/**
 * DataCleaner (community edition)
 * Copyright (C) 2014 Neopost - Customer Information Management
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.datacleaner.metamodel.datahub;

import java.util.List;

import org.apache.metamodel.MetaModelException;
import org.apache.metamodel.delete.AbstractRowDeletionBuilder;
import org.apache.metamodel.query.FilterItem;
import org.apache.metamodel.schema.Table;

public class DataHubDeleteBuilder extends AbstractRowDeletionBuilder {
    /**
     * Column that should be present in the where clause for golden records
     */
    private static final String GR_ID_COLUMN_NAME = "gr_id";
    /**
     * Columns that should be present in the where clause for source records 
     */
    private static final String SOURCE_ID_COLUMN_NAME = "datasource_record_id";
    private static final String SOURCE_NAME_COLUMN_NAME = "datasource_name";

    private final DataHubUpdateCallback _callback;

    public DataHubDeleteBuilder(final DataHubUpdateCallback callback, final Table table) {
        super(table);
        _callback = callback;
    }

    @Override
    public void execute() throws MetaModelException {
        final List<FilterItem> whereItems = getWhereItems();
        if (whereItems == null || whereItems.size() == 0) {
            throw new IllegalArgumentException("Delete requires a condition.");
        }
        final String firstColumnName = getConditionColumnName(whereItems.get(0));
        if (firstColumnName.equals(GR_ID_COLUMN_NAME)) {
            deleteGoldenRecord(whereItems);
        } else if (firstColumnName.equalsIgnoreCase(SOURCE_ID_COLUMN_NAME)) {
            deleteSourceRecord(whereItems);
        } else {
            throw new IllegalArgumentException("Delete condition is not valid.");
        }
    }

    private void deleteSourceRecord(final List<FilterItem> whereItems) {
        if (whereItems.size() != 2) {
            throw new IllegalArgumentException(
                    "Delete must be executed on a SourceRecordsGoldenRecordFormat table using " + SOURCE_ID_COLUMN_NAME
                            + " and " + SOURCE_NAME_COLUMN_NAME + " as condition values.");
        }
        final FilterItem firstWhereItem = whereItems.get(0);
        final FilterItem secondWhereItem = whereItems.get(1);

        final String secondColumnName = getConditionColumnName(secondWhereItem);
        if (SOURCE_NAME_COLUMN_NAME.equals(secondColumnName)) {
            final String id = getConditionColumnValue(firstWhereItem);
            final String sourceName = getConditionColumnValue(secondWhereItem);
            _callback.executeDeleteSourceRecord(sourceName, id, getRecordType());
        } else {
            throw new IllegalArgumentException(
                    "Delete must be executed on a SourceRecordsGoldenRecordFormat table using " + SOURCE_ID_COLUMN_NAME
                            + " and " + SOURCE_NAME_COLUMN_NAME + " as condition values.");
        }
    }

    private void deleteGoldenRecord(final List<FilterItem> whereItems) {
        if (whereItems.size() != 1) {
            throw new IllegalArgumentException(
                    "Delete requires the " + GR_ID_COLUMN_NAME + " as the sole condition value.");
        }
        final FilterItem whereItem = whereItems.get(0);
        final String grId = getConditionColumnValue(whereItem);
        _callback.executeDeleteGoldenRecord(grId);
    }

    private String getConditionColumnValue(final FilterItem filterItem) {
        return (String) filterItem.getOperand();
    }

    private String getConditionColumnName(final FilterItem filterItem) {
        return filterItem.getSelectItem().getColumn().getName();
    }

    private String getRecordType() {
        return getTable().getName();
    }

}