Refactor hologram-related objects, simplify editing

core/src/main/java/me/filoghost/holographicdisplays/core/hologram/StandardHologram.java

@@ -18,14 +18,14 @@ public interface StandardHologram {
 
     boolean isInChunk(Chunk chunk);
 
+    List<? extends StandardHologramLine> getLines();
+
+    int getLinesAmount();
+
     Plugin getOwnerPlugin();
 
-    List<? extends StandardHologramLine> getLinesUnsafe();
-
     boolean isVisibleTo(Player player);
 
-    String toFormattedString();
-
     void refresh();
 
     void refresh(boolean forceRespawn);
@@ -34,12 +34,10 @@ public interface StandardHologram {
 
     void despawnEntities();
 
-    void removeLine(StandardHologramLine line);
-
-    int size();
-
     boolean isDeleted();
 
     void setDeleted();
 
+    String toFormattedString();
+
 }

plugin/src/main/java/me/filoghost/holographicdisplays/bridge/protocollib/PacketSender.java

@@ -39,7 +39,7 @@ class PacketSender {
 
     public void sendDestroyEntitiesPacket(Player player, StandardHologram hologram) {
         List<Integer> ids = new ArrayList<>();
-        for (StandardHologramLine line : hologram.getLinesUnsafe()) { 
+        for (StandardHologramLine line : hologram.getLines()) { 
             line.collectEntityIDs(ids);
         }
 
@@ -49,7 +49,7 @@ class PacketSender {
     }
 
     public void sendCreateEntitiesPacket(Player player, StandardHologram hologram) {
-        for (StandardHologramLine line : hologram.getLinesUnsafe()) {
+        for (StandardHologramLine line : hologram.getLines()) {
             sendCreateEntitiesPacket(player, line);
         }
     }

plugin/src/main/java/me/filoghost/holographicdisplays/commands/HologramCommandValidate.java

@@ -20,9 +20,9 @@ import java.nio.file.Path;
 
 public class HologramCommandValidate {
     
-    public static InternalHologramLine parseHologramLine(InternalHologram hologram, String serializedLine, boolean validateMaterial) throws CommandException {
+    public static InternalHologramLine parseHologramLine(InternalHologram hologram, String serializedLine) throws CommandException {
         try {
-            return HologramLineParser.parseLine(hologram, serializedLine, validateMaterial);
+            return HologramLineParser.parseLine(hologram, serializedLine);
         } catch (HologramLoadException e) {
             throw new CommandException(Utils.formatExceptionMessage(e));
         }

plugin/src/main/java/me/filoghost/holographicdisplays/commands/subs/AddlineCommand.java

@@ -41,9 +41,8 @@ public class AddlineCommand extends LineEditingCommand implements QuickEditComma
         InternalHologram hologram = HologramCommandValidate.getInternalHologram(internalHologramManager, args[0]);
         String serializedLine = Utils.join(args, " ", 1, args.length);
         
-        InternalHologramLine line = HologramCommandValidate.parseHologramLine(hologram, serializedLine, true);
+        InternalHologramLine line = HologramCommandValidate.parseHologramLine(hologram, serializedLine);
-        hologram.getLinesUnsafe().add(line);
+        hologram.addLine(line);
-        hologram.refresh();
 
         configManager.saveHologramDatabase(internalHologramManager);
         Bukkit.getPluginManager().callEvent(new InternalHologramEditEvent(hologram));

plugin/src/main/java/me/filoghost/holographicdisplays/commands/subs/CopyCommand.java

@@ -16,6 +16,9 @@ import me.filoghost.holographicdisplays.object.internal.InternalHologramLine;
 import me.filoghost.holographicdisplays.object.internal.InternalHologramManager;
 import org.bukkit.command.CommandSender;
 
+import java.util.ArrayList;
+import java.util.List;
+
 public class CopyCommand extends HologramSubCommand {
 
     private final InternalHologramManager internalHologramManager;
@@ -35,14 +38,13 @@ public class CopyCommand extends HologramSubCommand {
     public void execute(CommandSender sender, String[] args, SubCommandContext context) throws CommandException {
         InternalHologram fromHologram = HologramCommandValidate.getInternalHologram(internalHologramManager, args[0]);
         InternalHologram toHologram = HologramCommandValidate.getInternalHologram(internalHologramManager, args[1]);
-        
+
-        toHologram.clearLines();
+        List<InternalHologramLine> clonedLines = new ArrayList<>();
-        for (InternalHologramLine line : fromHologram.getLinesUnsafe()) {
+        for (InternalHologramLine line : fromHologram.getLines()) {
-            InternalHologramLine clonedLine = HologramCommandValidate.parseHologramLine(toHologram, line.getSerializedConfigValue(), false);
+            clonedLines.add(HologramCommandValidate.parseHologramLine(toHologram, line.getSerializedConfigValue()));
-            toHologram.getLinesUnsafe().add(clonedLine);
         }
         
-        toHologram.refresh();
+        toHologram.setLines(clonedLines);
         
         configManager.saveHologramDatabase(internalHologramManager);
         

plugin/src/main/java/me/filoghost/holographicdisplays/commands/subs/CreateCommand.java

@@ -65,16 +65,15 @@ public class CreateCommand extends HologramSubCommand {
             String text = Utils.join(args, " ", 1, args.length);
             CommandValidate.check(!text.equalsIgnoreCase("{empty}"), "The first line should not be empty.");
             
-            line = HologramCommandValidate.parseHologramLine(hologram, text, true);
+            line = HologramCommandValidate.parseHologramLine(hologram, text);
             player.sendMessage(Colors.SECONDARY_SHADOW + "(Change the lines with /" + context.getRootLabel() + " edit " + hologram.getName() + ")");
         } else {
             String defaultText = "Default hologram. Change it with " 
                     + Colors.PRIMARY + "/" + context.getRootLabel() + " edit " + hologram.getName();
             line = hologram.createTextLine(defaultText, defaultText.replace(ChatColor.COLOR_CHAR, '&'));
         }
-
+        
-        hologram.getLinesUnsafe().add(line);
+        hologram.addLine(line);
-        hologram.refresh();
         
         configManager.saveHologramDatabase(internalHologramManager);
         Location look = player.getLocation();

plugin/src/main/java/me/filoghost/holographicdisplays/commands/subs/DebugCommand.java

@@ -66,7 +66,7 @@ public class DebugCommand extends HologramSubCommand {
                 for (Entry<StandardHologram, HologramDebugInfo> entry : hologramsDebugInfo.entrySet()) {
                     StandardHologram hologram = entry.getKey();
                     HologramDebugInfo debugInfo = entry.getValue();
-                    sender.sendMessage(Colors.PRIMARY_SHADOW + "- '" + hologram.toFormattedString() + "': " + hologram.size() + " lines, "
+                    sender.sendMessage(Colors.PRIMARY_SHADOW + "- '" + hologram.toFormattedString() + "': " + hologram.getLinesAmount() + " lines, "
                             + debugInfo.getTotalEntities() + " entities (" + debugInfo.aliveEntities + " alive, " + debugInfo.deadEntities + " dead)");
                 }
             }

plugin/src/main/java/me/filoghost/holographicdisplays/commands/subs/InfoCommand.java

@@ -39,7 +39,7 @@ public class InfoCommand extends LineEditingCommand implements QuickEditCommand
         Messages.sendTitle(sender, "Lines of the hologram '" + hologram.getName() + "'");
         int index = 0;
         
-        for (InternalHologramLine line : hologram.getLinesUnsafe()) {
+        for (InternalHologramLine line : hologram.getLines()) {
             sender.sendMessage(Colors.SECONDARY + Colors.BOLD + (++index) + Colors.SECONDARY_SHADOW + ". " + Colors.SECONDARY + line.getSerializedConfigValue());
         }
         commandManager.sendQuickEditCommands(context, hologram);

plugin/src/main/java/me/filoghost/holographicdisplays/commands/subs/InsertlineCommand.java

@@ -44,28 +44,27 @@ public class InsertlineCommand extends LineEditingCommand implements QuickEditCo
     @Override
     public void execute(CommandSender sender, String[] args, SubCommandContext context) throws CommandException {
         InternalHologram hologram = HologramCommandValidate.getInternalHologram(internalHologramManager, args[0]);
-        int insertAfter = CommandValidate.parseInteger(args[1]);
+        int insertAfterIndex = CommandValidate.parseInteger(args[1]);
         String serializedLine = Utils.join(args, " ", 2, args.length);
         
-        int oldLinesAmount = hologram.size();
+        int oldLinesAmount = hologram.getLinesAmount();
         
-        CommandValidate.check(insertAfter >= 0 && insertAfter <= oldLinesAmount, "The number must be between 0 and " + hologram.size() + "(amount of lines of the hologram).");
+        CommandValidate.check(insertAfterIndex >= 0 && insertAfterIndex <= oldLinesAmount, "The number must be between 0 and " + hologram.getLinesAmount() + "(amount of lines of the hologram).");
 
-        InternalHologramLine line = HologramCommandValidate.parseHologramLine(hologram, serializedLine, true);
+        InternalHologramLine line = HologramCommandValidate.parseHologramLine(hologram, serializedLine);
-        hologram.getLinesUnsafe().add(insertAfter, line);
+        hologram.insertLine(insertAfterIndex, line);
-        hologram.refresh();
             
         configManager.saveHologramDatabase(internalHologramManager);
         
         Bukkit.getPluginManager().callEvent(new InternalHologramEditEvent(hologram));
         
-        if (insertAfter == 0) {
+        if (insertAfterIndex == 0) {
             sender.sendMessage(Colors.PRIMARY + "Line inserted before first line.");
-        } else if (insertAfter == oldLinesAmount) {
+        } else if (insertAfterIndex == oldLinesAmount) {
             sender.sendMessage(Colors.PRIMARY + "Line appended at the end.");
             Messages.sendTip(sender, "You can use \"/" + context.getRootLabel() + " addline\" to append a line at the end.");
         } else {
-            sender.sendMessage(Colors.PRIMARY + "Line inserted between lines " + insertAfter + " and " + (insertAfter + 1) + ".");
+            sender.sendMessage(Colors.PRIMARY + "Line inserted between lines " + insertAfterIndex + " and " + (insertAfterIndex + 1) + ".");
         }
         commandManager.sendQuickEditCommands(context, hologram);
     }

plugin/src/main/java/me/filoghost/holographicdisplays/commands/subs/ListCommand.java

@@ -58,7 +58,7 @@ public class ListCommand extends HologramSubCommand {
                         + " " + Colors.SECONDARY_SHADOW + "at x: " + (int) hologram.getX() 
                         + ", y: " + (int) hologram.getY() 
                         + ", z: " + (int) hologram.getZ() 
-                        + " (lines: " + hologram.size() + ", world: \"" + hologram.getWorld().getName() + "\")");
+                        + " (lines: " + hologram.getLinesAmount() + ", world: \"" + hologram.getWorld().getName() + "\")");
             }
         }
         

plugin/src/main/java/me/filoghost/holographicdisplays/commands/subs/NearCommand.java

@@ -53,7 +53,7 @@ public class NearCommand extends HologramSubCommand {
         
         Messages.sendTitle(player, "Near holograms");
         for (InternalHologram nearHologram : nearHolograms) {
-            player.sendMessage(Colors.SECONDARY_SHADOW + "- " + Colors.SECONDARY + Colors.BOLD + nearHologram.getName() + " " + Colors.SECONDARY_SHADOW + "at x: " + (int) nearHologram.getX() + ", y: " + (int) nearHologram.getY() + ", z: " + (int) nearHologram.getZ() + " (lines: " + nearHologram.size() + ")");
+            player.sendMessage(Colors.SECONDARY_SHADOW + "- " + Colors.SECONDARY + Colors.BOLD + nearHologram.getName() + " " + Colors.SECONDARY_SHADOW + "at x: " + (int) nearHologram.getX() + ", y: " + (int) nearHologram.getY() + ", z: " + (int) nearHologram.getZ() + " (lines: " + nearHologram.getLinesAmount() + ")");
         }
     }
     

plugin/src/main/java/me/filoghost/holographicdisplays/commands/subs/ReadimageCommand.java

@@ -108,18 +108,17 @@ public class ReadimageCommand extends LineEditingCommand {
             }
 
             ImageMessage imageMessage = new ImageMessage(image, width);
-            String[] newLines = imageMessage.getLines();
+            List<InternalTextLine> newLines = new ArrayList<>();
+            for (String newLine : imageMessage.getLines()) {
+                newLines.add(hologram.createTextLine(newLine, newLine));
+            }
             
             if (!append) {
                 hologram.clearLines();
             }
-            for (String newLine : newLines) {
+            hologram.addLines(newLines);
-                InternalTextLine line = hologram.createTextLine(newLine, newLine);
-                hologram.getLinesUnsafe().add(line);
-            }
-            hologram.refresh();
             
-            if (newLines.length < 5) {
+            if (newLines.size() < 5) {
                 Messages.sendTip(sender, "The image has a very low height. You can increase it by increasing the width, it will scale automatically.");
             }
             

plugin/src/main/java/me/filoghost/holographicdisplays/commands/subs/ReadtextCommand.java

@@ -76,16 +76,14 @@ public class ReadtextCommand extends LineEditingCommand {
             List<InternalHologramLine> linesToAdd = new ArrayList<>();
             for (int i = 0; i < linesAmount; i++) {
                 try {
-                    InternalHologramLine line = HologramLineParser.parseLine(hologram, serializedLines.get(i), true);
+                    InternalHologramLine line = HologramLineParser.parseLine(hologram, serializedLines.get(i));
                     linesToAdd.add(line);
                 } catch (HologramLoadException e) {
                     throw new CommandException("Error at line " + (i + 1) + ": " + e.getMessage());
                 }
             }
             
-            hologram.clearLines();
+            hologram.setLines(linesToAdd);
-            hologram.getLinesUnsafe().addAll(linesToAdd);
-            hologram.refresh();
 
             configManager.saveHologramDatabase(internalHologramManager);
             

plugin/src/main/java/me/filoghost/holographicdisplays/commands/subs/RemovelineCommand.java

@@ -41,13 +41,12 @@ public class RemovelineCommand extends LineEditingCommand implements QuickEditCo
         
         int lineNumber = CommandValidate.parseInteger(args[1]);
 
-        CommandValidate.check(lineNumber >= 1 && lineNumber <= hologram.size(), "The line number must be between 1 and " + hologram.size() + ".");
+        CommandValidate.check(lineNumber >= 1 && lineNumber <= hologram.getLinesAmount(), "The line number must be between 1 and " + hologram.getLinesAmount() + ".");
         int index = lineNumber - 1;
         
-        CommandValidate.check(hologram.size() > 1, "The hologram should have at least 1 line. If you want to delete it, use /" + context.getRootLabel() + " delete.");
+        CommandValidate.check(hologram.getLinesAmount() > 1, "The hologram should have at least 1 line. If you want to delete it, use /" + context.getRootLabel() + " delete.");
 
         hologram.removeLine(index);
-        hologram.refresh();
         
         configManager.saveHologramDatabase(internalHologramManager);
         Bukkit.getPluginManager().callEvent(new InternalHologramEditEvent(hologram));

plugin/src/main/java/me/filoghost/holographicdisplays/commands/subs/SetlineCommand.java

@@ -43,14 +43,12 @@ public class SetlineCommand extends LineEditingCommand implements QuickEditComma
         String serializedLine = Utils.join(args, " ", 2, args.length);
         
         int lineNumber = CommandValidate.parseInteger(args[1]);
-        CommandValidate.check(lineNumber >= 1 && lineNumber <= hologram.size(), "The line number must be between 1 and " + hologram.size() + ".");
+        CommandValidate.check(lineNumber >= 1 && lineNumber <= hologram.getLinesAmount(), "The line number must be between 1 and " + hologram.getLinesAmount() + ".");
         int index = lineNumber - 1;
         
-        InternalHologramLine line = HologramCommandValidate.parseHologramLine(hologram, serializedLine, true);
+        InternalHologramLine line = HologramCommandValidate.parseHologramLine(hologram, serializedLine);
 
-        InternalHologramLine prevLine = hologram.getLinesUnsafe().set(index, line);
+        hologram.setLine(index, line);
-        prevLine.despawn();
-        hologram.refresh();
 
         configManager.saveHologramDatabase(internalHologramManager);
         Bukkit.getPluginManager().callEvent(new InternalHologramEditEvent(hologram));

plugin/src/main/java/me/filoghost/holographicdisplays/disk/HologramConfig.java

@@ -38,7 +38,7 @@ public class HologramConfig {
     public HologramConfig(InternalHologram hologram) {
         this.name = hologram.getName();
         this.serializedLines = new ArrayList<>();
-        for (InternalHologramLine line : hologram.getLinesUnsafe()) {
+        for (InternalHologramLine line : hologram.getLines()) {
             serializedLines.add(line.getSerializedConfigValue());
         }
 
@@ -62,17 +62,18 @@ public class HologramConfig {
 
         Location location = deserializeLocation(serializedLocation);
         InternalHologram hologram = internalHologramManager.createHologram(location, name);
+        List<InternalHologramLine> lines = new ArrayList<>();
 
         for (String serializedLine : serializedLines) {
             try {
-                InternalHologramLine line = HologramLineParser.parseLine(hologram, serializedLine, false);
+                lines.add(HologramLineParser.parseLine(hologram, serializedLine));
-                hologram.getLinesUnsafe().add(line);
             } catch (HologramLoadException e) {
                 // Rethrow with more details
                 throw new HologramLoadException("hologram \"" + hologram.getName() + "\" has an invalid line: " + e.getMessage(), e);
             }
         }
-
+        
+        hologram.setLines(lines);
         return hologram;
     }
 

plugin/src/main/java/me/filoghost/holographicdisplays/disk/HologramDatabase.java

@@ -36,7 +36,6 @@ public class HologramDatabase {
     }
 
     public void createHolograms(CommandSender sender, InternalHologramManager internalHologramManager) {
-        // Create all the holograms
         for (HologramConfig hologramConfig : hologramConfigs) {
             try {
                 hologramConfig.createHologram(internalHologramManager);
@@ -50,11 +49,6 @@ public class HologramDatabase {
                 Log.warning("Unexpected exception while loading the hologram \"" + hologramConfig.getName() + "\".", e);
             }
         }
-
-        // Then trigger a refresh for all of them
-        for (InternalHologram hologram : internalHologramManager.getHolograms()) {
-            hologram.refresh();
-        }
     }
 
     public static Config exportToConfig(InternalHologramManager hologramManager) {

plugin/src/main/java/me/filoghost/holographicdisplays/disk/HologramLineParser.java

@@ -20,12 +20,12 @@ public class HologramLineParser {
     private static final String ICON_PREFIX = "icon:";
     private static final String EMPTY_LINE_PLACEHOLDER = "{empty}";
 
-    public static InternalHologramLine parseLine(InternalHologram hologram, String serializedLine, boolean checkMaterialValidity) throws HologramLoadException {
+    public static InternalHologramLine parseLine(InternalHologram hologram, String serializedLine) throws HologramLoadException {
         InternalHologramLine hologramLine;
         
         if (serializedLine.toLowerCase().startsWith(ICON_PREFIX)) {
             String serializedIcon = serializedLine.substring(ICON_PREFIX.length());
-            ItemStack icon = parseItemStack(serializedIcon, checkMaterialValidity);
+            ItemStack icon = parseItemStack(serializedIcon);
             hologramLine = hologram.createItemLine(icon, serializedLine);
             
         } else {
@@ -44,7 +44,7 @@ public class HologramLineParser {
     
     
     @SuppressWarnings("deprecation")
-    private static ItemStack parseItemStack(String serializedItem, boolean checkMaterialValidity) throws HologramLoadException {
+    private static ItemStack parseItemStack(String serializedItem) throws HologramLoadException {
         serializedItem = serializedItem.trim();
         
         // Parse json
@@ -80,10 +80,7 @@ public class HologramLineParser {
         
         Material material = MaterialsHelper.matchMaterial(materialName);
         if (material == null) {
-            if (checkMaterialValidity) {
+            throw new HologramLoadException("\"" + materialName + "\" is not a valid material");
-                throw new HologramLoadException("\"" + materialName + "\" is not a valid material");
-            }
-            material = Material.BEDROCK;
         }
         
         ItemStack itemStack = new ItemStack(material, 1, dataValue);

plugin/src/main/java/me/filoghost/holographicdisplays/image/ImageMessage.java

@@ -189,9 +189,9 @@ public class ImageMessage {
         // Minecraft has 15 colors
         return bestColorMatch;
     }
-
+    
-
     public String[] getLines() {
         return lines;
     }
+    
 }

plugin/src/main/java/me/filoghost/holographicdisplays/object/api/APIHologram.java

@@ -12,23 +12,21 @@ import me.filoghost.holographicdisplays.api.line.HologramLine;
 import me.filoghost.holographicdisplays.api.line.ItemLine;
 import me.filoghost.holographicdisplays.api.line.TextLine;
 import me.filoghost.holographicdisplays.core.nms.NMSManager;
-import me.filoghost.holographicdisplays.object.base.BaseHologram;
 import me.filoghost.holographicdisplays.disk.Configuration;
+import me.filoghost.holographicdisplays.object.base.BaseHologram;
 import org.bukkit.Location;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.plugin.Plugin;
 
-import java.util.ArrayList;
 import java.util.List;
 
-public class APIHologram extends BaseHologram implements Hologram {
+public class APIHologram extends BaseHologram<APIHologramLine> implements Hologram {
     
     private final Plugin plugin;
     private final APIHologramManager apiHologramManager;
     private final VisibilityManager visibilityManager;
     private final long creationTimestamp;
-    private final List<APIHologramLine> lines;
 
     private boolean allowPlaceholders;
 
@@ -39,59 +37,42 @@ public class APIHologram extends BaseHologram implements Hologram {
         this.apiHologramManager = apiHologramManager;
         this.visibilityManager = new DefaultVisibilityManager(this);
         this.creationTimestamp = System.currentTimeMillis();
-        this.lines = new ArrayList<>();
-
     }
     
     @Override
     public Plugin getOwnerPlugin() {
         return plugin;
     }
-
+    
-    @Override
-    public List<APIHologramLine> getLinesUnsafe() {
-        return lines;
-    }
-
     @Override
     public TextLine appendTextLine(String text) {
-        checkState();
-
         APITextLine line = createTextLine(text);
-        lines.add(line);
+        addLine(line);
-        refresh();
         return line;
     }
 
     @Override
     public ItemLine appendItemLine(ItemStack itemStack) {
-        checkState();
         Preconditions.notNull(itemStack, "itemStack");
 
         APIItemLine line = createItemLine(itemStack);
-        lines.add(line);
+        addLine(line);
-        refresh();
         return line;
     }
 
     @Override
     public TextLine insertTextLine(int index, String text) {
-        checkState();
-
         APITextLine line = createTextLine(text);
-        lines.add(index, line);
+        addLine(line);
-        refresh();
         return line;
     }
 
     @Override
     public ItemLine insertItemLine(int index, ItemStack itemStack) {
-        checkState();
         Preconditions.notNull(itemStack, "itemStack");
 
         APIItemLine line = createItemLine(itemStack);
-        lines.add(index, line);
+        addLine(line);
-        refresh();
         return line;
     }
 
@@ -105,7 +86,12 @@ public class APIHologram extends BaseHologram implements Hologram {
 
     @Override
     public HologramLine getLine(int index) {
-        return lines.get(index);
+        return getLines().get(index);
+    }
+
+    @Override
+    public int size() {
+        return getLinesAmount();
     }
 
     @Override
@@ -130,6 +116,7 @@ public class APIHologram extends BaseHologram implements Hologram {
     
     @Override
     public double getHeight() {
+        List<APIHologramLine> lines = getLines();
         if (lines.isEmpty()) {
             return 0;
         }

plugin/src/main/java/me/filoghost/holographicdisplays/object/api/APIHologramLine.java

@@ -10,9 +10,12 @@ import me.filoghost.holographicdisplays.core.hologram.StandardHologramLine;
 
 public interface APIHologramLine extends HologramLine, StandardHologramLine {
 
+    @Override
+    APIHologram getParent();
+    
     @Override
     default void removeLine() {
-        getHologram().removeLine(this);
+        getParent().removeLine(this);
     }
 
 }

plugin/src/main/java/me/filoghost/holographicdisplays/object/api/APIItemLine.java

@@ -1,6 +1,5 @@
 package me.filoghost.holographicdisplays.object.api;
 
-import me.filoghost.holographicdisplays.api.Hologram;
 import me.filoghost.holographicdisplays.api.line.ItemLine;
 import me.filoghost.holographicdisplays.core.nms.NMSManager;
 import me.filoghost.holographicdisplays.object.base.BaseItemLine;
@@ -16,7 +15,7 @@ public class APIItemLine extends BaseItemLine implements ItemLine, APIHologramLi
     }
 
     @Override
-    public Hologram getParent() {
+    public APIHologram getParent() {
         return parent;
     }
 

plugin/src/main/java/me/filoghost/holographicdisplays/object/api/APITextLine.java

@@ -1,6 +1,5 @@
 package me.filoghost.holographicdisplays.object.api;
 
-import me.filoghost.holographicdisplays.api.Hologram;
 import me.filoghost.holographicdisplays.api.line.TextLine;
 import me.filoghost.holographicdisplays.core.nms.NMSManager;
 import me.filoghost.holographicdisplays.object.base.BaseTextLine;
@@ -15,7 +14,7 @@ public class APITextLine extends BaseTextLine implements TextLine, APIHologramLi
     }
 
     @Override
-    public Hologram getParent() {
+    public APIHologram getParent() {
         return parent;
     }
 

plugin/src/main/java/me/filoghost/holographicdisplays/object/base/BaseHologram.java

@@ -6,18 +6,23 @@
 package me.filoghost.holographicdisplays.object.base;
 
 import me.filoghost.fcommons.Preconditions;
-import me.filoghost.holographicdisplays.core.nms.NMSManager;
 import me.filoghost.holographicdisplays.core.hologram.StandardHologram;
 import me.filoghost.holographicdisplays.core.hologram.StandardHologramLine;
+import me.filoghost.holographicdisplays.core.nms.NMSManager;
 import me.filoghost.holographicdisplays.disk.Configuration;
 import org.bukkit.Location;
 import org.bukkit.World;
 
+import java.util.ArrayList;
+import java.util.Collections;
 import java.util.Iterator;
+import java.util.List;
 
-public abstract class BaseHologram extends BaseHologramComponent implements StandardHologram {
+public abstract class BaseHologram<T extends StandardHologramLine> extends BaseHologramComponent implements StandardHologram {
     
     private final NMSManager nmsManager;
+    private final List<T> lines;
+    private final List<T> unmodifiableLinesView;
     
     private boolean deleted;
 
@@ -25,64 +30,110 @@ public abstract class BaseHologram extends BaseHologramComponent implements Stan
         Preconditions.notNull(location, "location");
         this.setLocation(location);
         this.nmsManager = nmsManager;
+        this.lines = new ArrayList<>();
+        this.unmodifiableLinesView = Collections.unmodifiableList(lines);
+    }
+
+    protected final NMSManager getNMSManager() {
+        return nmsManager;
     }
 
     @Override
     public boolean isDeleted() {
         return deleted;
     }
-
+    
     @Override
     public void setDeleted() {
         if (!deleted) {
             deleted = true;
-            clearLines();
+            despawnEntities();
         }
     }
-    
-    protected final NMSManager getNMSManager() {
-        return nmsManager;
-    }
-    
-    public void removeLine(int index) {
-        checkState();
-
-        getLinesUnsafe().remove(index).despawn();
-        refresh();
-    }
 
     @Override
-    public void removeLine(StandardHologramLine line) {
+    public List<T> getLines() {
-        checkState();
+        return unmodifiableLinesView;
+    }
 
-        getLinesUnsafe().remove(line);
+    public void addLine(T line) {
+        checkNotDeleted();
+        
+        lines.add(line);
+        refresh();
+    }
+
+    public void addLines(List<? extends T> newLines) {
+        checkNotDeleted();
+        
+        lines.addAll(newLines);
+        refresh();
+    }
+
+    public void insertLine(int afterIndex, T line) {
+        checkNotDeleted();
+        
+        lines.add(afterIndex, line);
+        refresh();
+    }
+
+    public void setLine(int index, T line) {
+        checkNotDeleted();
+        
+        T previousLine = lines.set(index, line);
+        previousLine.despawn();
+        refresh();
+    }
+
+    public void setLines(List<T> newLines) {
+        checkNotDeleted();
+        
+        clearLines();
+        lines.addAll(newLines);
+        refresh();
+    }
+    
+    public void removeLine(int index) {
+        checkNotDeleted();
+
+        lines.remove(index).despawn();
+        refresh();
+    }
+    
+    public void removeLine(T line) {
+        checkNotDeleted();
+
+        lines.remove(line);
         line.despawn();
         refresh();
     }
     
     public void clearLines() {
-        Iterator<? extends StandardHologramLine> iterator = getLinesUnsafe().iterator();
+        checkNotDeleted();
+        
+        Iterator<T> iterator = lines.iterator();
         while (iterator.hasNext()) {
-            StandardHologramLine line = iterator.next();
+            T line = iterator.next();
             iterator.remove();
             line.despawn();
         }
+        
+        // No need to refresh, since there are no lines
     }
     
     @Override
-    public int size() {
+    public int getLinesAmount() {
-        return getLinesUnsafe().size();
+        return lines.size();
     }
     
     public void teleport(Location location) {
-        checkState();
         Preconditions.notNull(location, "location");
 
         teleport(location.getWorld(), location.getX(), location.getY(), location.getZ());
     }
     
     public void teleport(World world, double x, double y, double z) {
-        checkState();
+        checkNotDeleted();
         Preconditions.notNull(world, "world");
 
         setLocation(world, x, y, z);
@@ -101,7 +152,7 @@ public abstract class BaseHologram extends BaseHologramComponent implements Stan
 
     @Override
     public void refresh(boolean forceRespawn, boolean isChunkLoaded) {
-        checkState();
+        checkNotDeleted();
         
         if (isChunkLoaded) {
             respawnEntities(forceRespawn);
@@ -117,8 +168,8 @@ public abstract class BaseHologram extends BaseHologramComponent implements Stan
     private void respawnEntities(boolean forceRespawn) {
         double currentLineY = getY();
 
-        for (int i = 0; i < getLinesUnsafe().size(); i++) {
+        for (int i = 0; i < lines.size(); i++) {
-            StandardHologramLine line = getLinesUnsafe().get(i);
+            T line = lines.get(i);
             
             currentLineY -= line.getHeight();
             if (i > 0) {
@@ -134,18 +185,18 @@ public abstract class BaseHologram extends BaseHologramComponent implements Stan
 
     @Override
     public void despawnEntities() {
-        for (StandardHologramLine line : getLinesUnsafe()) {
+        for (T line : lines) {
             line.despawn();
         }
     }
 
-    protected void checkState() {
+    private void checkNotDeleted() {
-        Preconditions.checkState(!deleted, "hologram already deleted");
+        Preconditions.checkState(!deleted, "hologram is not usable after being deleted");
     }
 
     @Override
     public String toString() {
-        return "BaseHologram [location=" + getLocation() + ", lines=" + getLinesUnsafe() + ", deleted=" + deleted + "]";
+        return "BaseHologram [location=" + getLocation() + ", lines=" + lines + ", deleted=" + deleted + "]";
     }
 
     /*

plugin/src/main/java/me/filoghost/holographicdisplays/object/internal/InternalHologram.java

@@ -13,22 +13,13 @@ import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.plugin.Plugin;
 
-import java.util.ArrayList;
+public class InternalHologram extends BaseHologram<InternalHologramLine> {
-import java.util.List;
-
-public class InternalHologram extends BaseHologram {
 
     private final String name;
-    private final List<InternalHologramLine> lines;
 
     protected InternalHologram(Location source, String name, NMSManager nmsManager) {
         super(source, nmsManager);
         this.name = name;
-        this.lines = new ArrayList<>();
-    }
-
-    public String getName() {
-        return name;
     }
 
     public InternalTextLine createTextLine(String text, String serializedConfigValue) {
@@ -39,16 +30,15 @@ public class InternalHologram extends BaseHologram {
         return new InternalItemLine(this, getNMSManager(), icon, serializedConfigValue);
     }
 
+    public String getName() {
+        return name;
+    }
+
     @Override
     public Plugin getOwnerPlugin() {
         return HolographicDisplays.getInstance();
     }
-
+    
-    @Override
-    public List<InternalHologramLine> getLinesUnsafe() {
-        return lines;
-    }
-
     @Override
     public boolean isVisibleTo(Player player) {
         return true;