import { useEffect } from 'react';

export interface ShortcutDef {
  /** Key to match (e.g. 'k', 'n', 'Escape', '/') */
  key: string;
  /** Require Cmd (Mac) or Ctrl (Windows/Linux) — default: false */
  meta?: boolean;
  /** Require Shift — default: false */
  shift?: boolean;
  /** Require Alt/Option — default: false */
  alt?: boolean;
  /** Handler to invoke when shortcut fires */
  handler: () => void;
  /** Allow firing when focus is in input/textarea — default: false */
  allowInInput?: boolean;
  /** Human-readable description for help overlay / accessibility */
  description?: string;
}

function isInputElement(el: EventTarget | null): boolean {
  if (!el || !(el instanceof HTMLElement)) {
    return false;
  }
  const tag = el.tagName;
  return tag === 'INPUT' || tag === 'TEXTAREA' || el.isContentEditable;
}

export function useKeyboardShortcuts(shortcuts: ShortcutDef[]): void {
  useEffect(() => {
    if (shortcuts.length === 0) {
      return;
    }

    function handleKeyDown(e: KeyboardEvent) {
      if (!e.key) return;
      const inInput = isInputElement(e.target);

      for (const shortcut of shortcuts) {
        if (!shortcut.key) continue;
        const metaMatch = shortcut.meta ? e.metaKey || e.ctrlKey : !(e.metaKey || e.ctrlKey);
        const shiftMatch = shortcut.shift ? e.shiftKey : !e.shiftKey;
        const altMatch = shortcut.alt ? e.altKey : !e.altKey;

        // Normalize key comparison (case-insensitive for letters)
        const keyMatch = e.key.toLowerCase() === shortcut.key.toLowerCase();

        if (keyMatch && metaMatch && shiftMatch && altMatch) {
          if (inInput && !shortcut.allowInInput) {
            continue;
          }
          e.preventDefault();
          shortcut.handler();
          return;
        }
      }
    }

    window.addEventListener('keydown', handleKeyDown);
    return () => window.removeEventListener('keydown', handleKeyDown);
  }, [shortcuts]);
}