[ASTERIXDB-2877] Fix multi-byte character handling in CSV output

asterixdb/asterix-om/src/main/java/org/apache/asterix/dataflow/data/nontagged/printers/PrintTools.java

@@ -312,7 +312,7 @@ public static void writeUTF8StringAsCSV(byte[] b, int s, int l, PrintStream ps,
         boolean shouldQuote = forceQuote;
         if (!shouldQuote) {
             // Check if the string contains any special characters that require quoting
-            for (int i = position; i < maxPosition; i++) {
+            for (int i = position; i < maxPosition; i += UTF8StringUtil.charSize(b, i)) {
                 char c = UTF8StringUtil.charAt(b, i);
                 if (c == quote || c == '\r' || c == '\n' || c == escape || c == delimiter) {
                     shouldQuote = true;
@@ -340,9 +340,9 @@ public static void writeUTF8StringAsCSV(byte[] b, int s, int l, PrintStream ps,
                 continue;
             }
 
-            // Write the character bytes
+            // Write the character bytes as raw UTF-8 bytes to avoid charset encoding bugs
             while (sz > 0) {
-                ps.print(c);
+                ps.write(b[position]);
                 ++position;
                 --sz;
             }

asterixdb/asterix-om/src/test/java/org/apache/asterix/dataflow/data/nontagged/printers/PrintToolsTest.java

@@ -0,0 +1,175 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.asterix.dataflow.data.nontagged.printers;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import java.nio.charset.StandardCharsets;
+
+import org.apache.hyracks.util.string.UTF8StringUtil;
+import org.junit.Test;
+
+public class PrintToolsTest {
+
+    private static final char QUOTE = '"';
+    private static final char ESCAPE = '"';
+    private static final char DELIMITER = ',';
+
+    public static String csvOf(String input) throws Exception {
+        byte[] bytes = UTF8StringUtil.writeStringToBytes(input);
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        PrintStream ps = new PrintStream(baos, true, StandardCharsets.UTF_8);
+        PrintTools.writeUTF8StringAsCSV(bytes, 0, bytes.length, ps, QUOTE, false, ESCAPE, DELIMITER);
+        return baos.toString(StandardCharsets.UTF_8);
+    }
+
+    public static String jsonOf(String input) throws Exception {
+        byte[] bytes = UTF8StringUtil.writeStringToBytes(input);
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        PrintTools.writeUTF8StringAsJSON(bytes, 0, bytes.length, baos);
+        return baos.toString(StandardCharsets.UTF_8);
+    }
+
+    @Test
+    public void testCsvAsciiPlain() throws Exception {
+        assertEquals("hello", csvOf("hello"));
+    }
+
+    @Test
+    public void testCsvAsciiEmpty() throws Exception {
+        assertEquals("", csvOf(""));
+    }
+
+    @Test
+    public void testCsvAsciiQuotingOnComma() throws Exception {
+        assertEquals("\"a,b\"", csvOf("a,b"));
+    }
+
+    @Test
+    public void testCsvAsciiQuotingOnNewline() throws Exception {
+        assertEquals("\"a\nb\"", csvOf("a\nb"));
+    }
+
+    @Test
+    public void testCsvAsciiEscapeQuote() throws Exception {
+        assertEquals("\"say \"\"hi\"\"\"", csvOf("say \"hi\""));
+    }
+
+    @Test
+    public void testCsvTwoByteChar() throws Exception {
+        assertEquals("café", csvOf("café"));
+    }
+
+    @Test
+    public void testCsvTwoByteCharWithComma() throws Exception {
+        assertEquals("\"café,café\"", csvOf("café,café"));
+    }
+
+    @Test
+    public void testCsvThreeByteChar() throws Exception {
+        assertEquals("中文", csvOf("中文"));
+    }
+
+    @Test
+    public void testCsvEmoji() throws Exception {
+        assertEquals("💪", csvOf("💪"));
+    }
+
+    @Test
+    public void testCsvMixedEmojiString() throws Exception {
+        String input = "No more 💪🏻🦋";
+        assertEquals(input, csvOf(input));
+    }
+
+    @Test
+    public void testCsvMixedMultibyteAndAscii() throws Exception {
+        String input = "Hello 中文 café 😀!";
+        assertEquals(input, csvOf(input));
+    }
+
+    @Test
+    public void testCsvEmojiWithComma() throws Exception {
+        assertEquals("\"💪,💪\"", csvOf("💪,💪"));
+    }
+
+    @Test
+    public void testCsvEmojiWithNewline() throws Exception {
+        assertEquals("\"💪\n💪\"", csvOf("💪\n💪"));
+    }
+
+    @Test
+    public void testCsvEmojiWithQuote() throws Exception {
+        assertEquals("\"💪\"\"💪\"", csvOf("💪\"💪"));
+    }
+
+    @Test
+    public void testJsonAsciiPlain() throws Exception {
+        assertEquals("\"hello\"", jsonOf("hello"));
+    }
+
+    @Test
+    public void testJsonAsciiEmpty() throws Exception {
+        assertEquals("\"\"", jsonOf(""));
+    }
+
+    @Test
+    public void testJsonAsciiEscapeNewline() throws Exception {
+        assertEquals("\"line1\\nline2\"", jsonOf("line1\nline2"));
+    }
+
+    @Test
+    public void testJsonAsciiEscapeTab() throws Exception {
+        assertEquals("\"col1\\tcol2\"", jsonOf("col1\tcol2"));
+    }
+
+    @Test
+    public void testJsonAsciiEscapeBackslash() throws Exception {
+        assertEquals("\"a\\\\b\"", jsonOf("a\\b"));
+    }
+
+    @Test
+    public void testJsonTwoByteChar() throws Exception {
+        assertEquals("\"café\"", jsonOf("café"));
+    }
+
+    @Test
+    public void testJsonThreeByteChar() throws Exception {
+        assertEquals("\"中文\"", jsonOf("中文"));
+    }
+
+    @Test
+    public void testJsonEmoji() throws Exception {
+        assertEquals("\"💪\"", jsonOf("💪"));
+    }
+
+    @Test
+    public void testJsonMixedMultibyteAndAscii() throws Exception {
+        String input = "Hello 中文 café 😀!";
+        assertEquals("\"" + input + "\"", jsonOf(input));
+    }
+
+    @Test
+    public void testJsonMixedEmojiString() throws Exception {
+        String input = "No more 💪🏻🦋";
+        assertEquals("\"" + input + "\"", jsonOf(input));
+    }
+}