Refactor ReceiveMessageHandler

Introduce PlainTextWriter to improve indentation handling.

lib/src/main/java/org/asamk/signal/manager/groups/GroupId.java

@@ -33,7 +33,7 @@ public abstract class GroupId {
         }
     }
 
-    public GroupId(final byte[] id) {
+    protected GroupId(final byte[] id) {
         this.id = id;
     }
 

src/main/java/org/asamk/signal/JsonWriter.java

@@ -6,18 +6,20 @@ import com.fasterxml.jackson.core.JsonGenerator;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
+import java.io.BufferedWriter;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.io.OutputStreamWriter;
+import java.io.Writer;
 import java.nio.charset.StandardCharsets;
 
 public class JsonWriter {
 
-    private final OutputStreamWriter writer;
+    private final Writer writer;
     private final ObjectMapper objectMapper;
 
     public JsonWriter(final OutputStream writer) {
-        this.writer = new OutputStreamWriter(writer, StandardCharsets.UTF_8);
+        this.writer = new BufferedWriter(new OutputStreamWriter(writer, StandardCharsets.UTF_8));
 
         objectMapper = new ObjectMapper();
         objectMapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.PUBLIC_ONLY);

src/main/java/org/asamk/signal/PlainTextWriter.java

@@ -0,0 +1,23 @@
+package org.asamk.signal;
+
+import java.io.IOException;
+
+public interface PlainTextWriter {
+
+    void println(String format, Object... args) throws IOException;
+
+    PlainTextWriter indentedWriter();
+
+    default void println() throws IOException {
+        println("");
+    }
+
+    default void indent(final WriterConsumer subWriter) throws IOException {
+        subWriter.consume(indentedWriter());
+    }
+
+    interface WriterConsumer {
+
+        void consume(PlainTextWriter writer) throws IOException;
+    }
+}

src/main/java/org/asamk/signal/PlainTextWriterImpl.java

@@ -0,0 +1,67 @@
+package org.asamk.signal;
+
+import org.slf4j.helpers.MessageFormatter;
+
+import java.io.BufferedWriter;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+
+public final class PlainTextWriterImpl implements PlainTextWriter {
+
+    private final Writer writer;
+
+    private PlainTextWriter indentedWriter;
+
+    public PlainTextWriterImpl(final OutputStream outputStream) {
+        this.writer = new BufferedWriter(new OutputStreamWriter(outputStream));
+    }
+
+    @Override
+    public void println(String format, Object... args) throws IOException {
+        final String message = MessageFormatter.arrayFormat(format, args).getMessage();
+
+        writer.write(message);
+        writer.write(System.lineSeparator());
+        writer.flush();
+    }
+
+    @Override
+    public PlainTextWriter indentedWriter() {
+        if (indentedWriter == null) {
+            indentedWriter = new IndentedPlainTextWriter(this, writer);
+        }
+        return indentedWriter;
+    }
+
+    private static final class IndentedPlainTextWriter implements PlainTextWriter {
+
+        private final static int INDENTATION = 2;
+
+        private final String spaces = " ".repeat(INDENTATION);
+        private final PlainTextWriter plainTextWriter;
+        private final Writer writer;
+
+        private PlainTextWriter indentedWriter;
+
+        private IndentedPlainTextWriter(final PlainTextWriter plainTextWriter, final Writer writer) {
+            this.plainTextWriter = plainTextWriter;
+            this.writer = writer;
+        }
+
+        @Override
+        public void println(final String format, final Object... args) throws IOException {
+            writer.write(spaces);
+            plainTextWriter.println(format, args);
+        }
+
+        @Override
+        public PlainTextWriter indentedWriter() {
+            if (indentedWriter == null) {
+                indentedWriter = new IndentedPlainTextWriter(this, writer);
+            }
+            return indentedWriter;
+        }
+    }
+}

src/main/java/org/asamk/signal/util/DateUtils.java

@@ -14,7 +14,7 @@ public class DateUtils {
 
     public static String formatTimestamp(long timestamp) {
         Date date = new Date(timestamp);
-        final DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"); // Quoted "Z" to indicate UTC, no timezone offset
+        final DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSX"); // Quoted "Z" to indicate UTC, no timezone offset
         df.setTimeZone(tzUTC);
         return timestamp + " (" + df.format(date) + ")";
     }