chore: Simpler autofocus of function call (#39946)

## Description

Improves the autofocus logic as per
https://github.com/appsmithorg/appsmith/pull/39916#discussion_r2014507020



<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- **New Features**
- When adding a new function field, it now automatically receives focus,
making the configuration process smoother and more intuitive.
- The transition for adding fields has been streamlined to improve user
interaction without distractions from unnecessary scrolling behavior.
- New state management for tracking the most recently added function
field enhances user experience.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

app/client/src/components/formControls/FunctionCallingConfigControl/components/FunctionCallingConfigForm.tsx

@@ -1,5 +1,5 @@
 import { Button, Text } from "@appsmith/ads";
-import { default as React, useCallback, useRef, useEffect } from "react";
+import React, { useCallback, useState } from "react";
 import type { FieldArrayFieldsProps } from "redux-form";
 import styled from "styled-components";
 import { v4 as uuid } from "uuid";
@@ -29,17 +29,19 @@ export const FunctionCallingConfigForm = ({
   fields,
   formName,
 }: FunctionCallingConfigFormProps) => {
-  const latestFieldRef = useRef<HTMLDivElement>(null);
+  const [newlyAddedId, setNewlyAddedId] = useState<string | null>(null);
-  const previousFieldsLength = useRef(fields.length);
 
   const handleAddFunctionButtonClick = useCallback(() => {
+    const id = uuid();
+
     fields.push({
-      id: uuid(),
+      id,
       description: "",
       entityId: "",
       isApprovalRequired: false,
       entityType: "Query",
     });
+    setNewlyAddedId(id);
   }, [fields]);
 
   const handleRemoveToolButtonClick = useCallback(
@@ -49,38 +51,6 @@ export const FunctionCallingConfigForm = ({
     [fields],
   );
 
-  useEffect(
-    function handleAddFunction() {
-      // Only scroll and focus if a new field was added (length increased)
-      if (
-        fields.length > previousFieldsLength.current &&
-        latestFieldRef.current
-      ) {
-        // Scroll the new field into view
-        latestFieldRef.current.scrollIntoView({
-          behavior: "smooth",
-          block: "center",
-        });
-
-        // Focus the menu button in the latest field
-        // The menu button is rendered by the Menu component from @appsmith/ads
-        const menuButton = latestFieldRef.current.querySelector(
-          "button.rc-select-selector",
-        );
-
-        if (menuButton) {
-          // Use setTimeout to ensure the button is fully rendered
-          setTimeout(() => {
-            (menuButton as HTMLButtonElement).focus();
-          }, 100);
-        }
-      }
-
-      previousFieldsLength.current = fields.length;
-    },
-    [fields.length],
-  );
-
   return (
     <>
       <Header>
@@ -108,14 +78,21 @@ export const FunctionCallingConfigForm = ({
       ) : (
         <ConfigItems>
           {fields.map((field, index) => {
-            const isLastField = index === fields.length - 1;
+            const fieldValue = fields.get(index);
+            const isNewlyAdded = fieldValue.id === newlyAddedId;
+
+            // Reset the newly added ID after rendering to ensure focus only happens once
+            if (isNewlyAdded) {
+              setTimeout(() => setNewlyAddedId(null), 100);
+            }
 
             return (
-              <div key={field} ref={isLastField ? latestFieldRef : undefined}>
+              <div key={field}>
                 <FunctionCallingConfigToolField
                   fieldPath={field}
                   formName={formName}
                   index={index}
+                  isLastAdded={isNewlyAdded}
                   onRemove={handleRemoveToolButtonClick}
                 />
               </div>

app/client/src/components/formControls/FunctionCallingConfigControl/components/FunctionCallingConfigToolField.tsx

@@ -12,6 +12,7 @@ interface FunctionCallingConfigToolFieldProps {
   formName: string;
   index: number;
   onRemove: (index: number) => void;
+  isLastAdded?: boolean;
 }
 
 const ConfigItemRoot = styled.div`
@@ -39,6 +40,7 @@ const ConfigItemSelectWrapper = styled.div`
 
 export const FunctionCallingConfigToolField = ({
   index,
+  isLastAdded,
   onRemove,
   ...props
 }: FunctionCallingConfigToolFieldProps) => {
@@ -100,6 +102,7 @@ export const FunctionCallingConfigToolField = ({
       <ConfigItemRow>
         <ConfigItemSelectWrapper>
           <FunctionCallingMenuField
+            autoFocus={isLastAdded}
             name={`${props.fieldPath}.entityId`}
             onValueChange={handleFunctionChange}
           />

app/client/src/components/formControls/FunctionCallingConfigControl/components/FunctionCallingMenuField.tsx

@@ -1,3 +1,4 @@
+import React, { useCallback, useMemo } from "react";
 import {
   Button,
   Menu,
@@ -12,7 +13,6 @@ import {
   MenuSubTrigger,
   MenuSubContent,
 } from "@appsmith/ads";
-import React, { useCallback, useMemo } from "react";
 import { Field, type WrappedFieldProps, type BaseFieldProps } from "redux-form";
 import type {
   FunctionCallingEntityType,
@@ -35,6 +35,7 @@ interface FunctionCallingMenuFieldProps {
     value: string,
     entityType: FunctionCallingEntityType,
   ) => void;
+  autoFocus?: boolean;
 }
 
 interface FieldRenderProps
@@ -82,7 +83,7 @@ const getSelectedValueInfo = (
 };
 
 const FunctionCallingMenuFieldRender = (props: FieldRenderProps) => {
-  const { children, disabled, input, onValueChange } = props;
+  const { autoFocus, children, disabled, input, onValueChange } = props;
   const options = useSelector(selectEntityOptions);
 
   const dispatch = useDispatch();
@@ -154,6 +155,7 @@ const FunctionCallingMenuFieldRender = (props: FieldRenderProps) => {
     <Menu>
       <MenuTrigger>
         <Button
+          autoFocus={autoFocus}
           className="rc-select-selector"
           disabled={disabled}
           endIcon="arrow-down-s-line"