Add lectern support for versions 1.14 and higher (#9)

closes #6

Author: minoneer

pom.xml

@@ -118,7 +118,7 @@
         <dependency>
             <groupId>org.spigotmc</groupId>
             <artifactId>spigot-api</artifactId>
-            <version>1.13.2-R0.1-SNAPSHOT</version>
+            <version>1.14.4-R0.1-SNAPSHOT</version>
         </dependency>
         <dependency>
             <groupId>org.jetbrains</groupId>

src/main/java/me/minoneer/bukkit/bookexploit/BookExploitFix.java

@@ -6,6 +6,8 @@
 
 import java.util.Objects;
 import java.util.logging.Level;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 public final class BookExploitFix extends JavaPlugin {
 
@@ -24,6 +26,8 @@ public void onEnable() {
 
         registerEvents(config, filter);
 
+        registerLecternEvents(config, filter);
+
         enableProtocolLib(config, filter);
 
         getLogger().log(Level.INFO, "{0} by minoneer activated", getDescription().getFullName());
@@ -51,6 +55,27 @@ private void enableProtocolLib(ConfigHandler config, BookFilter filter) {
         }
     }
 
+    private void registerLecternEvents(ConfigHandler config, BookFilter filter) {
+        final boolean enableLectern;
+        final Pattern versionPattern = Pattern.compile("(\\d+)\\.(\\d+)\\.(\\d+).*");
+        String bukkitVersion = getServer().getBukkitVersion();
+        final Matcher matcher = versionPattern.matcher(bukkitVersion);
+        if (matcher.find()) {
+            final int major = Integer.parseInt(matcher.group(1));
+            final int minor = Integer.parseInt(matcher.group(2));
+            enableLectern = major > 1 || (major == 1 && minor >= 14);
+        } else {
+            enableLectern = false;
+            getLogger().severe("Unable to parse server version " + bukkitVersion +
+                    ", lectern support will not be enabled.");
+        }
+
+        if (enableLectern) {
+            getLogger().info("Detected server version 1.14 or higher, enabling lectern support");
+            getServer().getPluginManager().registerEvents(new LecternListener(config, filter, getLogger()), this);
+        }
+    }
+
     @Nullable
     public static String limitLoggingString(@Nullable final String input) {
         if (input == null) {

src/main/java/me/minoneer/bukkit/bookexploit/LecternListener.java

@@ -0,0 +1,58 @@
+package me.minoneer.bukkit.bookexploit;
+
+import org.bukkit.Material;
+import org.bukkit.block.Block;
+import org.bukkit.block.Lectern;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
+import org.bukkit.event.Listener;
+import org.bukkit.event.block.Action;
+import org.bukkit.event.player.PlayerInteractEvent;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public final class LecternListener implements Listener {
+
+    private final ConfigHandler config;
+    private final BookFilter bookFilter;
+    private final Logger logger;
+
+    public LecternListener(final ConfigHandler config, final BookFilter bookFilter, final Logger logger) {
+        this.config = config;
+        this.bookFilter = bookFilter;
+        this.logger = logger;
+    }
+
+    @EventHandler(priority = EventPriority.LOW)
+    public void onLecternRead(@NotNull final PlayerInteractEvent event) {
+        final Player player = event.getPlayer();
+        if (!config.checkReading()) {
+            return;
+        }
+        if (event.getAction() != Action.RIGHT_CLICK_BLOCK) {
+            return;
+        }
+        Block clickedBlock = event.getClickedBlock();
+        if (clickedBlock == null || clickedBlock.getType() != Material.LECTERN) {
+            return;
+        }
+
+        Lectern lectern = (Lectern) clickedBlock.getState();
+        final ItemStack toFilter = lectern.getInventory().getItem(0);
+        final ItemStack filtered = bookFilter.filterBook(toFilter);
+
+        if (filtered != null) {
+            logger.log(Level.WARNING, "Player {0} {1} tried to read a lectern book with illegal click events!",
+                    new Object[]{player.getName(), player.getUniqueId()});
+            lectern.getInventory().setItem(0, filtered);
+
+            if (config.getPlayerMessage() != null) {
+                player.sendMessage(config.getPlayerMessage());
+            }
+        }
+    }
+}