Add new pojo packets with automatic writing and read implementations …

…based on reflection

cory-core/src/main/java/moe/rafal/cory/pojo/PojoPacket.java

@@ -0,0 +1,39 @@
+/*
+ *    Copyright 2023 cory
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ *
+ */
+
+package moe.rafal.cory.pojo;
+
+import static moe.rafal.cory.pojo.PojoPacketUtils.parsePojo;
+import static moe.rafal.cory.pojo.PojoPacketUtils.writePojo;
+
+import java.io.IOException;
+import moe.rafal.cory.Packet;
+import moe.rafal.cory.serdes.PacketPacker;
+import moe.rafal.cory.serdes.PacketUnpacker;
+
+public class PojoPacket extends Packet {
+
+  @Override
+  public void write(final PacketPacker packer) throws IOException {
+    writePojo(packer, this);
+  }
+
+  @Override
+  public void read(final PacketUnpacker unpacker) throws IOException {
+    parsePojo(unpacker, this);
+  }
+}

cory-core/src/main/java/moe/rafal/cory/pojo/PojoPacketUtils.java

@@ -0,0 +1,110 @@
+/*
+ *    Copyright 2023 cory
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ *
+ */
+
+package moe.rafal.cory.pojo;
+
+import static java.lang.String.format;
+import static java.lang.reflect.Modifier.isTransient;
+import static java.util.function.Predicate.not;
+import static java.util.stream.Collectors.toUnmodifiableList;
+
+import java.io.IOException;
+import java.lang.reflect.Field;
+import java.util.Arrays;
+import java.util.List;
+import moe.rafal.cory.serdes.PacketPacker;
+import moe.rafal.cory.serdes.PacketUnpacker;
+
+final class PojoPacketUtils {
+
+  private PojoPacketUtils() {
+
+  }
+
+  static Field getDeclaredFieldByNameOrNull(final String name, final Class<?> clazz) {
+    try {
+      return clazz.getDeclaredField(name);
+    } catch (final NoSuchFieldException exception) {
+      return null;
+    }
+  }
+
+  static void writePojo(final PacketPacker packer, final Object value) throws IOException {
+    final Class<?> type = value.getClass();
+    try {
+      final List<Field> fields = Arrays.stream(type.getDeclaredFields())
+          .filter(not(field -> isTransient(field.getModifiers())))
+          .collect(toUnmodifiableList());
+
+      packer.packInt(fields.size());
+      for (final Field field : fields) {
+        writeField(packer, field, value);
+      }
+    } catch (final IllegalAccessException exception) {
+      throw new PojoWritingException(
+          format(
+              "Could not write pojo with name %s",
+              type.getName()
+          ),
+          exception
+      );
+    }
+  }
+
+  private static void writeField(final PacketPacker packer, final Field field, final Object value) throws IllegalAccessException, IOException {
+    field.setAccessible(true);
+    packer.packString(field.getName());
+    packer.packAuto(field.get(value));
+  }
+
+  static void parsePojo(final PacketUnpacker unpacker, final Object value) throws IOException {
+    final Class<?> type = value.getClass();
+    try {
+      final int fieldCount = unpacker.unpackInt();
+      for (int index = 0; index < fieldCount; index++) {
+        parseField(unpacker, value);
+      }
+    } catch (final IllegalAccessException exception) {
+      throw new PojoParsingException(
+          format(
+              "Could not parse pojo with name %s",
+              type.getName()
+          ),
+          exception
+      );
+    }
+  }
+
+  private static void parseField(final PacketUnpacker unpacker, final Object value)
+      throws IllegalAccessException, IOException {
+    final Class<?> type = value.getClass();
+
+    final String fieldName = unpacker.unpackString();
+    final Field field = getDeclaredFieldByNameOrNull(fieldName, type);
+    if (field == null) {
+      throw new PojoParsingException(
+          format(
+              "Could not find field with name %s",
+              fieldName
+          )
+      );
+    }
+
+    field.setAccessible(true);
+    field.set(value, unpacker.unpackAuto());
+  }
+}

cory-core/src/main/java/moe/rafal/cory/pojo/PojoParsingException.java

@@ -0,0 +1,29 @@
+/*
+ *    Copyright 2023 cory
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ *
+ */
+
+package moe.rafal.cory.pojo;
+
+public class PojoParsingException extends IllegalStateException {
+
+  PojoParsingException(final String message) {
+    super(message);
+  }
+
+  PojoParsingException(final String message, final Throwable cause) {
+    super(message, cause);
+  }
+}

cory-core/src/main/java/moe/rafal/cory/pojo/PojoWritingException.java

@@ -0,0 +1,25 @@
+/*
+ *    Copyright 2023 cory
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ *
+ */
+
+package moe.rafal.cory.pojo;
+
+public class PojoWritingException extends IllegalStateException {
+
+  PojoWritingException(final String message, final Throwable cause) {
+    super(message, cause);
+  }
+}