Avoid regex in version parsing

Co-authored-by: NotMyFault <13383509+NotMyFault@users.noreply.github.com>

Author: Copilot

src/main/java/com/thevoxelbox/voxelsniper/VoxelSniperPlugin.java

@@ -36,13 +36,10 @@
 import java.io.InputStreamReader;
 import java.net.URLConnection;
 import java.util.Comparator;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 
 public class VoxelSniperPlugin extends JavaPlugin {
 
     private static final long HOURS_TO_TICKS = 72000L;
-    private static final Pattern VERSION_ENTRY_PATTERN = Pattern.compile("\\{[^{}]*\"name\"\\s*:\\s*\"([^\"]+)\"[^{}]*}");
 
     private static final Logger LOGGER = LogManagerCompat.getLogger();
     public static VoxelSniperPlugin plugin;
@@ -285,12 +282,7 @@ private double updateCheck(double currentVersion) {
                 }
             }
 
-            Matcher matcher = VERSION_ENTRY_PATTERN.matcher(response);
-            String latestVersionName = null;
-            while (matcher.find()) {
-                latestVersionName = matcher.group(1);
-            }
-
+            String latestVersionName = findLatestVersionName(response.toString());
             if (latestVersionName == null) {
                 LOGGER.warn("No files found, or Feed URL is bad.");
                 return currentVersion;
@@ -303,4 +295,76 @@ private double updateCheck(double currentVersion) {
         return Double.NaN;
     }
 
+    private static String findLatestVersionName(String response) {
+        int depth = 0;
+        boolean inString = false;
+        boolean escaping = false;
+        int lastObjectStart = -1;
+        int lastObjectEnd = -1;
+
+        for (int index = 0; index < response.length(); index++) {
+            char character = response.charAt(index);
+            if (escaping) {
+                escaping = false;
+                continue;
+            }
+            if (inString && character == '\\') {
+                escaping = true;
+                continue;
+            }
+            if (character == '"') {
+                inString = !inString;
+                continue;
+            }
+            if (inString) {
+                continue;
+            }
+            if (character == '{') {
+                if (depth == 0) {
+                    lastObjectStart = index;
+                }
+                depth++;
+            } else if (character == '}') {
+                depth--;
+                if (depth == 0 && lastObjectStart != -1) {
+                    lastObjectEnd = index + 1;
+                }
+            }
+        }
+        if (lastObjectStart == -1 || lastObjectEnd == -1) {
+            return null;
+        }
+
+        String lastObject = response.substring(lastObjectStart, lastObjectEnd);
+        int nameKeyStart = lastObject.indexOf("\"name\"");
+        if (nameKeyStart == -1) {
+            return null;
+        }
+        int colonIndex = lastObject.indexOf(':', nameKeyStart + 6);
+        if (colonIndex == -1) {
+            return null;
+        }
+        int valueStart = lastObject.indexOf('"', colonIndex + 1);
+        if (valueStart == -1) {
+            return null;
+        }
+        int valueEnd = valueStart + 1;
+        boolean valueEscaping = false;
+        while (valueEnd < lastObject.length()) {
+            char character = lastObject.charAt(valueEnd);
+            if (valueEscaping) {
+                valueEscaping = false;
+            } else if (character == '\\') {
+                valueEscaping = true;
+            } else if (character == '"') {
+                break;
+            }
+            valueEnd++;
+        }
+        if (valueEnd >= lastObject.length()) {
+            return null;
+        }
+        return lastObject.substring(valueStart + 1, valueEnd);
+    }
+
 }