SPIGOT-7804: Fix written book serialization

* Account for null/missing values when deserializing the 'resolved' and
  'generation' fields.
* Serialize the book pages as JSON strings.
* Avoid redundant conversion from strings to components to JSON and back to
  components during deserialization.
  Add CraftChatMessage.fromJSONOrString that accepts a maxLength argument
  and remove the no longer used fromJSONOrStringToJSON, fromStringToJSON,
  and fromJSONComponent helper methods.

src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaBookSigned.java

@@ -3,6 +3,7 @@ package org.bukkit.craftbukkit.inventory;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap.Builder;
+import com.google.common.collect.Lists;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -35,8 +36,7 @@ public class CraftMetaBookSigned extends CraftMetaItem implements BookMeta {
 
     protected String title;
     protected String author;
-    // We store the pages in their raw original text representation. See SPIGOT-5063, SPIGOT-5350, SPIGOT-3206
+    // Stored as components and serialized as JSON. See SPIGOT-5063, SPIGOT-5350, SPIGOT-3206
-    // For written books (CraftMetaBookSigned) the pages are stored in Minecraft's JSON format.
     protected List<IChatBaseComponent> pages; // null and empty are two different states internally
     protected boolean resolved;
     protected int generation;
@@ -105,13 +105,13 @@ public class CraftMetaBookSigned extends CraftMetaItem implements BookMeta {
             this.pages = new ArrayList<IChatBaseComponent>();
             for (Object page : pages) {
                 if (page instanceof String) {
-                    internalAddPage(CraftChatMessage.fromJSON(CraftChatMessage.fromJSONOrStringToJSON((String) page, false, true, MAX_PAGE_LENGTH, false)));
+                    internalAddPage(CraftChatMessage.fromJSONOrString((String) page, false, true, MAX_PAGE_LENGTH, false));
                 }
             }
         }
 
-        resolved = SerializableMeta.getObject(Boolean.class, map, RESOLVED.BUKKIT, true);
+        resolved = SerializableMeta.getBoolean(map, RESOLVED.BUKKIT);
-        generation = SerializableMeta.getObject(Integer.class, map, GENERATION.BUKKIT, true);
+        generation = SerializableMeta.getInteger(map, GENERATION.BUKKIT);
     }
 
     @Override
@@ -351,7 +351,7 @@ public class CraftMetaBookSigned extends CraftMetaItem implements BookMeta {
         }
 
         if (pages != null) {
-            builder.put(BOOK_PAGES.BUKKIT, ImmutableList.copyOf(pages));
+            builder.put(BOOK_PAGES.BUKKIT, ImmutableList.copyOf(Lists.transform(pages, CraftChatMessage::toJSON)));
         }
 
         if (resolved) {

src/main/java/org/bukkit/craftbukkit/inventory/SerializableMeta.java

@@ -96,6 +96,11 @@ public final class SerializableMeta implements ConfigurationSerializable {
         return value != null && value;
     }
 
+    public static int getInteger(Map<?, ?> map, Object field) {
+        Integer value = getObject(Integer.class, map, field, true);
+        return value != null ? value : 0;
+    }
+
     public static <T> T getObject(Class<T> clazz, Map<?, ?> map, Object field, boolean nullable) {
         final Object object = map.get(field);
 

src/main/java/org/bukkit/craftbukkit/util/CraftChatMessage.java

@@ -231,51 +231,26 @@ public final class CraftChatMessage {
     }
 
     public static IChatBaseComponent fromJSONOrString(String message, boolean nullable, boolean keepNewlines) {
+        return fromJSONOrString(message, nullable, keepNewlines, Integer.MAX_VALUE, false);
+    }
+
+    public static IChatBaseComponent fromJSONOrString(String message, boolean nullable, boolean keepNewlines, int maxLength, boolean checkJsonContentLength) {
         if (message == null) message = "";
         if (nullable && message.isEmpty()) return null;
         IChatBaseComponent component = fromJSONOrNull(message);
-        if (component != null) {
-            return component;
-        } else {
-            return fromString(message, keepNewlines)[0];
-        }
-    }
-
-    public static String fromJSONOrStringToJSON(String message) {
-        return fromJSONOrStringToJSON(message, false);
-    }
-
-    public static String fromJSONOrStringToJSON(String message, boolean keepNewlines) {
-        return fromJSONOrStringToJSON(message, false, keepNewlines, Integer.MAX_VALUE, false);
-    }
-
-    public static String fromJSONOrStringOrNullToJSON(String message) {
-        return fromJSONOrStringOrNullToJSON(message, false);
-    }
-
-    public static String fromJSONOrStringOrNullToJSON(String message, boolean keepNewlines) {
-        return fromJSONOrStringToJSON(message, true, keepNewlines, Integer.MAX_VALUE, false);
-    }
-
-    public static String fromJSONOrStringToJSON(String message, boolean nullable, boolean keepNewlines, int maxLength, boolean checkJsonContentLength) {
-        if (message == null) message = "";
-        if (nullable && message.isEmpty()) return null;
-        // If the input can be parsed as JSON, we use that:
-        IChatBaseComponent component = fromJSONOrNull(message);
         if (component != null) {
             if (checkJsonContentLength) {
                 String content = fromComponent(component);
                 String trimmedContent = trimMessage(content, maxLength);
-                if (content != trimmedContent) { // identity comparison is fine here
+                if (content != trimmedContent) { // Identity comparison is fine here
                     // Note: The resulting text has all non-plain text features stripped.
-                    return fromStringToJSON(trimmedContent, keepNewlines);
+                    return fromString(trimmedContent, keepNewlines)[0];
                 }
             }
-            return message;
+            return component;
         } else {
-            // Else we interpret the input as legacy text:
             message = trimMessage(message, maxLength);
-            return fromStringToJSON(message, keepNewlines);
+            return fromString(message, keepNewlines)[0];
         }
     }
 
@@ -287,25 +262,6 @@ public final class CraftChatMessage {
         }
     }
 
-    public static String fromStringToJSON(String message) {
-        return fromStringToJSON(message, false);
-    }
-
-    public static String fromStringToJSON(String message, boolean keepNewlines) {
-        IChatBaseComponent component = CraftChatMessage.fromString(message, keepNewlines)[0];
-        return CraftChatMessage.toJSON(component);
-    }
-
-    public static String fromStringOrNullToJSON(String message) {
-        IChatBaseComponent component = CraftChatMessage.fromStringOrNull(message);
-        return CraftChatMessage.toJSONOrNull(component);
-    }
-
-    public static String fromJSONComponent(String jsonMessage) {
-        IChatBaseComponent component = CraftChatMessage.fromJSONOrNull(jsonMessage);
-        return CraftChatMessage.fromComponent(component);
-    }
-
     public static String fromComponent(IChatBaseComponent component) {
         if (component == null) return "";
         StringBuilder out = new StringBuilder();