chore: add schedule option to approved change requests (#5252)

The button doesn't do anything at the moment, but it's there visually.

Because this uses the same button as the dual-function button for
approve/reject, I extracted that component into a reusable
"multi-action" button. I could have copied the code wholesale, but it's
a complex component, so I thought this would be a better solution.

I'll add the dialog in a follow-up PR. This one already has a lot of
changes.

Visual:


![image](https://github.com/Unleash/unleash/assets/17786332/9a9bee77-4925-4054-9ef6-ef8ddbb61fae)

frontend/src/component/changeRequest/ChangeRequestOverview/ApplyButton/ApplyButton.tsx

@@ -0,0 +1,31 @@
+import { FC } from 'react';
+
+import CheckBox from '@mui/icons-material/Check';
+import Today from '@mui/icons-material/Today';
+import { MultiActionButton } from '../MultiActionButton/MultiActionButton';
+import { APPLY_CHANGE_REQUEST } from 'component/providers/AccessProvider/permissions';
+
+export const ApplyButton: FC<{
+    disabled: boolean;
+    onSchedule: () => void;
+    onApply: () => void;
+}> = ({ disabled, onSchedule, onApply, children }) => (
+    <MultiActionButton
+        permission={APPLY_CHANGE_REQUEST}
+        disabled={disabled}
+        actions={[
+            {
+                label: 'Apply changes',
+                onSelect: onApply,
+                icon: <CheckBox fontSize='small' />,
+            },
+            {
+                label: 'Schedule changes',
+                onSelect: onSchedule,
+                icon: <Today fontSize='small' />,
+            },
+        ]}
+    >
+        {children}
+    </MultiActionButton>
+);

frontend/src/component/changeRequest/ChangeRequestOverview/ChangeRequestOverview.tsx

@@ -24,6 +24,9 @@ import { Dialogue } from 'component/common/Dialogue/Dialogue';
 import { changesCount } from '../changesCount';
 import { ChangeRequestReviewers } from './ChangeRequestReviewers/ChangeRequestReviewers';
 import { ChangeRequestRejectDialogue } from './ChangeRequestRejectDialog/ChangeRequestRejectDialog';
+import { ApplyButton } from './ApplyButton/ApplyButton';
+import { useUiFlag } from 'hooks/useUiFlag';
+import { scheduler } from 'timers/promises';
 
 const StyledAsideBox = styled(Box)(({ theme }) => ({
     width: '30%',
@@ -87,6 +90,8 @@ export const ChangeRequestOverview: FC = () => {
         return null;
     }
 
+    const scheduleChangeRequests = useUiFlag('scheduledConfigurationChanges');
+
     const allowChangeRequestActions = isChangeRequestConfiguredForReview(
         changeRequest.environment,
     );
@@ -267,11 +272,32 @@ export const ChangeRequestOverview: FC = () => {
                             <ConditionallyRender
                                 condition={changeRequest.state === 'Approved'}
                                 show={
+                                    <ConditionallyRender
+                                        condition={scheduleChangeRequests}
+                                        show={
+                                            <ApplyButton
+                                                onApply={onApplyChanges}
+                                                disabled={
+                                                    !allowChangeRequestActions ||
+                                                    loading
+                                                }
+                                                onSchedule={() => {
+                                                    console.log(
+                                                        'I would schedule changes now',
+                                                    );
+                                                }}
+                                            >
+                                                Apply or schedule changes
+                                            </ApplyButton>
+                                        }
+                                        elseShow={
                                             <PermissionButton
                                                 variant='contained'
                                                 onClick={onApplyChanges}
                                                 projectId={projectId}
-                                        permission={APPLY_CHANGE_REQUEST}
+                                                permission={
+                                                    APPLY_CHANGE_REQUEST
+                                                }
                                                 environmentId={
                                                     changeRequest.environment
                                                 }
@@ -284,6 +310,8 @@ export const ChangeRequestOverview: FC = () => {
                                             </PermissionButton>
                                         }
                                     />
+                                }
+                            />
                             <ConditionallyRender
                                 condition={
                                     changeRequest.state !== 'Applied' &&

frontend/src/component/changeRequest/ChangeRequestOverview/MultiActionButton/MultiActionButton.tsx

@@ -0,0 +1,123 @@
+import React, { FC, useContext } from 'react';
+import { useRequiredPathParam } from 'hooks/useRequiredPathParam';
+import { useChangeRequest } from 'hooks/api/getters/useChangeRequest/useChangeRequest';
+
+import {
+    ClickAwayListener,
+    Grow,
+    ListItemIcon,
+    ListItemText,
+    MenuItem,
+    MenuList,
+    Paper,
+    Popper,
+} from '@mui/material';
+
+import ArrowDropDownIcon from '@mui/icons-material/ArrowDropDown';
+import PermissionButton from 'component/common/PermissionButton/PermissionButton';
+import { useAuthUser } from 'hooks/api/getters/useAuth/useAuthUser';
+import AccessContext from 'contexts/AccessContext';
+
+type Action = {
+    label: string;
+    onSelect: () => void;
+    icon: JSX.Element;
+};
+
+export const MultiActionButton: FC<{
+    disabled: boolean;
+    actions: Action[];
+    permission: string;
+}> = ({ disabled, children, actions, permission }) => {
+    const { isAdmin } = useContext(AccessContext);
+    const projectId = useRequiredPathParam('projectId');
+    const id = useRequiredPathParam('id');
+    const { user } = useAuthUser();
+    const { data } = useChangeRequest(projectId, id);
+
+    const [open, setOpen] = React.useState(false);
+    const anchorRef = React.useRef<HTMLButtonElement>(null);
+
+    const onToggle = () => {
+        setOpen((prevOpen) => !prevOpen);
+    };
+
+    const onClose = (event: Event) => {
+        if (anchorRef.current?.contains(event.target as HTMLElement)) {
+            return;
+        }
+
+        setOpen(false);
+    };
+    const popperWidth = anchorRef.current
+        ? anchorRef.current.offsetWidth
+        : null;
+
+    return (
+        <React.Fragment>
+            <PermissionButton
+                variant='contained'
+                disabled={
+                    disabled || (data?.createdBy.id === user?.id && !isAdmin)
+                }
+                aria-controls={open ? 'review-options-menu' : undefined}
+                aria-expanded={open ? 'true' : undefined}
+                aria-label='review changes'
+                aria-haspopup='menu'
+                onClick={onToggle}
+                ref={anchorRef}
+                endIcon={<ArrowDropDownIcon />}
+                permission={permission}
+                projectId={projectId}
+                environmentId={data?.environment}
+            >
+                {children}
+            </PermissionButton>
+            <Popper
+                sx={{
+                    zIndex: 1,
+                    width: popperWidth,
+                }}
+                open={open}
+                anchorEl={anchorRef.current}
+                role={undefined}
+                transition
+                disablePortal
+            >
+                {({ TransitionProps, placement }) => (
+                    <Grow
+                        {...TransitionProps}
+                        style={{
+                            transformOrigin:
+                                placement === 'bottom'
+                                    ? 'center top'
+                                    : 'center bottom',
+                        }}
+                    >
+                        <Paper className='dropdown-outline'>
+                            <ClickAwayListener onClickAway={onClose}>
+                                <MenuList
+                                    id='review-options-menu'
+                                    autoFocusItem
+                                >
+                                    {actions.map(
+                                        ({ label, onSelect, icon }) => (
+                                            <MenuItem onClick={onSelect}>
+                                                <ListItemIcon>
+                                                    {icon}
+                                                </ListItemIcon>
+                                                <ListItemText>
+                                                    {label}
+                                                </ListItemText>
+                                            </MenuItem>
+                                        ),
+                                    )}
+                                </MenuList>
+                            </ClickAwayListener>
+                        </Paper>
+                    </Grow>
+                )}
+            </Popper>
+        </React.Fragment>
+    );
+};

frontend/src/component/changeRequest/ChangeRequestOverview/ReviewButton/ReviewButton.tsx

@@ -1,124 +1,31 @@
-import React, { FC, useContext } from 'react';
-import { useRequiredPathParam } from 'hooks/useRequiredPathParam';
-import { useChangeRequest } from 'hooks/api/getters/useChangeRequest/useChangeRequest';
+import { FC } from 'react';
 
-import {
-    ClickAwayListener,
-    Grow,
-    ListItemIcon,
-    ListItemText,
-    MenuItem,
-    MenuList,
-    Paper,
-    Popper,
-} from '@mui/material';
-
-import ArrowDropDownIcon from '@mui/icons-material/ArrowDropDown';
-import { APPROVE_CHANGE_REQUEST } from 'component/providers/AccessProvider/permissions';
-import PermissionButton from 'component/common/PermissionButton/PermissionButton';
-import { useAuthUser } from 'hooks/api/getters/useAuth/useAuthUser';
-import AccessContext from 'contexts/AccessContext';
 import CheckBox from '@mui/icons-material/Check';
 import Clear from '@mui/icons-material/Clear';
+import { MultiActionButton } from '../MultiActionButton/MultiActionButton';
+import { APPROVE_CHANGE_REQUEST } from 'component/providers/AccessProvider/permissions';
 
 export const ReviewButton: FC<{
     disabled: boolean;
     onReject: () => void;
     onApprove: () => void;
-}> = ({ disabled, onReject, onApprove, children }) => {
-    const { isAdmin } = useContext(AccessContext);
-    const projectId = useRequiredPathParam('projectId');
-    const id = useRequiredPathParam('id');
-    const { user } = useAuthUser();
-    const { data } = useChangeRequest(projectId, id);
-
-    const [open, setOpen] = React.useState(false);
-    const anchorRef = React.useRef<HTMLButtonElement>(null);
-
-    const onToggle = () => {
-        setOpen((prevOpen) => !prevOpen);
-    };
-
-    const onClose = (event: Event) => {
-        if (anchorRef.current?.contains(event.target as HTMLElement)) {
-            return;
-        }
-
-        setOpen(false);
-    };
-    const popperWidth = anchorRef.current
-        ? anchorRef.current.offsetWidth
-        : null;
-
-    return (
-        <React.Fragment>
-            <PermissionButton
-                variant='contained'
-                disabled={
-                    disabled || (data?.createdBy.id === user?.id && !isAdmin)
-                }
-                aria-controls={open ? 'review-options-menu' : undefined}
-                aria-expanded={open ? 'true' : undefined}
-                aria-label='review changes'
-                aria-haspopup='menu'
-                onClick={onToggle}
-                ref={anchorRef}
-                endIcon={<ArrowDropDownIcon />}
+}> = ({ disabled, onReject, onApprove, children }) => (
+    <MultiActionButton
         permission={APPROVE_CHANGE_REQUEST}
-                projectId={projectId}
-                environmentId={data?.environment}
+        disabled={disabled}
+        actions={[
+            {
+                label: 'Approve',
+                onSelect: onApprove,
+                icon: <CheckBox fontSize='small' />,
+            },
+            {
+                label: 'Reject',
+                onSelect: onReject,
+                icon: <Clear fontSize='small' />,
+            },
+        ]}
     >
         {children}
-            </PermissionButton>
-            <Popper
-                sx={{
-                    zIndex: 1,
-                    width: popperWidth,
-                }}
-                open={open}
-                anchorEl={anchorRef.current}
-                role={undefined}
-                transition
-                disablePortal
-            >
-                {({ TransitionProps, placement }) => (
-                    <Grow
-                        {...TransitionProps}
-                        style={{
-                            transformOrigin:
-                                placement === 'bottom'
-                                    ? 'center top'
-                                    : 'center bottom',
-                        }}
-                    >
-                        <Paper className='dropdown-outline'>
-                            <ClickAwayListener onClickAway={onClose}>
-                                <MenuList
-                                    id='review-options-menu'
-                                    autoFocusItem
-                                >
-                                    <MenuItem onClick={onApprove}>
-                                        <ListItemIcon>
-                                            <CheckBox fontSize='small' />
-                                        </ListItemIcon>
-                                        <ListItemText>
-                                            Approve changes
-                                        </ListItemText>
-                                    </MenuItem>
-                                    <MenuItem onClick={onReject}>
-                                        <ListItemIcon>
-                                            <Clear fontSize='small' />
-                                        </ListItemIcon>
-                                        <ListItemText>
-                                            Reject changes
-                                        </ListItemText>
-                                    </MenuItem>
-                                </MenuList>
-                            </ClickAwayListener>
-                        </Paper>
-                    </Grow>
-                )}
-            </Popper>
-        </React.Fragment>
-    );
-};
+    </MultiActionButton>
+);