EDIT

/**

* Copyright (C) 2009 EDIT

* European Distributed Institute of Taxonomy

* http://www.e-taxonomy.eu

*

* The contents of this file are subject to the Mozilla Public License Version 1.1

* See LICENSE.TXT at the top of this package for the full license terms.

*/

package eu.etaxonomy.cdm.database.update;

import java.util.List;

import org.apache.logging.log4j.LogManager;import org.apache.logging.log4j.Logger;

import eu.etaxonomy.cdm.common.monitor.IProgressMonitor;

import eu.etaxonomy.cdm.database.DatabaseTypeEnum;

import eu.etaxonomy.cdm.database.ICdmDataSource;

/**

 * @author a.mueller

 * @since 16.09.2010

 */

public class TableDropper

        extends AuditedSchemaUpdaterStepBase{

    private static final Logger logger = LogManager.getLogger(TableDropper.class);

	private boolean ifExists = true;

	public static final TableDropper NewInstance(List<ISchemaUpdaterStep> stepList, String stepName, String tableName, boolean includeAudTable){

		return new TableDropper(stepList, stepName, tableName, includeAudTable, true);

	}

	/**

	 * @param stepName

	 * @param tableName

	 * @param includeAudTable

	 * @param ifExists if false, and error will be thrown if the table does not exist and can therefore not be dropped.

	 * @see #NewInstance(String, String, boolean)

	 * @return

	 */

	public static final TableDropper NewInstance(List<ISchemaUpdaterStep> stepList, String stepName, String tableName, boolean includeAudTable, boolean ifExists){

		return new TableDropper(stepList, stepName, tableName, includeAudTable, ifExists);

	}

	protected TableDropper(List<ISchemaUpdaterStep> stepList, String stepName, String tableName, boolean includeAudTable, boolean ifExists) {

		super(stepList, stepName, tableName, includeAudTable);

		this.ifExists = ifExists;

	}

    @Override

    protected void invokeOnTable(String tableName, ICdmDataSource datasource,

            IProgressMonitor monitor, CaseType caseType, SchemaUpdateResult result) {

        try {

			String updateQuery = getUpdateQueryString(tableName, datasource, monitor);

			datasource.executeUpdate(updateQuery);

			if (! this.isAuditing){

				removeFromHibernateSequences(datasource, monitor, tableName, result);

			}

			return;

		} catch ( Exception e) {

		    String message = e.getMessage();

			monitor.warning(message, e);

			logger.error(e);

			result.addException(e, message, getStepName() + ", TableDropper.invokeOnTable");

			return;

		}

	}

	private void removeFromHibernateSequences(ICdmDataSource datasource, IProgressMonitor monitor,

	        String tableName, SchemaUpdateResult result) {

		try {

			//TODO do we need to "case" this table name?

			String sql = " DELETE FROM hibernate_sequences WHERE sequence_name = '%s'";

			sql = String.format(sql, tableName);

			datasource.executeUpdate(sql);

			return;

		} catch (Exception e) {

			String message = "Exception occurred when trying to read or update hibernate_sequences table for value " + this.tableName + ": " + e.getMessage();

			monitor.warning(message, e);

			logger.error(message);

			result.addWarning(message, (String)null, getStepName());

			return;

		}

	}

	/**

	 * @param tableName cased tableName

	 * @param datasource

	 * @param monitor

	 * @param caseType

	 * @return

	 * @throws DatabaseTypeNotSupportedException

	 */

	public String getUpdateQueryString(String tableName, ICdmDataSource datasource, IProgressMonitor monitor) throws DatabaseTypeNotSupportedException {

		String updateQuery;

		DatabaseTypeEnum type = datasource.getDatabaseType();

		updateQuery = "DROP TABLE @ifExists @tableName ";

		if (type.equals(DatabaseTypeEnum.SqlServer2005)){

			//MySQL allows both syntaxes

			updateQuery = " if exists (select * from INFORMATION_SCHEMA.TABLES where TABLE_NAME='@tableName') BEGIN drop table @tableName end ";

		}else if (type.equals(DatabaseTypeEnum.H2) || type.equals(DatabaseTypeEnum.PostgreSQL) || type.equals(DatabaseTypeEnum.MySQL)){

//			updateQuery = "ALTER TABLE @tableName @addSeparator @columnName @columnType";

		}else{

			updateQuery = null;

			String warning = "Update step '" + this.getStepName() + "' is not supported by " + type.getName();

			monitor.warning(warning);

			throw new DatabaseTypeNotSupportedException(warning);

		}

		updateQuery = updateQuery.replace("@tableName", tableName);

		if (ifExists == true){

			updateQuery = updateQuery.replace("@ifExists", "IF EXISTS");

		}else{

			updateQuery = updateQuery.replace("@ifExists", "");

		}

		return updateQuery;

	}

}