// <Dropdown> — a small anchored option list, meant to sit directly under
// the `Badge` that opened it (../badge/Badge.tsx) so the control is
// visually attached to the thing it affects, instead of living three
// clicks away in a catch-all menu (the junk-drawer pattern
// `docs/web-ui/design-guide.md` calls out by name). Not a native `<dialog>` — a
// `showModal()` dialog's backdrop would visually detach it from its
// anchor badge, and a non-modal `show()` gets no click-outside-to-close
// for free, so this hand-rolls the same "outside click or Escape
// closes" contract `Dialog` gets from the platform.
//
// Positioning is the caller's job: render `<Dropdown>` as a child of a
// `position: relative` wrapper (the badge + dropdown pair) and it anchors to
// that box's bottom-left via CSS. Put the wrapper outside any scrolling
// container: an ancestor with `overflow-x: auto` computes `overflow-y` to `auto`
// too (per the CSS overflow spec), so it clips the dropdown vertically. A
// `position: fixed` list rendered through a portal escapes that, as
// `../../ui/table/Table.tsx` does for its column filters; this component had
// that mode for the agents table, and dropped it with the table.
import { useEffect, useRef } from "preact/hooks";
import type { ComponentChildren, RefObject } from "preact";
import "./Dropdown.css";

export interface DropdownOption {
  value: string;
  label: ComponentChildren;
  /** Optional dim secondary text, e.g. "sonnet (balanced)". */
  description?: ComponentChildren;
  /** Red-toned row for a destructive action (e.g. cancel turn), not a picker option. */
  danger?: boolean;
}

export interface DropdownProps {
  open: boolean;
  options: DropdownOption[];
  activeValue?: string;
  onSelect: (value: string) => void;
  onClose: () => void;
  /** `aria-label` for the option list (e.g. "select model"). */
  label: string;
  /**
   * Ref to the trigger badge/button that opened this dropdown. Without
   * it, a click on the trigger while open closes-then-reopens instead
   * of closing: the trigger's own `onClick` toggles `open`, but this
   * component's outside-click listener doesn't know the trigger is
   * "part of" the dropdown (it's a sibling, not a descendant of this
   * `<div>`), so it *also* fires `onClose` on the same click — the two
   * updates race, and the toggle's `!open` reads the pre-close value
   * and wins, reopening it (mara: "clicking badge with open drop down
   * reopens it instead of closing it"). Passing the same ref the
   * caller's wrapper div already needs for CSS positioning excludes
   * clicks on the trigger from the outside-click check, matching how
   * `MetaNav`'s own hand-rolled popover (which wraps trigger+popover in
   * one ref) already avoids this.
   */
  anchorRef?: RefObject<HTMLElement>;
}

export function Dropdown({
  open,
  options,
  activeValue,
  onSelect,
  onClose,
  label,
  anchorRef,
}: DropdownProps) {
  const ref = useRef<HTMLDivElement>(null);
  useEffect(() => {
    if (!open) return;
    function handlePointerDown(e: PointerEvent) {
      if (!(e.target instanceof Node)) return;
      if (ref.current?.contains(e.target)) return;
      if (anchorRef?.current?.contains(e.target)) return;
      onClose();
    }
    function handleKeyDown(e: KeyboardEvent) {
      if (e.key === "Escape") onClose();
    }
    // `pointerdown` (not `click`) so a drag-to-select that ends outside
    // still closes; capture phase so this sees the event before a
    // stopPropagation() elsewhere in the tree could swallow it.
    document.addEventListener("pointerdown", handlePointerDown, true);
    document.addEventListener("keydown", handleKeyDown);
    return () => {
      document.removeEventListener("pointerdown", handlePointerDown, true);
      document.removeEventListener("keydown", handleKeyDown);
    };
  }, [open, onClose]);

  if (!open) return null;

  return (
    <div class="ui-dropdown" role="menu" aria-label={label} ref={ref}>
      {options.map((opt) => (
        <button
          type="button"
          key={opt.value}
          role="menuitemradio"
          aria-checked={opt.value === activeValue}
          class={
            "ui-dropdown-item" +
            (opt.value === activeValue ? " ui-dropdown-item-active" : "") +
            (opt.danger ? " ui-dropdown-item-danger" : "")
          }
          onClick={() => onSelect(opt.value)}
        >
          <span class="ui-dropdown-item-label">{opt.label}</span>
          {opt.description ? (
            <span class="ui-dropdown-item-desc">{opt.description}</span>
          ) : null}
        </button>
      ))}
    </div>
  );
}