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/**
 * Copyright (c) 1997-2013, www.tinygroup.org ([email protected]).
 * 
 * Licensed under the GPL, Version 3.0 (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.gnu.org/licenses/gpl.html
 * 
 * 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.tinygroup.tinysqldsl.selectitem;

import org.tinygroup.tinysqldsl.base.Alias;
import org.tinygroup.tinysqldsl.base.Column;
import org.tinygroup.tinysqldsl.base.StatementSqlBuilder;
import org.tinygroup.tinysqldsl.operator.SimpleStatisticsOperator;

/**
 * A DISTINCT [(expression, ...)] clause
 */
public class Distinct extends SimpleStatisticsOperator implements SelectItem, Cloneable {

    private SelectItem selectItem;

    private Alias alias;

    public Distinct() {
        this.selectItem = new AllColumns();
    }

    public Distinct(String columnName) {
        this.selectItem = new Column(columnName);
    }

    public Distinct(SelectItem selectItem) {
        this.selectItem = selectItem;
    }

    public static Distinct distinct(SelectItem selectItem) {
        return new Distinct(selectItem);
    }

    public static Distinct distinct(String columnName) {
        return new Distinct(columnName);
    }

    public static Distinct distinct() {
        return new Distinct();
    }

    public Distinct as(String aliasName) {
        return as(aliasName, false);
    }

    public Distinct as(String aliasName, boolean withAs) {
        try {
            Distinct distinct = (Distinct) this.clone();
            distinct.setAlias(new Alias(aliasName, withAs));
            return distinct;
        } catch (CloneNotSupportedException e) {
            throw new RuntimeException(e);
        }
    }

    public Alias getAlias() {
        return alias;
    }

    public void setAlias(Alias alias) {
        this.alias = alias;
    }

    public SelectItem getSelectItem() {
        return selectItem;
    }

    public void setSelectItem(SelectItem selectItem) {
        this.selectItem = selectItem;
    }

    public String toString() {
        String sql = "DISTINCT";
        sql += "(" + selectItem + ")";
        return sql;
    }

    public void builderSelectItem(StatementSqlBuilder builder) {
        internalBuilder(builder);
        if (alias != null) {
            builder.appendSql(alias.toString());
        }
    }

    private void internalBuilder(StatementSqlBuilder builder) {
        StringBuilder buffer = builder.getStringBuilder();
        buffer.append("DISTINCT ");
        SelectItem selectItem = getSelectItem();
        if (selectItem != null) {
            buffer.append("(");
            selectItem.builderSelectItem(builder);
            buffer.append(") ");
        }
    }

    public void builderExpression(StatementSqlBuilder builder) {
        internalBuilder(builder);
    }

}