getting terminal colors working

src/utils/theme-observer.ts

@@ -0,0 +1,104 @@
+/**
+ * Theme observer utility for detecting and responding to theme changes.
+ *
+ * This module provides utilities for:
+ * - Listening to SIGUSR2 signals for theme reload
+ * - Emitting theme change events via the event bus
+ * - Tracking theme change state
+ */
+
+import { emit, on, off, type EventHandler } from "./event-bus"
+
+/**
+ * Subscribe to theme reload events.
+ * These are triggered by SIGUSR2 signals.
+ */
+export function onThemeReload(handler: EventHandler<{}>): () => void {
+  return on("theme.reload", handler)
+}
+
+/**
+ * Subscribe to theme changed events.
+ * These are triggered when the theme selection changes.
+ */
+export function onThemeChanged(
+  handler: EventHandler<{ theme: string; mode: "dark" | "light" }>
+): () => void {
+  return on("theme.changed", handler)
+}
+
+/**
+ * Subscribe to theme mode changed events.
+ * These are triggered when switching between dark/light mode.
+ */
+export function onThemeModeChanged(
+  handler: EventHandler<{ mode: "dark" | "light" }>
+): () => void {
+  return on("theme.mode.changed", handler)
+}
+
+/**
+ * Emit a theme reload event.
+ */
+export function emitThemeReload(): void {
+  emit("theme.reload", {})
+}
+
+/**
+ * Emit a theme changed event.
+ */
+export function emitThemeChanged(theme: string, mode: "dark" | "light"): void {
+  emit("theme.changed", { theme, mode })
+}
+
+/**
+ * Emit a theme mode changed event.
+ */
+export function emitThemeModeChanged(mode: "dark" | "light"): void {
+  emit("theme.mode.changed", { mode })
+}
+
+/**
+ * Setup SIGUSR2 signal handler for theme reload.
+ * This allows external tools to trigger a theme refresh by sending SIGUSR2 to the process.
+ *
+ * Usage: `kill -USR2 <pid>` to trigger a theme reload
+ *
+ * @param onReload - Callback to execute when SIGUSR2 is received
+ * @returns Cleanup function to remove the handler
+ */
+export function setupThemeSignalHandler(onReload: () => void): () => void {
+  const handler = () => {
+    emitThemeReload()
+    onReload()
+  }
+
+  process.on("SIGUSR2", handler)
+
+  return () => {
+    process.off("SIGUSR2", handler)
+  }
+}
+
+/**
+ * Create a debounced theme change handler to prevent rapid consecutive updates.
+ *
+ * @param handler - The handler to debounce
+ * @param delay - Delay in milliseconds (default: 100ms)
+ */
+export function createDebouncedThemeHandler<T>(
+  handler: (event: T) => void,
+  delay: number = 100
+): (event: T) => void {
+  let timeout: NodeJS.Timeout | null = null
+
+  return (event: T) => {
+    if (timeout) {
+      clearTimeout(timeout)
+    }
+    timeout = setTimeout(() => {
+      handler(event)
+      timeout = null
+    }, delay)
+  }
+}