Check if JSON data still matches what's on the sign

BlockLocker uses hidden JSON data to store the UUIDs of players.

Now that Spigot leaves the hidden JSON data intact when updating a sign (see https://hub.spigotmc.org/stash/projects/SPIGOT/repos/craftbukkit/commits/560b65c4f8a15619aaa4a1737c7040f21e725cce#src/main/java/org/bukkit/craftbukkit/block/CraftSign.java ), this data has the potential to become outdated. For example, the /blocklocker <line number> command didn't update the player UUIDs stored on the sign, because the old UUIDs weren't removed anymore.

Now the JSON-data is cross-checked against the text on the sign. If the JSON data doesn't match the text, it is now ignored.

Fixes #92, #93.

src/main/java/nl/rutgerkok/blocklocker/impl/SignParserImpl.java

@@ -41,6 +41,16 @@ class SignParserImpl implements SignParser {
         this.chestSettings = chestSettings;
     }
 
+    private int countProfileLines(String[] linesOnSign) {
+        int count = 0;
+        for (int i = 1; i < linesOnSign.length; i++) {
+            if (linesOnSign[i].length() > 0) {
+                count++;
+            }
+        }
+        return count;
+    }
+
     @Override
     public Optional<SignType> getSignType(Sign sign) {
         String header = sign.getLine(0);
@@ -72,36 +82,54 @@ public boolean hasValidHeader(Sign sign) {
      *
      * @param location
      *            The location of the sign.
-     * @param header
-     *            The header on the sign.
-     * @param list
-     *            The profile collection to add all profiles to.
+     * @param jsonSign
+     *            The hidden JSON stored on the sign.
+     * @param linesOnSign
+     *            The displayed lines stored on the sign.
      * @return The parsed sign, if the sign is actually a protection sign.
      */
-    private Optional<ProtectionSign> parseAdvancedSign(Location location, String header, Iterable<JsonObject> list) {
-        SignType signType = getSignTypeOrNull(header);
+    private Optional<ProtectionSign> parseAdvancedSign(Location location, JsonSign jsonSign, String[] linesOnSign) {
+        SignType signType = getSignTypeOrNull(jsonSign.getFirstLine());
         if (signType == null) {
             return Optional.empty();
         }
 
-        List<Profile> profiles = new ArrayList<Profile>();
-        for (JsonObject object : list) {
-            Optional<Profile> profile = profileFactory.fromSavedObject(object);
-            if (profile.isPresent()) {
-                profiles.add(profile.get());
+        List<Profile> profiles = new ArrayList<>();
+        int lineNumber = 1; // Starts as one, as line 0 contains the sign header`
+        for (JsonObject object : jsonSign) {
+            Optional<Profile> oProfile = profileFactory.fromSavedObject(object);
+            if (oProfile.isPresent()) {
+                Profile profile = oProfile.get();
+
+                String lineOnSign = linesOnSign[lineNumber];
+                if (!profile.getDisplayName().equals(lineOnSign)) {
+                    // JSON data doesn't match sign contents, so it must be corrupt or outdated
+                    // Therefore, ignore the data
+                    return parseSimpleSign(location, linesOnSign);
+                }
+
+                profiles.add(profile);
             }
+            lineNumber++;
         }
 
-        return Optional.<ProtectionSign> of(new ProtectionSignImpl(location, signType, profiles));
+        if (countProfileLines(linesOnSign) > profiles.size()) {
+            // JSON data is incomplete, therefore corrupt or outdated
+            // Therefore, ignore the data
+            return parseSimpleSign(location, linesOnSign);
+        }
+
+        return Optional.<ProtectionSign>of(new ProtectionSignImpl(location, signType, profiles));
     }
 
     @Override
     public Optional<ProtectionSign> parseSign(Block sign) {
         JsonSign foundTextData = nms.getJsonData(sign.getWorld(), sign.getX(), sign.getY(), sign.getZ());
+        String[] lines = ((Sign) sign.getState()).getLines();
         if (foundTextData.hasData()) {
-            return parseAdvancedSign(sign.getLocation(), foundTextData.getFirstLine(), foundTextData);
+            return parseAdvancedSign(sign.getLocation(), foundTextData, lines);
         } else {
-            return parseSimpleSign(sign.getLocation(), ((Sign)sign.getState()).getLines());
+            return parseSimpleSign(sign.getLocation(), lines);
         }
     }
 
@@ -127,7 +155,7 @@ private Optional<ProtectionSign> parseSimpleSign(Location location, String[] lin
             return Optional.empty();
         }
 
-        List<Profile> profiles = new ArrayList<Profile>();
+        List<Profile> profiles = new ArrayList<>();
         for (int i = 1; i < lines.length; i++) {
             String name = lines[i].trim();
             profiles.add(profileFactory.fromDisplayText(name));
@@ -137,7 +165,7 @@ private Optional<ProtectionSign> parseSimpleSign(Location location, String[] lin
         // advanced signs
         return Optional.<ProtectionSign> of(new ProtectionSignImpl(location, signType, profiles));
     }
-    
+
     @Override
     public void saveSign(ProtectionSign sign) {
         // Find sign
@@ -150,7 +178,7 @@ public void saveSign(ProtectionSign sign) {
 
         // Update sign, both visual and using raw JSON
         Sign signState = (Sign) blockState;
-        
+
         signState.setLine(0, chestSettings.getFancyLocalizedHeader(sign.getType(), signState.getLine(0)));
 
         JsonArray jsonArray = new JsonArray();