package net.minecraft.client.gui;

import net.fabricmc.api.EnvType;
import net.fabricmc.api.Environment;
import net.minecraft.client.gui.components.events.ContainerEventHandler;
import net.minecraft.client.gui.components.events.GuiEventListener;
import org.jetbrains.annotations.Nullable;

/**
 * Represents a path of components in a user interface hierarchy.
 * <p>
 * It provides methods to create and manipulate component paths.
 */
@Environment(EnvType.CLIENT)
public interface ComponentPath {
	/**
	 * Creates a leaf component path with the specified {@code GuiEventListener} component.
	 * <p>
	 * @return a new leaf component path.
	 * 
	 * @param component the component associated with the leaf path
	 */
	static ComponentPath leaf(GuiEventListener component) {
		return new ComponentPath.Leaf(component);
	}

	/**
	 * Creates a component path with the specified {@code ContainerEventHandler} component and an optional child path.
	 * <p>
	 * @return a new component path, or {@code null} if the child path is null
	 * 
	 * @param component the component associated with the path
	 * @param childPath the child path associated with the component
	 */
	@Nullable
	static ComponentPath path(ContainerEventHandler component, @Nullable ComponentPath childPath) {
		return childPath == null ? null : new ComponentPath.Path(component, childPath);
	}

	/**
	 * Creates a new {@code ComponentPath} leaf node with the specified {@code GuiEventListener} component and an array of {@code ContainerEventHandler} ancestors.
	 * <p>
	 * @return a new component path
	 * 
	 * @param leafComponent the new 'Leaf' component associated with the path
	 * @param ancestorComponents the array of ancestor components associated with the path, ordered in reverse ascending order towards root.
	 */
	static ComponentPath path(GuiEventListener leafComponent, ContainerEventHandler... ancestorComponents) {
		ComponentPath componentPath = leaf(leafComponent);

		for (ContainerEventHandler containerEventHandler : ancestorComponents) {
			componentPath = path(containerEventHandler, componentPath);
		}

		return componentPath;
	}

	/**
	 * {@return the {@code GuiEventListener} component associated with this component path}
	 */
	GuiEventListener component();

	/**
	 * Applies focus to or removes focus from the component associated with this component path.
	 * 
	 * @param focused {@code true} to apply focus, {@code false} to remove focus.
	 */
	void applyFocus(boolean focused);

	/**
	 * The {@code Leaf} class represents a leaf component path in the hierarchy.
	 */
	@Environment(EnvType.CLIENT)
	public record Leaf(GuiEventListener component) implements ComponentPath {
		@Override
		public void applyFocus(boolean focused) {
			this.component.setFocused(focused);
		}
	}

	/**
	 * The {@code Path} class represents a non-leaf component path in the hierarchy.
	 */
	@Environment(EnvType.CLIENT)
	public record Path(ContainerEventHandler component, ComponentPath childPath) implements ComponentPath {
		@Override
		public void applyFocus(boolean focused) {
			if (!focused) {
				this.component.setFocused(null);
			} else {
				this.component.setFocused(this.childPath.component());
			}

			this.childPath.applyFocus(focused);
		}
	}
}