import * as React from "react";
import { Check, ChevronsUpDown } from "lucide-react";
import { cn } from "@/lib/utils";
import { Popover, PopoverTrigger, PopoverContent } from "@/components/ui/popover";
import {
  Command,
  CommandInput,
  CommandList,
  CommandEmpty,
  CommandGroup,
  CommandItem,
} from "@/components/ui/command";

export type ComboboxOption = { value: string; label: string; keywords?: string };

/**
 * Searchable, single-select dropdown for long option lists (models,
 * providers, templates, …) where a plain <select> forces scrolling through
 * everything to find one item. Drop-in alternative to `Select` when a list
 * can realistically grow past ~8-10 items.
 */
export function Combobox({
  options,
  value,
  onChange,
  placeholder = "Select…",
  searchPlaceholder = "Search…",
  emptyText = "No match found.",
  disabled = false,
  className,
}: {
  options: ComboboxOption[];
  value: string;
  onChange: (v: string) => void;
  placeholder?: string;
  searchPlaceholder?: string;
  emptyText?: string;
  disabled?: boolean;
  className?: string;
}) {
  const [open, setOpen] = React.useState(false);
  const selected = options.find((o) => o.value === value);
  const unknownSelected = value && !selected;

  return (
    <Popover open={open} onOpenChange={setOpen}>
      <PopoverTrigger asChild>
        <button
          type="button"
          disabled={disabled}
          className={cn(
            "flex items-center justify-between gap-2 rounded-control border border-border bg-background px-3 py-2 text-sm text-left disabled:opacity-60 disabled:cursor-not-allowed",
            className,
          )}
        >
          <span
            className={cn("truncate", !selected && !unknownSelected && "text-muted-foreground")}
          >
            {selected
              ? selected.label
              : unknownSelected
                ? `Unknown (${value.slice(0, 8)})`
                : placeholder}
          </span>
          <ChevronsUpDown className="h-3.5 w-3.5 shrink-0 opacity-50" />
        </button>
      </PopoverTrigger>
      <PopoverContent className="w-[--radix-popover-trigger-width] p-0" align="start">
        <Command>
          <CommandInput placeholder={searchPlaceholder} />
          <CommandList>
            <CommandEmpty>{emptyText}</CommandEmpty>
            <CommandGroup>
              {options.map((o) => (
                <CommandItem
                  key={o.value}
                  value={`${o.label} ${o.keywords ?? ""}`}
                  onSelect={() => {
                    onChange(o.value);
                    setOpen(false);
                  }}
                >
                  <Check
                    className={cn(
                      "mr-2 h-4 w-4 shrink-0",
                      value === o.value ? "opacity-100" : "opacity-0",
                    )}
                  />
                  <span className="truncate">{o.label}</span>
                </CommandItem>
              ))}
            </CommandGroup>
          </CommandList>
        </Command>
      </PopoverContent>
    </Popover>
  );
}