'use client';

import { useEffect, useRef } from 'react';
import { X } from 'lucide-react';

interface KeyboardShortcutsModalProps {
  open: boolean;
  onClose: () => void;
}

const shortcuts = [
  { key: 'R', description: 'Rectangle tool' },
  { key: 'S', description: 'Span tool' },
  { key: 'L', description: 'Line tool' },
  { key: 'D', description: 'Delete tool' },
  { key: 'T', description: 'Toggle theme (light/dark)' },
  { key: 'Esc', description: 'Deselect tool / cancel action' },
  { key: 'Del / ⌫', description: 'Delete selected annotation' },
  { key: 'Enter', description: 'Edit selected span' },
  { key: '1–6', description: 'Quick-assign span label (during span creation)' },
  { key: '?', description: 'Show this help' },
];

const FOCUSABLE_SELECTORS = [
  'a[href]',
  'button:not([disabled])',
  'textarea:not([disabled])',
  'input:not([disabled])',
  'select:not([disabled])',
  '[tabindex]:not([tabindex="-1"])',
].join(', ');

export default function KeyboardShortcutsModal({ open, onClose }: KeyboardShortcutsModalProps) {
  const dialogRef = useRef<HTMLDivElement>(null);

  // Escape / ? key handler
  useEffect(() => {
    if (!open) return;
    const handleKey = (e: KeyboardEvent) => {
      if (e.key === 'Escape' || e.key === '?') {
        onClose();
      }
    };
    window.addEventListener('keydown', handleKey);
    return () => window.removeEventListener('keydown', handleKey);
  }, [open, onClose]);

  // Focus trapping
  useEffect(() => {
    if (!open) return;

    const dialog = dialogRef.current;
    if (!dialog) return;

    // Move focus into the dialog on open
    const firstFocusable = dialog.querySelector<HTMLElement>(FOCUSABLE_SELECTORS);
    firstFocusable?.focus();

    const handleTabKey = (e: KeyboardEvent) => {
      if (e.key !== 'Tab') return;

      const focusableElements = Array.from(
        dialog.querySelectorAll<HTMLElement>(FOCUSABLE_SELECTORS)
      ).filter((el) => !el.closest('[disabled]'));

      if (focusableElements.length === 0) {
        e.preventDefault();
        return;
      }

      const first = focusableElements[0];
      const last = focusableElements[focusableElements.length - 1];

      if (e.shiftKey) {
        if (document.activeElement === first) {
          e.preventDefault();
          last.focus();
        }
      } else {
        if (document.activeElement === last) {
          e.preventDefault();
          first.focus();
        }
      }
    };

    dialog.addEventListener('keydown', handleTabKey);
    return () => dialog.removeEventListener('keydown', handleTabKey);
  }, [open]);

  if (!open) return null;

  return (
    <div
      className="fixed inset-0 z-50 flex items-center justify-center bg-black/50"
      onClick={onClose}
    >
      <div
        ref={dialogRef}
        role="dialog"
        aria-modal="true"
        aria-labelledby="keyboard-shortcuts-title"
        className="bg-background border border-border rounded-lg shadow-xl w-96 p-5"
        onClick={(e) => e.stopPropagation()}
      >
        <div className="flex items-center justify-between mb-4">
          <h2
            id="keyboard-shortcuts-title"
            className="text-sm font-semibold text-foreground"
          >
            Keyboard Shortcuts
          </h2>
          <button
            onClick={onClose}
            className="p-1 rounded text-muted-foreground hover:text-foreground hover:bg-secondary transition-colors"
          >
            <X className="w-4 h-4" />
          </button>
        </div>

        <table className="w-full text-xs">
          <tbody>
            {shortcuts.map(({ key, description }) => (
              <tr key={key} className="border-b border-border last:border-0">
                <td className="py-1.5 pr-4 font-mono">
                  <kbd className="px-1.5 py-0.5 bg-secondary rounded text-foreground font-mono text-[11px]">
                    {key}
                  </kbd>
                </td>
                <td className="py-1.5 text-muted-foreground">{description}</td>
              </tr>
            ))}
          </tbody>
        </table>

        <p className="mt-4 text-[10px] text-muted-foreground text-center">
          Press <kbd className="px-1 py-0.5 bg-secondary rounded font-mono">?</kbd> or <kbd className="px-1 py-0.5 bg-secondary rounded font-mono">Esc</kbd> to close
        </p>
      </div>
    </div>
  );
}