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   *  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
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  package org.apache.cayenne.velocity;
  
  import java.io.IOException;
  import java.io.Writer;
  import java.sql.Types;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Map;
  
  import org.apache.cayenne.ObjectId;
  import org.apache.cayenne.Persistent;
  import org.apache.cayenne.access.translator.ParameterBinding;
  import org.apache.cayenne.dba.TypesMapping;
  import org.apache.velocity.context.InternalContextAdapter;
  import org.apache.velocity.exception.MethodInvocationException;
  import org.apache.velocity.exception.ParseErrorException;
  import org.apache.velocity.exception.ResourceNotFoundException;
  import org.apache.velocity.runtime.parser.node.Node;
  
  /**
   * A custom Velocity directive to create a set of SQL conditions to match an ObjectId of
   * an object. Usage in Velocity template is "WHERE #bindObjectEqual($object)" or "WHERE
   * #bindObjectEqual($object $columns $idValues)".
   * 
   * @since 3.0
   */
  public class BindObjectEqualDirective extends BindDirective {
  
      @Override
      public String getName() {
          return "bindObjectEqual";
      }
  
      @Override
      public boolean render(InternalContextAdapter context, Writer writer, Node node)
              throws IOException, ResourceNotFoundException, ParseErrorException,
              MethodInvocationException {
  
          Object object = getChild(context, node, 0);
          Map idMap = toIdMap(object);
  
          Object sqlColumns = getChild(context, node, 1);
          Object idColumns = getChild(context, node, 2);
  
          if (idMap == null) {
              // assume null object, and bind all null values
  
              if (sqlColumns == null || idColumns == null) {
                  throw new ParseErrorException("Invalid parameters. "
                          + "Either object has to be set "
                          + "or sqlColumns and idColumns or both.");
              }
  
              idMap = Collections.EMPTY_MAP;
          }
          else if (sqlColumns == null || idColumns == null) {
              // infer SQL columns from ID columns
              sqlColumns = idMap.keySet().toArray();
              idColumns = sqlColumns;
          }
  
          Object[] sqlColumnsArray = toArray(sqlColumns);
          Object[] idColumnsArray = toArray(idColumns);
  
          if (sqlColumnsArray.length != idColumnsArray.length) {
              throw new ParseErrorException(
                      "SQL columns and ID columns arrays have different sizes.");
          }
  
          for (int i = 0; i < sqlColumnsArray.length; i++) {
  
              Object value = idMap.get(idColumnsArray[i]);
  
              int jdbcType = (value != null) ? TypesMapping.getSqlTypeByJava(value
                      .getClass()) : Types.INTEGER;
  
              renderColumn(context, writer, sqlColumnsArray[i], i);
              writer.write(' ');
              render(context, writer, new ParameterBinding(value, jdbcType, -1));
          }
  
          return true;
      }
  
      protected Object[] toArray(Object columns) {
          if (columns instanceof Collection) {
              return ((Collection) columns).toArray();
          }
          else if (columns.getClass().isArray()) {
              return (Object[]) columns;
          }
          else {
              return new Object[] {
                  columns
              };
          }
      }
  
      protected Map toIdMap(Object object) throws ParseErrorException {
          if (object instanceof Persistent) {
              return ((Persistent) object).getObjectId().getIdSnapshot();
          }
          else if (object instanceof ObjectId) {
              return ((ObjectId) object).getIdSnapshot();
          }
          else if(object instanceof Map) {
              return (Map) object;
          }
          else if (object != null) {
              throw new ParseErrorException(
                      "Invalid object parameter, expected Persistent or ObjectId or null: "
                              + object);
          }
          else {
              return null;
          }
      }
  
      protected void renderColumn(
              InternalContextAdapter context,
              Writer writer,
              Object columnName,
              int columnIndex) throws IOException {
  
          if (columnIndex > 0) {
              writer.write(" AND ");
          }
  
          writer.write(columnName.toString());
      }
  
      @Override
      protected void render(
              InternalContextAdapter context,
              Writer writer,
              ParameterBinding binding) throws IOException {
  
          if (binding.getValue() != null) {
              bind(context, binding);
              writer.write("= ?");
          }
          else {
              writer.write("IS NULL");
          }
      }
  }
  