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  package org.apache.cayenne.velocity;
  
  import java.io.IOException;
  import java.io.Writer;
  import java.math.BigDecimal;
  import java.math.BigInteger;
  import java.sql.Date;
  import java.sql.Time;
  import java.sql.Timestamp;
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.Map;
  
  import org.apache.cayenne.access.jdbc.ColumnDescriptor;
  import org.apache.cayenne.util.Util;
  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.directive.Directive;
  import org.apache.velocity.runtime.parser.node.Node;
  
  /**
   * A custom Velocity directive to describe a ResultSet column. There are the
   * following possible invocation formats inside the template:
   * 
   * <pre>
   *       #result(column_name) - e.g. #result('ARTIST_ID')
   *       #result(column_name java_type) - e.g. #result('ARTIST_ID' 'String')
   *       #result(column_name java_type column_alias) - e.g. #result('ARTIST_ID' 'String' 'ID')
   *       #result(column_name java_type column_alias data_row_key) - e.g. #result('ARTIST_ID' 'String' 'ID' 'toArtist.ID')
   * </pre>
   * 
   * <p>
   * 'data_row_key' is needed if SQL 'column_alias' is not appropriate as a
   * DataRow key on the Cayenne side. One common case when this happens is when a
   * DataRow retrieved from a query is mapped using joint prefetch keys. In this
   * case DataRow must use DB_PATH expressions for joint column keys, and their
   * format is incompatible with most databases alias format.
   * </p>
   * <p>
   * Most common Java types used in JDBC can be specified without a package. This
   * includes all numeric types, primitives, String, SQL dates, BigDecimal and
   * BigInteger.
   * </p>
   * 
   * @since 1.1
   */
  public class ResultDirective extends Directive {
  
  	private static final Map<String, String> typesGuess;
  
  	static {
  		// init default types
  		typesGuess = new HashMap<>();
  
  		// primitives
  		typesGuess.put("long", Long.class.getName());
  		typesGuess.put("double", Double.class.getName());
  		typesGuess.put("byte", Byte.class.getName());
  		typesGuess.put("boolean", Boolean.class.getName());
  		typesGuess.put("float", Float.class.getName());
  		typesGuess.put("short", Short.class.getName());
  		typesGuess.put("int", Integer.class.getName());
  
  		// numeric
  		typesGuess.put("Long", Long.class.getName());
  		typesGuess.put("Double", Double.class.getName());
  		typesGuess.put("Byte", Byte.class.getName());
  		typesGuess.put("Boolean", Boolean.class.getName());
  		typesGuess.put("Float", Float.class.getName());
  		typesGuess.put("Short", Short.class.getName());
  		typesGuess.put("Integer", Integer.class.getName());
  
  		// other
  		typesGuess.put("String", String.class.getName());
  		typesGuess.put("Date", Date.class.getName());
  		typesGuess.put("Time", Time.class.getName());
  		typesGuess.put("Timestamp", Timestamp.class.getName());
  		typesGuess.put("BigDecimal", BigDecimal.class.getName());
  		typesGuess.put("BigInteger", BigInteger.class.getName());
  	}
  
  	@Override
  	public String getName() {
  		return "result";
  	}
  
  	@Override
  	public int getType() {
  		return LINE;
  	}
  
  	@Override
  	public boolean render(InternalContextAdapter context, Writer writer, Node node) throws IOException,
  			ResourceNotFoundException, ParseErrorException, MethodInvocationException {
  
  		String column = getChildAsString(context, node, 0);
  		if (column == null) {
  			throw new ParseErrorException("Column name expected at line " + node.getLine() + ", column "
  					+ node.getColumn());
  		}
  
  		String alias = getChildAsString(context, node, 2);
  		String dataRowKey = getChildAsString(context, node, 3);
  
  		// determine what we want to name this column in a resulting DataRow...
  		String label = (!Util.isEmptyString(dataRowKey)) ? dataRowKey : (!Util.isEmptyString(alias)) ? alias : null;
  
  		ColumnDescriptor columnDescriptor = new ColumnDescriptor();
  		columnDescriptor.setName(column);
  		columnDescriptor.setDataRowKey(label);
  
  		String type = getChildAsString(context, node, 1);
  		if (type != null) {
  			columnDescriptor.setJavaClass(guessType(type));
  		}
  
  		// TODO: andrus 6/27/2007 - this is an unofficial jdbcType parameter
  		// that is added
  		// temporarily pending CAY-813 implementation for the sake of EJBQL
  		// query...
  		Object jdbcType = getChild(context, node, 4);
  		if (jdbcType instanceof Number) {
  			columnDescriptor.setJdbcType(((Number) jdbcType).intValue());
  		}
  
  		writer.write(column);
  
  		// append column alias if needed.
  
  		// Note that if table aliases are used, this logic will result in SQL
  		// like
  		// "t0.ARTIST_NAME AS ARTIST_NAME". Doing extra regex matching to handle
  		// this
  		// won't probably buy us much.
  		if (!Util.isEmptyString(alias) && !alias.equals(column)) {
  			writer.write(" AS ");
  			writer.write(alias);
  		}
  
  		bindResult(context, columnDescriptor);
  		return true;
  	}
  
  	protected Object getChild(InternalContextAdapter context, Node node, int i) throws MethodInvocationException {
  		return (i >= 0 && i < node.jjtGetNumChildren()) ? node.jjtGetChild(i).value(context) : null;
  	}
  
  	/**
  	 * Returns a directive argument at a given index converted to String.
  	 * 
  	 * @since 1.2
  	 */
  	protected String getChildAsString(InternalContextAdapter context, Node node, int i)
  			throws MethodInvocationException {
  		Object value = getChild(context, node, i);
  		return (value != null) ? value.toString() : null;
  	}
  
  	/**
  	 * Converts "short" type notation to the fully qualified class name. Right
  	 * now supports all major standard SQL types, including primitives. All
  	 * other types are expected to be fully qualified, and are not converted.
  	 */
  	protected String guessType(String type) {
  		String guessed = typesGuess.get(type);
  		return guessed != null ? guessed : type;
  	}
  
  	/**
  	 * Adds value to the list of result columns in the context.
  	 */
  	protected void bindResult(InternalContextAdapter context, ColumnDescriptor columnDescriptor) {
  
  		@SuppressWarnings("unchecked")
  		Collection<Object> resultColumns = (Collection<Object>) context
  				.getInternalUserContext().get(VelocitySQLTemplateProcessor.RESULT_COLUMNS_LIST_KEY);
  
  		if (resultColumns != null) {
  			resultColumns.add(columnDescriptor);
  		}
  	}
  }
  