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/*
 * Copyright 2014-2020 the original author or authors.
 *
 * Licensed 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.dbflute.cbean.sqlclause;

import org.dbflute.cbean.sqlclause.orderby.OrderByClause;
import org.dbflute.dbway.DBDef;
import org.dbflute.dbway.DBWay;

/**
 * SqlClause for DB2.
 * @author jflute
 */
public class SqlClauseDb2 extends AbstractSqlClause {

    // ===================================================================================
    //                                                                          Definition
    //                                                                          ==========
    /** The serial version UID for object serialization. (Default) */
    private static final long serialVersionUID = 1L;

    // ===================================================================================
    //                                                                           Attribute
    //                                                                           =========
    /** String of fetch-scope as select-hint. */
    protected String _fetchScopeSelectHint = "";

    /** String of fetch-scope as sql-suffix. */
    protected String _fetchScopeSqlSuffix = "";

    /** String of lock as sql-suffix. */
    protected String _lockSqlSuffix = "";

    /** The bind value for paging as 'from'. */
    protected Integer _pagingBindFrom;

    /** The bind value for paging as 'to'. */
    protected Integer _pagingBindTo;

    // ===================================================================================
    //                                                                         Constructor
    //                                                                         ===========
    /**
     * Constructor.
     * @param tableDbName The DB name of table. (NotNull)
     **/
    public SqlClauseDb2(String tableDbName) {
        super(tableDbName);
    }

    // ===================================================================================
    //                                                                Main Clause Override
    //                                                                ====================
    @Override
    protected String prepareUnionClause(String selectClause) {
        // - - - - - - - - - - - - - - - - - - - - - - - - - - - -
        // Remove select-hint comment from select clause of union
        // for fetch-scope with union().
        // - - - - - - - - - - - - - - - - - - - - - - - - - - - -
        selectClause = replace(selectClause, SELECT_HINT, "");
        return super.prepareUnionClause(selectClause);
    }

    // ===================================================================================
    //                                                                    OrderBy Override
    //                                                                    ================
    @Override
    protected OrderByClause.OrderByNullsSetupper createOrderByNullsSetupper() {
        return createOrderByNullsSetupperByCaseWhen();
    }

    // ===================================================================================
    //                                                                 FetchScope Override
    //                                                                 ===================
    /**
     * {@inheritDoc}
     */
    protected void doFetchFirst() {
        doFetchPage();
    }

    /**
     * {@inheritDoc}
     */
    protected void doFetchPage() {
        final RownumPagingProcessor processor = createRownumPagingProcessor(getRownumExpression());
        processor.processRowNumberPaging();
        _fetchScopeSelectHint = processor.getSelectHint();
        _fetchScopeSqlSuffix = processor.getSqlSuffix();
        _pagingBindFrom = processor.getPagingBindFrom();
        _pagingBindTo = processor.getPagingBindTo();
    }

    protected RownumPagingProcessor createRownumPagingProcessor(String expression) {
        final RownumPagingProcessor processor = new RownumPagingProcessor(expression);
        if (isBindPagingCondition()) {
            processor.useBindVariable();
        }
        return processor;
    }

    protected boolean isBindPagingCondition() {
        return true; // as default
    }

    protected String getRownumExpression() {
        return "row_number() over()";
    }

    /**
     * {@inheritDoc}
     */
    protected void doClearFetchPageClause() {
        _fetchScopeSelectHint = "";
        _fetchScopeSqlSuffix = "";
    }

    // ===================================================================================
    //                                                                       Lock Override
    //                                                                       =============
    /**
     * {@inheritDoc}
     */
    public void lockForUpdate() {
        _lockSqlSuffix = " for update with RS";
    }

    // ===================================================================================
    //                                                                       Hint Override
    //                                                                       =============
    /**
     * {@inheritDoc}
     */
    protected String createSelectHint() {
        return _fetchScopeSelectHint;
    }

    /**
     * {@inheritDoc}
     */
    protected String createFromBaseTableHint() {
        return "";
    }

    /**
     * {@inheritDoc}
     */
    protected String createFromHint() {
        return "";
    }

    /**
     * {@inheritDoc}
     */
    protected String createSqlSuffix() {
        return _fetchScopeSqlSuffix + _lockSqlSuffix;
    }

    // [DBFlute-0.7.9]
    // ===================================================================================
    //                                                                 Database Dependency
    //                                                                 ===================
    public void lockWithRR() {
        _lockSqlSuffix = " with RR";
    }

    public void lockWithRS() {
        _lockSqlSuffix = " with RS";
    }

    public void lockWithCS() {
        _lockSqlSuffix = " with CS";
    }

    public void lockWithUR() {
        _lockSqlSuffix = " with UR";
    }

    // [DBFlute-0.9.8.4]
    // ===================================================================================
    //                                                                               DBWay
    //                                                                               =====
    public DBWay dbway() {
        return DBDef.DB2.dbway();
    }

    // [DBFlute-0.9.6.9]
    // ===================================================================================
    //                                                                            Accessor
    //                                                                            ========
    public Integer getPagingBindFrom() { // for parameter comment
        return _pagingBindFrom;
    }

    public Integer getPagingBindTo() { // for parameter comment
        return _pagingBindTo;
    }
}