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 *  or more contributor license agreements.  See the NOTICE file
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 *  to you under the Apache License, Version 2.0 (the
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package org.apache.cayenne.access.trans;

import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Types;
import java.util.Iterator;
import java.util.List;

import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.dba.DbAdapter;
import org.apache.cayenne.dba.TypesMapping;
import org.apache.cayenne.map.DbAttribute;
import org.apache.cayenne.query.BatchQuery;

/**
 * Superclass of query builders for the DML operations involving LOBs.
 * 
 * @author Andrei Adamchik
 */
public abstract class LOBBatchQueryBuilder extends BatchQueryBuilder {

    protected String newClobFunction;
    protected String newBlobFunction;

    public LOBBatchQueryBuilder(DbAdapter adapter) {
        super(adapter);
    }

    public abstract List getValuesForLOBUpdateParameters(BatchQuery query);

    public String createLOBSelectString(
            BatchQuery updateQuery,
            List selectedLOBAttributes,
            List qualifierAttributes) {

        StringBuffer buf = new StringBuffer();
        buf.append("SELECT ");

        Iterator it = selectedLOBAttributes.iterator();
        while (it.hasNext()) {
            buf.append(((DbAttribute) it.next()).getName());

            if (it.hasNext()) {
                buf.append(", ");
            }
        }

        buf
                .append(" FROM ")
                .append(updateQuery.getDbEntity().getFullyQualifiedName())
                .append(" WHERE ");

        it = qualifierAttributes.iterator();
        while (it.hasNext()) {
            DbAttribute attribute = (DbAttribute) it.next();
            appendDbAttribute(buf, attribute);
            buf.append(" = ?");
            if (it.hasNext()) {
                buf.append(" AND ");
            }
        }

        buf.append(" FOR UPDATE");
        return buf.toString();
    }

    /**
     * Appends parameter placeholder for the value of the column being updated. If
     * requested, performs special handling on LOB columns.
     */
    protected void appendUpdatedParameter(
            StringBuffer buf,
            DbAttribute dbAttribute,
            Object value) {

        int type = dbAttribute.getType();

        if (isUpdateableColumn(value, type)) {
            buf.append('?');
        }
        else {
            if (type == Types.CLOB) {
                buf.append(newClobFunction);
            }
            else if (type == Types.BLOB) {
                buf.append(newBlobFunction);
            }
            else {
                throw new CayenneRuntimeException("Unknown LOB column type: "
                        + type
                        + "("
                        + TypesMapping.getSqlNameByType(type)
                        + "). Query buffer: "
                        + buf);
            }
        }
    }

    /**
     * Binds BatchQuery parameters to the PreparedStatement.
     */
    public void bindParameters(PreparedStatement statement, BatchQuery query)
            throws SQLException, Exception {

        List dbAttributes = query.getDbAttributes();
        int attributeCount = dbAttributes.size();

        // i - attribute position in the query
        // j - PreparedStatement parameter position (starts with "1")
        for (int i = 0, j = 1; i < attributeCount; i++) {
            Object value = query.getValue(i);
            DbAttribute attribute = (DbAttribute) dbAttributes.get(i);
            int type = attribute.getType();

            // TODO: (Andrus) This works as long as there is no LOBs in qualifier
            if (isUpdateableColumn(value, type)) {
                adapter
                        .bindParameter(statement, value, j, type, attribute
                                .getPrecision());

                j++;
            }
        }
    }

    protected boolean isUpdateableColumn(Object value, int type) {
        return value == null || (type != Types.BLOB && type != Types.CLOB);
    }

    public String getNewBlobFunction() {
        return newBlobFunction;
    }

    public String getNewClobFunction() {
        return newClobFunction;
    }

    public void setNewBlobFunction(String string) {
        newBlobFunction = string;
    }

    public void setNewClobFunction(String string) {
        newClobFunction = string;
    }
}