package bjc.utils.gui.panels;

import javax.swing.*;
import javax.swing.border.EmptyBorder;
import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

/**
 * A JPanel with a clickable header that can collapse/expand its content.
 *
 * Features:
 *  - Title + arrow (▶ / ▼)
 *  - Optional custom header component on the right side (e.g., buttons, filters)
 *  - Add children like a normal JPanel (they go into the content area)
 */
public class CollapsiblePanel extends JPanel {
	private static final long serialVersionUID = -5941733171067755926L;
	
	private final JPanel headerPanel;
	private final JPanel headerClickableArea;
	private final JPanel headerExtrasPanel;
	private final JButton toggleButton;
	private final JLabel titleLabel;
	private final JPanel contentPanel;

	private boolean collapsed = false;
	private boolean internalAdd = false; // guard for addImpl

	/**
	 * Create a new collapsible panel.
	 * 
	 * @param title The title for the panel
	 */
	public CollapsiblePanel(String title) {
		this(title, new FlowLayout(FlowLayout.LEFT, 4, 4));
	}

	/**
	 * Create a new collapsible panel, using the following layout manager for the content.
	 * 
	 * @param title The title for the panel
	 * @param contentLayout The layout manager for the panel
	 */
	public CollapsiblePanel(String title, LayoutManager contentLayout) {
		super(new BorderLayout());

		// === Header ===
		headerPanel = new JPanel(new BorderLayout(4, 0));
		headerPanel.setBorder(new EmptyBorder(2, 4, 2, 4));
		headerPanel.setOpaque(false);

		// Left side: clickable region (arrow + title)
		headerClickableArea = new JPanel(new BorderLayout(4, 0));
		headerClickableArea.setOpaque(false);

		toggleButton = new JButton("\u25BC"); // ▼ expanded
		toggleButton.setMargin(new Insets(0, 4, 0, 4));
		toggleButton.setFocusable(false);
		toggleButton.setBorderPainted(false);
		toggleButton.setContentAreaFilled(false);

		titleLabel = new JLabel(title);
		titleLabel.setBorder(new EmptyBorder(0, 2, 0, 0));
		titleLabel.setFont(titleLabel.getFont().deriveFont(Font.BOLD));

		headerClickableArea.add(toggleButton, BorderLayout.WEST);
		headerClickableArea.add(titleLabel, BorderLayout.CENTER);

		// Right side: custom header component container
		headerExtrasPanel = new JPanel(new FlowLayout(FlowLayout.RIGHT, 4, 0));
		headerExtrasPanel.setOpaque(false);

		headerPanel.add(headerClickableArea, BorderLayout.CENTER);
		headerPanel.add(headerExtrasPanel, BorderLayout.EAST);

		// === Content ===
		contentPanel = new JPanel(contentLayout);

		// === Wiring: toggle behavior ===
		toggleButton.addActionListener(e -> setCollapsed(!isCollapsed()));

		MouseAdapter headerClick = new MouseAdapter() {
			@Override
			public void mouseClicked(MouseEvent e) {
				if (SwingUtilities.isLeftMouseButton(e)) {
					setCollapsed(!isCollapsed());
				}
			}
		};
		// Only the left side (arrow + title) toggles; extras panel is not clickable for
		// toggle
		headerClickableArea.addMouseListener(headerClick);
		titleLabel.addMouseListener(headerClick);
		toggleButton.addMouseListener(headerClick);

		// Add header + content to this panel
		internalAdd = true;
		add(headerPanel, BorderLayout.NORTH);
		add(contentPanel, BorderLayout.CENTER);
		internalAdd = false;
	}

	/**
	 * Returns the content panel; you can use this if you want direct access.
	 * 
	 * @return The content panel
	 */
	public JPanel getContentPanel() {
		return contentPanel;
	}

	/**
	 * Returns the panel that holds extra header components (right side). 
	 * 
	 * @return The header extras panel
	 */
	public JPanel getHeaderExtrasPanel() {
		return headerExtrasPanel;
	}

	/**
	 * Replace any existing header extras with a single component. Pass null to
	 * clear.
	 * 
	 * @param comp The header component to use
	 */
	public void setHeaderComponent(Component comp) {
		headerExtrasPanel.removeAll();
		if (comp != null) {
			headerExtrasPanel.add(comp);
		}
		headerExtrasPanel.revalidate();
		headerExtrasPanel.repaint();
	}

	/**
	 * Add an extra component to the header (right side) without clearing existing
	 * ones.
	 * 
	 * 
	 * @param comp The component to add
	 */
	public void addHeaderComponent(Component comp) {
		headerExtrasPanel.add(comp);
		headerExtrasPanel.revalidate();
		headerExtrasPanel.repaint();
	}

	/**
	 *  Set the header title text.
	 *  
	 *  @param title The header title
	 */
	public void setTitle(String title) {
		titleLabel.setText(title);
	}

	/**
	 * Get the header title
	 * 
	 * @return The header title
	 */
	public String getTitle() {
		return titleLabel.getText();
	}

	/**
	 * Collapse or expand the content.
	 * 
	 * @param collapsed True to collapse the panel, false to expand it
	 */
	public void setCollapsed(boolean collapsed) {
		if (this.collapsed == collapsed)
			return;
		this.collapsed = collapsed;
		contentPanel.setVisible(!collapsed);
		toggleButton.setText(collapsed ? "\u25B6" : "\u25BC"); // ▶ / ▼
		revalidate();
		repaint();
	}

	/**
	 * Check if the panel is collapsed or not.
	 * 
	 * @return Is the panel collapsed or not?
	 */
	public boolean isCollapsed() {
		return collapsed;
	}

	/**
	 * Override addImpl so that user-added components go into the content area
	 * instead of directly into the outer BorderLayout.
	 */
	@Override
	protected void addImpl(Component comp, Object constraints, int index) {
		if (internalAdd) {
			super.addImpl(comp, constraints, index);
		} else {
			contentPanel.add(comp, constraints, index);
		}
	}

	/**
	 * Convenience factory for a titled, initially-collapsed panel. 
	 *  
	 * @param title The title for the panel
	 * @param layout The layout manager for the content
	 * @return The panel created
	 */
	public static CollapsiblePanel collapsed(String title, LayoutManager layout) {
		CollapsiblePanel p = new CollapsiblePanel(title, layout);
		p.setCollapsed(true);
		return p;
	}
}