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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
   *  with the License.  You may obtain a copy of the License at
   *
   *    https://www.apache.org/licenses/LICENSE-2.0
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  package org.apache.cayenne.dba.frontbase;
  
  import org.apache.cayenne.CayenneRuntimeException;
  import org.apache.cayenne.access.sqlbuilder.QuotingAppendable;
  import org.apache.cayenne.access.sqlbuilder.sqltree.FunctionNode;
  import org.apache.cayenne.access.sqlbuilder.sqltree.Node;
  import org.apache.cayenne.access.sqlbuilder.sqltree.OpExpressionNode;
  import org.apache.cayenne.access.sqlbuilder.sqltree.TextNode;
  import org.apache.cayenne.access.translator.select.BaseSQLTreeProcessor;
  
  /**
   * @since 4.2
   */
  public class FrontBaseSQLTreeProcessor extends BaseSQLTreeProcessor {
  
      @Override
      protected void onFunctionNode(Node parent, FunctionNode child, int index) {
          switch (child.getFunctionName()) {
              case "CONCAT":
                  replaceChild(parent, index, new OpExpressionNode("||"));
                  break;
              case "LOCATE":
                  // POSITION (substr IN str)
                  replaceChild(parent, index, new FunctionNode("POSITION", child.getAlias()) {
                      @Override
                      public void appendChildrenSeparator(QuotingAppendable buffer, int childIdx) {
                          buffer.append(" IN ");
                      }
                  });
                  break;
              case "LENGTH":
                  replaceChild(parent, index, new FunctionNode("CHAR_LENGTH", child.getAlias()));
                  break;
              case "SUBSTRING":
                  // SUBSTRING (str FROM offset FOR length)
                  replaceChild(parent, index, new FunctionNode("SUBSTRING", child.getAlias()){
                      @Override
                      public void appendChildrenSeparator(QuotingAppendable buffer, int childIdx) {
                          if(childIdx == 0) {
                              buffer.append(" FROM ");
                          } else if(childIdx == 1) {
                              buffer.append(" FOR ");
                          }
                      }
                  });
                  break;
              case "YEAR":
              case "MONTH":
              case "DAY":
              case "DAY_OF_MONTH":
              case "HOUR":
              case "MINUTE":
              case "SECOND":
                  Node functionReplacement = new ExtractFunctionNode(child.getAlias());
                  String functionName = child.getFunctionName();
                  if("DAY_OF_MONTH".equals(functionName)) {
                      functionName = "DAY";
                  }
                  functionReplacement.addChild(new TextNode(functionName));
                  replaceChild(parent, index, functionReplacement);
                  break;
  
              case "DAY_OF_WEEK":
              case "DAY_OF_YEAR":
              case "WEEK":
                  throw new CayenneRuntimeException("Function %s() is unsupported in FrontBase.", child.getFunctionName());
          }
      }
  
      private static class ExtractFunctionNode extends FunctionNode {
          public ExtractFunctionNode(String alias) {
              super("EXTRACT", alias, true);
          }
  
          @Override
          public void appendChildrenSeparator(QuotingAppendable buffer, int childIdx) {
              buffer.append(" FROM ");
          }
  
          @Override
          public Node copy() {
              return new ExtractFunctionNode(getAlias());
          }
      }
  }
  