From 03cc959fbdc7d7b46f3714f335f36307076aa121 Mon Sep 17 00:00:00 2001
From: Frede Hundewadt <noreply@wonky.codeberg.org>
Date: Tue, 30 May 2023 10:04:53 +0200
Subject: [PATCH] added EAN13 validation

---
 Ean13Validator.cs          | 85 ++++++++++++++++++++++++++++++++++++++
 FCS.Lib.Utility.csproj     |  1 +
 Properties/AssemblyInfo.cs |  4 +-
 Squid.cs                   |  9 +---
 4 files changed, 90 insertions(+), 9 deletions(-)
 create mode 100644 Ean13Validator.cs

diff --git a/Ean13Validator.cs b/Ean13Validator.cs
new file mode 100644
index 0000000..46908ec
--- /dev/null
+++ b/Ean13Validator.cs
@@ -0,0 +1,85 @@
+// ***********************************************************************
+// Assembly         : FCS.Lib.Utility
+// Author           : inno
+// Created          : 2023 05 24 12:23
+// 
+// Last Modified By : inno
+// Last Modified On : 2023 05 24 12:23
+// ***********************************************************************
+// <copyright file="Ean13Validator.cs" company="FCS">
+//     Copyright (C) 2023-2023 FCS Frede's Computer Services.
+//     This program is free software: you can redistribute it and/or modify
+//     it under the terms of the GNU Affero General Public License as
+//     published by the Free Software Foundation, either version 3 of the
+//     License, or (at your option) any later version.
+// 
+//     This program is distributed in the hope that it will be useful,
+//     but WITHOUT ANY WARRANTY; without even the implied warranty of
+//     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//     GNU Affero General Public License for more details.
+// 
+//     You should have received a copy of the GNU Affero General Public License
+//     along with this program.  If not, see [https://www.gnu.org/licenses]
+// </copyright>
+// <summary></summary>
+// ***********************************************************************
+
+using System;
+
+namespace FCS.Lib.Utility;
+
+public class Ean13Validator
+{
+    private const int Size = 12;
+
+    public static bool Validate(string number)
+    {
+        if (number.Length != Size + 1)
+            return false;
+        return number == ParsedNumber(number.Substring(0, 12));
+    }
+    
+    private static string Ean13(int[]? firstDigits)
+    {
+        var summedProduct = 0;
+        var randomDigits = new Random();
+        bool isNull;
+        if (firstDigits == null)
+        {
+            firstDigits = new int[Size];
+            isNull = true;
+        }
+        else
+            isNull = false;
+        for (var idx = 0; idx < Size; idx++)
+        {
+            var alt = idx % 2 == 0 ? 1 : 3;
+            int digit;
+            if (isNull)
+            {
+                digit = randomDigits.Next(10);
+                firstDigits[idx] = digit;
+            }
+            else
+                digit = firstDigits[idx];
+            summedProduct += digit * alt;
+        }
+        var checkDigit = 10 - summedProduct % 10;
+        if (checkDigit == 10)
+            checkDigit = 0;
+        return string.Join("", firstDigits) + checkDigit;
+    }
+
+    private static string ParsedNumber(string number)
+    {
+        var firstDigits = new int[Size];
+        if (number.Length != Size | !long.TryParse(number, out _))
+            return null;
+        for (var idx = 0; idx < Size; idx++)
+        {
+            var digit = int.Parse(number[idx].ToString());
+            firstDigits[idx] = digit;
+        }
+        return Ean13(firstDigits);
+    }    
+}
\ No newline at end of file
diff --git a/FCS.Lib.Utility.csproj b/FCS.Lib.Utility.csproj
index b5c2bb4..81c21ad 100644
--- a/FCS.Lib.Utility.csproj
+++ b/FCS.Lib.Utility.csproj
@@ -52,6 +52,7 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Ean13Validator.cs" />
     <Compile Include="ExtensionsEx.cs" />
     <Compile Include="Generators.cs" />
     <Compile Include="GuidGenerator.cs" />
diff --git a/Properties/AssemblyInfo.cs b/Properties/AssemblyInfo.cs
index 7323968..2fb5514 100644
--- a/Properties/AssemblyInfo.cs
+++ b/Properties/AssemblyInfo.cs
@@ -17,5 +17,5 @@ using System.Runtime.InteropServices;
 [assembly: ComVisible(false)]
 [assembly: Guid("8D850197-78DB-4D16-A91F-E5BB6E8880A7")]
 
-[assembly: AssemblyVersion("1.0.23077.1334")]
-[assembly: AssemblyFileVersion("1.0.23077.1334")]
\ No newline at end of file
+[assembly: AssemblyVersion("1.0.23146.0802")]
+[assembly: AssemblyFileVersion("1.0.23146.0802")]
\ No newline at end of file
diff --git a/Squid.cs b/Squid.cs
index 1a46c3e..df9a8d6 100644
--- a/Squid.cs
+++ b/Squid.cs
@@ -40,14 +40,13 @@ public readonly struct Squid : IEquatable<Squid>
     /// <summary>
     ///     A read-only object of the Squid struct.
     ///     Value is guaranteed to be all zeroes.
-    ///     Equivalent to <see cref="Guid.Empty" />.
     /// </summary>
     public static readonly Squid Empty = new(Guid.Empty);
 
     /// <summary>
     ///     Creates a new Squid from a Squid encoded string.
     /// </summary>
-    /// <param name="value">A valid Squid encodd string.</param>
+    /// <param name="value">A valid Squid encoded string.</param>
     public Squid(string value)
     {
         Value = value;
@@ -68,9 +67,7 @@ public readonly struct Squid : IEquatable<Squid>
     ///     Gets the underlying <see cref="System.Guid" /> for the encoded Squid.
     /// </summary>
     /// <value>The unique identifier.</value>
-#pragma warning disable CA1720 // Identifier contains type name
     public Guid Guid { get; }
-#pragma warning restore CA1720 // Identifier contains type name
 
     /// <summary>
     ///     The encoded string value of the <see cref="Guid" />
@@ -92,7 +89,7 @@ public readonly struct Squid : IEquatable<Squid>
     ///     Returns a value indicating whether this object and a specified object represent the same type and value.
     ///     Compares for equality against other string, Guid and Squid types.
     /// </summary>
-    /// <param name="obj">A Systerm.String, System.Guid or Squid object</param>
+    /// <param name="obj">A System.String, System.Guid or Squid object</param>
     /// <returns><c>true</c> if the specified <see cref="object" /> is equal to this instance; otherwise, <c>false</c>.</returns>
     public override bool Equals(object obj)
     {
@@ -213,9 +210,7 @@ public readonly struct Squid : IEquatable<Squid>
             obj = DecodeSquid(value);
             return true;
         }
-#pragma warning disable CA1031 // Do not catch general exception types
         catch (Exception)
-#pragma warning restore CA1031 // Do not catch general exception types
         {
             // Return empty Guid
             obj = Guid.Empty;