From 0e4a99332b3b03991cd0c5f90fc36f4dfe62d158 Mon Sep 17 00:00:00 2001
From: Thorsten Sommer <mail@tsommer.org>
Date: Mon, 18 Jul 2022 21:32:39 +0200
Subject: [PATCH] Fixes #29 by generating valid keys

---
 I18N Commander/Processor/SectionProcessor.cs  | 17 ++-----
 .../Processor/TextElementProcessor.cs         | 15 +-----
 I18N Commander/Processor/Utils.cs             | 49 +++++++++++++++++++
 3 files changed, 54 insertions(+), 27 deletions(-)
 create mode 100644 I18N Commander/Processor/Utils.cs

diff --git a/I18N Commander/Processor/SectionProcessor.cs b/I18N Commander/Processor/SectionProcessor.cs
index 7b291b7..f66275b 100644
--- a/I18N Commander/Processor/SectionProcessor.cs	
+++ b/I18N Commander/Processor/SectionProcessor.cs	
@@ -42,21 +42,10 @@ public static class SectionProcessor
     public static async Task<ProcessorResult<Section>> AddSection(string text, string? parentKey)
     {
         await using var db = ProcessorMeta.ServiceProvider.GetRequiredService<DataContext>();
-        
-        // Remove any whitespaces from the section name, regardless of how many e.g. spaces the user typed:
-        var key = string.Join('_', text.Split(' ', StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries)).ToUpperInvariant();
-        
-        // Check, if this key already exists:
-        if (await db.Sections.AnyAsync(n => n.DataKey == key))
-        {
-            var rng = new Random();
-            while (await db.Sections.AnyAsync(n => n.DataKey == key))
-            {
-                // Add a random number to the end of the key:
-                key += $"_{rng.Next(1, 10_000)}";
-            }
-        }
 
+        // Generate the key:
+        var key = await Utils.GenerateCode(text, db.Sections, (n, key) => n.DataKey == key);
+        
         // In the case, when the user adds a section to the root, handle the insert differently:
         if (string.IsNullOrWhiteSpace(parentKey))
         {
diff --git a/I18N Commander/Processor/TextElementProcessor.cs b/I18N Commander/Processor/TextElementProcessor.cs
index be918a9..c8e304b 100644
--- a/I18N Commander/Processor/TextElementProcessor.cs	
+++ b/I18N Commander/Processor/TextElementProcessor.cs	
@@ -23,20 +23,9 @@ public static class TextElementProcessor
         var currentSection = await db.Sections.FirstOrDefaultAsync(n => n.DataKey == currentSectionKey);
         if (currentSection is null)
             throw new ArgumentOutOfRangeException(nameof(currentSectionKey));
-
-        // Remove any whitespaces from the element name, regardless of how many e.g. spaces the user typed:
-        var code = string.Join('_', elementName.Split(' ', StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries)).ToUpperInvariant();
         
-        // Check, if this key already exists:
-        if (await db.TextElements.AnyAsync(n => n.Section == currentSection && n.Code == code))
-        {
-            var rng = new Random();
-            while (await db.TextElements.AnyAsync(n => n.Section == currentSection && n.Code == code))
-            {
-                // Add a random number to the end of the key:
-                code += $"_{rng.Next(1, 10_000)}";
-            }
-        }
+        // Generate a code:
+        var code = await Utils.GenerateCode(elementName, db.TextElements, (n, code) => n.Section == currentSection && n.Code == code);
         
         var textElement = new TextElement
         {
diff --git a/I18N Commander/Processor/Utils.cs b/I18N Commander/Processor/Utils.cs
new file mode 100644
index 0000000..9c19df2
--- /dev/null
+++ b/I18N Commander/Processor/Utils.cs	
@@ -0,0 +1,49 @@
+using System.Linq.Expressions;
+using Microsoft.EntityFrameworkCore;
+
+namespace Processor;
+
+internal static class Utils
+{
+    private static readonly Random RNG = new();
+
+    /// <summary>
+    /// Generates a code out of this name.
+    /// </summary>
+    /// <param name="name">The name where the code based on</param>
+    /// <param name="db">The data class</param>
+    /// <param name="selector">The selector to check, if that key already exists. The string parameter is the current code to check.</param>
+    /// <returns>The generated code</returns>
+    internal static async Task<string> GenerateCode<TDbSet>(string name, DbSet<TDbSet> db, Expression<Func<TDbSet, string, bool>> selector) where TDbSet : class
+    {
+        // Filter all non-alphanumeric characters from the name by allowing only A-Z, a-z, 0-9, and spaces from the ASCII table:
+        name = new string(name.Where(c => c is >= 'a' and <= 'z' or >= 'A' and <= 'Z' or >= '0' and <= '9' or ' ').ToArray());
+
+        // Remove any whitespaces from the element name, regardless of how many e.g. spaces the user typed:
+        var code = string.Join('_', name.Split(' ', StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries)).ToUpperInvariant();
+        
+        //
+        // The Any() query want's an Expression<T, bool>, but we have an Expression<T, string, bool>, though.
+        // Therefore, we have to currying the string away:
+        var typeDbSet = Expression.Parameter(typeof(TDbSet), null);
+        var curriedSelector = Expression.Lambda<Func<TDbSet, bool>>(
+            Expression.Invoke(selector, typeDbSet, Expression.Constant(code)),
+            typeDbSet
+        );
+        
+        // Check, if this key already exists. If so, add a random number to the end of the key:
+        if (await db.AnyAsync(curriedSelector))
+            while (await db.AnyAsync(curriedSelector))
+            {
+                code += $"_{RNG.Next(1, 10_000)}";
+                
+                // Due to the changed code & since the string is a constant, we have to re-currying the string away:
+                curriedSelector = Expression.Lambda<Func<TDbSet, bool>>(
+                    Expression.Invoke(selector, typeDbSet, Expression.Constant(code)),
+                    typeDbSet
+                );
+            }
+
+        return code;
+    }
+}
\ No newline at end of file