fix: confirm email changes and enforce clean backend build

backend/src/Socialize.Api/Modules/CalendarIntegrations/Services/IcsCalendarParser.cs

@@ -1,4 +1,5 @@
 using System.Globalization;
+using System.Text;
 
 namespace Socialize.Api.Modules.CalendarIntegrations.Services;
 
@@ -39,9 +40,9 @@ internal sealed record IcsRawEvent(
     string? SourceUrl,
     DateTimeOffset? LastModifiedAt);
 
-internal sealed class IcsCalendarParser
+internal static class IcsCalendarParser
 {
-    public IReadOnlyCollection<ParsedCalendarEvent> Parse(
+    public static IReadOnlyCollection<ParsedCalendarEvent> Parse(
         string content,
         DateOnly rangeStart,
         DateOnly rangeEnd)
@@ -63,10 +64,12 @@ internal sealed class IcsCalendarParser
     private static IEnumerable<IcsRawEvent> ReadRawEvents(string content)
     {
         List<string> lines = UnfoldLines(content).ToList();
-        for (int index = 0; index < lines.Count; index++)
+        int index = 0;
+        while (index < lines.Count)
         {
             if (!lines[index].Equals("BEGIN:VEVENT", StringComparison.OrdinalIgnoreCase))
             {
+                index++;
                 continue;
             }
 
@@ -74,9 +77,10 @@ internal sealed class IcsCalendarParser
                 new(StringComparer.OrdinalIgnoreCase);
 
             index++;
-            for (; index < lines.Count && !lines[index].Equals("END:VEVENT", StringComparison.OrdinalIgnoreCase); index++)
+            while (index < lines.Count && !lines[index].Equals("END:VEVENT", StringComparison.OrdinalIgnoreCase))
             {
                 ParseProperty(lines[index], properties);
+                index++;
             }
 
             if (!TryGetFirst(properties, "DTSTART", out var startProperty))
@@ -105,32 +109,34 @@ internal sealed class IcsCalendarParser
                 TryGetFirst(properties, "LAST-MODIFIED", out var lastModified)
                     ? ParseDateTimeValue(lastModified.Value, lastModified.Parameters).UtcDateTime
                     : null);
+
+            index++;
         }
     }
 
     private static IEnumerable<string> UnfoldLines(string content)
     {
-        string? current = null;
+        StringBuilder? current = null;
         using StringReader reader = new(content.Replace("\r\n", "\n", StringComparison.Ordinal).Replace('\r', '\n'));
         while (reader.ReadLine() is { } line)
         {
             if ((line.StartsWith(' ') || line.StartsWith('\t')) && current is not null)
             {
-                current += line[1..];
+                current.Append(line[1..]);
                 continue;
             }
 
             if (current is not null)
             {
-                yield return current;
+                yield return current.ToString();
             }
 
-            current = line;
+            current = new StringBuilder(line);
         }
 
         if (current is not null)
         {
-            yield return current;
+            yield return current.ToString();
         }
     }
 
@@ -309,7 +315,7 @@ internal sealed class IcsCalendarParser
         return TimeSpan.Zero;
     }
 
-    private static IReadOnlyCollection<DateOnly> ExpandStartDates(
+    private static List<DateOnly> ExpandStartDates(
         IcsRawEvent rawEvent,
         DateOnly rangeStart,
         DateOnly rangeEnd)