[feat] Group Admin can remove settle-up member.

src/pages/groups/[groupId].tsx

@@ -53,6 +53,14 @@ const BalancePage: NextPageWithUser<{
   const expensesQuery = api.group.getExpenses.useQuery({ groupId });
   const deleteGroupMutation = api.group.delete.useMutation();
   const leaveGroupMutation = api.group.leaveGroup.useMutation();
+  const removeMemberMutation = api.group.removeMember.useMutation({
+    onSuccess: () => {
+      void groupDetailQuery.refetch();
+    },
+    onError: (err) => {
+      toast.error(err.message ?? 'Failed to remove member');
+    },
+  });
 
   const [isInviteCopied, setIsInviteCopied] = useState(false);
   const [showDeleteTrigger, setShowDeleteTrigger] = useState(false);
@@ -188,15 +196,54 @@ const BalancePage: NextPageWithUser<{
               <div className="">
                 <p className="font-semibold">Members</p>
                 <div className="mt-2 flex flex-col gap-2">
-                  {groupDetailQuery.data?.groupUsers.map((groupUser) => (
-                    <div
-                      key={groupUser.userId}
-                      className={clsx('flex items-center gap-2 rounded-md py-1.5')}
-                    >
-                      <UserAvatar user={groupUser.user} />
-                      <p>{groupUser.user.name ?? groupUser.user.email}</p>
-                    </div>
-                  ))}
+                  {groupDetailQuery.data?.groupUsers.map((groupUser) => {
+                    const hasBalance = groupDetailQuery.data?.groupBalances.some(
+                      (b) => b.userId === groupUser.userId && b.amount !== 0
+                    );
+                    const canDeleteUser =
+                      isAdmin && groupUser.userId !== user.id && !hasBalance;
+
+                    return (
+                      <div
+                        key={groupUser.userId}
+                        className="flex items-center justify-between gap-2 rounded-md py-1.5"
+                      >
+                        <div className="flex items-center gap-2">
+                          <UserAvatar user={groupUser.user} />
+                          <p>{groupUser.user.name ?? groupUser.user.email}</p>
+                        </div>
+                        {canDeleteUser && (
+                          <AlertDialog>
+                            <AlertDialogTrigger asChild>
+                              <button>
+                                <Trash2 className="h-4 w-4 text-red-500 hover:opacity-70" />
+                              </button>
+                            </AlertDialogTrigger>
+                            <AlertDialogContent className="max-w-xs rounded-lg">
+                              <AlertDialogHeader>
+                                <AlertDialogTitle>Remove member?</AlertDialogTitle>
+                                <AlertDialogDescription>
+                                  This action cannot be undone. The user will be removed from this group.
+                                </AlertDialogDescription>
+                              </AlertDialogHeader>
+                              <AlertDialogFooter>
+                                <AlertDialogCancel>Cancel</AlertDialogCancel>
+                                <Button
+                                  variant="destructive"
+                                  onClick={() =>
+                                    removeMemberMutation.mutate({ groupId, userId: groupUser.userId })
+                                  }
+                                >
+                                  Remove
+                                </Button>
+                              </AlertDialogFooter>
+                            </AlertDialogContent>
+                          </AlertDialog>
+                        )}
+                      </div>
+                    );
+                  })}
+
                 </div>
               </div>
               {groupDetailQuery?.data?.createdAt && (

src/server/api/routers/group.ts

@@ -350,4 +350,47 @@ export const groupRouter = createTRPCRouter({
 
       return group;
     }),
+
+  removeMember: groupProcedure
+    .input(z.object({ groupId: z.number(), userId: z.number() }))
+    .mutation(async ({ ctx, input }) => {
+      const { groupId, userId } = input;
+
+      // 確保呼叫者是 group 擁有者
+      const group = await ctx.db.group.findUnique({
+        where: { id: groupId },
+      });
+
+      if (group?.userId !== ctx.session.user.id) {
+        throw new TRPCError({ code: 'UNAUTHORIZED', message: 'Only admin can remove members' });
+      }
+
+      if (userId === ctx.session.user.id) {
+        throw new TRPCError({ code: 'BAD_REQUEST', message: 'You cannot remove yourself' });
+      }
+
+      const balance = await ctx.db.groupBalance.findFirst({
+        where: {
+          groupId,
+          userId,
+          amount: { not: 0 },
+        },
+      });
+
+      if (balance) {
+        throw new TRPCError({
+          code: 'BAD_REQUEST',
+          message: 'This member has unsettled balance and cannot be removed',
+        });
+      }
+
+      await ctx.db.groupUser.delete({
+        where: {
+          groupId_userId: { groupId, userId },
+        },
+      });
+
+      return { success: true };
+    }),
+
 });