Create SelectChallengeGUI that allows to choose one challenge from input challenge list and return it into GUI.

src/main/java/world/bentobox/challenges/panel/util/SelectChallengeGUI.java

@@ -0,0 +1,138 @@
+package world.bentobox.challenges.panel.util;
+
+
+import org.bukkit.Material;
+import java.util.List;
+import java.util.function.BiConsumer;
+
+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.database.object.Challenges;
+
+
+/**
+ * This class creates new GUI that allows to select single challenge, which is returned via consumer.
+ */
+public class SelectChallengeGUI
+{
+	public SelectChallengeGUI(User user, List<Challenges> challengesList, BiConsumer<Boolean, Challenges> consumer)
+	{
+		this.consumer = consumer;
+		this.user = user;
+		this.challengesList = challengesList;
+
+		this.build(0);
+	}
+
+
+	/**
+	 * This method builds panel that allows to select single challenge from input challenges.
+	 */
+	private void build(int pageIndex)
+	{
+		PanelBuilder panelBuilder = new PanelBuilder().user(this.user).name(this.user.getTranslation("challenges.gui.choose-challenge-title"));
+
+		// Maximal elements in page.
+		final int MAX_ELEMENTS = 36;
+
+		final int correctPage;
+
+		if (pageIndex < 0)
+		{
+			correctPage = this.challengesList.size() / MAX_ELEMENTS;
+		}
+		else if (pageIndex > (this.challengesList.size() / MAX_ELEMENTS))
+		{
+			correctPage = 0;
+		}
+		else
+		{
+			correctPage = pageIndex;
+		}
+
+		// Navigation buttons
+
+		panelBuilder.item(3,
+			new PanelItemBuilder().
+				icon(Material.SIGN).
+				name(this.user.getTranslation("challenges.gui.buttons.previous")).
+				clickHandler( (panel, user1, clickType, slot) -> {
+					this.build(correctPage - 1);
+					return true;
+				}).build());
+
+		panelBuilder.item(4,
+			new PanelItemBuilder().
+				icon(Material.OAK_DOOR).
+				name(this.user.getTranslation("challenges.gui.buttons.return")).
+				clickHandler( (panel, user1, clickType, slot) -> {
+					this.consumer.accept(false, null);
+					return true;
+				}).build());
+
+		panelBuilder.item(5,
+			new PanelItemBuilder().
+				icon(Material.SIGN).
+				name(this.user.getTranslation("challenges.gui.buttons.next")).
+				clickHandler( (panel, user1, clickType, slot) -> {
+					this.build(correctPage + 1);
+					return true;
+				}).build());
+
+		int challengesIndex = MAX_ELEMENTS * correctPage;
+
+		// I want first row to be only for navigation and return button.
+		int index = 9;
+
+		while (challengesIndex < ((correctPage + 1) * MAX_ELEMENTS) &&
+			challengesIndex < this.challengesList.size())
+		{
+			panelBuilder.item(index++, this.createChallengeButton(this.challengesList.get(challengesIndex++)));
+		}
+
+		panelBuilder.build();
+
+		panelBuilder.build();
+	}
+
+
+	/**
+	 * This method builds PanelItem for given challenge.
+	 * @param challenge Challenge which PanelItem must be created.
+	 * @return new PanelItem for given Challenge.
+	 */
+	private PanelItem createChallengeButton(Challenges challenge)
+	{
+		return new PanelItemBuilder().
+			name(challenge.getFriendlyName()).
+			description(challenge.getDescription()).
+			icon(challenge.getIcon()).
+			clickHandler((panel, user1, clickType, slot) -> {
+				this.consumer.accept(true, challenge);
+				return true;
+			}).build();
+	}
+
+
+// ---------------------------------------------------------------------
+// Section: Variables
+// ---------------------------------------------------------------------
+
+
+	/**
+	 * This variable stores consumer.
+	 */
+	private BiConsumer<Boolean, Challenges> consumer;
+
+	/**
+	 * User who runs GUI.
+	 */
+	private User user;
+
+	/**
+	 * Current value.
+	 */
+	private List<Challenges> challengesList;
+}