/*
 * The contents of this file are subject to the terms 
 * of the Common Development and Distribution License 
 * (the "License").  You may not use this file except 
 * in compliance with the License.
 * 
 * You can obtain a copy of the license at 
 * glassfish/bootstrap/legal/CDDLv1.0.txt or 
 * https://glassfish.dev.java.net/public/CDDLv1.0.html. 
 * See the License for the specific language governing 
 * permissions and limitations under the License.
 * 
 * When distributing Covered Code, include this CDDL 
 * HEADER in each file and include the License file at 
 * glassfish/bootstrap/legal/CDDLv1.0.txt.  If applicable, 
 * add the following below this CDDL HEADER, with the 
 * fields enclosed by brackets "[]" replaced with your 
 * own identifying information: Portions Copyright [yyyy] 
 * [name of copyright owner]
 */
// Copyright (c) 1998, 2005, Oracle. All rights reserved.  
package oracle.toplink.essentials.platform.database;

import java.io.*;
import java.util.*;
import oracle.toplink.essentials.exceptions.ValidationException;
import oracle.toplink.essentials.expressions.ExpressionOperator;
import oracle.toplink.essentials.descriptors.ClassDescriptor;
import oracle.toplink.essentials.internal.databaseaccess.FieldTypeDefinition;
import oracle.toplink.essentials.internal.expressions.FunctionExpression;
import oracle.toplink.essentials.internal.expressions.RelationExpression;
import oracle.toplink.essentials.internal.sessions.AbstractSession;
import oracle.toplink.essentials.internal.helper.*;
import oracle.toplink.essentials.queryframework.ValueReadQuery;
import oracle.toplink.essentials.tools.schemaframework.FieldDefinition;

/**
 * <p><b>Purpose</b>: Provides Postgres specific behaviour.
 * <p><b>Responsibilities</b>:<ul>
 * <li> Native SQL for Date, Time, & Timestamp.
 * <li> Native sequencing.
 * <li> Mapping of class types to database types for the schema framework.
 * <li> Pessimistic locking.
 * <li> Platform specific operators.
 * </ul>
 *
 * @since OracleAS TopLink 10<i>g</i> (10.1.3)
 */
public class PostgreSQLPlatform extends DatabasePlatform {
    
    public PostgreSQLPlatform() {
        super();
    }
        /**
     * INTERNAL:
     * TODO: Need to find out how can byte arrays be inlined in Derby
     */
    protected void appendByteArray(byte[] bytes, Writer writer) throws IOException {
            super.appendByteArray(bytes, writer);
    }

    /**
     * INTERNAL:
     * Initialize any platform-specific operators
     */
    protected void initializePlatformOperators() {
        super.initializePlatformOperators();
        addOperator(ExpressionOperator.simpleLogicalNoParens(ExpressionOperator.Concat, "||"));
        addOperator(ExpressionOperator.simpleTwoArgumentFunction(ExpressionOperator.Nvl, "NULLIF"));
        addOperator(operatorLocate());
    }


    /**
     * INTERNAL:
     * This method returns the query to select the timestamp from the server
     * for Derby.
     */
    public ValueReadQuery getTimestampQuery() {
        if (timestampQuery == null) {
            timestampQuery = new ValueReadQuery();
            timestampQuery.setSQLString("SELECT NOW()");
        }
        return timestampQuery;

    }


    /**
     * This method is used to print the output parameter token when stored
     * procedures are called
     */
    public String getInOutputProcedureToken() {
        return "OUT";
    }

    /**
     * This is required in the construction of the stored procedures with
     * output parameters
     */
    public boolean shouldPrintOutputTokenAtStart() {
        //TODO: Check with the reviewer where this is used
        return false;
    }

    /**
     * INTERNAL:
     * Answers whether platform is Derby
     */
    public boolean isPostgreSQL() {
        return true;
    }

    /**
     * INTERNAL:
     */
    protected String getCreateTempTableSqlSuffix() {
        // http://pgsqld.active-venture.com/sql-createtable.html
        return " ON COMMIT PRESERVE ROWS";
    }

    public boolean supportsNativeSequenceNumbers() {
        return true;
    }

    /**
     *  INTERNAL:
     *    Indicates whether NativeSequence should retrieve
     *  sequence value after the object has been inserted into the db
     *  This method is to be used *ONLY* by sequencing classes
     */
    public boolean shouldNativeSequenceAcquireValueAfterInsert() {
        return true;
    }


    /**
     * INTERNAL:
     * Build the identity query for native sequencing.
     */
    public ValueReadQuery buildSelectQueryForNativeSequence(String seqName, Integer size) {
        ValueReadQuery selectQuery = new ValueReadQuery(); 
        selectQuery.setSQLString("select currval(current_schema()" + "|| \'."  + seqName + "\')"); 
        return selectQuery;
    }


    /**
     * INTERNAL:
     */
     protected String getCreateTempTableSqlBodyForTable(DatabaseTable table) {
        // returning null includes fields of the table in body
        // see javadoc of DatabasePlatform#getCreateTempTableSqlBodyForTable(DataBaseTable)
        // for details
        return null;
     }

    /**
     * INTERNAL:
     * Append the receiver's field 'identity' constraint clause to a writer
     */
    public void printFieldIdentityClause(Writer writer) throws ValidationException {
        try {            
            writer.write(" SERIAL");
        } catch (IOException ioException) {
            throw ValidationException.fileError(ioException);
        }
    }

    protected Hashtable buildFieldTypes() {
        Hashtable fieldTypeMapping = new Hashtable();

        fieldTypeMapping.put(Boolean.class, new FieldTypeDefinition("SMALLINT DEFAULT 0", false));

        fieldTypeMapping.put(Integer.class, new FieldTypeDefinition("INTEGER", false));
        fieldTypeMapping.put(Long.class, new FieldTypeDefinition("BIGINT", false));
        fieldTypeMapping.put(Float.class, new FieldTypeDefinition("FLOAT", false));
        fieldTypeMapping.put(Double.class, new FieldTypeDefinition("FLOAT", false));
        fieldTypeMapping.put(Short.class, new FieldTypeDefinition("SMALLINT", false));
        fieldTypeMapping.put(Byte.class, new FieldTypeDefinition("SMALLINT", false));
        fieldTypeMapping.put(java.math.BigInteger.class, new FieldTypeDefinition("BIGINT", false));
        fieldTypeMapping.put(java.math.BigDecimal.class, new FieldTypeDefinition("DECIMAL(38)", false));
        fieldTypeMapping.put(Number.class, new FieldTypeDefinition("DECIMAL(15)", false));

        fieldTypeMapping.put(String.class, new FieldTypeDefinition("VARCHAR", 255));
        fieldTypeMapping.put(Character.class, new FieldTypeDefinition("CHAR", 1));
        fieldTypeMapping.put(Byte[].class, new FieldTypeDefinition("BYTEA"));
        fieldTypeMapping.put(Character[].class, new FieldTypeDefinition("TEXT"));

        fieldTypeMapping.put(java.sql.Date.class, new FieldTypeDefinition("DATE", false));
        fieldTypeMapping.put(java.sql.Time.class, new FieldTypeDefinition("TIME", false));
        fieldTypeMapping.put(java.sql.Timestamp.class, new FieldTypeDefinition("TIMESTAMP", false));

        return fieldTypeMapping;
    }  
    
    /**
     * INTERNAL:
     * Override the default locate operator
     */
    protected ExpressionOperator operatorLocate() {
        ExpressionOperator result = new ExpressionOperator();
        result.setSelector(ExpressionOperator.Locate);
        Vector v = new Vector(3);
        v.addElement("STRPOS(");
        v.addElement(", ");
        v.addElement(")");
        result.printsAs(v);
        result.bePrefix();
        result.setNodeClass(RelationExpression.class);
        return result;
    }


    /**
     * INTERNAL:
     */
    public boolean supportsGlobalTempTables() {
        return true;
    }

    /**
     * INTERNAL:
     */
    protected String getCreateTempTableSqlPrefix() {
        return "CREATE GLOBAL TEMPORARY TABLE ";
    }
                
    /**
     * INTERNAL:
     * returns the maximum number of characters that can be used in a field
     * name on this platform.
     */
    public int getMaxFieldNameSize() {
        // The system uses no more than NAMEDATALEN-1 characters of an identifier; longer names can be written in commands, 
        //    but they will be truncated. By default, NAMEDATALEN is 64 so the maximum identifier length is 63 (but at the time PostgreSQL 
        //    is built, NAMEDATALEN can be changed in src/include/postgres_ext.h).
        // http://www.postgresql.org/docs/7.3/interactive/sql-syntax.html#SQL-SYNTAX-IDENTIFIERS
        return 63;
    }

    // http://www.postgresql.org/docs/8.1/interactive/plpgsql-declarations.html
    /**
     * INTERNAL:
     * Used for sp calls.
     */
    public String getProcedureBeginString() {
        return "AS $$  BEGIN ";
    }

    /**
     * INTERNAL:
     * Used for sp calls.
     */
    public String getProcedureEndString() {
        return "; END ; $$ LANGUAGE plpgsql;";
    }

    /**
     * INTERNAL:
     * Used for sp calls.
     */
    public String getProcedureCallHeader() {
        return "EXECUTE ";
    }
    
    /**
     * INTERNAL
     * Used for stored function calls.
     */
    public String getAssignmentString() {
        return ":= ";
    }    
    
    public void printFieldTypeSize(Writer writer, FieldDefinition field, 
            FieldTypeDefinition fieldType, AbstractSession session, String qualifiedFieldName) throws IOException {
        if(!shouldAcquireSequenceValueAfterInsert(session,  qualifiedFieldName)) {
            writer.write(fieldType.getName());
            if ((fieldType.isSizeAllowed()) && ((field.getSize() != 0) || (fieldType.isSizeRequired()))) {
                writer.write("(");
                if (field.getSize() == 0) {
                    writer.write(new Integer(fieldType.getDefaultSize()).toString());
                } else {
                    writer.write(new Integer(field.getSize()).toString());
                }
                if (field.getSubSize() != 0) {
                    writer.write(",");
                    writer.write(new Integer(field.getSubSize()).toString());
                } else if (fieldType.getDefaultSubSize() != 0) {
                    writer.write(",");
                    writer.write(new Integer(fieldType.getDefaultSubSize()).toString());
                }
                writer.write(")");
            }
        }
    }
    
    public void printFieldUnique(Writer writer,  boolean isUnique, 
            AbstractSession session, String qualifiedFieldName) throws IOException {
       if(!shouldAcquireSequenceValueAfterInsert(session,  qualifiedFieldName)) {
            if (isUnique) {
                if (supportsPrimaryKeyConstraint()) {
                    writer.write(" UNIQUE");
                }
            }
       }
    }
    
}