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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:
 * 
 *  *       #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')
 * 
 * 
 * 
 * '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.
 * 
 * 
 * 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.
 * 
 * 
 * @since 1.1
 */
public class ResultDirective extends Directive {

	private static final Map 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