/*
 * (c) Copyright 2011 by Volker Bergmann. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, is permitted under the terms of the
 * GNU General Public License (GPL).
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * WITHOUT A WARRANTY OF ANY KIND. ALL EXPRESS OR IMPLIED CONDITIONS,
 * REPRESENTATIONS AND WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE
 * HEREBY EXCLUDED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package org.databene.platform.dbunit;

import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;

import org.databene.benerator.engine.BeneratorContext;
import org.databene.commons.ArrayBuilder;
import org.databene.commons.ArrayUtil;
import org.databene.commons.SyntaxError;
import org.databene.model.data.ComplexTypeDescriptor;
import org.databene.model.data.Entity;
import org.databene.script.ScriptUtil;
import org.databene.webdecs.DataContainer;
import org.databene.webdecs.DataIterator;

/**
 * Reads the nested form of a DbUnit XML dataset file and provides its content as Entities 
 * through the {@link DataIterator} interface.<br/><br/>
 * Created: 20.09.2011 07:55:49
 * @since 0.7.2
 * @author Volker Bergmann
 */
public class NestedDbUnitEntityIterator extends AbstractDbUnitEntityIterator {
	
	private Table currentTable;

    public NestedDbUnitEntityIterator(String uri, BeneratorContext context) {
    	super(uri, context);
    	DbUnitUtil.skipRootElement(reader);
        this.currentTable = null;
    }
    
    // DataIterator interface implementation ---------------------------------------------------------------------------

	public DataContainer<Entity> next(DataContainer<Entity> container) {
		try {
			DbUnitUtil.skipNonStartTags(reader);
			if (reader.getEventType() == XMLStreamConstants.END_DOCUMENT)
				return null;
			String elementName = reader.getLocalName();
			Row row;
			if ("table".equals(elementName))
				row = parseTableAndFirstRow();
			else if ("row".equals(elementName) || "column".equals(elementName))
			    row = parseRow();
			else
				throw new SyntaxError("Not an allowed element", "<" + elementName + ">");
			if (row == null)
				return null;
		    ComplexTypeDescriptor descriptor = getType(row);
			Entity result = new Entity(descriptor);
		    String[] cells = row.getValues();
		    for (int i = 0; i < cells.length; i++) {
		        String rowValue = String.valueOf(ScriptUtil.evaluate(cells[i], context));
				result.setComponent(row.getColumnName(i), rowValue);
		    }
		    return container.setData(result);
		} catch (XMLStreamException e) {
			throw new RuntimeException(e);
		}
    }

	// private helpers -------------------------------------------------------------------------------------------------

	private Row parseTableAndFirstRow() throws XMLStreamException {
		String tableName = reader.getAttributeValue(null, "name");
		currentTable = new Table(tableName);
		parseColumns();
		return parseRow();
	}

	protected void parseColumns() throws XMLStreamException {
		String column;
		while ((column = parseColumn()) != null)
			currentTable.addColumn(column);
	}

    private String parseColumn() throws XMLStreamException {
    	// format: <column>column_name</column>
    	// parse <column>
    	reader.nextTag();
    	if (!"column".equals(reader.getLocalName()))
    		return null;
    	reader.next(); 
    	// parse column_name
    	String columnName = reader.getText();
    	// parse </column>
    	reader.next();
    	return columnName;
	}

    private Row parseRow() throws XMLStreamException {
    	if (reader.getEventType() != XMLStreamConstants.START_ELEMENT)
    		return null;
		if ("row".equals(reader.getLocalName()))
			reader.next();
		return parseValues();
	}

	private Row parseValues() throws XMLStreamException {
		String value;
		ArrayBuilder<String> builder = new ArrayBuilder<String>(String.class);
		while ((value = parseValue()) != null)
			builder.add(value);
		return new Row(currentTable.name, currentTable.getColumnNames(), builder.toArray());
    }

    private String parseValue() throws XMLStreamException {
		// <value>cell_value</value>
    	// parse <value>
    	reader.nextTag();
    	if (!"value".equals(reader.getLocalName()))
    		return null;
    	reader.next(); 
    	// parse cell_value
    	String columnName = reader.getText();
    	// parse </value>
    	reader.next();
    	return columnName;
	}

	private static class Table {
        protected String name;
        private String[] columnNames;

        public Table(String name) {
            this.name = name;
            this.columnNames = null;
        }

        public void addColumn(String column) {
			this.columnNames = ArrayUtil.append(column, this.columnNames);
		}

		@Override
        public String toString() {
            return name + columnNames;
        }

        public String[] getColumnNames() {
            return columnNames;
        }
    }

}