Code cleanup. Implemented dummy parameter result set. Drafted prepared stmt metadata

Author: chernser

jdbc-v2/src/main/java/com/clickhouse/jdbc/PreparedStatementImpl.java

@@ -1,7 +1,11 @@
 package com.clickhouse.jdbc;
 
+import com.clickhouse.client.api.metadata.TableSchema;
 import com.clickhouse.data.Tuple;
 import com.clickhouse.jdbc.internal.ExceptionUtils;
+import com.clickhouse.jdbc.internal.JdbcUtils;
+import com.clickhouse.jdbc.metadata.ParameterMetaDataImpl;
+import com.clickhouse.jdbc.metadata.ResultSetMetaDataImpl;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -39,12 +43,7 @@
 import java.time.format.DateTimeFormatter;
 import java.time.format.DateTimeFormatterBuilder;
 import java.time.temporal.ChronoField;
-import java.util.ArrayList;
-import java.util.Calendar;
-import java.util.Collection;
-import java.util.GregorianCalendar;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 
 public class PreparedStatementImpl extends StatementImpl implements PreparedStatement, JdbcV2Wrapper {
     private static final Logger LOG = LoggerFactory.getLogger(PreparedStatementImpl.class);
@@ -64,6 +63,11 @@ public class PreparedStatementImpl extends StatementImpl implements PreparedStat
     String insertIntoSQL;
 
     StatementType statementType;
+
+    private final ParameterMetaData parameterMetaData;
+
+    private ResultSetMetaData resultSetMetaData = null;
+
     public PreparedStatementImpl(ConnectionImpl connection, String sql) throws SQLException {
         super(connection);
         this.originalSql = sql.trim();
@@ -83,7 +87,7 @@ public PreparedStatementImpl(ConnectionImpl connection, String sql) throws SQLEx
         } else {
             this.parameters = new Object[0];
         }
-
+        this.parameterMetaData = new ParameterMetaDataImpl(this.parameters.length);
         this.defaultCalendar = connection.defaultCalendar;
     }
 
@@ -305,7 +309,30 @@ public void setArray(int parameterIndex, Array x) throws SQLException {
     @Override
     public ResultSetMetaData getMetaData() throws SQLException {
         checkClosed();
-        return null;
+
+        if (resultSetMetaData == null && currentResultSet == null) {
+            // before execution
+            if (statementType == StatementType.SELECT) {
+                try {
+                    String sql = JdbcUtils.replaceQuestionMarks(originalSql, JdbcUtils.NULL);
+                    TableSchema tSchema = connection.getClient().getTableSchemaFromQuery(sql);
+                    resultSetMetaData = new ResultSetMetaDataImpl(tSchema.getColumns(),
+                            tSchema.getDatabaseName(), "", tSchema.getTableName(), Collections.emptyMap());
+                } catch (Exception e) {
+                    // fallback to empty until
+                }
+            } else if (statementType == StatementType.SHOW) {
+                // predefined
+            } else if (statementType == StatementType.DESCRIBE) {
+                // predefined
+            } else {
+                // fallback to empty
+            }
+        } else if (resultSetMetaData == null) {
+            resultSetMetaData = currentResultSet.getMetaData();
+        }
+
+        return resultSetMetaData;
     }
 
     @Override
@@ -352,10 +379,19 @@ public void setURL(int parameterIndex, URL x) throws SQLException {
         parameters[parameterIndex - 1] = encodeObject(x);
     }
 
+    /**
+     * Current JDBC driver implementation implement this functionality.
+     * But specification doesn't expect throwing an exception what
+     * for makes us return a "dummy" object. Returned metadata reflects only
+     * information we can guarantee like parameter count.
+     * @see ParameterMetaDataImpl
+     * @return {@link ParameterMetaDataImpl}
+     * @throws SQLException if the statement is close
+     */
     @Override
     public ParameterMetaData getParameterMetaData() throws SQLException {
         checkClosed();
-        return null;
+        return parameterMetaData;
     }
 
     @Override

jdbc-v2/src/main/java/com/clickhouse/jdbc/ResultSetImpl.java

@@ -8,11 +8,9 @@
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
 import java.sql.*;
+import java.sql.Date;
 import java.time.ZonedDateTime;
-import java.util.Calendar;
-import java.util.GregorianCalendar;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 
 import com.clickhouse.client.api.data_formats.ClickHouseBinaryFormatReader;
 import com.clickhouse.client.api.metadata.TableSchema;
@@ -21,6 +19,7 @@
 import com.clickhouse.data.ClickHouseDataType;
 import com.clickhouse.jdbc.internal.ExceptionUtils;
 import com.clickhouse.jdbc.internal.JdbcUtils;
+import com.clickhouse.jdbc.metadata.ResultSetMetaDataImpl;
 import com.clickhouse.jdbc.types.Array;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -39,7 +38,10 @@ public ResultSetImpl(StatementImpl parentStatement, QueryResponse response, Clic
         this.parentStatement = parentStatement;
         this.response = response;
         this.reader = reader;
-        this.metaData = new com.clickhouse.jdbc.metadata.ResultSetMetaData(this);
+        TableSchema tableMetadata = reader.getSchema();
+        this.metaData = new ResultSetMetaDataImpl(tableMetadata
+                .getColumns(), tableMetadata.getDatabaseName(), "", tableMetadata.getTableName(),
+                Collections.emptyMap());
         this.closed = false;
         this.wasNull = false;
         this.defaultCalendar = parentStatement.connection.defaultCalendar;
@@ -49,7 +51,10 @@ protected ResultSetImpl(ResultSetImpl resultSet) {
         this.parentStatement = resultSet.parentStatement;
         this.response = resultSet.response;
         this.reader = resultSet.reader;
-        this.metaData = new com.clickhouse.jdbc.metadata.ResultSetMetaData(this);
+        TableSchema tableMetadata = resultSet.getSchema();
+        this.metaData = new ResultSetMetaDataImpl(tableMetadata
+                .getColumns(), tableMetadata.getDatabaseName(), "", tableMetadata.getTableName(),
+                Collections.emptyMap());
         this.closed = false;
         this.wasNull = false;
         this.defaultCalendar = parentStatement.connection.defaultCalendar;

jdbc-v2/src/main/java/com/clickhouse/jdbc/StatementImpl.java

@@ -31,7 +31,7 @@ public class StatementImpl implements Statement, JdbcV2Wrapper {
     ConnectionImpl connection;
     private int queryTimeout;
     protected boolean closed;
-    private ResultSetImpl currentResultSet;
+    protected ResultSetImpl currentResultSet;
     private OperationMetrics metrics;
     protected List<String> batch;
     private String lastSql;

jdbc-v2/src/main/java/com/clickhouse/jdbc/internal/JdbcUtils.java

@@ -22,6 +22,8 @@
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 public class JdbcUtils {
     //Define a map to store the mapping between ClickHouse data types and SQL data types
@@ -271,4 +273,26 @@ public static String escapeQuotes(String str) {
                 .replace("'", "\\'")
                 .replace("\"", "\\\"");
     }
+
+    public static final String NULL = "NULL";
+
+    private static final Pattern REPLACE_Q_MARK_PATTERN = Pattern.compile("(\"[^\"]*\"|`[^`]*`)|(\\?)");
+
+    public static String replaceQuestionMarks(String sql, String replacement) {
+        Matcher matcher = REPLACE_Q_MARK_PATTERN.matcher(sql);
+
+        StringBuilder result = new StringBuilder();
+
+        while (matcher.find()) {
+            if (matcher.group(1) != null) {
+                // Quoted string — keep as-is
+                matcher.appendReplacement(result, Matcher.quoteReplacement(matcher.group(1)));
+            } else if (matcher.group(2) != null) {
+                // Question mark outside quotes — replace it
+                matcher.appendReplacement(result, Matcher.quoteReplacement(replacement));
+            }
+        }
+        matcher.appendTail(result);
+        return result.toString();
+    }
 }