Introduced GUI relationships.

* NEW: Gui: can now have a parent. If so, a closing GUI will
  open its parent, like a modal dialog.
* NEW: Gui: can now be immune to the next close event, if needed.
* BUG: Gui: getOpenGui() does not throw an NPE anymore if no open
  GUI was found.
* OPT: PromptGui: removed unneeded fields.

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

@@ -21,6 +21,7 @@ package fr.moribus.imageonmap.guiproko.core;
 import fr.moribus.imageonmap.PluginLogger;
 import java.lang.reflect.Constructor;
 import java.util.HashMap;
+import org.bukkit.Bukkit;
 import org.bukkit.entity.HumanEntity;
 import org.bukkit.entity.Player;
 import org.bukkit.event.Listener;
@@ -33,6 +34,10 @@ abstract public class Gui
      */
     private Player player;
     
+    /**
+     * The parent of this GUI (if any).
+     */
+    private Gui parent;
     
     /**
      * If the inventory is currently open.
@@ -40,13 +45,10 @@ abstract public class Gui
     private boolean open = false;
     
     /**
-     * Closes this inventory.
+     * If the GUI is immune to close events.
+     * Useful to filter out excessive InventoryCloseEvents Bukkit sends ...
      */
-    public void close()
+    private boolean immune = false;
-    {
-        setClosed();
-    }
-    
     
     /* ===== Public API ===== */
     
@@ -59,6 +61,27 @@ abstract public class Gui
         onAfterUpdate();
     }
     
+    /**
+     * Closes this inventory.
+     */
+    public void close()
+    {
+        close(false);
+    }
+    
+    /**
+     * Closes this inventory.
+     * (Dirty hack edition)
+     * @param immune if true, the parent of this GUI will be set immune when opened
+     */
+    protected void close(boolean immune)
+    {
+        onClose();
+        
+        if(parent != null)
+           Gui.open(player, parent).setImmune(immune);
+    }
+    
     /* ===== Protected API ===== */
     
     /**
@@ -74,7 +97,7 @@ abstract public class Gui
     protected void onAfterUpdate() {}
     
     
-    protected final void setClosed()
+    protected void onClose()
     {
         if(open == false) return;
         open = false;
@@ -94,9 +117,31 @@ abstract public class Gui
     /** @return If the GUI is currently open or not. */
     public final boolean isOpen() { return open; }
     
+    /** @return The parent of this GUI. */
+    public final Gui getParent() { return parent; }
+    
+    private void setParent(Gui parent)
+    {
+        if(parent == this)
+            throw new IllegalArgumentException("A GUI cannot be its own parent.");
+        this.parent = parent;
+    }
+    
     /** @return The player this Gui instance is associated to. */
     protected final Player getPlayer() { return player; }
     
+    protected boolean checkImmune()
+    {
+        if(!immune) return false;
+        immune = false;
+        return true;
+    }
+    
+    private void setImmune(boolean immune)
+    {
+        this.immune = immune;
+    }
+    
     /* ===== Static API ===== */
     
     /**
@@ -159,6 +204,31 @@ abstract public class Gui
         }
     }
     
+    /**
+     * Opens a GUI for a player.
+     * @param <T> A GUI type.
+     * @param owner The player the GUI will be shown to.
+     * @param gui The GUI.
+     * @param parent The parent of the newly created GUI. Can be null.
+     * @return The opened GUI.
+     */
+    static public final <T extends Gui> T open(final Player owner, final T gui, final Gui parent)
+    {
+        Gui openGui = openGuis.get(owner);
+        if(openGui != null) openGui.onClose();
+        if(parent != null) ((Gui)gui).setParent(parent);
+        
+         Bukkit.getScheduler().runTaskLater(plugin, new Runnable() {
+                @Override
+                public void run()
+                {
+                    ((Gui)gui).open(owner);/* JAVA GENERICS Y U NO WORK */
+                }
+            }, 0);
+        
+        return gui;
+    }
+    
     /**
      * Opens a GUI for a player.
      * @param <T> A GUI type.
@@ -168,10 +238,7 @@ abstract public class Gui
      */
     static public final <T extends Gui> T open(Player owner, T gui)
     {
-        close(owner);
+        return open(owner, gui, null);
-        ((Gui)gui).open(owner);/* JAVA GENERICS Y U NO WORK */
-
-        return gui;
     }
     
     /**
@@ -193,6 +260,7 @@ abstract public class Gui
     static public final <T extends Gui> T getOpenGui(HumanEntity entity, Class<T> guiClass)
     {
         Gui openGui = getOpenGui(entity);
+        if(openGui == null) return null;
         if(!guiClass.isAssignableFrom(openGui.getClass())) return null;
         return (T) openGui;
     }

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

@@ -112,8 +112,13 @@ abstract public class InventoryGui extends Gui
     @Override
     public void close()
     {
-        super.close();
+        if(!isOpen()) return;
+        
+        //If close() is called manually, not from InventoryCloseEvent
+        if(getPlayer().getOpenInventory().equals(inventory))
             getPlayer().closeInventory();
+        
+        super.close();
     }
     
     /**
@@ -236,11 +241,16 @@ abstract public class InventoryGui extends Gui
         @EventHandler
         public void onInventoryClose(InventoryCloseEvent event)
         {
-            Gui openGui = getOpenGui(event.getPlayer());
+            InventoryGui openGui = getOpenGui(event.getPlayer(), InventoryGui.class);
             if(openGui == null) return;
             
-            if(!openGui.isOpen());
+            if(!event.getInventory().equals(openGui.inventory)) return;
-                openGui.setClosed();
+            
+            if(openGui.isOpen())
+            {
+                if(openGui.checkImmune()) return;
+                openGui.close();
+            }
         }
     }
     

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

@@ -23,8 +23,6 @@ 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;
@@ -46,10 +44,8 @@ public class PromptGui extends Gui
     
     /* ===== 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()
@@ -60,12 +56,12 @@ public class PromptGui extends Gui
     
     static public void prompt(Player owner, Callback<String> callback)
     {
-        prompt(owner, callback, "");
+        prompt(owner, callback, "", null);
     }
     
-    static public void prompt(Player owner, Callback<String> callback, String contents)
+    static public void prompt(Player owner, Callback<String> callback, String contents, Gui parent)
     {
-        Gui.open(owner, new PromptGui(callback, contents));
+        Gui.open(owner, new PromptGui(callback, contents), parent);
     }
     
     static private void init()
@@ -81,10 +77,8 @@ public class PromptGui extends Gui
             
             
             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)
         {
@@ -144,17 +138,17 @@ public class PromptGui extends Gui
     }
     
     @Override
-    public void close()
+    protected void onClose()
     {
         Block block = getPlayer().getWorld().getBlockAt(signLocation);
         block.setType(Material.AIR);
-        super.close();
+        super.onClose();
     }
     
     private void validate(String[] lines)
     {
         callback.call(getSignContents(lines));
-        this.close();
+        this.close(true);//Bukkit sends extra InventoryCloseEvents when closing a sign GUI...
     }
     
     static private String getSignContents(String[] lines)

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

@@ -69,12 +69,6 @@ public class ConfirmDeleteMapGui extends ActionGui
      */
     private final ImageMap mapToDelete;
 
-    /**
-     * The previously-viewed page of the list GUI.
-     * Used to be able to bring the user back to the same page.
-     */
-    private final int currentPage;
-
     /**
      * A source of randomness.
      *
@@ -86,12 +80,10 @@ public class ConfirmDeleteMapGui extends ActionGui
     /**
      *
      * @param mapToDelete The map being deleted.
-     * @param currentPage The previously-viewed page of the list GUI.
      */
-    public ConfirmDeleteMapGui(ImageMap mapToDelete, int currentPage)
+    public ConfirmDeleteMapGui(ImageMap mapToDelete)
     {
         this.mapToDelete = mapToDelete;
-        this.currentPage = currentPage;
     }
 
     @Override
@@ -165,7 +157,7 @@ public class ConfirmDeleteMapGui extends ActionGui
     @GuiAction
     protected void action_cancel()
     {
-        Gui.open(getPlayer(), new MapDetailGui(mapToDelete)).setCurrentPageX(currentPage);
+        close();
     }
     
     @GuiAction
@@ -184,6 +176,6 @@ public class ConfirmDeleteMapGui extends ActionGui
             getPlayer().sendMessage(ChatColor.RED + ex.getMessage());
         }
 
-        Gui.open(getPlayer(), new MapListGui(/* currentPage */));
+        close();
     }
 }

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

@@ -84,13 +84,13 @@ public class MapDetailGui extends ExplorerGui<Void>
                 map.rename(newName);
                 getPlayer().sendMessage(ChatColor.GRAY + "Map successfuly renamed.");
             }
-        }, map.getName());
+        }, map.getName(), this);
     }
     
     @GuiAction
     private void delete()
     {
-        Gui.open(getPlayer(), new ConfirmDeleteMapGui(map, getCurrentPageX()));
+        Gui.open(getPlayer(), new ConfirmDeleteMapGui(map), this);
     }
 
     @Override

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

@@ -69,7 +69,7 @@ public class MapListGui extends ExplorerGui<ImageMap>
     @Override
     protected void onRightClick(ImageMap map)
     {
-        Gui.open(getPlayer(), new MapDetailGui(map));
+        Gui.open(getPlayer(), new MapDetailGui(map), this);
     }
     
     @Override