import { useState, useEffect, useRef } from 'react';
import axios from 'axios';
import {
  IconPlus,
  IconSearch,
  IconEdit,
  IconTrash,
  IconCheck,
  IconX,
  IconDatabase,
  IconRefresh,
  IconUpload,
  IconDownload,
  IconDeviceFloppy
} from '@tabler/icons-react';

const API_URL = '/api';

function IPRangesManager() {
  const [items, setItems] = useState([]);
  const [newItem, setNewItem] = useState({ ipRange: '', community: '' });
  const [newInvalid, setNewInvalid] = useState({ ipRange: false, community: false });
  const [error, setError] = useState('');
  const [success, setSuccess] = useState('');
  const [searchTerm, setSearchTerm] = useState('');
  const [editingIp, setEditingIp] = useState(null);
  const [editingValue, setEditingValue] = useState('');
  const [loading, setLoading] = useState(false);
  const [showDeleteModal, setShowDeleteModal] = useState(false);
  const [itemToDelete, setItemToDelete] = useState(null);
  const [currentPage, setCurrentPage] = useState(1);
  const [sortField, setSortField] = useState('ipRange');
  const [sortOrder, setSortOrder] = useState('asc');
  const [filterCommunity, setFilterCommunity] = useState('');
  const editInputRef = useRef(null);
  const pageSize = 10;

  const isValidIPv4 = (ip) => {
    const octets = ip.split('.');
    if (octets.length !== 4) return false;
    return octets.every(o => /^\d{1,3}$/.test(o) && Number(o) >= 0 && Number(o) <= 255);
  };

  const isValidCidr = (value) => {
    const v = String(value).trim();
    const parts = v.split('/');
    if (parts.length !== 2) return false;
    const [ip, mask] = parts;
    if (!isValidIPv4(ip)) return false;
    if (!/^\d{1,2}$/.test(mask)) return false;
    const m = Number(mask);
    return m >= 0 && m <= 32;
  };

  const isValidCommunity = (value) => /^[0-9]+$/.test(String(value).trim());

  useEffect(() => {
    fetchItems();
  }, []);

  const fetchItems = async () => {
    setLoading(true);
    try {
      const response = await axios.get(`${API_URL}/ip-ranges`);
      setItems(response.data);
      setError('');
    } catch (error) {
      console.error('Error fetching ip-ranges:', error);
      setError('Не удалось загрузить IP-диапазоны. Проверьте, запущен ли бэкенд.');
    } finally {
      setLoading(false);
    }
  };

  const handleAddItem = () => {
    const cidrOk = isValidCidr(newItem.ipRange);
    const communityOk = isValidCommunity(newItem.community);
    setNewInvalid({ ipRange: !cidrOk, community: !communityOk });
    if (!cidrOk || !communityOk) {
      setError('Введите корректный IP-диапазон в формате CIDR (например 192.168.1.0/24) и числовой community.');
      return;
    }
    setError('');
    setItems([...items, { ipRange: newItem.ipRange.trim(), community: String(newItem.community).trim() }]);
    setNewItem({ ipRange: '', community: '' });
    setNewInvalid({ ipRange: false, community: false });
  };

  const handleEdit = (item) => {
    setEditingIp(item.ipRange);
    setEditingValue(item.community);
  };

  const handleSaveEdit = (ipRange) => {
    if (!isValidCommunity(editingValue)) {
      setError('Community должен быть числом.');
      return;
    }
    const updatedItems = items.map(i =>
      i.ipRange === ipRange ? { ...i, community: String(editingValue).trim() } : i
    );
    setItems(updatedItems);
    setEditingIp(null);
  };

  const handleCancelEdit = () => {
    setEditingIp(null);
  };

  const handleDeleteItem = (ipRangeToDelete) => {
    setItems(items.filter(i => i.ipRange !== ipRangeToDelete));
  };

  const confirmDelete = (item) => {
    setItemToDelete(item);
    setShowDeleteModal(true);
  };

  const executeDelete = () => {
    if (itemToDelete) {
      handleDeleteItem(itemToDelete.ipRange);
      setShowDeleteModal(false);
      setItemToDelete(null);
    }
  };

  const handleSaveChanges = async () => {
    setLoading(true);
    try {
      const valid = items.filter(i => isValidCidr(i.ipRange) && isValidCommunity(i.community));
      await axios.post(`${API_URL}/ip-ranges`, { ipRanges: valid });
      setSuccess('Изменения успешно сохранены!');
      setTimeout(() => setSuccess(''), 3000);
    } catch (error) {
      console.error('Error saving changes:', error);
      setError('Не удалось сохранить изменения.');
    } finally {
      setLoading(false);
    }
  };

  const handleImport = () => {
    const text = window.prompt('Вставьте строки: CIDR ПРОБЕЛ COMMUNITY (по одной записи на строку)');
    if (!text) return;
    const lines = text.split(/\r?\n/).map(l => l.trim()).filter(Boolean);
    const parsed = lines.map(l => {
      const [cidr, c] = l.split(/\s+/);
      return { ipRange: cidr || '', community: c || '' };
    });
    setItems(prev => [...prev, ...parsed]);
  };

  const handleExport = () => {
    const header = ['ipRange', 'community'];
    const csv = [header, ...items.map(i => [i.ipRange, i.community])]
      .map(r => r.map(x => `"${(x ?? '').toString().replace(/"/g, '""')}"`).join(','))
      .join('\n');
    const blob = new Blob([csv], { type: 'text/csv;charset=utf-8;' });
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = `ip_ranges_${new Date().toISOString().split('T')[0]}.csv`;
    a.click();
    URL.revokeObjectURL(url);
  };

  const clearInvalid = () => {
    setItems(prev => prev.filter(i => i.ipRange || i.community)
      .filter(i => isValidCidr(i.ipRange) && isValidCommunity(i.community))
    );
  };

  // Сортировка
  const sortedItems = [...items].sort((a, b) => {
    let valA = a[sortField] || '';
    let valB = b[sortField] || '';
    if (typeof valA === 'string') valA = valA.toLowerCase();
    if (typeof valB === 'string') valB = valB.toLowerCase();
    if (valA < valB) return sortOrder === 'asc' ? -1 : 1;
    if (valA > valB) return sortOrder === 'asc' ? 1 : -1;
    return 0;
  });

  // Фильтрация по community
  const filteredByCommunity = filterCommunity
    ? sortedItems.filter(i => i.community === filterCommunity)
    : sortedItems;

  // Поиск
  const filteredItems = filteredByCommunity.filter(i =>
    i.ipRange.toLowerCase().includes(searchTerm.toLowerCase())
  );

  // Пагинация
  const totalPages = Math.ceil(filteredItems.length / pageSize);
  const paginatedItems = filteredItems.slice((currentPage - 1) * pageSize, currentPage * pageSize);

  // Для фильтра - список всех уникальных community
  const allCommunities = Array.from(new Set(items.map(i => i.community)));

  // Сортировка по клику
  const handleSort = (field) => {
    if (sortField === field) {
      setSortOrder(sortOrder === 'asc' ? 'desc' : 'asc');
    } else {
      setSortField(field);
      setSortOrder('asc');
    }
  };

  // Улучшенный инлайн-редакт
  useEffect(() => {
    if (editingIp && editInputRef.current) {
      editInputRef.current.focus();
    }
  }, [editingIp]);

  const handleEditKeyDown = (e, ipRange) => {
    if (e.key === 'Enter') handleSaveEdit(ipRange);
    if (e.key === 'Escape') handleCancelEdit();
  };

  return (
    <>
      {error && (
        <div className="alert alert-danger alert-dismissible" role="alert">
          <div className="d-flex">
            <div>
              <IconX className="icon alert-icon" />
            </div>
            <div>
              {error}
            </div>
          </div>
          <button type="button" className="btn-close" onClick={() => setError('')}></button>
        </div>
      )}
      
      {success && (
        <div className="alert alert-success alert-dismissible" role="alert">
          <div className="d-flex">
            <div>
              <IconCheck className="icon alert-icon" />
            </div>
            <div>
              {success}
            </div>
          </div>
          <button type="button" className="btn-close" onClick={() => setSuccess('')}></button>
        </div>
      )}

      <div className="row">
        <div className="col-lg-3">
          {/* Add New Item Card */}
          <div className="card card-md">
            <div className="card-header">
              <h3 className="card-title">
                <IconPlus className="icon me-2" />
                Добавить новый IP-диапазон
              </h3>
            </div>
            <div className="card-body">
              <form onSubmit={(e) => { e.preventDefault(); handleAddItem(); }}>
                <div className="mb-3">
                  <label className="form-label">IP-диапазон</label>
                  <input
                    type="text"
                    className={`form-control${newInvalid.ipRange ? ' is-invalid' : ''}`}
                    placeholder="192.168.1.0/24"
                    value={newItem.ipRange}
                    onChange={(e) => setNewItem({ ...newItem, ipRange: e.target.value })}
                  />
                  {newInvalid.ipRange && <div className="invalid-feedback">Некорректный CIDR</div>}
                </div>
                <div className="mb-3">
                  <label className="form-label">Community</label>
                  <input
                    type="text"
                    className={`form-control${newInvalid.community ? ' is-invalid' : ''}`}
                    placeholder="65001:100"
                    value={newItem.community}
                    onChange={(e) => setNewItem({ ...newItem, community: e.target.value })}
                  />
                  {newInvalid.community && <div className="invalid-feedback">Только цифры</div>}
                </div>
                <div className="form-footer">
                  <button type="submit" className="btn btn-primary w-100">
                    <IconPlus className="icon me-2" />
                    Добавить
                  </button>
                </div>
              </form>
            </div>
          </div>

          {/* Actions Card */}
          <div className="card card-md">
            <div className="card-header">
              <h3 className="card-title">
                <IconDatabase className="icon me-2" />
                Действия
              </h3>
            </div>
            <div className="card-body">
              <div className="d-grid gap-2">
                <button 
                  className="btn btn-primary"
                  onClick={handleSaveChanges}
                  disabled={loading}
                >
                  {loading ? (
                    <>
                      <span className="spinner-border spinner-border-sm me-2" role="status"></span>
                      Сохранение...
                    </>
                  ) : (
                    <>
                      <IconDeviceFloppy className="icon me-2" />
                      Сохранить в S3
                    </>
                  )}
                </button>
                <button 
                  className="btn btn-outline-secondary"
                  onClick={fetchItems}
                  disabled={loading}
                >
                  <IconRefresh className="icon me-2" />
                  Обновить
                </button>
                <button 
                  className="btn btn-outline-primary"
                  onClick={handleImport}
                >
                  <IconUpload className="icon me-2" />
                  Импорт из буфера
                </button>
                <button 
                  className="btn btn-outline-primary"
                  onClick={handleExport}
                  disabled={items.length === 0}
                >
                  <IconDownload className="icon me-2" />
                  Экспорт CSV
                </button>
                <button 
                  className="btn btn-outline-secondary"
                  onClick={clearInvalid}
                  disabled={items.length === 0}
                >
                  Очистить пустые/невалидные
                </button>
              </div>
            </div>
          </div>
        </div>

        <div className="col-lg-9">
          <div className="card">
            <div className="card-header d-flex justify-content-between align-items-center">
              <h3 className="card-title mb-0">Список IP-диапазонов <span className="badge bg-blue-lt text-blue ms-2">{items.length}</span></h3>
              <div className="d-flex gap-2 w-50">
                {/* Фильтр по community */}
                <select className="form-select w-auto" value={filterCommunity} onChange={e => { setFilterCommunity(e.target.value); setCurrentPage(1); }}>
                  <option value="">Все community</option>
                  {allCommunities.map(community => (
                    <option key={community} value={community}>{community}</option>
                  ))}
                </select>
                {/* Поиск */}
                <div className="input-icon flex-grow-1">
                  <span className="input-icon-addon">
                    <IconSearch size={18} />
                  </span>
                  <input
                    type="text"
                    className="form-control"
                    placeholder="Поиск IP-диапазона..."
                    value={searchTerm}
                    onChange={e => { setSearchTerm(e.target.value); setCurrentPage(1); }}
                  />
                </div>
              </div>
            </div>
            <div className="table-responsive">
              <table className="table card-table table-vcenter table-nowrap mb-0">
                <thead>
                  <tr>
                    <th style={{cursor:'pointer'}} onClick={() => handleSort('ipRange')}>
                      IP-диапазон
                      {sortField === 'ipRange' && (
                        <span className="ms-1">
                          {sortOrder === 'asc' ? '▲' : '▼'}
                        </span>
                      )}
                    </th>
                    <th style={{cursor:'pointer'}} onClick={() => handleSort('community')}>
                      Community
                      {sortField === 'community' && (
                        <span className="ms-1">
                          {sortOrder === 'asc' ? '▲' : '▼'}
                        </span>
                      )}
                    </th>
                    <th className="text-end"> </th>
                  </tr>
                </thead>
                <tbody>
                  {paginatedItems.map((item) => (
                    <tr key={item.ipRange} className={editingIp === item.ipRange ? 'table-info' : ''}>
                      <td>{item.ipRange}</td>
                      <td><span className="badge bg-blue-lt text-blue">{item.community}</span></td>
                      <td className="text-end">
                        {editingIp === item.ipRange ? (
                          <>
                            <input
                              type="text"
                              className={`form-control d-inline-block w-auto me-2${isValidCommunity(editingValue) ? '' : ' is-invalid'}`}
                              value={editingValue}
                              ref={editInputRef}
                              onChange={e => setEditingValue(e.target.value)}
                              onKeyDown={e => handleEditKeyDown(e, item.ipRange)}
                              style={{maxWidth: 120}}
                            />
                            <button className="btn btn-success btn-icon me-1" onClick={() => handleSaveEdit(item.ipRange)} disabled={!isValidCommunity(editingValue)}><IconCheck size={18} /></button>
                            <button className="btn btn-secondary btn-icon" onClick={handleCancelEdit}><IconX size={18} /></button>
                          </>
                        ) : (
                          <>
                            <button className="btn btn-outline-primary btn-icon me-1" onClick={() => handleEdit(item)}><IconEdit size={18} /></button>
                            <button className="btn btn-outline-danger btn-icon" onClick={() => confirmDelete(item)}><IconTrash size={18} /></button>
                          </>
                        )}
                      </td>
                    </tr>
                  ))}
                </tbody>
              </table>
            </div>
            {/* Пагинация */}
            {totalPages > 1 && (
              <div className="card-footer d-flex align-items-center justify-content-between">
                <div className="text-muted">
                  Показано {((currentPage - 1) * pageSize) + 1} - {Math.min(currentPage * pageSize, filteredItems.length)} из {filteredItems.length}
                </div>
                <ul className="pagination m-0">
                  <li className={`page-item${currentPage === 1 ? ' disabled' : ''}`}>
                    <button className="page-link" onClick={() => setCurrentPage(1)} tabIndex={-1} disabled={currentPage === 1}>Первая</button>
                  </li>
                  <li className={`page-item${currentPage === 1 ? ' disabled' : ''}`}>
                    <button className="page-link" onClick={() => setCurrentPage(currentPage - 1)} tabIndex={-1} disabled={currentPage === 1}>Назад</button>
                  </li>
                  {(() => {
                    const pages = [];
                    const maxToShow = 7; // 1 .. 5 .. N
                    let start = Math.max(1, currentPage - 2);
                    let end = Math.min(totalPages, currentPage + 2);
                    if (currentPage <= 3) { end = Math.min(totalPages, 5); }
                    if (currentPage >= totalPages - 2) { start = Math.max(1, totalPages - 4); }
                    if (start > 1) pages.push('start-ellipsis');
                    for (let p = start; p <= end; p++) pages.push(p);
                    if (end < totalPages) pages.push('end-ellipsis');
                    const renderItem = (p) => {
                      if (p === 'start-ellipsis' || p === 'end-ellipsis') {
                        return (
                          <li key={p} className="page-item disabled"><span className="page-link">…</span></li>
                        );
                      }
                      return (
                        <li key={p} className={`page-item${currentPage === p ? ' active' : ''}`}>
                          <button className="page-link" onClick={() => setCurrentPage(p)}>{p}</button>
                        </li>
                      );
                    };
                    return pages.map(renderItem);
                  })()}
                  <li className={`page-item${currentPage === totalPages ? ' disabled' : ''}`}>
                    <button className="page-link" onClick={() => setCurrentPage(currentPage + 1)} tabIndex={-1} disabled={currentPage === totalPages}>Вперед</button>
                  </li>
                  <li className={`page-item${currentPage === totalPages ? ' disabled' : ''}`}>
                    <button className="page-link" onClick={() => setCurrentPage(totalPages)} tabIndex={-1} disabled={currentPage === totalPages}>Последняя</button>
                  </li>
                </ul>
              </div>
            )}
          </div>
        </div>
      </div>

      {/* Delete Confirmation Modal */}
      {showDeleteModal && (
        <div className="modal modal-blur fade show" style={{display: 'block'}} tabIndex="-1">
          <div className="modal-dialog modal-sm modal-dialog-centered" role="document">
            <div className="modal-content">
              <button 
                type="button" 
                className="btn-close" 
                onClick={() => setShowDeleteModal(false)}
              ></button>
              <div className="modal-status bg-danger"></div>
              <div className="modal-body text-center py-4">
                <IconTrash className="icon mb-2 text-danger icon-lg" />
                <h3>Удалить IP-диапазон?</h3>
                <div className="text-muted">
                  Вы уверены, что хотите удалить "{itemToDelete?.ipRange}"? Это действие необратимо.
                </div>
              </div>
              <div className="modal-footer">
                <div className="w-100">
                  <div className="row">
                    <div className="col">
                      <button 
                        className="btn w-100" 
                        onClick={() => setShowDeleteModal(false)}
                      >
                        Отмена
                      </button>
                    </div>
                    <div className="col">
                      <button 
                        className="btn btn-danger w-100" 
                        onClick={executeDelete}
                      >
                        Удалить
                      </button>
                    </div>
                  </div>
                </div>
              </div>
            </div>
          </div>
        </div>
      )}
    </>
  );
}

export default IPRangesManager;