package org.opentrafficsim.editor;
   
   import java.awt.event.ActionEvent;
   import java.util.LinkedList;
   
   import javax.swing.AbstractAction;
   import javax.swing.Action;
   import javax.swing.KeyStroke;
   
  /**
   * Navigation through coupled nodes.
   * <p>
   * Copyright (c) 2026-2026 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="https://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
   * </p>
   * @author Wouter Schakel
   */
  public class Navigation
  {
  
      /** OTS editor. */
      private final OtsEditor editor;
  
      /** Maximum number of navigation steps in the list. */
      private final int maxNavigate;
  
      /** Candidate keyref node that was coupled from to a key node, may be {@code null}. */
      private XsdTreeNode candidateBackNode;
  
      /** Keyref node that was coupled from to a key node, may be {@code null}. */
      private final LinkedList<XsdTreeNode> backNode = new LinkedList<>();
  
      /** Candidate attribute of back node referring to coupled node, may be {@code null}. */
      private String candidateBackAttribute;
  
      /** Attribute of back node referring to coupled node, may be {@code null}. */
      private final LinkedList<String> backAttribute = new LinkedList<>();
  
      /** Key node that is coupled to from a keyref node, may be {@code null}. */
      private XsdTreeNode coupledNode;
  
      /**
       * Constructor.
       * @param editor editor
       * @param maxNavigate maximum number of navigation steps
       */
      public Navigation(final OtsEditor editor, final int maxNavigate)
      {
          this.editor = editor;
          this.maxNavigate = maxNavigate;
          clear();
      }
  
      /**
       * Clear navigation list.
       */
      public void clear()
      {
          this.goBackAction.setEnabled(false);
          this.goBackAction.putValue(Action.NAME, "Go back");
          this.goToCoupledNodeAction.setEnabled(false);
          this.goToCoupledNodeAction.putValue(Action.NAME, "Go to coupled item");
      }
  
      /**
       * Sets coupled node from user action, i.e. the node that contains the key value to which a user selected node with keyref
       * refers to.
       * @param toNode key node that is coupled to from a keyref node, may be {@code null}.
       * @param fromNode keyref node that is coupled from to a key node, may be {@code null}.
       * @param fromAttribute attribute in keyref node that refers to coupled node, may be {@code null}.
       */
      public void setCoupledNode(final XsdTreeNode toNode, final XsdTreeNode fromNode, final String fromAttribute)
      {
          if (toNode == null)
          {
              this.goToCoupledNodeAction.setEnabled(false);
              this.goToCoupledNodeAction.putValue(Action.NAME, "Go to coupled item");
          }
          else
          {
              this.goToCoupledNodeAction.setEnabled(true);
              this.goToCoupledNodeAction.putValue(Action.NAME,
                      "Go to " + (fromAttribute != null ? fromNode.getAttributeValueOrDefault(fromAttribute)
                              : (fromNode.isIdentifiable() ? fromNode.getId() : fromNode.getValueOrDefault())));
          }
          this.coupledNode = toNode;
          this.candidateBackNode = fromNode;
          this.candidateBackAttribute = fromAttribute;
      }
  
      /**
       * Returns the go-back action.
       * @return go-back action
       */
      public Action getGoBackAction()
      {
          return this.goBackAction;
      }
  
     /** Go-back action. */
     private final Action goBackAction = new AbstractAction()
     {
         {
             putValue(Action.ACCELERATOR_KEY, KeyStroke.getKeyStroke("pressed F3"));
         }
 
         @Override
         public void actionPerformed(final ActionEvent e)
         {
             Navigation.this.editor.show(Navigation.this.backNode.pollLast(), Navigation.this.backAttribute.pollLast());
             if (Navigation.this.backNode.isEmpty())
             {
                 putValue(NAME, "Go back");
                 setEnabled(false);
             }
             else
             {
                 XsdTreeNode back = Navigation.this.backNode.peekLast();
                 Navigation.this.goBackAction.putValue(NAME,
                         "Go back to " + back.getNodeName() + (back.isIdentifiable() ? " " + back.getId() : ""));
                 Navigation.this.goBackAction.setEnabled(true);
             }
         }
     };
 
     /**
      * Returns go-to-coupled-item action.
      * @return go-to-coupled-item action
      */
     public Action getGotoCoupledNodeAction()
     {
         return this.goToCoupledNodeAction;
     }
 
     /** Go-to-coupled-item action. */
     private final Action goToCoupledNodeAction = new AbstractAction()
     {
         {
             putValue(Action.ACCELERATOR_KEY, KeyStroke.getKeyStroke("pressed F4"));
         }
 
         @Override
         public void actionPerformed(final ActionEvent e)
         {
             if (Navigation.this.coupledNode != null)
             {
                 Navigation.this.backNode.add(Navigation.this.candidateBackNode);
                 Navigation.this.backAttribute.add(Navigation.this.candidateBackAttribute);
                 while (Navigation.this.backNode.size() > Navigation.this.maxNavigate)
                 {
                     Navigation.this.backNode.remove();
                     Navigation.this.backAttribute.remove();
                 }
                 XsdTreeNode back = Navigation.this.backNode.peekLast();
                 Navigation.this.goBackAction.putValue(NAME,
                         "Go back to " + back.getNodeName() + (back.isIdentifiable() ? " " + back.getId() : ""));
                 Navigation.this.goBackAction.setEnabled(Navigation.this.backNode.peekLast() != null);
                 Navigation.this.editor.show(Navigation.this.coupledNode, null);
             }
         }
     };
 
 }