CoreControl/app/dashboard/settings/Settings.tsx

import { AppSidebar } from "@/components/app-sidebar";
import {
  Breadcrumb,
  BreadcrumbItem,
  BreadcrumbList,
  BreadcrumbPage,
  BreadcrumbSeparator,
} from "@/components/ui/breadcrumb";
import { Separator } from "@/components/ui/separator";
import {
  SidebarInset,
  SidebarProvider,
  SidebarTrigger,
} from "@/components/ui/sidebar";
import { Card, CardHeader } from "@/components/ui/card";
import { useTheme } from "next-themes";
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from "@/components/ui/select";

export default function Settings() {
  const { theme, setTheme } = useTheme();

  return (
    <SidebarProvider>
      <AppSidebar />
      <SidebarInset>
        <header className="flex h-16 shrink-0 items-center gap-2 transition-[width,height] ease-linear group-has-[[data-collapsible=icon]]/sidebar-wrapper:h-12">
          <div className="flex items-center gap-2 px-4">
            <SidebarTrigger className="-ml-1" />
            <Separator orientation="vertical" className="mr-2 h-4" />
            <Breadcrumb>
              <BreadcrumbList>
                <BreadcrumbItem className="hidden md:block">
                  <BreadcrumbPage>/</BreadcrumbPage>
                </BreadcrumbItem>
                <BreadcrumbSeparator className="hidden md:block" />
                <BreadcrumbItem>
                  <BreadcrumbPage>Dashboard</BreadcrumbPage>
                </BreadcrumbItem>
                <BreadcrumbSeparator className="hidden md:block" />
                <BreadcrumbItem>
                  <BreadcrumbPage>Settings</BreadcrumbPage>
                </BreadcrumbItem>
              </BreadcrumbList>
            </Breadcrumb>
          </div>
        </header>
        <div className="pl-4 pr-4">
          <span className="text-2xl font-semibold">Settings</span>
          <div className="pt-4">
            <Card className="w-full mb-4 relative">
              <CardHeader>
                <span className="text-xl font-bold">Theme</span>
                <Select 
                  value={theme} 
                  onValueChange={(value: string) => setTheme(value)}
                >
                  <SelectTrigger className="w-full [&_svg]:hidden">
                    <SelectValue>
                      {(theme ?? 'system').charAt(0).toUpperCase() + (theme ?? 'system').slice(1)}
                    </SelectValue>
                  </SelectTrigger>
                  <SelectContent>
                    <SelectItem value="light">Light</SelectItem>
                    <SelectItem value="dark">Dark</SelectItem>
                    <SelectItem value="system">System</SelectItem>
                  </SelectContent>
                </Select>
              </CardHeader>
            </Card>
          </div>
        </div>
      </SidebarInset>
    </SidebarProvider>
  );
}