/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.tuscany.das.rdb.generator.impl;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.apache.log4j.Logger;
import org.apache.tuscany.das.rdb.config.Column;
import org.apache.tuscany.das.rdb.config.Table;
import org.apache.tuscany.das.rdb.config.wrapper.MappingWrapper;
import org.apache.tuscany.das.rdb.config.wrapper.RelationshipWrapper;
import org.apache.tuscany.das.rdb.config.wrapper.TableWrapper;
import org.apache.tuscany.das.rdb.impl.ManagedParameterImpl;
import org.apache.tuscany.das.rdb.impl.OptimisticWriteCommandImpl;
import org.apache.tuscany.das.rdb.impl.ParameterImpl;
import org.apache.tuscany.das.rdb.impl.UpdateCommandImpl;
import org.apache.tuscany.das.rdb.util.LoggerFactory;

import commonj.sdo.ChangeSummary;
import commonj.sdo.DataObject;
import commonj.sdo.Property;
import commonj.sdo.Type;

public final class UpdateGenerator extends BaseGenerator {

    public static final UpdateGenerator INSTANCE = new UpdateGenerator();

    private final Logger logger = LoggerFactory.INSTANCE.getLogger(UpdateGenerator.class);

    private UpdateGenerator() {
        super();
    }

    public UpdateCommandImpl getUpdateCommand(MappingWrapper mapping, DataObject changedObject, Table table) {
        List updatedProperties = new ArrayList();
        List managedProperties = new ArrayList();
        List whereClauseProperties = new ArrayList();
        Type type = changedObject.getType();
        TableWrapper t = new TableWrapper(table);
        StringBuffer statement = new StringBuffer("update ");
        statement.append(table.getTableName());
        statement.append(" set ");

        ChangeSummary summary = changedObject.getDataGraph().getChangeSummary();
        Iterator i = getChangedFields(mapping, summary, changedObject).iterator();

        while (i.hasNext()) {
            Property property = (Property) i.next();
            Column c = t.getColumnByPropertyName(property.getName());
            if ((c != null) && (c.isCollision() || c.isPrimaryKey())) {
                // get rid of comma if OCC or PK is last field
                if (!i.hasNext()) {
                    statement.delete(statement.length() - 2, statement.length());
                }
            } else {
                updatedProperties.add(property);
                statement.append(c == null ? property.getName() : c.getColumnName());
                statement.append(" = ?");
                if (i.hasNext()) {
                    statement.append(", ");
                }
            }
        }

        Column c = t.getManagedColumn();
        if (c != null) {
            statement.append(", ");
            statement.append(c.getColumnName());
            statement.append(" = ?");
            managedProperties.add(changedObject.getProperty(t.getManagedColumnPropertyName()));
        }
        statement.append(" where ");

        Iterator names = t.getPrimaryKeyNames().iterator();
        Iterator pkProperties = t.getPrimaryKeyProperties().iterator();
        while (names.hasNext() && pkProperties.hasNext()) {
            String name = (String) names.next();
            String property = (String) pkProperties.next();
            statement.append(name);
            statement.append(" = ?");
            if (names.hasNext() && pkProperties.hasNext()) {
                statement.append(" and ");
            }
            whereClauseProperties.add(type.getProperty(property));
        }

        if (t.getCollisionColumn() != null) {
            statement.append(" and ");
            statement.append(t.getCollisionColumn().getColumnName());
            statement.append(" = ?");
            whereClauseProperties.add(type.getProperty(t.getCollisionColumnPropertyName()));
        }

        UpdateCommandImpl updateCommand;
        if (t.getCollisionColumn() != null) {
            updateCommand = new OptimisticWriteCommandImpl(statement.toString());
        } else {
            updateCommand = new UpdateCommandImpl(statement.toString());
        }

        int idx = 1;
        Iterator params = updatedProperties.iterator();
        while (params.hasNext()) {
            Property p = (Property) params.next();
            updateCommand.addParameter(createParameter(t, p, idx++));
        }

        params = managedProperties.iterator();
        while (params.hasNext()) {
            Property p = (Property) params.next();
            updateCommand.addParameter(createManagedParameter(t, p, idx++));
        }

        params = whereClauseProperties.iterator();
        while (params.hasNext()) {
            Property p = (Property) params.next();
            updateCommand.addParameter(createParameter(t, p, idx++));
        }

        if (this.logger.isDebugEnabled()) {
            this.logger.debug(statement.toString());
        }

        return updateCommand;
    }

    private List getChangedFields(MappingWrapper mapping, ChangeSummary summary, DataObject obj) {
        List changes = new ArrayList();
        Iterator i = summary.getOldValues(obj).iterator();
        while (i.hasNext()) {
            ChangeSummary.Setting setting = (ChangeSummary.Setting) i.next();
            if (setting.getProperty().getType().isDataType()) {
                changes.add(setting.getProperty());
            } else {
                Property ref = setting.getProperty();
                if (!ref.isMany()) {
                    RelationshipWrapper r = new RelationshipWrapper(mapping.getRelationshipByReference(ref));

                    Iterator keys = r.getForeignKeys().iterator();
                    while (keys.hasNext()) {
                        String key = (String) keys.next();
                        Property p = obj.getType().getProperty(key);
                        changes.add(p);
                    }
                }

            }
        }
        return changes;
    }

    private ParameterImpl createManagedParameter(TableWrapper table, Property property, int idx) {
        ParameterImpl param = new ManagedParameterImpl();
        param.setName(property.getName());
        param.setType(property.getType());
        param.setConverter(getConverter(table.getConverter(property.getName())));
        if (idx != -1) {
            param.setIndex(idx);
        }

        return param;
    }

    private ParameterImpl createParameter(TableWrapper table, Property property, int idx) {
        ParameterImpl param = new ParameterImpl();
        param.setName(property.getName());
        param.setType(property.getType());
        param.setConverter(getConverter(table.getConverter(property.getName())));
        if (idx != -1) {
            param.setIndex(idx);
        }

        return param;
    }

}