// components/ui/Dropdown.tsx
'use client';

import * as React from 'react';
import {
  Menu,
  MenuButton,
  MenuItem,
  MenuItems,
  Portal,
} from '@headlessui/react';
import {
  ChevronDownIcon,
  EllipsisVerticalIcon,
} from '@heroicons/react/20/solid';
import clsx from 'clsx';

type DropdownTone = 'default' | 'danger';

export type DropdownItem = {
  id?: string;
  label: string;
  href?: string;
  onClick?: () => void;
  icon?: React.ReactNode;
  tone?: DropdownTone;
  disabled?: boolean;
};

export type DropdownSection = {
  id?: string;
  label?: string;
  items: DropdownItem[];
};

export type DropdownTriggerVariant = 'button' | 'icon';

export interface DropdownProps {
  label?: string;
  ariaLabel?: string;
  align?: 'left' | 'right';
  triggerVariant?: DropdownTriggerVariant;
  header?: React.ReactNode;
  sections: DropdownSection[];

  triggerClassName?: string;
  menuClassName?: string;

  /** Dropdown komplett deaktivieren (Trigger klickt nicht) */
  disabled?: boolean;
}

/* ───────── interne Helfer ───────── */

const itemBaseClasses =
  'block px-4 py-2 text-sm ' +
  // Default Text
  'text-gray-700 dark:text-gray-300 ' +
  // Hover (Maus)
  'hover:bg-gray-100 hover:text-gray-900 ' +
  'dark:hover:bg-white/5 dark:hover:text-white ' +
  // Focus Outline weglassen
  'focus:outline-none';

const itemWithIconClasses =
  'group flex items-center gap-x-3 px-4 py-2 text-sm ' +
  // Default Text
  'text-gray-700 dark:text-gray-300 ' +
  // Hover
  'hover:bg-gray-100 hover:text-gray-900 ' +
  'dark:hover:bg-white/5 dark:hover:text-white ' +
  'focus:outline-none';

const iconClasses =
  'flex size-5 shrink-0 items-center justify-center text-gray-400 ' +
  'group-hover:text-gray-500 ' +
  'dark:text-gray-500 dark:group-hover:text-white';

const toneClasses: Record<DropdownTone, string> = {
  default: '',
  danger:
    'text-rose-600 data-focus:text-rose-700 dark:text-rose-400 dark:data-focus:text-rose-300',
};

function renderItemContent(item: DropdownItem) {
  const hasIcon = !!item.icon;

  if (hasIcon) {
    return (
      <span
        className={clsx(
          itemWithIconClasses,
          item.tone && toneClasses[item.tone],
        )}
      >
        <span aria-hidden="true" className={iconClasses}>
          {item.icon}
        </span>
        {item.label}
      </span>
    );
  }

  return (
    <span
      className={clsx(
        itemBaseClasses,
        item.tone && toneClasses[item.tone],
      )}
    >
      {item.label}
    </span>
  );
}

/* ───────── Dropdown-Komponente (mit Portal) ───────── */

export function Dropdown({
  label = 'Options',
  ariaLabel = 'Open options',
  align = 'right',
  triggerVariant = 'button',
  header,
  sections,
  triggerClassName,
  menuClassName,
  disabled = false,
}: DropdownProps) {
  const hasDividers = sections.length > 1;
  const triggerIsButton = triggerVariant === 'button';

  const buttonRef = React.useRef<HTMLButtonElement | null>(null);
  const [position, setPosition] = React.useState<{
    top: number;
    left: number;
  } | null>(null);

  return (
    <Menu as="div" className="relative inline-block text-left">
      {({ open }) => {
        React.useEffect(() => {
          if (!open || !buttonRef.current) return;

          const rect = buttonRef.current.getBoundingClientRect();
          const scrollX =
            window.pageXOffset || document.documentElement.scrollLeft;
          const scrollY =
            window.pageYOffset || document.documentElement.scrollTop;

          const left =
            align === 'left' ? rect.left + scrollX : rect.right + scrollX;

          setPosition({
            top: rect.bottom + scrollY + 4,
            left,
          });
        }, [open, align]);

        return (
          <>
            <MenuButton
              ref={buttonRef}
              disabled={disabled}
              className={clsx(
                triggerIsButton
                  ? 'inline-flex w-full justify-center gap-x-1.5 rounded-md bg-white px-3 py-2 text-sm font-semibold text-gray-900 shadow-xs inset-ring-1 inset-ring-gray-300 hover:bg-gray-50 dark:bg-white/10 dark:text-white dark:shadow-none dark:inset-ring-white/5 dark:hover:bg-white/20'
                  : 'flex items-center rounded-full text-gray-400 hover:text-gray-600 focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-indigo-600 dark:text-gray-400 dark:hover:text-gray-300 dark:focus-visible:outline-indigo-500',
                disabled && 'opacity-50 cursor-not-allowed hover:bg-white dark:hover:bg-white/10',
                triggerClassName,
              )}
            >
              {triggerIsButton ? (
                <>
                  {label}
                  <ChevronDownIcon
                    aria-hidden="true"
                    className="-mr-1 size-5 text-gray-400 dark:text-gray-500"
                  />
                </>
              ) : (
                <>
                  <span className="sr-only">{ariaLabel}</span>
                  <EllipsisVerticalIcon
                    aria-hidden="true"
                    className="size-5"
                  />
                </>
              )}
            </MenuButton>

            {open && position && !disabled && (
              <Portal>
                <MenuItems
                  static
                  style={{
                    position: 'fixed',
                    top: position.top,
                    left: align === 'left' ? position.left : undefined,
                    right:
                      align === 'right'
                        ? window.innerWidth - position.left
                        : undefined,
                  }}
                  className={clsx(
                    'z-[9999] w-56 max-h-[60vh] overflow-y-auto rounded-md bg-white shadow-lg outline-1 outline-black/5 ' +
                      'dark:bg-gray-800 dark:shadow-none dark:-outline-offset-1 dark:outline-white/10',
                    hasDividers &&
                      'divide-y divide-gray-100 dark:divide-white/10',
                    menuClassName,
                  )}
                >
                  {header && <div className="px-4 py-3">{header}</div>}

                  {sections.map((section, sectionIndex) => (
                  <div
                    key={section.id ?? sectionIndex}
                    className="py-1"
                  >
                    {/* NEU: Gruppen-Label als "Trenner" */}
                    {section.label && (
                      <div className="px-4 py-1 text-xs font-semibold uppercase tracking-wide text-gray-500 dark:text-gray-400">
                        {section.label}
                      </div>
                    )}

                    {section.items.map((item, itemIndex) => {
                      const key = item.id ?? `${sectionIndex}-${itemIndex}`;

                      return (
                        <MenuItem
                          key={key}
                          disabled={item.disabled}
                        >
                          {item.href ? (
                            <a
                              href={item.href}
                              onClick={item.onClick}
                              className="block"
                            >
                              {renderItemContent(item)}
                            </a>
                          ) : (
                            <button
                              type="button"
                              onClick={item.onClick}
                              className="block w-full text-left"
                            >
                              {renderItemContent(item)}
                            </button>
                          )}
                        </MenuItem>
                      );
                    })}
                  </div>
                ))}
                </MenuItems>
              </Portal>
            )}
          </>
        );
      }}
    </Menu>
  );
}

export default Dropdown;