chore: refactor for sonarqube issues

src/Strata.SqlTools.SqlBreakdown/Classes/SqlExpressionClause.cs

@@ -89,10 +89,7 @@ public class SqlExpressionClause : SqlClause, ISqlExpressionClause
     {
         var items = new List<string>();
         var current = new StringBuilder();
-        var parenDepth = 0;
-        var inSingleQuote = false;
-        var inDoubleQuote = false;
-        var inBracket = false;
+        var state = new SplitScanState();
 
         for (int i = 0; i < clause.Length; i++)
         {
@@ -106,39 +103,10 @@ public class SqlExpressionClause : SqlClause, ISqlExpressionClause
                 continue;
             }
 
-            // Toggle quote states
-            if (ch == '\'' && !inDoubleQuote && !inBracket)
-            {
-                inSingleQuote = !inSingleQuote;
-            }
-            else if (ch == '"' && !inSingleQuote && !inBracket)
-            {
-                inDoubleQuote = !inDoubleQuote;
-            }
-            else if (ch == '[' && !inSingleQuote && !inDoubleQuote)
-            {
-                inBracket = true;
-            }
-            else if (ch == ']' && inBracket && !inSingleQuote && !inDoubleQuote)
-            {
-                inBracket = false;
-            }
-
-            // Track parenthesis depth
-            if (!inSingleQuote && !inDoubleQuote && !inBracket)
-            {
-                if (ch == '(')
-                {
-                    parenDepth++;
-                }
-                else if (ch == ')')
-                {
-                    parenDepth--;
-                }
-            }
+            state.UpdateForCharacter(ch);
 
             // Split on comma only when not inside quotes, brackets, or parentheses
-            if (ch == ',' && !inSingleQuote && !inDoubleQuote && !inBracket && parenDepth == 0)
+            if (ch == ',' && !state.InsideDelimiter && state.ParenDepth == 0)
             {
                 items.Add(current.ToString());
                 current.Clear();
@@ -157,5 +125,55 @@ public class SqlExpressionClause : SqlClause, ISqlExpressionClause
 
         return items;
     }
+
+    /// <summary>
+    /// Tracks quote, bracket, and parenthesis nesting while scanning a clause character by character,
+    /// so the splitter knows when a comma is at the top level.
+    /// </summary>
+    private struct SplitScanState
+    {
+        public int ParenDepth;
+        public bool InSingleQuote;
+        public bool InDoubleQuote;
+        public bool InBracket;
+
+        /// <summary>Gets whether the scanner is currently inside a quoted string or bracketed identifier.</summary>
+        public readonly bool InsideDelimiter => InSingleQuote || InDoubleQuote || InBracket;
+
+        /// <summary>Updates the quote/bracket states and parenthesis depth for the given character.</summary>
+        public void UpdateForCharacter(char ch)
+        {
+            // Toggle quote/bracket states
+            if (ch == '\'' && !InDoubleQuote && !InBracket)
+            {
+                InSingleQuote = !InSingleQuote;
+            }
+            else if (ch == '"' && !InSingleQuote && !InBracket)
+            {
+                InDoubleQuote = !InDoubleQuote;
+            }
+            else if (ch == '[' && !InSingleQuote && !InDoubleQuote)
+            {
+                InBracket = true;
+            }
+            else if (ch == ']' && InBracket && !InSingleQuote && !InDoubleQuote)
+            {
+                InBracket = false;
+            }
+
+            // Track parenthesis depth only when outside quotes/brackets
+            if (!InsideDelimiter)
+            {
+                if (ch == '(')
+                {
+                    ParenDepth++;
+                }
+                else if (ch == ')')
+                {
+                    ParenDepth--;
+                }
+            }
+        }
+    }
 }
 

src/Strata.SqlTools.SqlBreakdown/Expressions/Literals/DateTimeLiteralExpression.cs

@@ -1,7 +1,5 @@
 using Strata.SqlTools.SqlBreakdown.Interfaces.Core;
 
-using Strata.SqlTools.SqlBreakdown.Interfaces.Core;
-
 namespace Strata.SqlTools.SqlBreakdown.Expressions.Literals;
 
 /// <summary>

src/Strata.SqlTools.SqlBreakdown/Extensions/StringExtensions.cs

@@ -48,7 +48,7 @@ public static class StringExtensions
 
         if (aCharCount < 0)
         {
-            throw new ArgumentException();
+            throw new ArgumentException("Character count cannot be negative.", nameof(aCharCount));
         }
 
         if (aCharCount == 0)
@@ -75,7 +75,7 @@ public static class StringExtensions
 
         if (aCharCount < 0)
         {
-            throw new ArgumentException();
+            throw new ArgumentException("Character count cannot be negative.", nameof(aCharCount));
         }
 
         if (aCharCount == 0)

src/Strata.SqlTools.SqlBreakdown/Utilities/SqlSchemaHelpers.cs

@@ -44,12 +44,6 @@ public static partial class SqlUtils
         try
         {
             // Would need to execute SQL here - skipping for this conversion
-            // var cmd = new StrataSimpleSQLRunner.SimpleSQLCommand("select * from sys.schemas where principal_id=1");
-            // var dt = StrataSimpleSQLRunner.ExecuteDatatable(cmd);
-            // foreach (DataRow row in dt.Rows)
-            // {
-            //     list.Add(row[0].ToString());
-            // }
 
             // Remove system schemas
             return list.Except(GetSystemSchemas()).ToList();