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package com.hardcode.gdbms.engine.data.persistence;

import java.util.Stack;

import org.xml.sax.Attributes;

import org.xml.sax.ContentHandler;

import org.xml.sax.Locator;

import org.xml.sax.SAXException;

import com.hardcode.driverManager.DriverLoadException;

import com.hardcode.gdbms.driver.exceptions.ReadDriverException;

import com.hardcode.gdbms.engine.data.DataSource;

import com.hardcode.gdbms.engine.data.DataSourceFactory;

import com.hardcode.gdbms.engine.data.NoSuchTableException;

import com.hardcode.gdbms.engine.instruction.EvaluationException;

import com.hardcode.gdbms.engine.instruction.SemanticException;

import com.hardcode.gdbms.parser.ParseException;

/**

 * ContentHandler that receives SAXEvents and generates a DataSource

 *

 * @author Fernando Gonz?lez Cort?s

 */

public class MementoContentHandler implements ContentHandler {

    private Stack mementos = new Stack();

    private Memento root;

    /**

     * @see org.xml.sax.ContentHandler#endDocument()

     */

    public void endDocument() throws SAXException {

    }

    /**

     * @see org.xml.sax.ContentHandler#startDocument()

     */

    public void startDocument() throws SAXException {

    }

    /**

     * @see org.xml.sax.ContentHandler#characters(char[], int, int)

     */

    public void characters(char[] ch, int start, int length)

        throws SAXException {

    }

    /**

     * @see org.xml.sax.ContentHandler#ignorableWhitespace(char[], int, int)

     */

    public void ignorableWhitespace(char[] ch, int start, int length)

        throws SAXException {

    }

    /**

     * @see org.xml.sax.ContentHandler#endPrefixMapping(java.lang.String)

     */

    public void endPrefixMapping(String prefix) throws SAXException {

    }

    /**

     * @see org.xml.sax.ContentHandler#skippedEntity(java.lang.String)

     */

    public void skippedEntity(String name) throws SAXException {

    }

    /**

     * @see org.xml.sax.ContentHandler#setDocumentLocator(org.xml.sax.Locator)

     */

    public void setDocumentLocator(Locator locator) {

    }

    /**

     * @see org.xml.sax.ContentHandler#processingInstruction(java.lang.String,

     *      java.lang.String)

     */

    public void processingInstruction(String target, String data)

        throws SAXException {

    }

    /**

     * @see org.xml.sax.ContentHandler#startPrefixMapping(java.lang.String,

     *      java.lang.String)

     */

    public void startPrefixMapping(String prefix, String uri)

        throws SAXException {

    }

    /**

     * @see org.xml.sax.ContentHandler#endElement(java.lang.String,

     *      java.lang.String, java.lang.String)

     */

    public void endElement(String namespaceURI, String localName, String qName)

        throws SAXException {

        if (("operation".equals(localName)) || ("table".equals(localName))) {

            root = (Memento) mementos.pop();

        }

    }

    /**

     * @see org.xml.sax.ContentHandler#startElement(java.lang.String,

     *      java.lang.String, java.lang.String, org.xml.sax.Attributes)

     */

    public void startElement(String namespaceURI, String localName,

        String qName, Attributes atts) throws SAXException {

        if ("operation".equals(localName)) {

            OperationLayerMemento memento = new OperationLayerMemento(atts.getValue(

                        "dataSourceName"), atts.getValue("sql"));

            if (mementos.size() > 0) {

                Memento m = (Memento) mementos.peek();

                if (m instanceof OperationLayerMemento) {

                    OperationLayerMemento mem = (OperationLayerMemento) m;

                    mem.addMemento(memento);

                }

            }

            mementos.push(memento);

        } else if ("table".equals(localName)) {

            DataSourceLayerMemento memento = new DataSourceLayerMemento(atts.getValue(

                        "table-name"), atts.getValue("table-alias"));

            if (mementos.size() > 0) {

                Memento m = (Memento) mementos.peek();

                if (m instanceof OperationLayerMemento) {

                    OperationLayerMemento mem = (OperationLayerMemento) m;

                    mem.addMemento(memento);

                }

            }

            mementos.push(memento);

        }

    }

    /**

     * Get's the root memento of the XML parsed. Null if no parse has been done

     *

     * @return The memento

     */

    public Memento getRoot() {

        return root;

    }

    /**

     * DOCUMENT ME!

     *

     * @param m DOCUMENT ME!

     * @param dsf DOCUMENT ME!

     * @param mode DOCUMENT ME!

     *

     * @return DOCUMENT ME!

     * @throws ParseException DOCUMENT ME!

     * @throws SemanticException DOCUMENT ME!

     * @throws DriverLoadException DOCUMENT ME!

     * @throws NoSuchTableException DOCUMENT ME!

     * @throws ReadDriverException TODO

     * @throws RuntimeException DOCUMENT ME!

     */

    private DataSource createDataSource(Memento m, DataSourceFactory dsf,

        int mode)

        throws ParseException, SemanticException, DriverLoadException, NoSuchTableException, EvaluationException, ReadDriverException {

        if (m instanceof OperationLayerMemento) {

            OperationLayerMemento olm = (OperationLayerMemento) m;

            for (int i = 0; i < olm.getMementoCount(); i++) {

                DataSource ds = createDataSource(olm.getMemento(i), dsf, mode);

            }

            DataSource ds = dsf.executeSQL(olm.getSql(), mode);

            dsf.changeDataSourceName(ds.getName(), olm.getName());

            return ds;

        } else if (m instanceof DataSourceLayerMemento) {

            DataSourceLayerMemento dslm = (DataSourceLayerMemento) m;

            return dsf.createRandomDataSource(dslm.getTableName(),

                dslm.getTableAlias(), mode);

        }

        throw new RuntimeException("unrecognized data source type");

    }

    /**

     * DOCUMENT ME!

     *

     * @param dsf DOCUMENT ME!

     * @param mode DOCUMENT ME!

     *

     * @return DOCUMENT ME!

     * @throws DriverLoadException DOCUMENT ME!

     * @throws ParseException DOCUMENT ME!

     * @throws SemanticException DOCUMENT ME!

     * @throws NoSuchTableException DOCUMENT ME!

     * @throws EvaluationException If there's any problem during expresion evaluation

     * @throws ReadDriverException TODO

     */

    public DataSource getDataSource(DataSourceFactory dsf, int mode)

        throws DriverLoadException, ParseException, SemanticException, NoSuchTableException,

            EvaluationException, ReadDriverException {

        return createDataSource(root, dsf, mode);

    }

}