package jalview.io.cache;

import jalview.util.MessageManager;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;

import javax.swing.JComboBox;
import javax.swing.JLabel;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JPopupMenu;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;

public class JvCacheableInputBox<E> extends JComboBox<String>
{

  private static final long serialVersionUID = 5774610435079326695L;

  private String cacheKey;

  private AppCache appCache;

  JPanel pnlDefaultCache = new JPanel();

  JLabel lblDefaultCacheSize = new JLabel();

  JTextField txtDefaultCacheSize = new JTextField();

  JPopupMenu popup = new JPopupMenu();

  JMenuItem menuItemClearCache = new JMenuItem();

  final static int INPUT_LIMIT = 2;

  final static String SPACE = "    ";

  public JvCacheableInputBox(String cacheKey)
  {
    super();
    this.cacheKey = cacheKey;
    setEditable(true);
    setPrototypeDisplayValue("XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX");
    appCache = AppCache.getInstance();
    initCachePopupMenu();
    appCache.initCache(cacheKey);
    updateCache();
  }


  /**
   * Initialise this cache's pop-up menu
   */
  private void initCachePopupMenu()
  {
    add(popup);
    setComponentPopupMenu(popup);
    pnlDefaultCache.setBackground(Color.WHITE);
    txtDefaultCacheSize.setPreferredSize(new Dimension(45, 20));
    lblDefaultCacheSize.setText(SPACE
            + MessageManager.getString("label.default_cache_size"));
    // Force input to accept only Integer entries up to length - INPUT_LIMIT
    txtDefaultCacheSize.setDocument(new PlainDocument()
    {
      private static final long serialVersionUID = 1L;

      @Override
      public void insertString(int offs, String str, AttributeSet a)
              throws BadLocationException
      {
        if (getLength() + str.length() <= INPUT_LIMIT && isInteger(str))
        {
          super.insertString(offs, str, a);
        }
      }
    });
    txtDefaultCacheSize.setText(appCache.getCacheLmit(cacheKey));
    pnlDefaultCache.add(lblDefaultCacheSize);
    pnlDefaultCache.add(txtDefaultCacheSize);
    popup.insert(pnlDefaultCache, 0);

    menuItemClearCache.setText(MessageManager
            .getString("action.clear_cached_items"));
    menuItemClearCache.addActionListener(new ActionListener()
    {
      @Override
      public void actionPerformed(ActionEvent e)
      {
        System.out.println(">>>>> Clear cache items");
        setSelectedItem("");
        appCache.deleteCacheItems(cacheKey);
        updateCache();
      }
    });

    popup.add(menuItemClearCache);
  }

  /**
   * Answers true if input text is an integer
   * 
   * @param text
   * @return
   */
  private boolean isInteger(String text)
  {
    try
    {
      Integer.parseInt(text);
      return true;
    } catch (NumberFormatException e)
    {
      return false;
    }
  }

  /**
   * Method called to update the cache with the last user input
   */
  public void updateCache()
  {
    SwingUtilities.invokeLater(new Runnable()
    {
      @Override
      public void run()
      {
        int cacheLimit = appCache.updateCacheLimit(cacheKey,
                txtDefaultCacheSize.getText());
        String userInput = getUserInput();
        if (userInput != null && !userInput.isEmpty())
        {
          LinkedHashSet<String> foundCache = appCache
                  .getAllCachedItemsFor(cacheKey);
          // remove old cache item so as to place current input at the top of
          // the result
          foundCache.remove(userInput);
          foundCache.add(userInput);
          appCache.putCache(cacheKey, foundCache);
        }

        String lastSearch = userInput;
        if (getItemCount() > 0)
        {
          removeAllItems();
        }
        Set<String> cacheItems = appCache.getAllCachedItemsFor(cacheKey);
        List<String> reversedCacheItems = new ArrayList<String>();
        reversedCacheItems.addAll(cacheItems);
        cacheItems = null;
        Collections.reverse(reversedCacheItems);
        if (lastSearch.isEmpty())
        {
          addItem("");
        }

        if (reversedCacheItems != null && !reversedCacheItems.isEmpty())
        {
          LinkedHashSet<String> foundCache = appCache
                  .getAllCachedItemsFor(cacheKey);
          boolean prune = reversedCacheItems.size() > cacheLimit;
          int count = 1;
          boolean limitExceeded = false;
          for (String cacheItem : reversedCacheItems)
          {
            limitExceeded = (count++ > cacheLimit);
            if (prune)
            {
              if (limitExceeded)
              {
                foundCache.remove(cacheItem);
              }
              else
              {
                addItem(cacheItem);
              }
            }
            else
            {
              addItem(cacheItem);
            }
          }
          appCache.putCache(cacheKey, foundCache);
        }
        setSelectedItem(lastSearch.isEmpty() ? "" : lastSearch);
      }
    });
  }


  /**
   * This method should be called to persist the in-memory cache when this
   * components parent frame is closed / exited
   */
  public void persistCache()
  {
    appCache.persistCache(cacheKey);
    appCache.updateCacheLimit(cacheKey, txtDefaultCacheSize.getText());
  }

  /**
   * Method to obtain input text from the cache box
   * 
   * @return
   */
  public String getUserInput()
  {
    return getEditor().getItem() == null ? "" : getEditor().getItem()
            .toString().trim();
  }

}