import type { KeyboardEvent } from 'react';

interface TabItem {
  id: string;
  label: string;
  count?: number;
  disabled?: boolean;
}

interface TabsProps {
  items: TabItem[];
  activeId: string;
  onChange: (id: string) => void;
}

export function Tabs({ items, activeId, onChange }: TabsProps): JSX.Element {
  function nextEnabled(from: number, direction: 1 | -1): string {
    const len = items.length;
    let i = (from + direction + len) % len;
    while (i !== from) {
      if (!items[i].disabled) return items[i].id;
      i = (i + direction + len) % len;
    }
    return items[from].id;
  }

  function handleKeyDown(e: KeyboardEvent<HTMLButtonElement>, index: number) {
    if (e.key === 'ArrowRight') {
      e.preventDefault();
      onChange(nextEnabled(index, 1));
    } else if (e.key === 'ArrowLeft') {
      e.preventDefault();
      onChange(nextEnabled(index, -1));
    }
  }

  return (
    <div
      role="tablist"
      className="flex items-end border-b border-hairline gap-xs"
    >
      {items.map((item, index) => {
        const isActive = item.id === activeId;
        const isDisabled = item.disabled ?? false;
        return (
          <button
            key={item.id}
            id={`tab-${item.id}`}
            role="tab"
            aria-selected={isActive}
            aria-controls={`tabpanel-${item.id}`}
            aria-disabled={isDisabled || undefined}
            disabled={isDisabled}
            type="button"
            onClick={() => { if (!isDisabled) onChange(item.id); }}
            onKeyDown={(e) => handleKeyDown(e, index)}
            className={`tab-underline${isActive ? ' tab-underline-active' : ''}${isDisabled ? ' tab-underline-disabled' : ''} pb-xs`}
          >
            {item.label}
            {item.count !== undefined ? (
              <span
                className={`ml-xxs tab-count-pill${isActive ? ' tab-count-pill-active' : ''}`}
              >
                {item.count}
              </span>
            ) : null}
          </button>
        );
      })}
    </div>
  );
}