/*
 * Copyright 1999-2011 Alibaba Group Holding Ltd.
 *
 * 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 com.alibaba.druid.sql.dialect.postgresql.ast;

import com.alibaba.druid.sql.ast.SQLOrderingSpecification;
import com.alibaba.druid.sql.ast.statement.SQLSelectOrderByItem;
import com.alibaba.druid.sql.dialect.postgresql.visitor.PGASTVisitor;
import com.alibaba.druid.sql.visitor.SQLASTVisitor;

public class PGOrderByItem extends SQLSelectOrderByItem {

    private static final long serialVersionUID = 1L;

    private NullsOrderType    nullsOrderType;

    public PGOrderByItem(){

    }

    public NullsOrderType getNullsOrderType() {
        return this.nullsOrderType;
    }

    public void setNullsOrderType(NullsOrderType nullsOrderType) {
        this.nullsOrderType = nullsOrderType;
    }

    protected void accept0(SQLASTVisitor visitor) {
        if (visitor instanceof PGASTVisitor) {
            accept0((PGASTVisitor) visitor);
        } else {
            super.accept0(visitor);
        }
    }

    protected void accept0(PGASTVisitor visitor) {
        if (visitor.visit(this)) {
            acceptChild(visitor, this.expr);
        }

        visitor.endVisit(this);
    }

    public void output(StringBuffer buf) {
        this.expr.output(buf);
        if (SQLOrderingSpecification.ASC.equals(this.type)) {
            buf.append(" ASC");
        } else if (SQLOrderingSpecification.DESC.equals(this.type)) {
            buf.append(" DESC");
        }
        if (NullsOrderType.NullsFirst.equals(this.nullsOrderType)) {
            buf.append(" NULLS FIRST");
        } else if (NullsOrderType.NullsLast.equals(this.nullsOrderType)) {
            buf.append(" NULLS LAST");
        }
    }

    public static enum NullsOrderType {
        NullsFirst, NullsLast;

        public String toFormalString() {
            if (NullsFirst.equals(this)) {
                return "NULLS FIRST";
            }

            if (NullsLast.equals(this)) {
                return "NULLS LAST";
            }

            throw new IllegalArgumentException();
        }
    }

}
