whether the user already has the bot by
reading the fs instead of checking the in-memory `ACTIVE_BOT_STORE`

## Limitations

N/A

## Checklist

- [x] my PR is focused and contains one holistic change
- [ ] I have added screenshots or screen recordings to show the changes

Author: yurijmikhalevich

other/botCodeStore.ts

@@ -13,7 +13,7 @@ export interface BotCode {
 
 export type BotCodes = Record<string, BotCode>;
 
-let STORE: BotCodes = {};
+let ACTIVE_BOT_STORE: BotCodes = {};
 
 const botEventEmitter = new EventEmitter();
 
@@ -23,11 +23,36 @@ type SubmitBotCodeArgs = {
   userId: number;
 };
 
+function formatBotCodeFilename({ username, id, userId }: { username: string; id: string; userId: number }) {
+  return `${BOT_CODE_DIR}/${username}-${id}-${userId}.js`;
+}
+
+function extractBotMetadataFromFilename(filename: string) {
+  const username = filename.split("-")[0];
+  const id = filename.split("-")[1];
+  const userId = filename.split("-")[2]?.replace(".js", "");
+  if (!id || !username || !userId) {
+    throw new Error(`Invalid bot code file: ${filename}`);
+  }
+  return { id, username, userId: Number(userId) };
+}
+
+async function getFirstUserBotMetadata(userId: number) {
+  const userBotFiles = await fs.readdir(BOT_CODE_DIR);
+  for (const file of userBotFiles) {
+    const { username, id, userId: fileUserId } = extractBotMetadataFromFilename(file);
+    if (fileUserId === userId) {
+      return { id, username, userId: fileUserId };
+    }
+  }
+}
+
 export async function submitBotCode({ code, username, userId }: SubmitBotCodeArgs) {
-  // ensure each user has only one bot
-  const id = Object.values(STORE).find(botCode => botCode.username === username)?.id || Math.random().toString(36).substring(5);
+  const existingBotMetadata = await getFirstUserBotMetadata(userId);
+  // Ensure that every user has only one bot
+  const id = existingBotMetadata?.id || Math.random().toString(36).substring(5);
   const botCode = { id, code, username, userId };
-  STORE[id] = botCode;
+  ACTIVE_BOT_STORE[id] = botCode;
   await saveBot(botCode);
 
   // Submitting code makes the user active
@@ -36,15 +61,15 @@ export async function submitBotCode({ code, username, userId }: SubmitBotCodeArg
     data: { inactive: false },
   });
 
-  botEventEmitter.emit("update", STORE);
+  botEventEmitter.emit("update", ACTIVE_BOT_STORE);
 }
 
 export function clearBots() {
-  STORE = {};
+  ACTIVE_BOT_STORE = {};
 }
 
 export function getBots() {
-  return { ...STORE };
+  return { ...ACTIVE_BOT_STORE };
 }
 
 export function subscribeToBotsUpdate(onUpdate: (bots: BotCodes) => void): () => void {
@@ -75,34 +100,36 @@ async function loadBots() {
   const inactiveUserIds = new Set(inactiveUsers.map(user => user.id));
 
   for (const file of files) {
-    const code = await fs.readFile(`${BOT_CODE_DIR}/${file}`, "utf8");
-    const username = file.split("-")[0];
-    const id = file.split("-")[1];
-    const userId = file.split("-")[2]?.replace(".js", "");
-    if (!id || !code || !username || !userId) {
+    const { username, id, userId } = extractBotMetadataFromFilename(file);
+    if (!id || !username || !userId) {
       throw new Error(`Invalid bot code file: ${file}`);
     }
 
-    if (inactiveUserIds.has(+userId)) {
+    if (inactiveUserIds.has(userId)) {
       continue;
     }
 
-    STORE[id] = { id, code, username, userId: +userId };
+    const code = await fs.readFile(`${BOT_CODE_DIR}/${file}`, "utf8");
+    if (!code) {
+      throw new Error(`Failed to read bot code file: ${file}`);
+    }
+
+    ACTIVE_BOT_STORE[id] = { id, code, username, userId };
   }
 
-  botEventEmitter.emit("update", STORE);
+  botEventEmitter.emit("update", ACTIVE_BOT_STORE);
 }
 
 async function saveBot({ id, code, username, userId }: BotCode) {
   if (!await fsExists(BOT_CODE_DIR)) {
     await fs.mkdir(BOT_CODE_DIR);
   }
-  const botCodeFile = `${BOT_CODE_DIR}/${username}-${id}-${userId}.js`;
+  const botCodeFile = formatBotCodeFilename({ username, id, userId });
 
   await fs.writeFile(botCodeFile, code);
 }
 
 loadBots()
   .then(() => {
-    console.log(`Loaded ${Object.keys(STORE).length} bots`);
+    console.log(`Loaded ${Object.keys(ACTIVE_BOT_STORE).length} bots`);
   });