feat: Implement sortable project list with dynamic sorting functionality

src/app/projects/page.js

@@ -29,6 +29,10 @@ export default function ProjectListPage() {
 	});
 
 	const [customers, setCustomers] = useState([]);
+	const [sortConfig, setSortConfig] = useState({
+		key: 'finish_date',
+		direction: 'desc'
+	});
 	
 	// Load phoneOnly filter from localStorage after mount to avoid hydration issues
 	useEffect(() => {
@@ -125,8 +129,44 @@ export default function ProjectListPage() {
 			setSearchMatchType(null);
 		}
 
+		// Apply sorting
+		if (sortConfig.key) {
+			filtered = [...filtered].sort((a, b) => {
+				let aVal = a[sortConfig.key];
+				let bVal = b[sortConfig.key];
+				
+				// Handle null/undefined
+				if (!aVal && !bVal) return 0;
+				if (!aVal) return sortConfig.direction === 'asc' ? 1 : -1;
+				if (!bVal) return sortConfig.direction === 'asc' ? -1 : 1;
+				
+				// Handle dates
+				if (sortConfig.key === 'finish_date') {
+					aVal = new Date(aVal);
+					bVal = new Date(bVal);
+				}
+				// Handle numbers (project_number)
+				else if (sortConfig.key === 'project_number') {
+					// Extract numeric part if it's a string like "P-123" or "123"
+					const aNum = parseInt(String(aVal).replace(/\D/g, '')) || 0;
+					const bNum = parseInt(String(bVal).replace(/\D/g, '')) || 0;
+					aVal = aNum;
+					bVal = bNum;
+				}
+				// Handle strings
+				else if (typeof aVal === 'string') {
+					aVal = aVal.toLowerCase();
+					bVal = String(bVal).toLowerCase();
+				}
+				
+				if (aVal < bVal) return sortConfig.direction === 'asc' ? -1 : 1;
+				if (aVal > bVal) return sortConfig.direction === 'asc' ? 1 : -1;
+				return 0;
+			});
+		}
+
 		setFilteredProjects(filtered);
-	}, [searchTerm, projects, filters, session]);
+	}, [searchTerm, projects, filters, session, sortConfig]);
 
 	async function handleDelete(id) {
 		const confirmed = confirm(t('projects.deleteConfirm'));
@@ -171,6 +211,13 @@ export default function ProjectListPage() {
 		setSearchTerm('');
 	};
 
+	const handleSort = (key) => {
+		setSortConfig(prev => ({
+			key,
+			direction: prev.key === key && prev.direction === 'asc' ? 'desc' : 'asc'
+		}));
+	};
+
 	const handleExportExcel = async () => {
 		try {
 			const response = await fetch('/api/projects/export');
@@ -228,6 +275,42 @@ export default function ProjectListPage() {
 			default: return "-";
 		}
 	};
+
+	// Sortable header component
+	const SortableHeader = ({ columnKey, label, className = "" }) => {
+		const isSorted = sortConfig.key === columnKey;
+		const direction = isSorted ? sortConfig.direction : null;
+		
+		return (
+			<th 
+				className={`text-left px-2 py-3 font-semibold text-xs text-gray-700 dark:text-gray-300 cursor-pointer hover:bg-gray-200 dark:hover:bg-gray-600 transition-colors select-none ${className}`}
+				onClick={() => handleSort(columnKey)}
+				title={`Sort by ${label}`}
+			>
+				<div className="flex items-center gap-1">
+					<span>{label}</span>
+					<span className="text-gray-400 flex-shrink-0">
+						{!isSorted && (
+							<svg className="w-3 h-3 opacity-30" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+								<path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M7 16V4m0 0L3 8m4-4l4 4m6 0v12m0 0l4-4m-4 4l-4-4" />
+							</svg>
+						)}
+						{isSorted && direction === 'asc' && (
+							<svg className="w-3 h-3" fill="currentColor" viewBox="0 0 24 24">
+								<path d="M7 14l5-5 5 5H7z" />
+							</svg>
+						)}
+						{isSorted && direction === 'desc' && (
+							<svg className="w-3 h-3" fill="currentColor" viewBox="0 0 24 24">
+								<path d="M7 10l5 5 5-5H7z" />
+							</svg>
+						)}
+					</span>
+				</div>
+			</th>
+		);
+	};
+
 	return (
 		<PageContainer>
 			<PageHeader title={t('projects.title')} description={t('projects.subtitle')}>
@@ -606,9 +689,30 @@ export default function ProjectListPage() {
 
 							{/* Results and clear button row */}
 							<div className="flex items-center justify-between pt-2 border-t border-gray-100">
+								<div className="flex items-center gap-4">
 									<div className="text-sm text-gray-500">
 										{t('projects.showingResults', { shown: filteredProjects.length, total: projects.length }) || `Wyświetlono ${filteredProjects.length} z ${projects.length} projektów`}
 									</div>
+									{sortConfig.key && (
+										<div className="text-xs text-gray-500 flex items-center gap-1">
+											<span>•</span>
+											<span>Sortowanie:</span>
+											<span className="font-medium text-gray-700 dark:text-gray-300">
+												{sortConfig.key === 'project_number' && 'Nr.'}
+												{sortConfig.key === 'project_name' && t('projects.projectName')}
+												{sortConfig.key === 'address' && t('projects.address')}
+												{sortConfig.key === 'wp' && 'WP'}
+												{sortConfig.key === 'city' && t('projects.city')}
+												{sortConfig.key === 'plot' && t('projects.plot')}
+												{sortConfig.key === 'finish_date' && t('projects.finishDate')}
+												{sortConfig.key === 'project_type' && t('common.type')}
+												{sortConfig.key === 'project_status' && t('common.status')}
+												{sortConfig.key === 'assigned_to' && t('projects.assigned')}
+											</span>
+											<span>{sortConfig.direction === 'asc' ? '↑' : '↓'}</span>
+										</div>
+									)}
+								</div>
 								
 								{(filters.status !== 'all' || filters.type !== 'all' || filters.customer !== 'all' || filters.mine || searchTerm) && (
 									<Button 
@@ -699,36 +803,56 @@ export default function ProjectListPage() {
 						<table className="w-full min-w-[600px] table-fixed">
 							<thead>
 								<tr className="bg-gray-100 dark:bg-gray-700 border-b dark:border-gray-600">
-									<th className="text-left px-2 py-3 font-semibold text-xs text-gray-700 dark:text-gray-300 w-20 md:w-24">
-										Nr.
-									</th>
-									<th className="text-left px-2 py-3 font-semibold text-xs text-gray-700 dark:text-gray-300 w-[200px] md:w-[250px]">
-										{t('projects.projectName')}
-									</th>
-									<th className="text-left px-2 py-3 font-semibold text-xs text-gray-700 dark:text-gray-300 w-20 md:w-24 hidden lg:table-cell">
-										{t('projects.address')}
-									</th>
-									<th className="text-left px-2 py-3 font-semibold text-xs text-gray-700 dark:text-gray-300 w-16 md:w-20 hidden sm:table-cell">
-										WP
-									</th>
-									<th className="text-left px-2 py-3 font-semibold text-xs text-gray-700 dark:text-gray-300 w-14 md:w-16 hidden md:table-cell">
-										{t('projects.city')}
-									</th>
-									<th className="text-left px-2 py-3 font-semibold text-xs text-gray-700 dark:text-gray-300 w-14 md:w-16 hidden sm:table-cell">
-										{t('projects.plot')}
-									</th>
-									<th className="text-left px-2 py-3 font-semibold text-xs text-gray-700 dark:text-gray-300 w-18 md:w-20 hidden md:table-cell">
-										{t('projects.finishDate')}
-									</th>
-									<th className="text-left px-2 py-3 font-semibold text-xs text-gray-700 dark:text-gray-300 w-10">
-										{t('common.type') || 'Typ'}
-									</th>
-									<th className="text-left px-2 py-3 font-semibold text-xs text-gray-700 dark:text-gray-300 w-10">
-										{t('common.status') || 'Status'}
-									</th>
-									<th className="text-left px-2 py-3 font-semibold text-xs text-gray-700 dark:text-gray-300 w-14 md:w-16">
-										{t('projects.assigned') || 'Przypisany'}
-									</th>
+									<SortableHeader 
+										columnKey="project_number" 
+										label="Nr." 
+										className="w-20 md:w-24"
+									/>
+									<SortableHeader 
+										columnKey="project_name" 
+										label={t('projects.projectName')} 
+										className="w-[200px] md:w-[250px]"
+									/>
+									<SortableHeader 
+										columnKey="address" 
+										label={t('projects.address')} 
+										className="w-20 md:w-24 hidden lg:table-cell"
+									/>
+									<SortableHeader 
+										columnKey="wp" 
+										label="WP" 
+										className="w-16 md:w-20 hidden sm:table-cell"
+									/>
+									<SortableHeader 
+										columnKey="city" 
+										label={t('projects.city')} 
+										className="w-14 md:w-16 hidden md:table-cell"
+									/>
+									<SortableHeader 
+										columnKey="plot" 
+										label={t('projects.plot')} 
+										className="w-14 md:w-16 hidden sm:table-cell"
+									/>
+									<SortableHeader 
+										columnKey="finish_date" 
+										label={t('projects.finishDate')} 
+										className="w-18 md:w-20 hidden md:table-cell"
+									/>
+									<SortableHeader 
+										columnKey="project_type" 
+										label={t('common.type') || 'Typ'} 
+										className="w-10"
+									/>
+									<SortableHeader 
+										columnKey="project_status" 
+										label={t('common.status') || 'Status'} 
+										className="w-10"
+									/>
+									<SortableHeader 
+										columnKey="assigned_to" 
+										label={t('projects.assigned') || 'Przypisany'} 
+										className="w-14 md:w-16"
+									/>
 								</tr>
 							</thead>
 						<tbody>

src/lib/i18n.js

@@ -186,7 +186,7 @@ const translations = {
       plot: "Działka",
       district: "Jednostka ewidencyjna",
       unit: "Obręb",
-      finishDate: "Data zakończenia",
+      finishDate: "Termin zakończenia",
       type: "Typ",
       contact: "Kontakt",
       coordinates: "Współrzędne",
@@ -294,7 +294,7 @@ const translations = {
       customer: "Klient",
       investor: "Inwestor",
       dateSigned: "Data zawarcia",
-      finishDate: "Data zakończenia",
+      finishDate: "Termin zakończenia",
       searchPlaceholder: "Szukaj umów po numerze, nazwie, kliencie lub inwestorze...",
       noContracts: "Brak umów",
       noContractsMessage: "Rozpocznij od utworzenia swojej pierwszej umowy.",
@@ -325,7 +325,7 @@ const translations = {
       customer: "Klient",
       investor: "Inwestor",
       dateSigned: "Data zawarcia",
-      finishDate: "Data zakończenia",
+      finishDate: "Termin zakończenia",
       summary: "Podsumowanie",
       projectsCount: "Liczba projektów",
       projects: "projektów",
@@ -534,7 +534,7 @@ const translations = {
       dateCreated: "Data utworzenia",
       dateModified: "Data modyfikacji",
       startDate: "Data rozpoczęcia",
-      finishDate: "Data zakończenia"
+      finishDate: "Termin zakończenia"
     },
 
     // Date formats