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package com.openexchange.groupware.update.tasks;

import static com.openexchange.tools.sql.DBUtils.closeSQLStuff;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import com.openexchange.database.DBPoolingException;
import com.openexchange.databaseold.Database;
import com.openexchange.groupware.AbstractOXException;
import com.openexchange.groupware.update.Schema;
import com.openexchange.groupware.update.UpdateException;
import com.openexchange.groupware.update.UpdateExceptionCodes;
import com.openexchange.groupware.update.UpdateTask;

/**
 * {@link CalendarExtendDNColumnTask} - Extends size of <tt>VARCHAR</tt> column <i>dn</i> in both working and backup table of
 * <i>prg_date_rights</i>.
 * 
 * @author <a href="mailto:thorben.betten@open-xchange.com">Thorben Betten</a>
 */
public class CalendarExtendDNColumnTask implements UpdateTask {

    private static final org.apache.commons.logging.Log LOG = org.apache.commons.logging.LogFactory.getLog(CalendarExtendDNColumnTask.class);

    /**
     * Desired size for display name taken from ContactsFieldSizeUpdateTask.
     */
    private static final int DESIRED_SIZE = 320;

    public int addedWithVersion() {
        return 33;
    }

    public int getPriority() {
        /*
         * Modification on database: highest priority.
         */
        return UpdateTask.UpdateTaskPriority.HIGHEST.priority;
    }

    public void perform(final Schema schema, final int contextId) throws AbstractOXException {
        if (LOG.isInfoEnabled()) {
            LOG.info("Starting " + CalendarExtendDNColumnTask.class.getSimpleName());
        }
        modifyColumnInTable("prg_date_rights", contextId);
        modifyColumnInTable("del_date_rights", contextId);
        if (LOG.isInfoEnabled()) {
            LOG.info(CalendarExtendDNColumnTask.class.getSimpleName() + " finished.");
        }
    }

    private static final String SQL_MODIFY = "ALTER TABLE #TABLE# MODIFY dn varchar(" + DESIRED_SIZE + ") collate utf8_unicode_ci default NULL";

    private void modifyColumnInTable(final String tableName, final int contextId) throws UpdateException {
        if (checkColumnInTable(tableName, contextId)) {
            if (LOG.isInfoEnabled()) {
                LOG.info(CalendarExtendDNColumnTask.class.getSimpleName() + ": Going to extend size of column `dn` in table `" + tableName + "`.");
            }
            /*
             * Column does not exist yet
             */
            final Connection writeCon;
            try {
                writeCon = Database.getNoTimeout(contextId, true);
            } catch (final DBPoolingException e) {
                throw new UpdateException(e);
            }
            PreparedStatement stmt = null;
            try {
                try {
                    stmt = writeCon.prepareStatement(SQL_MODIFY.replaceFirst("#TABLE#", tableName));
                    stmt.executeUpdate();
                } catch (final SQLException e) {
                    throw wrapSQLException(e);
                }
            } finally {
                closeSQLStuff(null, stmt);
                if (writeCon != null) {
                    Database.backNoTimeout(contextId, true, writeCon);
                }
            }
            if (LOG.isInfoEnabled()) {
                LOG.info(CalendarExtendDNColumnTask.class.getSimpleName() + ": Size of column `dn` in table `" + tableName + "` successfully extended.");
            }
        }
    }

    private boolean checkColumnInTable(final String tableName, final int contextId) throws UpdateException {
        final Connection writeCon;
        try {
            writeCon = Database.get(contextId, true);
        } catch (final DBPoolingException e) {
            throw new UpdateException(e);
        }
        ResultSet rs = null;
        try {
            final DatabaseMetaData metadata = writeCon.getMetaData();
            rs = metadata.getColumns(null, null, tableName, null);
            while (rs.next()) {
                final String name = rs.getString("COLUMN_NAME");
                if ("dn".equals(name)) {
                    final int size = rs.getInt("COLUMN_SIZE");
                    return (size < DESIRED_SIZE);
                }
            }
            throw notFound(tableName);
        } catch (final SQLException e) {
            throw wrapSQLException(e);
        } finally {
            closeSQLStuff(rs);
            Database.back(contextId, true, writeCon);
        }
    }

    private static UpdateException wrapSQLException(final SQLException e) {
        return UpdateExceptionCodes.SQL_PROBLEM.create(e, e.getMessage());
    }

    private static UpdateException notFound(final String tableName) {
        return UpdateExceptionCodes.COLUMN_NOT_FOUND.create("dn", tableName);
    }
}
