add price policy

lib/features/price_policy/domain/entities/price_document.dart

@@ -0,0 +1,166 @@
+/// Domain Entity: Price Document
+///
+/// Pure business entity representing a price policy or price list document.
+/// This entity is framework-independent and contains only business logic.
+library;
+
+/// Price policy document entity
+class PriceDocument {
+  /// Unique document ID
+  final String id;
+
+  /// Document title
+  final String title;
+
+  /// Document description
+  final String description;
+
+  /// Date the document was published
+  final DateTime publishedDate;
+
+  /// Type of document (PDF or Excel)
+  final DocumentType documentType;
+
+  /// Category (policy or price list)
+  final DocumentCategory category;
+
+  /// URL to download the document
+  final String downloadUrl;
+
+  /// Optional file size display string
+  final String? fileSize;
+
+  /// Constructor
+  const PriceDocument({
+    required this.id,
+    required this.title,
+    required this.description,
+    required this.publishedDate,
+    required this.documentType,
+    required this.category,
+    required this.downloadUrl,
+    this.fileSize,
+  });
+
+  /// Check if document is a PDF
+  bool get isPdf => documentType == DocumentType.pdf;
+
+  /// Check if document is an Excel file
+  bool get isExcel => documentType == DocumentType.excel;
+
+  /// Check if document is a policy document
+  bool get isPolicy => category == DocumentCategory.policy;
+
+  /// Check if document is a price list
+  bool get isPriceList => category == DocumentCategory.priceList;
+
+  /// Get formatted published date (dd/MM/yyyy)
+  String get formattedDate {
+    return '${publishedDate.day.toString().padLeft(2, '0')}/'
+        '${publishedDate.month.toString().padLeft(2, '0')}/'
+        '${publishedDate.year}';
+  }
+
+  /// Get formatted date with prefix based on category
+  String get formattedDateWithPrefix {
+    final prefix = isPolicy ? 'Công bố' : 'Cập nhật';
+    return '$prefix: $formattedDate';
+  }
+
+  /// Get icon name based on document type
+  String get iconName => documentType == DocumentType.pdf ? 'PDF' : 'Excel';
+
+  /// Copy with method for immutability
+  PriceDocument copyWith({
+    String? id,
+    String? title,
+    String? description,
+    DateTime? publishedDate,
+    DocumentType? documentType,
+    DocumentCategory? category,
+    String? downloadUrl,
+    String? fileSize,
+  }) {
+    return PriceDocument(
+      id: id ?? this.id,
+      title: title ?? this.title,
+      description: description ?? this.description,
+      publishedDate: publishedDate ?? this.publishedDate,
+      documentType: documentType ?? this.documentType,
+      category: category ?? this.category,
+      downloadUrl: downloadUrl ?? this.downloadUrl,
+      fileSize: fileSize ?? this.fileSize,
+    );
+  }
+
+  /// Equality operator
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) return true;
+
+    return other is PriceDocument &&
+        other.id == id &&
+        other.title == title &&
+        other.description == description &&
+        other.publishedDate == publishedDate &&
+        other.documentType == documentType &&
+        other.category == category &&
+        other.downloadUrl == downloadUrl &&
+        other.fileSize == fileSize;
+  }
+
+  /// Hash code
+  @override
+  int get hashCode {
+    return Object.hash(
+      id,
+      title,
+      description,
+      publishedDate,
+      documentType,
+      category,
+      downloadUrl,
+      fileSize,
+    );
+  }
+
+  /// String representation
+  @override
+  String toString() {
+    return 'PriceDocument(id: $id, title: $title, description: $description, '
+        'publishedDate: $publishedDate, documentType: $documentType, '
+        'category: $category, downloadUrl: $downloadUrl, fileSize: $fileSize)';
+  }
+}
+
+/// Document type enum
+enum DocumentType { pdf, excel }
+
+/// Document category enum
+enum DocumentCategory {
+  policy, // Chính sách giá
+  priceList, // Bảng giá
+}
+
+// Extension for display
+extension DocumentTypeX on DocumentType {
+  String get displayName {
+    switch (this) {
+      case DocumentType.pdf:
+        return 'PDF';
+      case DocumentType.excel:
+        return 'Excel';
+    }
+  }
+}
+
+extension DocumentCategoryX on DocumentCategory {
+  String get displayName {
+    switch (this) {
+      case DocumentCategory.policy:
+        return 'Chính sách giá';
+      case DocumentCategory.priceList:
+        return 'Bảng giá';
+    }
+  }
+}