Handle stdin for prompts using readline for escape character parsing (#1972)

packages/cli/src/ui/hooks/useBracketedPaste.ts

@@ -0,0 +1,37 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { useEffect } from 'react';
+
+const ENABLE_BRACKETED_PASTE = '\x1b[?2004h';
+const DISABLE_BRACKETED_PASTE = '\x1b[?2004l';
+
+/**
+ * Enables and disables bracketed paste mode in the terminal.
+ *
+ * This hook ensures that bracketed paste mode is enabled when the component
+ * mounts and disabled when it unmounts or when the process exits.
+ */
+export const useBracketedPaste = () => {
+  const cleanup = () => {
+    process.stdout.write(DISABLE_BRACKETED_PASTE);
+  };
+
+  useEffect(() => {
+    process.stdout.write(ENABLE_BRACKETED_PASTE);
+
+    process.on('exit', cleanup);
+    process.on('SIGINT', cleanup);
+    process.on('SIGTERM', cleanup);
+
+    return () => {
+      cleanup();
+      process.removeListener('exit', cleanup);
+      process.removeListener('SIGINT', cleanup);
+      process.removeListener('SIGTERM', cleanup);
+    };
+  }, []);
+};

packages/cli/src/ui/hooks/useKeypress.ts

@@ -0,0 +1,104 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { useEffect, useRef } from 'react';
+import { useStdin } from 'ink';
+import readline from 'readline';
+
+export interface Key {
+  name: string;
+  ctrl: boolean;
+  meta: boolean;
+  shift: boolean;
+  paste: boolean;
+  sequence: string;
+}
+
+/**
+ * A hook that listens for keypress events from stdin, providing a
+ * key object that mirrors the one from Node's `readline` module,
+ * adding a 'paste' flag for characters input as part of a bracketed
+ * paste (when enabled).
+ *
+ * Pastes are currently sent as a single key event where the full paste
+ * is in the sequence field.
+ *
+ * @param onKeypress - The callback function to execute on each keypress.
+ * @param options - Options to control the hook's behavior.
+ * @param options.isActive - Whether the hook should be actively listening for input.
+ */
+export function useKeypress(
+  onKeypress: (key: Key) => void,
+  { isActive }: { isActive: boolean },
+) {
+  const { stdin, setRawMode } = useStdin();
+  const onKeypressRef = useRef(onKeypress);
+
+  useEffect(() => {
+    onKeypressRef.current = onKeypress;
+  }, [onKeypress]);
+
+  useEffect(() => {
+    if (!isActive || !stdin.isTTY) {
+      return;
+    }
+
+    setRawMode(true);
+
+    const rl = readline.createInterface({ input: stdin });
+    let isPaste = false;
+    let pasteBuffer = Buffer.alloc(0);
+
+    const handleKeypress = (_: unknown, key: Key) => {
+      if (key.name === 'paste-start') {
+        isPaste = true;
+      } else if (key.name === 'paste-end') {
+        isPaste = false;
+        onKeypressRef.current({
+          name: '',
+          ctrl: false,
+          meta: false,
+          shift: false,
+          paste: true,
+          sequence: pasteBuffer.toString(),
+        });
+        pasteBuffer = Buffer.alloc(0);
+      } else {
+        if (isPaste) {
+          pasteBuffer = Buffer.concat([pasteBuffer, Buffer.from(key.sequence)]);
+        } else {
+          // Handle special keys
+          if (key.name === 'return' && key.sequence === '\x1B\r') {
+            key.meta = true;
+          }
+          onKeypressRef.current({ ...key, paste: isPaste });
+        }
+      }
+    };
+
+    readline.emitKeypressEvents(stdin, rl);
+    stdin.on('keypress', handleKeypress);
+
+    return () => {
+      stdin.removeListener('keypress', handleKeypress);
+      rl.close();
+      setRawMode(false);
+
+      // If we are in the middle of a paste, send what we have.
+      if (isPaste) {
+        onKeypressRef.current({
+          name: '',
+          ctrl: false,
+          meta: false,
+          shift: false,
+          paste: true,
+          sequence: pasteBuffer.toString(),
+        });
+        pasteBuffer = Buffer.alloc(0);
+      }
+    };
+  }, [isActive, stdin, setRawMode]);
+}