import { useEffect, useState } from 'react';
import { BulkApi } from '../api/client.js';

/// <summary>
/// Keyboard navigation for an email list. Shortcuts:
///   j / ArrowDown  move focus down
///   k / ArrowUp    move focus up
///   e              archive the focused email
///   u              mark the focused email unread
///   #  (shift+3)   trash the focused email
/// All shortcuts are ignored while an input/textarea/select (or any
/// contenteditable) has focus, and modifier chords (Ctrl/Cmd/Alt) are left
/// alone, so typing and browser/OS shortcuts are never hijacked.
/// `onRemoved(id)` lets the caller drop the row from local state after a
/// successful archive/trash.
/// </summary>
export default function useListKeyboardNav(emails, onRemoved) {
  const [focusedId, setFocusedId] = useState(null);

  useEffect(() => {
    const isEditable = (el) => {
      if (!el) return false;
      const tag = el.tagName;
      return tag === 'INPUT' || tag === 'TEXTAREA' || tag === 'SELECT' || el.isContentEditable;
    };

    const handler = async (e) => {
      // Never hijack typing or modifier chords (Ctrl+C, Cmd+K, Alt+…).
      if (isEditable(document.activeElement)) return;
      if (e.ctrlKey || e.metaKey || e.altKey) return;
      if (!emails.length) return;

      const idx = emails.findIndex((x) => x.id === focusedId);

      switch (e.key) {
        case 'j':
        case 'ArrowDown': {
          e.preventDefault();
          const next = idx < 0 ? 0 : Math.min(idx + 1, emails.length - 1);
          setFocusedId(emails[next].id);
          break;
        }
        case 'k':
        case 'ArrowUp': {
          e.preventDefault();
          const prev = idx < 0 ? 0 : Math.max(idx - 1, 0);
          setFocusedId(emails[prev].id);
          break;
        }
        case 'e': {
          if (idx < 0) break;
          e.preventDefault();
          const id = emails[idx].id;
          await BulkApi.archive([id]);
          onRemoved(id);
          break;
        }
        case 'u': {
          if (idx < 0) break;
          e.preventDefault();
          await BulkApi.markUnread([emails[idx].id]);
          break;
        }
        case '#': {
          if (idx < 0) break;
          e.preventDefault();
          const id = emails[idx].id;
          await BulkApi.trash([id]);
          onRemoved(id);
          break;
        }
        default:
          break;
      }
    };

    window.addEventListener('keydown', handler);
    return () => window.removeEventListener('keydown', handler);
  }, [emails, focusedId, onRemoved]);

  return focusedId;
}