/*
 * Copyright 2011, Mysema 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.mysema.query.sql;

import java.math.BigInteger;

import com.mysema.query.QueryMetadata;
import com.mysema.query.QueryModifiers;
import com.mysema.query.types.Ops;

/**
 * OracleTemplates is an SQL dialect for Oracle
 *
 * tested with Oracle 10g XE
 *
 * @author tiwe
 */
public class OracleTemplates extends SQLTemplates {

    private String outerQueryEnd = "\n ) a) where ";

    private String outerQueryStart = "select * from (\n select a.*, rownum rn from (\n  ";

    private String limitQueryEnd = "\n) where rownum <= {0}";

    private String limitQueryStart = "select * from (\n  ";

    private String limitOffsetTemplate = "rn > {0s} and rn <= {1s}";

    private String offsetTemplate = "rn > {0}";

    public OracleTemplates() {
        this('\\', false);
    }
    
    public OracleTemplates(boolean quote) {
        this('\\',quote);
    }

    public OracleTemplates(char escape, boolean quote) {
        super("\"", escape, quote);
        setParameterMetadataAvailable(false);
        setBatchCountViaGetUpdateCount(true);
        // type mappings
        addClass2TypeMappings("number(3,0)", Byte.class);
        addClass2TypeMappings("number(1,0)", Boolean.class);
        addClass2TypeMappings("number(19,0)", BigInteger.class, Long.class);
        addClass2TypeMappings("number(5,0)", Short.class);
        addClass2TypeMappings("number(10,0)", Integer.class);
        addClass2TypeMappings("double precision", Double.class);
        addClass2TypeMappings("varchar(4000 char)", String.class);

        add(Ops.ALIAS, "{0} {1}");
        add(NEXTVAL, "{0s}.nextval");

        // String
        add(Ops.INDEX_OF, "instrb({0},{1})-1");
        add(Ops.INDEX_OF_2ARGS, "instrb({0},{1},{2}+1)-1");
        add(Ops.MATCHES, "regexp_like({0},{1})");
        add(Ops.StringOps.SPACE, "lpad('',{0},' ')");
        
        // Number
        add(Ops.MathOps.CEIL, "ceil({0})");
        add(Ops.MathOps.RANDOM, "dbms_random.value");
        add(Ops.MathOps.LN, "ln({0})");
        add(Ops.MathOps.LOG, "log({1},{0})");        
        add(Ops.MathOps.COT, "(cos({0}) / sin({0}))");
        add(Ops.MathOps.COTH, "(exp({0} * 2) + 1) / (exp({0} * 2) - 1)");
        add(Ops.MathOps.DEG, "({0} * 180 / "+Math.PI+")");
        add(Ops.MathOps.RAD, "({0} * "+Math.PI+" / 180)");

        // Date / time
        add(Ops.DateTimeOps.YEAR, "extract(year from {0})");
        add(Ops.DateTimeOps.YEAR_MONTH, "extract(year from {0}) * 100 + extract(month from {0})");
        add(Ops.DateTimeOps.MONTH, "extract(month from {0})");
        add(Ops.DateTimeOps.WEEK, "to_number(to_char({0},'WW'))");
        add(Ops.DateTimeOps.DAY_OF_MONTH, "to_number(to_char({0},'DD'))");
        add(Ops.DateTimeOps.DAY_OF_WEEK, "to_number(to_char({0},'D')) + 1");
        add(Ops.DateTimeOps.DAY_OF_YEAR, "to_number(to_char({0},'DDD'))");
        add(Ops.DateTimeOps.HOUR, "to_number(to_char({0},'HH24'))");
        add(Ops.DateTimeOps.MINUTE, "to_number(to_char({0},'MI'))");
        add(Ops.DateTimeOps.SECOND, "to_number(to_char({0},'SS'))");

    }

    @Override
    public void serialize(QueryMetadata metadata, boolean forCountRow, SerializationContext context) {
        if (!forCountRow && metadata.getModifiers().isRestricting() && !metadata.getJoins().isEmpty()) {
            QueryModifiers mod = metadata.getModifiers();

            if (mod.getOffset() == null) {
                context.append(limitQueryStart);
                context.serialize(metadata, forCountRow);
                context.handle(limitQueryEnd, mod.getLimit());
            } else {
                context.append(outerQueryStart);
                context.serialize(metadata, forCountRow);
                context.append(outerQueryEnd);

                if (mod.getLimit() == null) {
                    context.handle(offsetTemplate, mod.getOffset());
                } else {
                    context.handle(limitOffsetTemplate, mod.getOffset(), mod.getLimit() + mod.getOffset());
                }
            }

        } else {
            context.serialize(metadata, forCountRow);
        }
    }
    
    @Override
    protected void serializeModifiers(QueryMetadata metadata, SerializationContext context) {
        // do nothing
    }

}