chore: make the Unleash AI chat resizable (#8456)

https://linear.app/unleash/issue/2-2840/make-the-unleash-ai-chat-window-resizable

This PR makes the Unleash AI chat resizable, providing users with a
flexible way to adjust the chat window's size.

Implements a reusable `Resizable` wrapper component that allows
configuration of:
 - Minimum, maximum, and default sizes.
- Customizable resize handlers for each edge and corner of the
container.
 - Optional resize event callbacks.

Double-clicking any resize handler maximizes the container along that
axis (or both, if it's a corner). If the container is already maximized,
double-clicking again will revert it to the default size.

frontend/src/component/ai/AIChat.tsx

@@ -13,6 +13,7 @@ import useUiConfig from 'hooks/api/getters/useUiConfig/useUiConfig';
 import { AIChatInput } from './AIChatInput';
 import { AIChatMessage } from './AIChatMessage';
 import { AIChatHeader } from './AIChatHeader';
+import { Resizable } from 'component/common/Resizable/Resizable';
 
 const StyledAIIconContainer = styled('div')(({ theme }) => ({
     position: 'fixed',
@@ -37,19 +38,26 @@ const StyledAIChatContainer = styled(StyledAIIconContainer)({
     right: 10,
 });
 
+const StyledResizable = styled(Resizable)(({ theme }) => ({
+    boxShadow: theme.boxShadows.popup,
+    borderRadius: theme.shape.borderRadiusLarge,
+}));
+
 const StyledAIIconButton = styled(IconButton)(({ theme }) => ({
     background: theme.palette.primary.light,
     color: theme.palette.primary.contrastText,
     boxShadow: theme.boxShadows.popup,
+    transition: 'background 0.3s',
     '&:hover': {
         background: theme.palette.primary.dark,
     },
 }));
 
 const StyledChat = styled('div')(({ theme }) => ({
-    borderRadius: theme.shape.borderRadiusLarge,
+    display: 'flex',
+    flex: 1,
+    flexDirection: 'column',
     overflow: 'hidden',
-    boxShadow: theme.boxShadows.popup,
     background: theme.palette.background.paper,
 }));
 
@@ -58,9 +66,9 @@ const StyledChatContent = styled('div')(({ theme }) => ({
     flexDirection: 'column',
     padding: theme.spacing(2),
     paddingBottom: theme.spacing(1),
-    width: '30vw',
+    flex: 1,
-    height: '50vh',
+    overflowY: 'auto',
-    overflow: 'auto',
+    overflowX: 'hidden',
 }));
 
 const initialMessages: ChatMessage[] = [
@@ -134,6 +142,13 @@ export const AIChat = () => {
 
     return (
         <StyledAIChatContainer>
+            <StyledResizable
+                handlers={['top-left', 'top', 'left']}
+                minSize={{ width: '270px', height: '200px' }}
+                maxSize={{ width: '90vw', height: '90vh' }}
+                defaultSize={{ width: '320px', height: '450px' }}
+                onResize={scrollToEnd}
+            >
                 <StyledChat>
                     <AIChatHeader
                         onNew={() => setMessages(initialMessages)}
@@ -152,6 +167,7 @@ export const AIChat = () => {
                     </StyledChatContent>
                     <AIChatInput onSend={onSend} loading={loading} />
                 </StyledChat>
+            </StyledResizable>
         </StyledAIChatContainer>
     );
 };

frontend/src/component/common/Resizable/Resizable.tsx

@@ -0,0 +1,296 @@
+import { styled } from '@mui/material';
+import { type HTMLAttributes, useRef, useState, type ReactNode } from 'react';
+
+const StyledResizableWrapper = styled('div', {
+    shouldForwardProp: (prop) => prop !== 'animate',
+})<{ animate: boolean }>(({ animate }) => ({
+    display: 'flex',
+    position: 'relative',
+    overflow: 'hidden',
+    transition: animate ? 'width 0.3s, height 0.3s' : 'none',
+}));
+
+const StyledResizeHandle = styled('div')({
+    position: 'absolute',
+    background: 'transparent',
+    zIndex: 1,
+    '&.top-left': {
+        top: 0,
+        left: 0,
+        cursor: 'nwse-resize',
+        width: '10px',
+        height: '10px',
+        zIndex: 2,
+    },
+    '&.top-right': {
+        top: 0,
+        right: 0,
+        cursor: 'nesw-resize',
+        width: '10px',
+        height: '10px',
+        zIndex: 2,
+    },
+    '&.bottom-left': {
+        bottom: 0,
+        left: 0,
+        cursor: 'nesw-resize',
+        width: '10px',
+        height: '10px',
+        zIndex: 2,
+    },
+    '&.bottom-right': {
+        bottom: 0,
+        right: 0,
+        cursor: 'nwse-resize',
+        width: '10px',
+        height: '10px',
+        zIndex: 2,
+    },
+    '&.top': {
+        top: 0,
+        left: '50%',
+        cursor: 'ns-resize',
+        width: '100%',
+        height: '5px',
+        transform: 'translateX(-50%)',
+    },
+    '&.right': {
+        top: '50%',
+        right: 0,
+        cursor: 'ew-resize',
+        width: '5px',
+        height: '100%',
+        transform: 'translateY(-50%)',
+    },
+    '&.bottom': {
+        bottom: 0,
+        left: '50%',
+        cursor: 'ns-resize',
+        width: '100%',
+        height: '5px',
+        transform: 'translateX(-50%)',
+    },
+    '&.left': {
+        top: '50%',
+        left: 0,
+        cursor: 'ew-resize',
+        width: '5px',
+        height: '100%',
+        transform: 'translateY(-50%)',
+    },
+});
+
+type Handler =
+    | 'top'
+    | 'right'
+    | 'bottom'
+    | 'left'
+    | 'top-left'
+    | 'top-right'
+    | 'bottom-left'
+    | 'bottom-right';
+
+type Size = { width: string; height: string };
+
+interface IResizableProps extends HTMLAttributes<HTMLDivElement> {
+    handlers: Handler[];
+    minSize: Size;
+    maxSize: Size;
+    defaultSize?: Size;
+    onResize?: () => void;
+    onResizeEnd?: () => void;
+    children: ReactNode;
+}
+
+export const Resizable = ({
+    handlers,
+    minSize,
+    maxSize,
+    defaultSize = minSize,
+    onResize,
+    onResizeEnd,
+    children,
+    ...props
+}: IResizableProps) => {
+    const containerRef = useRef<HTMLDivElement | null>(null);
+    const [currentSize, setCurrentSize] = useState(defaultSize);
+    const [animate, setAnimate] = useState(false);
+
+    const handleResize = (
+        e: React.MouseEvent<HTMLDivElement>,
+        direction:
+            | 'top'
+            | 'right'
+            | 'bottom'
+            | 'left'
+            | 'top-left'
+            | 'top-right'
+            | 'bottom-left'
+            | 'bottom-right',
+    ) => {
+        e.preventDefault();
+
+        const chatContainer = containerRef.current;
+        if (!chatContainer) return;
+
+        const startX = e.clientX;
+        const startY = e.clientY;
+        const startWidth = chatContainer.offsetWidth;
+        const startHeight = chatContainer.offsetHeight;
+
+        setAnimate(false);
+
+        const onMouseMove = (moveEvent: MouseEvent) => {
+            let newWidth = startWidth;
+            let newHeight = startHeight;
+
+            if (direction.includes('top')) {
+                newHeight = Math.max(
+                    Number.parseInt(minSize.height),
+                    startHeight - (moveEvent.clientY - startY),
+                );
+            }
+
+            if (direction.includes('bottom')) {
+                newHeight = Math.max(
+                    Number.parseInt(minSize.height),
+                    startHeight + (moveEvent.clientY - startY),
+                );
+            }
+
+            if (direction.includes('left')) {
+                newWidth = Math.max(
+                    Number.parseInt(minSize.width),
+                    startWidth - (moveEvent.clientX - startX),
+                );
+            }
+
+            if (direction.includes('right')) {
+                newWidth = Math.max(
+                    Number.parseInt(minSize.width),
+                    startWidth + (moveEvent.clientX - startX),
+                );
+            }
+
+            setCurrentSize({
+                width: `${newWidth}px`,
+                height: `${newHeight}px`,
+            });
+
+            onResize?.();
+        };
+
+        const onMouseUp = () => {
+            document.removeEventListener('mousemove', onMouseMove);
+            document.removeEventListener('mouseup', onMouseUp);
+
+            onResizeEnd?.();
+        };
+
+        document.addEventListener('mousemove', onMouseMove);
+        document.addEventListener('mouseup', onMouseUp);
+    };
+
+    const handleDoubleClick = (direction: Handler) => {
+        const chatContainer = containerRef.current;
+        if (!chatContainer) return;
+
+        const currentWidth = chatContainer.style.width;
+        const currentHeight = chatContainer.style.height;
+
+        setAnimate(true);
+
+        if (direction.includes('top') || direction.includes('bottom')) {
+            if (currentHeight === maxSize.height) {
+                chatContainer.style.height = defaultSize.height;
+            } else {
+                chatContainer.style.height = maxSize.height;
+            }
+        }
+
+        if (direction.includes('left') || direction.includes('right')) {
+            if (currentWidth === maxSize.width) {
+                chatContainer.style.width = defaultSize.width;
+            } else {
+                chatContainer.style.width = maxSize.width;
+            }
+        }
+
+        onResizeEnd?.();
+    };
+
+    return (
+        <StyledResizableWrapper
+            ref={containerRef}
+            animate={animate}
+            {...props}
+            style={{
+                width: currentSize.width,
+                height: currentSize.height,
+                minWidth: minSize.width,
+                minHeight: minSize.height,
+                maxWidth: maxSize.width,
+                maxHeight: maxSize.height,
+            }}
+        >
+            {children}
+
+            {handlers.includes('top-left') && (
+                <StyledResizeHandle
+                    className='top-left'
+                    onMouseDown={(e) => handleResize(e, 'top-left')}
+                    onDoubleClick={() => handleDoubleClick('top-left')}
+                />
+            )}
+            {handlers.includes('top-right') && (
+                <StyledResizeHandle
+                    className='top-right'
+                    onMouseDown={(e) => handleResize(e, 'top-right')}
+                    onDoubleClick={() => handleDoubleClick('top-right')}
+                />
+            )}
+            {handlers.includes('bottom-left') && (
+                <StyledResizeHandle
+                    className='bottom-left'
+                    onMouseDown={(e) => handleResize(e, 'bottom-left')}
+                    onDoubleClick={() => handleDoubleClick('bottom-left')}
+                />
+            )}
+            {handlers.includes('bottom-right') && (
+                <StyledResizeHandle
+                    className='bottom-right'
+                    onMouseDown={(e) => handleResize(e, 'bottom-right')}
+                    onDoubleClick={() => handleDoubleClick('bottom-right')}
+                />
+            )}
+            {handlers.includes('top') && (
+                <StyledResizeHandle
+                    className='top'
+                    onMouseDown={(e) => handleResize(e, 'top')}
+                    onDoubleClick={() => handleDoubleClick('top')}
+                />
+            )}
+            {handlers.includes('right') && (
+                <StyledResizeHandle
+                    className='right'
+                    onMouseDown={(e) => handleResize(e, 'right')}
+                    onDoubleClick={() => handleDoubleClick('right')}
+                />
+            )}
+            {handlers.includes('bottom') && (
+                <StyledResizeHandle
+                    className='bottom'
+                    onMouseDown={(e) => handleResize(e, 'bottom')}
+                    onDoubleClick={() => handleDoubleClick('bottom')}
+                />
+            )}
+            {handlers.includes('left') && (
+                <StyledResizeHandle
+                    className='left'
+                    onMouseDown={(e) => handleResize(e, 'left')}
+                    onDoubleClick={() => handleDoubleClick('left')}
+                />
+            )}
+        </StyledResizableWrapper>
+    );
+};