Update all admin panels.

Admin panels will not contain better locales codding and easier-to-improve design.

Remove old and unused GUIs.

src/main/java/world/bentobox/challenges/panel/CommonPagedPanel.java

@@ -0,0 +1,183 @@
+//
+// Created by BONNe
+// Copyright - 2021
+//
+
+
+package world.bentobox.challenges.panel;
+
+
+import org.bukkit.Material;
+import org.bukkit.World;
+import org.bukkit.inventory.ItemStack;
+import org.eclipse.jdt.annotation.NonNull;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Function;
+
+import world.bentobox.bentobox.api.panels.PanelItem;
+import world.bentobox.bentobox.api.panels.builders.PanelBuilder;
+import world.bentobox.bentobox.api.panels.builders.PanelItemBuilder;
+import world.bentobox.bentobox.api.user.User;
+import world.bentobox.challenges.ChallengesAddon;
+import world.bentobox.challenges.utils.Constants;
+
+
+/**
+ * This panel implements common things for Paged pages.
+ */
+public abstract class CommonPagedPanel extends CommonPanel
+{
+    /**
+     * Instantiates a new Common paged panel.
+     *
+     * @param addon the addon
+     * @param user the user
+     * @param world the world
+     * @param topLabel the top label
+     * @param permissionPrefix the permission prefix
+     */
+    protected CommonPagedPanel(ChallengesAddon addon,
+        User user,
+        World world, String topLabel, String permissionPrefix)
+    {
+        super(addon, user, world, topLabel, permissionPrefix);
+    }
+
+
+    /**
+     * Instantiates a new Common paged panel.
+     *
+     * @param parentPanel the parent panel
+     */
+    protected CommonPagedPanel(@NonNull CommonPanel parentPanel)
+    {
+        super(parentPanel);
+    }
+
+
+    /**
+     * Populate elements.
+     *
+     * @param panelBuilder the panel builder
+     * @param objectList the object list
+     * @param buttonBuilder the button builder
+     */
+    protected void populateElements(PanelBuilder panelBuilder,
+        List<?> objectList,
+        Function<Object, PanelItem> buttonBuilder)
+    {
+        final int MAX_ELEMENTS = 21;
+        final int size = objectList.size();
+
+        if (this.pageIndex < 0)
+        {
+            this.pageIndex = size / MAX_ELEMENTS;
+        }
+        else if (this.pageIndex > (size / MAX_ELEMENTS))
+        {
+            this.pageIndex = 0;
+        }
+
+        int objectIndex = MAX_ELEMENTS * this.pageIndex;
+
+        // I want first row to be only for navigation and return button.
+        int index = 10;
+
+        while (objectIndex < ((this.pageIndex + 1) * MAX_ELEMENTS) &&
+            objectIndex < size &&
+            index < 36)
+        {
+            if (!panelBuilder.slotOccupied(index))
+            {
+                panelBuilder.item(index, buttonBuilder.apply(objectList.get(objectIndex++)));
+            }
+
+            index++;
+        }
+
+        if (size > MAX_ELEMENTS && !(1.0 * size / MAX_ELEMENTS <= this.pageIndex + 1))
+        {
+            panelBuilder.item(26, this.getButton(CommonButtons.NEXT));
+
+        }
+
+        if (this.pageIndex > 0)
+        {
+            panelBuilder.item(18, this.getButton(CommonButtons.PREVIOUS));
+        }
+    }
+
+
+    /**
+     * This method returns PanelItem that represents given Button.
+     * @param button Button that must be returned.
+     * @return PanelItem with requested functionality.
+     */
+    protected PanelItem getButton(CommonButtons button)
+    {
+        final String reference = Constants.BUTTON + button.name().toLowerCase() + ".";
+
+        final String name = this.user.getTranslation(reference + "name");
+        final List<String> description = new ArrayList<>(3);
+
+        ItemStack icon;
+        PanelItem.ClickHandler clickHandler;
+
+        if (button == CommonButtons.NEXT)
+        {
+            description.add(this.user.getTranslation(reference + "description",
+                Constants.NUMBER, String.valueOf(this.pageIndex + 2)));
+
+            icon = new ItemStack(Material.OAK_SIGN, this.pageIndex + 2);
+            clickHandler = (panel, user, clickType, slot) ->
+            {
+                this.pageIndex++;
+                this.build();
+                return true;
+            };
+        }
+        else if (button == CommonButtons.PREVIOUS)
+        {
+            description.add(this.user.getTranslation(reference + "description",
+                Constants.NUMBER, String.valueOf(this.pageIndex)));
+
+            icon = new ItemStack(Material.OAK_SIGN, Math.max(1, this.pageIndex));
+            clickHandler = (panel, user, clickType, slot) ->
+            {
+                this.pageIndex--;
+                this.build();
+                return true;
+            };
+        }
+        else
+        {
+            icon = new ItemStack(Material.PAPER);
+            clickHandler = null;
+        }
+
+        return new PanelItemBuilder().
+            icon(icon).
+            name(name).
+            description(description).
+            clickHandler(clickHandler).
+            build();
+    }
+
+
+    /**
+     * Next and Previous Buttons.
+     */
+    private enum CommonButtons
+    {
+        NEXT,
+        PREVIOUS
+    }
+
+
+    /**
+     * Current page index.
+     */
+    private int pageIndex;
+}