Disabling double registering

^ as well as trying to cancel the droping of items.

src/main/java/org/samo_lego/simpleauth/SimpleAuth.java

@@ -14,7 +14,8 @@ import org.samo_lego.simpleauth.database.SimpleAuthDatabase;
 import org.samo_lego.simpleauth.event.AuthEventHandler;
 import org.samo_lego.simpleauth.event.block.BreakBlockCallback;
 import org.samo_lego.simpleauth.event.block.InteractBlockCallback;
-import org.samo_lego.simpleauth.event.entity.player.InteractItemCallback;
+import org.samo_lego.simpleauth.event.item.DropItemCallback;
+import org.samo_lego.simpleauth.event.item.InteractItemCallback;
 import org.samo_lego.simpleauth.event.entity.player.PlayerJoinServerCallback;
 import org.samo_lego.simpleauth.event.entity.player.PlayerLeaveServerCallback;
 
@@ -48,11 +49,14 @@ public class SimpleAuth implements DedicatedServerModInitializer {
 
 		// Registering the events
 		InteractBlockCallback.EVENT.register(AuthEventHandler::onInteractBlock);
-		AttackBlockCallback.EVENT.register((playerEntity, world, hand, blockPos, direction) -> AuthEventHandler.interact(playerEntity));
+		BreakBlockCallback.EVENT.register((world, pos, state, player) -> AuthEventHandler.onBlockBroken(player));
 		InteractItemCallback.EVENT.register(AuthEventHandler::onInteractItem);
+		DropItemCallback.EVENT.register(AuthEventHandler::onDropItem);
 		PlayerJoinServerCallback.EVENT.register(AuthEventHandler::onPlayerJoin);
 		PlayerLeaveServerCallback.EVENT.register(AuthEventHandler::onPlayerLeave);
-		BreakBlockCallback.EVENT.register((world, pos, state, player) -> AuthEventHandler.onBlockBroken(player));
+		// From Fabric API
+		AttackBlockCallback.EVENT.register((playerEntity, world, hand, blockPos, direction) -> AuthEventHandler.onAttackBlock(playerEntity));
+
         db.makeTable();
     }
     public static HashSet<ServerPlayerEntity> authenticatedUsers = new HashSet<>();

src/main/java/org/samo_lego/simpleauth/commands/RegisterCommand.java

@@ -55,12 +55,15 @@ public class RegisterCommand {
                 // Hash password
                 String hash = argon2.hash(10, 65536, 1, password);
                 // Writing into database
-                SimpleAuth.db.insert(Objects.requireNonNull(source.getEntity()).getUuidAsString(), source.getName(), hash);
+                if(SimpleAuth.db.registerUser(Objects.requireNonNull(source.getEntity()).getUuidAsString(), source.getName(), hash)) {
                     SimpleAuth.authenticatedUsers.add(player);
                     // Letting the player know it was successful
                     player.sendMessage(
                             new LiteralText(source.getName() + ", you have registered successfully!")
                     );
+                }
+                else
+                    player.sendMessage(alreadyRegistered);
             } catch (Error e) {
                 player.sendMessage(alreadyRegistered);
             } finally {

src/main/java/org/samo_lego/simpleauth/database/SimpleAuthDatabase.java

@@ -46,20 +46,32 @@ public class SimpleAuthDatabase {
     }
 
     // When player registers, we insert the data into DB
-    public void insert(String uuid, String username, String password) {
+    public boolean registerUser(String uuid, String username, String password) {
         String sql = "INSERT INTO users(uuid, username, password) VALUES(?,?,?)";
+        String sqlCheck = "SELECT UUID, Password "
+                + "FROM users WHERE UUID = ?";
         try (
             Connection conn = this.connect();
-            PreparedStatement pstmt = conn.prepareStatement(sql)) {
+            PreparedStatement pstmt = conn.prepareStatement(sql);
+            PreparedStatement pstmtCheck = conn.prepareStatement(sql)) {
 
+            pstmtCheck.setString(1,uuid);
+            ResultSet rs  = pstmtCheck.executeQuery();
+
+            // Getting the password
+            String dbUuid = rs.getString("UUID");
+            if(dbUuid != null) {
                 pstmt.setString(1, uuid);
                 pstmt.setString(2, username);
                 pstmt.setString(3, password);
 
                 pstmt.executeUpdate();
+                return true;
+            }
         } catch (SQLException e) {
             LOGGER.error(e.getMessage());
         }
+        return false;
     }
 
     // Deletes row containing the username provided

src/main/java/org/samo_lego/simpleauth/event/AuthEventHandler.java

@@ -1,6 +1,7 @@
 package org.samo_lego.simpleauth.event;
 
 import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.item.ItemStack;
 import net.minecraft.server.network.ServerPlayerEntity;
 import net.minecraft.text.LiteralText;
 import net.minecraft.text.TranslatableText;
@@ -45,7 +46,7 @@ public class AuthEventHandler {
     }
 
     // Punching a block
-    public static ActionResult interact(PlayerEntity playerEntity) {
+    public static ActionResult onAttackBlock(PlayerEntity playerEntity) {
         if(!SimpleAuth.authenticatedUsers.contains(playerEntity)) {
             playerEntity.sendMessage(notAuthenticated);
             return ActionResult.FAIL;
@@ -62,4 +63,12 @@ public class AuthEventHandler {
 
         return ActionResult.PASS;
     }
+    // Dropping an item
+    public static boolean onDropItem(ServerPlayerEntity player) {
+        if(!SimpleAuth.authenticatedUsers.contains(player)) {
+            player.sendMessage(notAuthenticated);
+            return true;
+        }
+        return false;
+    }
 }

src/main/java/org/samo_lego/simpleauth/event/item/DropItemCallback.java

@@ -0,0 +1,18 @@
+package org.samo_lego.simpleauth.event.item;
+
+import net.fabricmc.fabric.api.event.Event;
+import net.fabricmc.fabric.api.event.EventFactory;
+import net.minecraft.server.network.ServerPlayerEntity;
+
+public interface DropItemCallback {
+    Event<DropItemCallback> EVENT = EventFactory.createArrayBacked(DropItemCallback.class, listeners -> (playerEntity) -> {
+        for(DropItemCallback callback : listeners) {
+            if(callback.onDropItem(playerEntity)) {
+                return true;
+            }
+        }
+        return false;
+    });
+
+    boolean onDropItem(ServerPlayerEntity playerEntity);
+}

src/main/java/org/samo_lego/simpleauth/event/item/InteractItemCallback.java

@@ -1,4 +1,4 @@
-package org.samo_lego.simpleauth.event.entity.player;
+package org.samo_lego.simpleauth.event.item;
 
 import net.fabricmc.fabric.api.event.Event;
 import net.fabricmc.fabric.api.event.EventFactory;

src/main/java/org/samo_lego/simpleauth/mixin/MixinPlayerEntity.java

@@ -2,13 +2,23 @@ package org.samo_lego.simpleauth.mixin;
 
 import net.minecraft.entity.player.PlayerEntity;
 import net.minecraft.item.ItemStack;
+import net.minecraft.server.network.ServerPlayerEntity;
+import org.samo_lego.simpleauth.event.item.DropItemCallback;
 import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
 
 @Mixin(PlayerEntity.class)
 public abstract class MixinPlayerEntity {
-    /*@Inject(method = "dropItem", at = @At("HEAD"))
+    // Thanks to AbusedLib https://github.com/abused/AbusedLib
-    private void dropItem(ItemStack itemStack_1, boolean boolean_1) {
+    @Inject(method = "dropItem(Lnet/minecraft/item/ItemStack;ZZ)Lnet/minecraft/entity/ItemEntity;", at = @At("HEAD"))
-    }*/
+    private void dropItem(ItemStack stack, boolean boolean_1, boolean boolean_2, CallbackInfoReturnable<ItemStack> info) {
+        ServerPlayerEntity player = (ServerPlayerEntity) (Object) this;
+        if(DropItemCallback.EVENT.invoker().onDropItem(player)) {
+            player.giveItemStack(stack);
+            info.setReturnValue(ItemStack.EMPTY);
+        }
+    }
 }

src/main/java/org/samo_lego/simpleauth/mixin/MixinServerPlayNetworkHandler.java

@@ -1,17 +0,0 @@
-package org.samo_lego.simpleauth.mixin;
-
-import net.minecraft.server.network.packet.PlayerMoveC2SPacket;
-import net.minecraft.util.PacketByteBuf;
-import org.spongepowered.asm.mixin.Mixin;
-import org.spongepowered.asm.mixin.injection.At;
-import org.spongepowered.asm.mixin.injection.Inject;
-import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
-
-@Mixin(PlayerMoveC2SPacket.class)
-public abstract class MixinServerPlayNetworkHandler {
-
-    @Inject(method = "read", at = @At("RETURN"))
-    private void read(PacketByteBuf packetByteBuf_1, CallbackInfo ci) {
-        System.out.println("Packet "+packetByteBuf_1);
-    }
-}

src/main/java/org/samo_lego/simpleauth/mixin/MixinServerPlayerInteractionManager.java

@@ -12,7 +12,7 @@ import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.World;
 import org.samo_lego.simpleauth.event.block.BreakBlockCallback;
 import org.samo_lego.simpleauth.event.block.InteractBlockCallback;
-import org.samo_lego.simpleauth.event.entity.player.InteractItemCallback;
+import org.samo_lego.simpleauth.event.item.InteractItemCallback;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Shadow;
 import org.spongepowered.asm.mixin.injection.At;

src/main/resources/fabric.mod.json

@@ -21,7 +21,7 @@
     ]
   },
   "mixins": [
-    "simpleauth.mixins.json"
+    "mixins.simpleauth.json"
   ],
 
   "depends": {

src/main/resources/mixins.simpleauth.json

@@ -6,7 +6,8 @@
   ],
   "server": [
     "MixinServerPlayerInteractionManager",
-    "MixinPlayerManager"
+    "MixinPlayerManager",
+    "MixinPlayerEntity"
   ],
   "injectors": {
     "defaultRequire": 1