analyze performance upgrade

frontend/src/lib/logger.ts

@@ -0,0 +1,92 @@
+// Browser-side logger with levels, timestamps and a ring buffer.
+//
+// Level: NEXT_PUBLIC_LOG_LEVEL at build time, overridable per browser with
+// localStorage.setItem("iotp_log_level", "debug"). The last 300 entries are
+// kept in window.__iotpLogs and can be copied with window.__iotpDumpLogs().
+
+export type LogLevel = "debug" | "info" | "warn" | "error"
+
+const ORDER: Record<LogLevel, number> = { debug: 10, info: 20, warn: 30, error: 40 }
+const BUFFER_SIZE = 300
+
+interface LogEntry {
+  ts: string
+  level: LogLevel
+  scope: string
+  message: string
+  data?: unknown
+}
+
+declare global {
+  interface Window {
+    __iotpLogs?: LogEntry[]
+    __iotpDumpLogs?: () => string
+  }
+}
+
+function configuredLevel(): LogLevel {
+  let level = (process.env.NEXT_PUBLIC_LOG_LEVEL || (process.env.NODE_ENV === "production" ? "info" : "debug")) as LogLevel
+  if (typeof window !== "undefined") {
+    try {
+      const override = window.localStorage.getItem("iotp_log_level") as LogLevel | null
+      if (override && override in ORDER) level = override
+    } catch { /* storage may be unavailable */ }
+  }
+  return level in ORDER ? level : "info"
+}
+
+function buffer(): LogEntry[] {
+  if (typeof window === "undefined") return []
+  if (!window.__iotpLogs) {
+    window.__iotpLogs = []
+    window.__iotpDumpLogs = () =>
+      (window.__iotpLogs || [])
+        .map((e) => `${e.ts} ${e.level.toUpperCase().padEnd(5)} [${e.scope}] ${e.message}${e.data !== undefined ? " " + safeJson(e.data) : ""}`)
+        .join("\n")
+  }
+  return window.__iotpLogs
+}
+
+function safeJson(v: unknown): string {
+  try { return JSON.stringify(v) } catch { return String(v) }
+}
+
+function emit(level: LogLevel, scope: string, message: string, data?: unknown) {
+  if (ORDER[level] < ORDER[configuredLevel()]) return
+  const ts = new Date().toISOString()
+  const buf = buffer()
+  buf.push({ ts, level, scope, message, data })
+  if (buf.length > BUFFER_SIZE) buf.splice(0, buf.length - BUFFER_SIZE)
+  const line = `[iotp ${ts.slice(11, 23)}] [${scope}] ${message}`
+  const fn = level === "error" ? console.error : level === "warn" ? console.warn : level === "info" ? console.info : console.debug
+  if (data !== undefined) fn(line, data)
+  else fn(line)
+}
+
+export function getLogger(scope: string) {
+  return {
+    debug: (message: string, data?: unknown) => emit("debug", scope, message, data),
+    info: (message: string, data?: unknown) => emit("info", scope, message, data),
+    warn: (message: string, data?: unknown) => emit("warn", scope, message, data),
+    error: (message: string, data?: unknown) => emit("error", scope, message, data),
+  }
+}
+
+// Describe any thrown value for logs and user messages.
+export function describeError(err: unknown): string {
+  if (err instanceof Error) return `${err.name}: ${err.message}`
+  if (typeof err === "string") return err
+  return safeJson(err)
+}
+
+// Global handlers so uncaught browser errors land in the buffer too.
+export function installGlobalErrorLogging() {
+  if (typeof window === "undefined") return
+  const w = window as Window & { __iotpGlobalInstalled?: boolean }
+  if (w.__iotpGlobalInstalled) return
+  w.__iotpGlobalInstalled = true
+  const log = getLogger("window")
+  window.addEventListener("error", (ev) => log.error(`Uncaught: ${ev.message}`, { file: ev.filename, line: ev.lineno }))
+  window.addEventListener("unhandledrejection", (ev) => log.error(`Unhandled rejection: ${describeError(ev.reason)}`))
+  log.debug(`Logging active at level "${configuredLevel()}"; call window.__iotpDumpLogs() to copy the buffer`)
+}