New Sign-based Prompt GUI API.

* NEW: Added new Callback class.
* NEW: Added ReflectionUtils module.
* NEW: Added new PromptGui class.
* NEW: MapDetailGui: Implement renaming using new prompt API.
* BUG: ExplorerGUI: Fix a crash when setting null data.
* BUG: InventoryGUI: Fix titles longer than 32 characters.

src/main/java/fr/moribus/imageonmap/ReflectionUtils.java

@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2013 Moribus
+ * Copyright (C) 2015 ProkopyL <prokopylmc@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package fr.moribus.imageonmap;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import org.bukkit.Bukkit;
+
+abstract public class ReflectionUtils 
+{
+    static public String getBukkitPackageVersion()
+    {
+        return getBukkitPackageName().substring("org.bukkit.craftbukkit.".length());
+    }
+    
+    static public String getBukkitPackageName()
+    {
+        return Bukkit.getServer().getClass().getPackage().getName();
+    }
+    
+    static public String getMinecraftPackageName()
+    {
+        return "net.minecraft.server." + getBukkitPackageVersion();
+    }
+    
+    static public Class getBukkitClassByName(String name) throws ClassNotFoundException
+    {
+        return Class.forName(getBukkitPackageName() + "." + name);
+    }
+    
+    static public Class getMinecraftClassByName(String name) throws ClassNotFoundException
+    {
+        return Class.forName(getMinecraftPackageName() + "." + name);
+    }
+    
+    static public Object getFieldValue(Class hClass, Object instance, String name) 
+            throws NoSuchFieldException, IllegalArgumentException, IllegalAccessException
+    {
+        return getField(hClass, name).get(instance);
+    }
+    
+    static public Object getFieldValue(Object instance, String name) 
+            throws NoSuchFieldException, IllegalArgumentException, IllegalAccessException
+    {
+        return getFieldValue(instance.getClass(), instance, name);
+    }
+    
+    static public Field getField(Class klass, String name) throws NoSuchFieldException
+    {
+        Field field = klass.getDeclaredField(name);
+        field.setAccessible(true);
+        return field;
+    }
+    
+    static public Field getField(Class klass, Class type) throws NoSuchFieldException
+    {
+        for(Field field : klass.getDeclaredFields())
+        {
+            if(field.getType().equals(type))
+            {
+                field.setAccessible(true);
+                return field;
+            }
+        }
+        throw new NoSuchFieldException("Class " + klass.getName() + " does not define any field of type " + type.getName());
+    }
+    
+    static public void setFieldValue(Object instance, String name, Object value) 
+            throws NoSuchFieldException, IllegalArgumentException, IllegalAccessException
+    {
+        setFieldValue(instance.getClass(), instance, name, value);
+    }
+    
+    static public void setFieldValue(Class hClass, Object instance, String name, Object value) 
+            throws NoSuchFieldException, IllegalArgumentException, IllegalAccessException
+    {
+        getField(hClass, name).set(instance, value);
+    }
+    
+    static public Object call(Class hClass, String name, Object ... parameters) 
+            throws NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException
+    {
+        return call(hClass, null, name, parameters);
+    }
+    
+    static public Object call(Object instance, String name, Object ... parameters) 
+            throws NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException
+    {
+        return call(instance.getClass(), instance, name, parameters);
+    }
+    
+    static public Object call(Class hClass, Object instance, String name, Object ... parameters) 
+            throws NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException
+    {
+        Method method = hClass.getMethod(name, getTypes(parameters));
+        return method.invoke(instance, parameters);
+    }
+    
+    static public Object instanciate(Class hClass, Object ... parameters) 
+            throws NoSuchMethodException, InstantiationException, 
+            IllegalAccessException, IllegalArgumentException, InvocationTargetException
+    {
+        Constructor constructor = hClass.getConstructor(getTypes(parameters));
+        return constructor.newInstance(parameters);
+    }
+    
+    static public Class[] getTypes(Object[] objects)
+    {
+        Class[] types = new Class[objects.length];
+        for(int i = 0; i < objects.length; i++)
+        {
+            types[i] = objects[i].getClass();
+        }
+        return types;
+    }
+}

src/main/java/fr/moribus/imageonmap/guiproko/core/Callback.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2013 Moribus
+ * Copyright (C) 2015 ProkopyL <prokopylmc@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package fr.moribus.imageonmap.guiproko.core;
+
+public interface Callback<T>
+{
+    public void call(T parameter);
+}

src/main/java/fr/moribus/imageonmap/guiproko/core/ExplorerGui.java

@@ -98,10 +98,11 @@ abstract public class ExplorerGui<T> extends ActionGui
     protected void setData(T[] data, int dataWidth)
     {
         this.data = data;
+        int dataLength = data == null ? 0 : data.length;
         if(dataWidth > 0)
-            setDataShape(dataWidth, (int) Math.ceil((double) data.length / (double) dataWidth));
+            setDataShape(dataWidth, (int) Math.ceil((double) dataLength / (double) dataWidth));
         else
-            setDataShape(0, data.length);
+            setDataShape(0, dataLength);
     }
 
     /**

src/main/java/fr/moribus/imageonmap/guiproko/core/InventoryGui.java

@@ -35,6 +35,7 @@ abstract public class InventoryGui extends Gui
     static protected final int INVENTORY_ROW_SIZE = 9;
     static protected final int MAX_INVENTORY_COLUMN_SIZE = 6;
     static protected final int MAX_INVENTORY_SIZE = INVENTORY_ROW_SIZE * MAX_INVENTORY_COLUMN_SIZE;
+    static protected final int MAX_TITLE_LENGTH = 32;
     
     public InventoryGui()
     {
@@ -197,7 +198,14 @@ abstract public class InventoryGui extends Gui
      * It will be applied on the next GUI update.
      * @param title The new title of the inventory
      */
-    protected void setTitle(String title){this.title = title;}
+    protected void setTitle(String title)
+    {
+        if(title != null && title.length() > MAX_TITLE_LENGTH)
+        {
+            title = title.substring(0, MAX_TITLE_LENGTH - 4) + "...";
+        }
+        this.title = title;
+    }
     
     /** @return The underlying inventory, or null if the Gui has not been opened yet. */
     public Inventory getInventory() { return inventory; }

src/main/java/fr/moribus/imageonmap/guiproko/core/PromptGui.java

@@ -0,0 +1,257 @@
+/*
+ * Copyright (C) 2013 Moribus
+ * Copyright (C) 2015 ProkopyL <prokopylmc@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package fr.moribus.imageonmap.guiproko.core;
+
+import fr.moribus.imageonmap.ImageOnMap;
+import fr.moribus.imageonmap.PluginLogger;
+import fr.moribus.imageonmap.ReflectionUtils;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import org.bukkit.Bukkit;
+import org.bukkit.Chunk;
+import org.bukkit.Location;
+import org.bukkit.Material;
+import org.bukkit.World;
+import org.bukkit.block.Block;
+import org.bukkit.block.Sign;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.block.SignChangeEvent;
+
+public class PromptGui extends Gui
+{
+    static private final int SIGN_LINES_COUNT = 4;
+    static private final int SIGN_COLUMNS_COUNT = 15;
+    
+    static private boolean isInitialized = false;
+    
+    /* ===== Reflection to Sign API ===== */
+    static private Field fieldSign = null;//CraftSign.sign
+    static private Field fieldIsEditable = null;//TileEntitySign.isEditable
+    static private Method methodGetHandle = null;//CraftPlayer.getHandle()
+    static private Method methodOpenSign = null;//EntityHuman.openSign()
+    static private Field fieldSignEditor = null;//TileEntitySign.k{EntityHuman}
+    static private Class classTileEntitySign = null;//CraftBlock.class
+    
+    static public boolean isAvailable()
+    {
+        if(!isInitialized) init();
+        return fieldSign != null;
+    }
+    
+    static public void prompt(Player owner, Callback<String> callback)
+    {
+        prompt(owner, callback, "");
+    }
+    
+    static public void prompt(Player owner, Callback<String> callback, String contents)
+    {
+        Gui.open(owner, new PromptGui(callback, contents));
+    }
+    
+    static private void init()
+    {
+        isInitialized = true;
+        
+        try
+        {
+            Class CraftSign = ReflectionUtils.getBukkitClassByName("block.CraftSign");
+            classTileEntitySign = ReflectionUtils.getMinecraftClassByName("TileEntitySign");
+            Class CraftPlayer = ReflectionUtils.getBukkitClassByName("entity.CraftPlayer");
+            Class EntityHuman = ReflectionUtils.getMinecraftClassByName("EntityHuman");
+            
+            
+            fieldSign = ReflectionUtils.getField(CraftSign, "sign");
+            fieldIsEditable = ReflectionUtils.getField(classTileEntitySign, "isEditable");
+            methodGetHandle = CraftPlayer.getDeclaredMethod("getHandle");
+            methodOpenSign = EntityHuman.getDeclaredMethod("openSign", classTileEntitySign);
+            fieldSignEditor = ReflectionUtils.getField(classTileEntitySign, EntityHuman);
+        }
+        catch (Exception ex)
+        {
+            PluginLogger.error("Unable to initialize Sign Prompt API", ex);
+            fieldSign = null;
+        }
+    }
+    
+    private final Callback<String> callback;
+    private Location signLocation;
+    private String contents;
+    
+    public PromptGui(Callback<String> callback, String contents)
+    {
+        this(callback);
+        this.contents = contents;
+    }
+    
+    public PromptGui(Callback<String> callback)
+    {
+        super();
+        registerListener(PromptGuiListener.class);
+        if(!isAvailable()) throw new IllegalStateException("Sign-based prompt GUI are not available");
+        this.callback = callback;
+    }
+    
+    @Override
+    protected void open(final Player player)
+    {
+        super.open(player);
+        
+        signLocation = findAvailableLocation(player);
+        Block block = player.getWorld().getBlockAt(signLocation);
+        block.setType(Material.SIGN_POST, false);
+        final Sign sign = (Sign) block.getState();
+        setSignContents(sign, contents);
+        sign.update();
+        
+        Bukkit.getScheduler().scheduleSyncDelayedTask(ImageOnMap.getPlugin(), new Runnable()
+        {
+            @Override
+            public void run()
+            {
+                try
+                {
+                    Object signTE = fieldSign.get(sign);
+                    Object playerEntity = methodGetHandle.invoke(player);
+                    methodOpenSign.invoke(playerEntity, signTE);
+                }
+                catch(Throwable ex)
+                {
+                    PluginLogger.error("Error while opening Sign prompt", ex);
+                }
+            }  
+        }, 3);
+        
+    }
+    
+    @Override
+    public void close()
+    {
+        Block block = getPlayer().getWorld().getBlockAt(signLocation);
+        block.setType(Material.AIR);
+        super.close();
+    }
+    
+    private void validate(String[] lines)
+    {
+        callback.call(getSignContents(lines));
+        this.close();
+    }
+    
+    static private String getSignContents(String[] lines)
+    {
+        String content = lines[0].trim();
+        
+        for(int i = 1; i < lines.length; i++)
+        {
+            if(lines[i] == null || lines[i].isEmpty()) continue;
+            content += " " + lines[i].trim();
+        }
+        return content.trim();
+    }
+    
+    static private void setSignContents(Sign sign, String content)
+    {
+        String[] lines = new String[SIGN_LINES_COUNT + 1];
+        String curLine;
+        int curLineIndex = 0, spacePos;
+        
+        if(content != null)
+        {
+            lines[0] = content;
+            while(curLineIndex < SIGN_LINES_COUNT)
+            {
+                curLine = lines[curLineIndex];
+                if(curLine.length() <= SIGN_COLUMNS_COUNT)
+                    break;
+
+                spacePos = curLine.lastIndexOf(' ', SIGN_COLUMNS_COUNT);
+                if(spacePos < 0) break;
+                lines[curLineIndex + 1] = curLine.substring(spacePos + 1);
+                lines[curLineIndex] = curLine.substring(0, spacePos);
+                curLineIndex++;
+            }
+        }
+        
+        for(int i = SIGN_LINES_COUNT; i --> 0;)
+        {
+            sign.setLine(i, lines[i]);
+        }
+    }
+    
+    static private Location findAvailableLocation(Player player)
+    {
+        World world = player.getWorld();
+        Chunk playerChunk = player.getLocation().getChunk();
+        Chunk firstChunk = world.getChunkAt(playerChunk.getX() - 1, playerChunk.getZ() - 1);
+        Location firstLoc = firstChunk.getBlock(0, 255, 0).getLocation();
+        Location loc;
+        
+        for(int i = 48; i --> 0;)
+        {
+            for(int j = 0; j --> -10;)
+            {
+                for(int k = 48; k --> 0;)
+                {
+                    loc = firstLoc.add(i, j, k);
+                    if(hasSpace(world, loc))
+                        return loc;
+                }
+            }
+        }
+        
+        return null;
+    }
+    
+    static private boolean hasSpace(World world, Location loc)
+    {
+        if(!Material.AIR.equals(world.getBlockAt(loc).getType()))
+            return false;
+        
+        for(int i = 1; i --> -1;)
+        {
+            for(int j = 1; j --> -1;)
+            {
+                for(int k = 1; k --> -1;)
+                {
+                    if(!Material.AIR.equals(world.getBlockAt(
+                            loc.getBlockX() + i, loc.getBlockY() + j, loc.getBlockZ() + k)
+                            .getType()))
+                        return false;
+                }
+            }
+        }
+            
+        return true;
+    }
+    
+    static private final class PromptGuiListener implements Listener
+    {
+        @EventHandler
+        public void onSignChange(SignChangeEvent event)
+        {
+            PromptGui gui = Gui.getOpenGui(event.getPlayer(), PromptGui.class);
+            if(gui == null) return;
+            gui.validate(event.getLines());
+        }
+    }
+}

src/main/java/fr/moribus/imageonmap/guiproko/list/MapDetailGui.java

@@ -68,6 +68,25 @@ public class MapDetailGui extends ExplorerGui<Void>
         else return super.getEmptyViewItem();
     }
     
+    @GuiAction
+    private void rename()
+    {
+        PromptGui.prompt(getPlayer(), new Callback<String>()
+        {
+            @Override
+            public void call(String newName)
+            {
+                if(newName == null || newName.isEmpty())
+                {
+                    getPlayer().sendMessage(ChatColor.RED + "Map names can't be empty.");
+                    return;
+                }
+                map.rename(newName);
+                getPlayer().sendMessage(ChatColor.GRAY + "Map successfuly renamed.");
+            }
+        }, map.getName());
+    }
+    
     @GuiAction
     private void delete()
     {