/**
 * KundenKarte PWA - Mobile Schaltschrank-Dokumentation
 * Offline-First App für Elektriker
 */

(function() {
	'use strict';

	// ============================================
	// APP STATE
	// ============================================

	const App = {
		// Auth
		token: null,
		user: null,

		// Current selection
		customerId: null,
		customerName: '',
		anlageId: null,
		anlageName: '',

		// Data
		panels: [],
		carriers: [],
		equipment: [],
		equipmentTypes: [],

		// Offline queue
		offlineQueue: [],
		isOnline: navigator.onLine,

		// Current modal state
		currentCarrierId: null,
		selectedTypeId: null,
	};

	// ============================================
	// INIT
	// ============================================

	function init() {
		// Register Service Worker
		if ('serviceWorker' in navigator) {
			navigator.serviceWorker.register('sw.js')
				.then(reg => console.log('[PWA] Service Worker registered'))
				.catch(err => console.error('[PWA] SW registration failed:', err));
		}

		// Check online status
		window.addEventListener('online', () => {
			App.isOnline = true;
			hideOfflineBar();
			syncOfflineChanges();
		});

		window.addEventListener('offline', () => {
			App.isOnline = false;
			showOfflineBar();
		});

		// Check stored auth
		const storedToken = localStorage.getItem('kundenkarte_pwa_token');
		const storedUser = localStorage.getItem('kundenkarte_pwa_user');
		if (storedToken && storedUser) {
			App.token = storedToken;
			App.user = JSON.parse(storedUser);
			showScreen('search');
		}

		// Load offline queue
		const storedQueue = localStorage.getItem('kundenkarte_offline_queue');
		if (storedQueue) {
			App.offlineQueue = JSON.parse(storedQueue);
			updateSyncBadge();
		}

		// Bind events
		bindEvents();
	}

	// ============================================
	// EVENTS
	// ============================================

	function bindEvents() {
		// Login
		$('#login-form').on('submit', handleLogin);
		$('#btn-logout').on('click', handleLogout);

		// Navigation
		$('#btn-back-search').on('click', () => showScreen('search'));
		$('#btn-back-anlagen').on('click', () => showScreen('anlagen'));

		// Search
		$('#search-customer').on('input', debounce(handleSearch, 300));

		// Customer/Anlage selection
		$('#customer-list').on('click', '.list-item', handleCustomerSelect);
		$('#anlagen-list').on('click', '.anlage-card', handleAnlageSelect);

		// Editor actions
		$('#btn-add-panel').on('click', () => openModal('add-panel'));
		$('#btn-save-panel').on('click', handleSavePanel);

		$('#editor-content').on('click', '.btn-add-carrier', handleAddCarrier);
		$('#btn-save-carrier').on('click', handleSaveCarrier);

		$('#editor-content').on('click', '.btn-add-equipment', handleAddEquipment);
		$('#editor-content').on('click', '.equipment-block', handleEquipmentClick);

		// Equipment modal
		$('#type-grid').on('click', '.type-btn', handleTypeSelect);
		$('#btn-save-equipment').on('click', handleSaveEquipment);
		$('#btn-cancel-equipment').on('click', () => closeModal('add-equipment'));

		// TE buttons
		$('.te-btn').on('click', function() {
			$('.te-btn').removeClass('selected');
			$(this).addClass('selected');
		});

		// Modal close
		$('.modal-close').on('click', function() {
			$(this).closest('.modal').removeClass('active');
		});

		// Sync button
		$('#btn-sync').on('click', syncOfflineChanges);
	}

	// ============================================
	// AUTH
	// ============================================

	async function handleLogin(e) {
		e.preventDefault();
		const user = $('#login-user').val().trim();
		const pass = $('#login-pass').val();

		if (!user || !pass) {
			$('#login-error').text('Bitte Benutzername und Passwort eingeben');
			return;
		}

		$('#login-error').text('');

		try {
			const response = await apiCall('pwa_auth.php', {
				action: 'login',
				username: user,
				password: pass
			});

			if (response.success) {
				App.token = response.token;
				App.user = response.user;
				localStorage.setItem('kundenkarte_pwa_token', response.token);
				localStorage.setItem('kundenkarte_pwa_user', JSON.stringify(response.user));
				showScreen('search');
			} else {
				$('#login-error').text(response.error || 'Login fehlgeschlagen');
			}
		} catch (err) {
			$('#login-error').text('Verbindungsfehler');
		}
	}

	function handleLogout() {
		App.token = null;
		App.user = null;
		localStorage.removeItem('kundenkarte_pwa_token');
		localStorage.removeItem('kundenkarte_pwa_user');
		showScreen('login');
	}

	// ============================================
	// SCREENS
	// ============================================

	function showScreen(name) {
		$('.screen').removeClass('active');
		$('#screen-' + name).addClass('active');

		// Load data if needed
		if (name === 'search') {
			$('#search-customer').val('').focus();
			$('#customer-list').html('<div class="list-empty">Suchbegriff eingeben...</div>');
		}
	}

	// ============================================
	// CUSTOMER SEARCH
	// ============================================

	async function handleSearch() {
		const query = $('#search-customer').val().trim();
		if (query.length < 2) {
			$('#customer-list').html('<div class="list-empty">Mindestens 2 Zeichen eingeben...</div>');
			return;
		}

		$('#customer-list').html('<div class="loading-container"><div class="spinner"></div></div>');

		try {
			const response = await apiCall('ajax/pwa_api.php', {
				action: 'search_customers',
				query: query
			});

			if (response.success && response.customers) {
				renderCustomerList(response.customers);
			} else {
				$('#customer-list').html('<div class="list-empty">Keine Kunden gefunden</div>');
			}
		} catch (err) {
			$('#customer-list').html('<div class="list-empty">Fehler bei der Suche</div>');
		}
	}

	function renderCustomerList(customers) {
		if (!customers.length) {
			$('#customer-list').html('<div class="list-empty">Keine Kunden gefunden</div>');
			return;
		}

		let html = '';
		customers.forEach(c => {
			html += `
				<div class="list-item" data-id="${c.id}">
					<div class="list-item-icon">
						<svg viewBox="0 0 24 24"><path d="M12 7V3H2v18h20V7H12zM6 19H4v-2h2v2zm0-4H4v-2h2v2zm0-4H4V9h2v2zm0-4H4V5h2v2zm4 12H8v-2h2v2zm0-4H8v-2h2v2zm0-4H8V9h2v2zm0-4H8V5h2v2zm10 12h-8v-2h2v-2h-2v-2h2v-2h-2V9h8v10zm-2-8h-2v2h2v-2zm0 4h-2v2h2v-2z"/></svg>
					</div>
					<div class="list-item-content">
						<div class="list-item-title">${escapeHtml(c.name)}</div>
						<div class="list-item-subtitle">${escapeHtml(c.town || '')}</div>
					</div>
					<svg class="list-item-arrow" viewBox="0 0 24 24"><path d="M10 6L8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"/></svg>
				</div>
			`;
		});

		$('#customer-list').html(html);
	}

	// ============================================
	// CUSTOMER & ANLAGE SELECTION
	// ============================================

	async function handleCustomerSelect() {
		const id = $(this).data('id');
		const name = $(this).find('.list-item-title').text();

		App.customerId = id;
		App.customerName = name;
		$('#customer-name').text(name);

		showScreen('anlagen');
		$('#anlagen-list').html('<div class="loading-container"><div class="spinner"></div></div>');

		try {
			const response = await apiCall('ajax/pwa_api.php', {
				action: 'get_anlagen',
				customer_id: id
			});

			if (response.success && response.anlagen) {
				renderAnlagenList(response.anlagen);
				// Cache for offline
				localStorage.setItem('kundenkarte_anlagen_' + id, JSON.stringify(response.anlagen));
			} else {
				$('#anlagen-list').html('<div class="list-empty">Keine Anlagen gefunden</div>');
			}
		} catch (err) {
			// Try cached
			const cached = localStorage.getItem('kundenkarte_anlagen_' + id);
			if (cached) {
				renderAnlagenList(JSON.parse(cached));
				showToast('Offline - Zeige gecachte Daten', 'warning');
			} else {
				$('#anlagen-list').html('<div class="list-empty">Fehler beim Laden</div>');
			}
		}
	}

	function renderAnlagenList(anlagen) {
		// Filter nur Anlagen mit Editor
		const withEditor = anlagen.filter(a => a.has_editor);

		if (!withEditor.length) {
			$('#anlagen-list').html('<div class="list-empty">Keine Anlagen mit Schaltplan-Editor</div>');
			return;
		}

		let html = '';
		withEditor.forEach(a => {
			html += `
				<div class="anlage-card" data-id="${a.id}">
					<div class="anlage-card-icon">
						<svg viewBox="0 0 24 24"><path d="M21 3H3c-1.1 0-2 .9-2 2v14c0 1.1.9 2 2 2h18c1.1 0 2-.9 2-2V5c0-1.1-.9-2-2-2zm0 16H3V5h18v14zM9 7H7v2h2V7zm0 4H7v2h2v-2zm0 4H7v2h2v-2zm8-8h-6v2h6V7zm0 4h-6v2h6v-2zm0 4h-6v2h6v-2z"/></svg>
					</div>
					<div class="anlage-card-title">${escapeHtml(a.label || 'Anlage ' + a.id)}</div>
				</div>
			`;
		});

		$('#anlagen-list').html(html);
	}

	async function handleAnlageSelect() {
		const id = $(this).data('id');
		const name = $(this).find('.anlage-card-title').text();

		App.anlageId = id;
		App.anlageName = name;
		$('#anlage-name').text(name);

		showScreen('editor');
		await loadEditorData();
	}

	// ============================================
	// EDITOR
	// ============================================

	async function loadEditorData() {
		$('#editor-content').html('<div class="loading-container"><div class="spinner"></div><div class="text-muted">Lade Daten...</div></div>');

		try {
			const response = await apiCall('ajax/pwa_api.php', {
				action: 'get_anlage_data',
				anlage_id: App.anlageId
			});

			if (response.success) {
				App.panels = response.panels || [];
				App.carriers = response.carriers || [];
				App.equipment = response.equipment || [];
				App.equipmentTypes = response.types || [];

				// Cache for offline
				localStorage.setItem('kundenkarte_data_' + App.anlageId, JSON.stringify({
					panels: App.panels,
					carriers: App.carriers,
					equipment: App.equipment,
					types: App.equipmentTypes
				}));

				renderEditor();
			}
		} catch (err) {
			// Try cached
			const cached = localStorage.getItem('kundenkarte_data_' + App.anlageId);
			if (cached) {
				const data = JSON.parse(cached);
				App.panels = data.panels || [];
				App.carriers = data.carriers || [];
				App.equipment = data.equipment || [];
				App.equipmentTypes = data.types || [];
				renderEditor();
				showToast('Offline - Zeige gecachte Daten', 'warning');
			} else {
				$('#editor-content').html('<div class="list-empty">Fehler beim Laden</div>');
			}
		}
	}

	function renderEditor() {
		if (!App.panels.length) {
			$('#editor-content').html('<div class="list-empty">Noch keine Felder angelegt.<br>Tippe auf "+ Feld" um zu beginnen.</div>');
			return;
		}

		let html = '';

		App.panels.forEach(panel => {
			const panelCarriers = App.carriers.filter(c => c.fk_panel == panel.id);

			html += `
				<div class="panel-card" data-panel-id="${panel.id}">
					<div class="panel-header">
						<div class="panel-title">${escapeHtml(panel.label || 'Feld ' + panel.id)}</div>
					</div>
					<div class="panel-body">
			`;

			panelCarriers.forEach(carrier => {
				const carrierEquipment = App.equipment.filter(e => e.fk_carrier == carrier.id);
				carrierEquipment.sort((a, b) => (a.position_te || 0) - (b.position_te || 0));

				html += `
					<div class="carrier-item" data-carrier-id="${carrier.id}">
						<div class="carrier-header">
							<span class="carrier-label">${escapeHtml(carrier.label || 'Hutschiene')}</span>
							<span class="carrier-te">${carrier.total_te || 12} TE</span>
						</div>
						<div class="carrier-body">
				`;

				carrierEquipment.forEach(eq => {
					const type = App.equipmentTypes.find(t => t.id == eq.fk_equipment_type);
					const typeLabel = type ? (type.label_short || type.ref) : '?';
					const fieldVals = eq.field_values ? (typeof eq.field_values === 'string' ? JSON.parse(eq.field_values) : eq.field_values) : {};
					const value = fieldVals.ampere ? fieldVals.ampere + 'A' : (fieldVals.characteristic || '');

					html += `
						<div class="equipment-block" data-equipment-id="${eq.id}" style="background:${type?.color || '#3498db'}">
							<div class="equipment-block-type">${escapeHtml(typeLabel)}</div>
							<div class="equipment-block-value">${escapeHtml(value)}</div>
							${eq.label ? '<div class="equipment-block-label">' + escapeHtml(eq.label) + '</div>' : ''}
						</div>
					`;
				});

				html += `
							<button class="btn-add-equipment" data-carrier-id="${carrier.id}">
								<svg viewBox="0 0 24 24"><path d="M19 13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z"/></svg>
							</button>
						</div>
					</div>
				`;
			});

			html += `
						<button class="btn-add-carrier" data-panel-id="${panel.id}">
							<svg viewBox="0 0 24 24"><path d="M19 13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z"/></svg>
							Hutschiene hinzufügen
						</button>
					</div>
				</div>
			`;
		});

		$('#editor-content').html(html);

		// Load type grid
		renderTypeGrid();
	}

	function renderTypeGrid() {
		let html = '';
		App.equipmentTypes.forEach(type => {
			html += `
				<button class="type-btn" data-type-id="${type.id}" data-width="${type.width_te || 1}">
					<div class="type-btn-icon" style="color:${type.color || '#3498db'}">⚡</div>
					<div class="type-btn-label">${escapeHtml(type.label_short || type.ref || type.label)}</div>
				</button>
			`;
		});
		$('#type-grid').html(html);
	}

	// ============================================
	// PANEL (FELD) ACTIONS
	// ============================================

	async function handleSavePanel() {
		const label = $('#panel-label').val().trim() || 'Feld ' + (App.panels.length + 1);

		const data = {
			action: 'create_panel',
			anlage_id: App.anlageId,
			label: label
		};

		closeModal('add-panel');
		$('#panel-label').val('');

		if (App.isOnline) {
			try {
				const response = await apiCall('ajax/pwa_api.php', data);
				if (response.success) {
					App.panels.push({ id: response.panel_id, label: label });
					renderEditor();
					showToast('Feld angelegt');
				}
			} catch (err) {
				queueOfflineAction(data);
			}
		} else {
			queueOfflineAction(data);
			// Optimistic UI
			App.panels.push({ id: 'temp_' + Date.now(), label: label });
			renderEditor();
			showToast('Feld wird synchronisiert...', 'warning');
		}
	}

	// ============================================
	// CARRIER (HUTSCHIENE) ACTIONS
	// ============================================

	function handleAddCarrier() {
		const panelId = $(this).data('panel-id');
		App.currentPanelId = panelId;
		$('.te-btn').removeClass('selected');
		$('#carrier-label').val('');
		openModal('add-carrier');
	}

	async function handleSaveCarrier() {
		const teBtn = $('.te-btn.selected');
		if (!teBtn.length) {
			showToast('Bitte Größe wählen', 'error');
			return;
		}

		const totalTe = parseInt(teBtn.data('te'));
		const label = $('#carrier-label').val().trim() || 'Hutschiene';

		const data = {
			action: 'create_carrier',
			panel_id: App.currentPanelId,
			total_te: totalTe,
			label: label
		};

		closeModal('add-carrier');

		if (App.isOnline) {
			try {
				const response = await apiCall('ajax/pwa_api.php', data);
				if (response.success) {
					App.carriers.push({
						id: response.carrier_id,
						fk_panel: App.currentPanelId,
						total_te: totalTe,
						label: label
					});
					renderEditor();
					showToast('Hutschiene angelegt');
				}
			} catch (err) {
				queueOfflineAction(data);
			}
		} else {
			queueOfflineAction(data);
			App.carriers.push({
				id: 'temp_' + Date.now(),
				fk_panel: App.currentPanelId,
				total_te: totalTe,
				label: label
			});
			renderEditor();
			showToast('Wird synchronisiert...', 'warning');
		}
	}

	// ============================================
	// EQUIPMENT (AUTOMAT) ACTIONS
	// ============================================

	function handleAddEquipment() {
		const carrierId = $(this).data('carrier-id');
		App.currentCarrierId = carrierId;
		App.selectedTypeId = null;

		// Reset modal
		$('.type-btn').removeClass('selected');
		$('#step-type').addClass('active');
		$('#step-values').removeClass('active');
		$('#equipment-label').val('');
		$('#value-fields').html('');

		openModal('add-equipment');
	}

	function handleTypeSelect() {
		$('.type-btn').removeClass('selected');
		$(this).addClass('selected');

		App.selectedTypeId = $(this).data('type-id');
		const type = App.equipmentTypes.find(t => t.id == App.selectedTypeId);

		// Show value step
		$('#step-type').removeClass('active');
		$('#step-values').addClass('active');

		// Build value fields based on type
		let html = '';

		// Quick select for common values
		if (type && (type.ref?.includes('LS') || type.label?.includes('Leitungsschutz'))) {
			html += '<p class="step-label">Kennlinie + Ampere:</p>';
			html += '<div class="value-quick">';
			['B6', 'B10', 'B13', 'B16', 'B20', 'B25', 'B32', 'C6', 'C10', 'C13', 'C16', 'C20', 'C25', 'C32'].forEach(v => {
				html += `<button type="button" class="value-chip" data-char="${v[0]}" data-amp="${v.slice(1)}">${v}</button>`;
			});
			html += '</div>';
		} else if (type && (type.ref?.includes('FI') || type.label?.includes('RCD'))) {
			html += '<p class="step-label">Ampere:</p>';
			html += '<div class="value-quick">';
			['25', '40', '63', '80'].forEach(v => {
				html += `<button type="button" class="value-chip" data-amp="${v}">${v}A</button>`;
			});
			html += '</div>';
			html += '<p class="step-label" style="margin-top:12px;">Empfindlichkeit:</p>';
			html += '<div class="value-quick">';
			['30', '100', '300'].forEach(v => {
				html += `<button type="button" class="value-chip chip-sens" data-sens="${v}">${v}mA</button>`;
			});
			html += '</div>';
		}

		$('#value-fields').html(html);

		// Bind chip clicks
		$('#value-fields .value-chip').on('click', function() {
			if ($(this).hasClass('chip-sens')) {
				$('.chip-sens').removeClass('selected');
			} else {
				$('.value-chip:not(.chip-sens)').removeClass('selected');
			}
			$(this).addClass('selected');
		});
	}

	async function handleSaveEquipment() {
		if (!App.selectedTypeId) {
			showToast('Bitte Typ wählen', 'error');
			return;
		}

		const type = App.equipmentTypes.find(t => t.id == App.selectedTypeId);
		const label = $('#equipment-label').val().trim();

		// Collect field values
		const fieldValues = {};
		const selectedChip = $('.value-chip.selected:not(.chip-sens)');
		const selectedSens = $('.chip-sens.selected');

		if (selectedChip.length) {
			if (selectedChip.data('char')) fieldValues.characteristic = selectedChip.data('char');
			if (selectedChip.data('amp')) fieldValues.ampere = selectedChip.data('amp');
		}
		if (selectedSens.length) {
			fieldValues.sensitivity = selectedSens.data('sens');
		}

		// Calculate position
		const carrierEquipment = App.equipment.filter(e => e.fk_carrier == App.currentCarrierId);
		let nextPos = 1;
		carrierEquipment.forEach(e => {
			const endPos = (parseInt(e.position_te) || 1) + (parseInt(e.width_te) || 1);
			if (endPos > nextPos) nextPos = endPos;
		});

		const data = {
			action: 'create_equipment',
			carrier_id: App.currentCarrierId,
			type_id: App.selectedTypeId,
			label: label,
			position_te: nextPos,
			field_values: JSON.stringify(fieldValues)
		};

		closeModal('add-equipment');

		if (App.isOnline) {
			try {
				const response = await apiCall('ajax/pwa_api.php', data);
				if (response.success) {
					App.equipment.push({
						id: response.equipment_id,
						fk_carrier: App.currentCarrierId,
						fk_equipment_type: App.selectedTypeId,
						label: label,
						position_te: nextPos,
						width_te: type?.width_te || 1,
						field_values: fieldValues
					});
					renderEditor();
					showToast('Automat angelegt');
				}
			} catch (err) {
				queueOfflineAction(data);
			}
		} else {
			queueOfflineAction(data);
			App.equipment.push({
				id: 'temp_' + Date.now(),
				fk_carrier: App.currentCarrierId,
				fk_equipment_type: App.selectedTypeId,
				label: label,
				position_te: nextPos,
				width_te: type?.width_te || 1,
				field_values: fieldValues
			});
			renderEditor();
			showToast('Wird synchronisiert...', 'warning');
		}
	}

	function handleEquipmentClick() {
		const eqId = $(this).data('equipment-id');
		// TODO: Edit/Delete popup
		showToast('Bearbeiten kommt noch...');
	}

	// ============================================
	// OFFLINE SYNC
	// ============================================

	function queueOfflineAction(data) {
		data._timestamp = Date.now();
		App.offlineQueue.push(data);
		localStorage.setItem('kundenkarte_offline_queue', JSON.stringify(App.offlineQueue));
		updateSyncBadge();
	}

	function updateSyncBadge() {
		const count = App.offlineQueue.length;
		const $badge = $('#sync-badge');
		if (count > 0) {
			$badge.text(count).removeClass('hidden');
		} else {
			$badge.addClass('hidden');
		}
	}

	async function syncOfflineChanges() {
		if (!App.offlineQueue.length) {
			showToast('Alles synchronisiert');
			return;
		}

		if (!App.isOnline) {
			showToast('Offline - Sync nicht möglich', 'error');
			return;
		}

		showToast('Synchronisiere...');

		const queue = [...App.offlineQueue];
		let successCount = 0;

		for (const data of queue) {
			try {
				const response = await apiCall('ajax/pwa_api.php', data);
				if (response.success) {
					successCount++;
					// Remove from queue
					const idx = App.offlineQueue.findIndex(q => q._timestamp === data._timestamp);
					if (idx > -1) App.offlineQueue.splice(idx, 1);
				}
			} catch (err) {
				console.error('Sync failed for:', data, err);
			}
		}

		localStorage.setItem('kundenkarte_offline_queue', JSON.stringify(App.offlineQueue));
		updateSyncBadge();

		if (successCount === queue.length) {
			showToast('Alle Änderungen synchronisiert', 'success');
			// Reload data
			loadEditorData();
		} else {
			showToast(`${successCount}/${queue.length} synchronisiert`, 'warning');
		}
	}

	// ============================================
	// API HELPER
	// ============================================

	async function apiCall(endpoint, data = {}) {
		const url = window.MODULE_URL + '/' + endpoint;

		// Add token
		if (App.token) {
			data.token = App.token;
		}

		const response = await fetch(url, {
			method: 'POST',
			headers: {
				'Content-Type': 'application/x-www-form-urlencoded',
			},
			body: new URLSearchParams(data)
		});

		if (!response.ok) {
			throw new Error('Network error');
		}

		return response.json();
	}

	// ============================================
	// UI HELPERS
	// ============================================

	function openModal(name) {
		$('#modal-' + name).addClass('active');
	}

	function closeModal(name) {
		$('#modal-' + name).removeClass('active');
	}

	function showToast(message, type = '') {
		const $toast = $('#toast');
		$toast.text(message).removeClass('success error warning visible').addClass(type);
		setTimeout(() => $toast.addClass('visible'), 10);
		setTimeout(() => $toast.removeClass('visible'), 3000);
	}

	function showOfflineBar() {
		$('#offline-indicator').removeClass('hidden');
	}

	function hideOfflineBar() {
		$('#offline-indicator').addClass('hidden');
	}

	function escapeHtml(text) {
		if (!text) return '';
		const div = document.createElement('div');
		div.textContent = text;
		return div.innerHTML;
	}

	function debounce(func, wait) {
		let timeout;
		return function(...args) {
			clearTimeout(timeout);
			timeout = setTimeout(() => func.apply(this, args), wait);
		};
	}

	// jQuery shorthand
	function $(selector) {
		if (typeof selector === 'string') {
			const elements = document.querySelectorAll(selector);
			return new ElementCollection(elements);
		}
		return new ElementCollection([selector]);
	}

	class ElementCollection {
		constructor(elements) {
			this.elements = Array.from(elements);
			this.length = this.elements.length;
		}

		on(event, selectorOrHandler, handler) {
			if (typeof selectorOrHandler === 'function') {
				// Direct event
				this.elements.forEach(el => el.addEventListener(event, selectorOrHandler));
			} else {
				// Delegated event
				this.elements.forEach(el => {
					el.addEventListener(event, function(e) {
						const target = e.target.closest(selectorOrHandler);
						if (target && el.contains(target)) {
							handler.call(target, e);
						}
					});
				});
			}
			return this;
		}

		addClass(className) {
			this.elements.forEach(el => el.classList.add(className));
			return this;
		}

		removeClass(className) {
			this.elements.forEach(el => el.classList.remove(className));
			return this;
		}

		hasClass(className) {
			return this.elements[0]?.classList.contains(className);
		}

		html(content) {
			if (content === undefined) {
				return this.elements[0]?.innerHTML;
			}
			this.elements.forEach(el => el.innerHTML = content);
			return this;
		}

		text(content) {
			if (content === undefined) {
				return this.elements[0]?.textContent;
			}
			this.elements.forEach(el => el.textContent = content);
			return this;
		}

		val(value) {
			if (value === undefined) {
				return this.elements[0]?.value;
			}
			this.elements.forEach(el => el.value = value);
			return this;
		}

		data(key) {
			return this.elements[0]?.dataset[key];
		}

		find(selector) {
			const found = [];
			this.elements.forEach(el => {
				found.push(...el.querySelectorAll(selector));
			});
			return new ElementCollection(found);
		}

		closest(selector) {
			return new ElementCollection([this.elements[0]?.closest(selector)].filter(Boolean));
		}

		focus() {
			this.elements[0]?.focus();
			return this;
		}
	}

	// ============================================
	// START
	// ============================================

	document.addEventListener('DOMContentLoaded', init);

})();