refactor: centralize domain values and enforce numeric lint

src/config/env.validation.ts

@@ -1,3 +1,8 @@
+const DEFAULT_PORT = 3000;
+const DEFAULT_TBANK_RATE_LIMIT_PER_SECOND = 5;
+const MAX_PORT = 65_535;
+const MIN_JWT_SECRET_LENGTH = 32;
+const TOKEN_KEY_BYTES = 32;
 export interface Environment {
   DATABASE_URL: string;
   FRONTEND_ORIGIN: string;
@@ -13,12 +18,14 @@ export interface Environment {
 export function validateEnv(config: Record<string, unknown>): Environment {
   const databaseUrl = config['DATABASE_URL'];
   const frontendOrigin = config['FRONTEND_ORIGIN'];
-  const port = config['PORT'] ?? 3000;
+  const port = config['PORT'] ?? DEFAULT_PORT;
   const jwtSecret = config['JWT_SECRET'];
   const tokenEncryptionKey = config['TOKEN_ENCRYPTION_KEY'];
   const tbankEndpoint =
     config['TBANK_GRPC_ENDPOINT'] ?? 'invest-public-api.tbank.ru:443';
-  const tbankRateLimit = config['TBANK_RATE_LIMIT_PER_SECOND'] ?? 5;
+  const tbankRateLimit =
+    config['TBANK_RATE_LIMIT_PER_SECOND'] ??
+    DEFAULT_TBANK_RATE_LIMIT_PER_SECOND;
   const tbankCaCertPath = config['TBANK_CA_CERT_PATH'];
   const logLevel = config['LOG_LEVEL'] ?? 'info';
 
@@ -47,18 +54,25 @@ export function validateEnv(config: Record<string, unknown>): Environment {
   }
 
   const parsedPort = Number(port);
-  if (!Number.isInteger(parsedPort) || parsedPort < 1 || parsedPort > 65535) {
+  if (
+    !Number.isInteger(parsedPort) ||
+    parsedPort < 1 ||
+    parsedPort > MAX_PORT
+  ) {
     throw new Error('PORT must be a valid port number');
   }
 
-  if (typeof jwtSecret !== 'string' || jwtSecret.length < 32) {
+  if (
+    typeof jwtSecret !== 'string' ||
+    jwtSecret.length < MIN_JWT_SECRET_LENGTH
+  ) {
     throw new Error('JWT_SECRET must be at least 32 characters long');
   }
 
   if (
     typeof tokenEncryptionKey !== 'string' ||
     !/^[A-Za-z0-9+/]+={0,2}$/.test(tokenEncryptionKey) ||
-    Buffer.from(tokenEncryptionKey, 'base64').length !== 32
+    Buffer.from(tokenEncryptionKey, 'base64').length !== TOKEN_KEY_BYTES
   ) {
     throw new Error(
       'TOKEN_ENCRYPTION_KEY must be a base64-encoded 32-byte key',