로깅 추가

packages/backend/src/logger.ts

@@ -0,0 +1,92 @@
+import type { RequestHandler } from 'express';
+
+type LogLevel = 'INFO' | 'WARN' | 'ERROR';
+type LogDetails = Record<string, unknown>;
+
+function formatDetails(details?: LogDetails): string {
+  if (!details) return '';
+  const normalized = Object.fromEntries(
+    Object.entries(details).map(([key, value]) => [
+      key,
+      value instanceof Error ? value.stack ?? value.message : value,
+    ]),
+  );
+  return ` ${JSON.stringify(normalized)}`;
+}
+
+function write(level: LogLevel, message: string, details?: LogDetails) {
+  const line = `[${new Date().toISOString()}] [${level}] ${message}${formatDetails(details)}`;
+  if (level === 'ERROR') {
+    console.error(line);
+  } else if (level === 'WARN') {
+    console.warn(line);
+  } else {
+    console.log(line);
+  }
+}
+
+export const logger = {
+  info: (message: string, details?: LogDetails) =>
+    write('INFO', message, details),
+  warn: (message: string, details?: LogDetails) =>
+    write('WARN', message, details),
+  error: (message: string, details?: LogDetails) =>
+    write('ERROR', message, details),
+};
+
+function browserSummary(userAgent = ''): string {
+  const browsers: [RegExp, string][] = [
+    [/Edg\/([\d.]+)/, 'Edge'],
+    [/OPR\/([\d.]+)/, 'Opera'],
+    [/Chrome\/([\d.]+)/, 'Chrome'],
+    [/Firefox\/([\d.]+)/, 'Firefox'],
+    [/Version\/([\d.]+).*Safari\//, 'Safari'],
+    [/curl\/([\d.]+)/, 'curl'],
+  ];
+  const browser = browsers
+    .map(([pattern, name]) => {
+      const match = userAgent.match(pattern);
+      return match ? `${name} ${match[1]}` : null;
+    })
+    .find(Boolean) ?? 'Unknown';
+
+  const os = /Windows NT/.test(userAgent)
+    ? 'Windows'
+    : /Android/.test(userAgent)
+      ? 'Android'
+      : /iPhone|iPad/.test(userAgent)
+        ? 'iOS'
+        : /Mac OS X/.test(userAgent)
+          ? 'macOS'
+          : /Linux/.test(userAgent)
+            ? 'Linux'
+            : 'Unknown';
+
+  return `${browser} / ${os}`;
+}
+
+function requestIp(forwardedFor: string | string[] | undefined, remote?: string) {
+  const forwarded = Array.isArray(forwardedFor)
+    ? forwardedFor[0]
+    : forwardedFor?.split(',')[0]?.trim();
+  return (forwarded || remote || '-').replace(/^::ffff:/, '');
+}
+
+export const requestLogger: RequestHandler = (req, res, next) => {
+  const startedAt = performance.now();
+  res.on('finish', () => {
+    const durationMs = Math.round(performance.now() - startedAt);
+    const ip = requestIp(
+      req.headers['x-forwarded-for'],
+      req.socket.remoteAddress,
+    );
+    const browser = browserSummary(req.headers['user-agent']);
+    const message =
+      `${req.method} ${req.originalUrl} ${res.statusCode} ${durationMs}ms` +
+      ` ip=${ip} browser="${browser}"`;
+    if (res.statusCode >= 500) logger.error(message);
+    else if (res.statusCode >= 400) logger.warn(message);
+    else logger.info(message);
+  });
+  next();
+};