A class that keeps track of recent block events

PlayerInteractionListener.java

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.commons.lang.NullArgumentException;
import org.bukkit.Location;
import org.bukkit.entity.HumanEntity;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.EventPriority;
import org.bukkit.event.Listener;
import org.bukkit.event.inventory.InventoryCloseEvent;
import org.bukkit.event.player.PlayerInteractEvent;
import org.bukkit.event.player.PlayerQuitEvent;

/**
 * Keeps track of a player's last block interaction.
 * 
 * @author Kristian
 */
public class PlayerInteractionListener implements Listener {

    // Last clicked block
    private Map<String, ClickEvent> lastRightClicked = new ConcurrentHashMap<String, ClickEvent>();

    // Last clicked event
    private class ClickEvent {
        // public org.bukkit.event.block.Action ...
        public long time;
        public Location location;
    }
    
    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = false)
    public void onPlayerInteractEvent(PlayerInteractEvent event) {
        
        Player player = event.getPlayer();
        
        // Make sure this is a valid block right-click event
        if (player != null && event.hasBlock() && 
                event.getAction() == org.bukkit.event.block.Action.RIGHT_CLICK_BLOCK) {
        
            // Store relevant information
            ClickEvent click = new ClickEvent();
            click.location = event.getClickedBlock().getLocation();
            click.time = System.currentTimeMillis();

            // Store this block (by copy, so we don't keep chunks in memory)
            lastRightClicked.put(player.getName(), click);
        }
    }
    
    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
    public void onInventoryCloseEvent(InventoryCloseEvent event) {
    
        long current = System.currentTimeMillis();
        HumanEntity player = event.getPlayer();
        
        // Make sure this is a valid inventory open event
        if (player instanceof Player) {

            ClickEvent click = lastRightClicked.get(player.getName());
            
            // Ignore very recent close events - they are likely to be wrong
            if (click != null && (current - click.time) >= 25) {

                // This information is now outdated
                lastRightClicked.remove(player.getName());    
            }
        }
    }
    
    /**
     * Retrieves the given player's most recent right click event.
     * @param player - the player whose interaction we're looking for.
     * @param maxAge - the maximum age (in milliseconds) of the action. NULL indicates infinity.
     * @return The location of the last clicked block.
     */
    public Location getLastRightClick(Player player, Integer maxAge) {
        if (player == null)
            throw new NullArgumentException("player");
        
        return getLastRightClick(player, maxAge, System.currentTimeMillis());
    }
    
    /**
     * Retrieves the given player's most recent right click event.
     * @param player - the player whose interaction we're looking for.
     * @param maxAge - the maximum age (in milliseconds) of the action. NULL indicates infinity.
     * @param currentTime - the current time in milliseconds since midnight, January 1, 1970.
     * @return The location of the last clicked block.
     */
    public Location getLastRightClick(Player player, Integer maxAge, long currentTime) {
        if (player == null)
            throw new NullArgumentException("player");
        
        ClickEvent last = lastRightClicked.get(player.getName());
        
        // Make sure we're not outside the age limit
        if (last != null && (
                 maxAge == null ||
                 last.time + maxAge > currentTime
           )) {
            
            return last.location;
        }
    
        // No action found
        return null;
    }

    /**
     * Determines if a last right click event has been recorded for a given player.
     * @param player - the given player.
     * @return TRUE if a right click event has been recorded, FALSE otherwise.
     */
    public boolean hasLastRightClick(Player player) {
        return lastRightClicked.containsKey(player.getName());
    }
    
    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
    public void onPlayerQuitEvent(PlayerQuitEvent event) {
    
        Player player = event.getPlayer();
            
        if (player != null) {
            String name = player.getName();
        
            // Cleanup
            lastRightClicked.remove(name);
        }
    }
}