feat: close #782 select prompt with arrow down / up

app/components/chat.tsx

@@ -224,18 +224,63 @@ export function PromptHints(props: {
   prompts: Prompt[];
   onPromptSelect: (prompt: Prompt) => void;
 }) {
-  if (props.prompts.length === 0) return null;
+  const noPrompts = props.prompts.length === 0;
+  const [selectIndex, setSelectIndex] = useState(0);
+  const selectedRef = useRef<HTMLDivElement>(null);
 
+  useEffect(() => {
+    setSelectIndex(0);
+  }, [props.prompts.length]);
+
+  useEffect(() => {
+    const onKeyDown = (e: KeyboardEvent) => {
+      if (noPrompts) return;
+
+      // arrow up / down to select prompt
+      const changeIndex = (delta: number) => {
+        e.stopPropagation();
+        e.preventDefault();
+        const nextIndex = Math.max(
+          0,
+          Math.min(props.prompts.length - 1, selectIndex + delta),
+        );
+        setSelectIndex(nextIndex);
+        selectedRef.current?.scrollIntoView({
+          block: "center",
+        });
+      };
+
+      if (e.key === "ArrowUp") {
+        changeIndex(1);
+      } else if (e.key === "ArrowDown") {
+        changeIndex(-1);
+      } else if (e.key === "Enter") {
+        const selectedPrompt = props.prompts.at(selectIndex);
+        if (selectedPrompt) {
+          props.onPromptSelect(selectedPrompt);
+        }
+      }
+    };
+
+    window.addEventListener("keydown", onKeyDown);
+
+    return () => window.removeEventListener("keydown", onKeyDown);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [noPrompts, selectIndex]);
+
+  if (noPrompts) return null;
   return (
     <div className={styles["prompt-hints"]}>
       {props.prompts.map((prompt, i) => (
         <div
-          className={styles["prompt-hint"]}
+          ref={i === selectIndex ? selectedRef : null}
+          className={
+            styles["prompt-hint"] +
+            ` ${i === selectIndex ? styles["prompt-hint-selected"] : ""}`
+          }
           key={prompt.title + i.toString()}
-          onClick={() => {
-            console.log("click hint");
-            props.onPromptSelect(prompt);
-          }}
+          onClick={() => props.onPromptSelect(prompt)}
+          onMouseEnter={() => setSelectIndex(i)}
         >
           <div className={styles["hint-title"]}>{prompt.title}</div>
           <div className={styles["hint-content"]}>{prompt.content}</div>