add classes

Administration.cs

@@ -0,0 +1,10 @@
+namespace Bücherwurm
+{
+    class Administration
+    {
+        
+        public Administration()
+        {
+        }
+    }
+}

Book.cs

@@ -0,0 +1,38 @@
+namespace Bücherwurm
+{
+    class Book
+    {
+        public int BookId {get;}
+
+        public string Title {get; set;}
+
+        public string Author {get; set;}
+
+        public string Country {get; set;}
+
+        public string ImageLink {get; set;}
+
+        public string Link {get; set;}
+
+        public string Language {get; set;}
+
+        public int Pages {get; set;}
+
+        public int Year {get; set;}
+
+        public Book(int Id, string Title, string Author,
+            string Country, string ILink, string Link, string Language,
+            int Pages, int Year)
+        {
+            BookId = Id;
+            this.Title = Title;
+            this.Author = Author;
+            this.Country = Country;
+            ImageLink = ILink;
+            this.Link = Link;
+            this.Language = Language;
+            this.Pages = Pages;
+            this.Year = Year;
+        }
+    }
+}

Item.cs

@@ -0,0 +1,18 @@
+namespace Bücherwurm
+{
+    partial class Item
+    {
+        public int ItemId {get;}
+
+        public int BookId {get;}
+
+        public StatusEnum Status {get; set;}
+
+        public Item(int Id, int BookId)
+        {
+            ItemId = Id;
+            this.BookId = BookId;
+            Status = StatusEnum.Available;
+        }
+    }
+}

Lending.cs

@@ -0,0 +1,23 @@
+using System;
+
+namespace Bücherwurm
+{
+    class Lending
+    {
+        public int LendId {get;}
+
+        public int[] LendItems {get; set;}
+
+        public DateTime ReturnDate {get;}
+
+        public string Customer {get; }
+
+        public Lending(int Id, int[] Items, string Customer)
+        {
+            LendId = Id;
+            LendItems = Items;
+            ReturnDate = DateTime.Now.AddDays(30);
+            this.Customer = Customer;
+        }
+    }
+}

StatusEnum.cs

@@ -0,0 +1,11 @@
+namespace Bücherwurm
+{
+    partial class Item
+    {
+        public enum StatusEnum
+        {
+            Available,
+            Lended
+        }
+    }
+}