/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle, IBM Corporation and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the 
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0 
 * which accompanies this distribution. 
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at 
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
 *     12/11/2014 - Dalia Abo Sheasha
 *       - 454917 : Wrong SQL statement generated for Informix when GenerationType.IDENTITY strategy is used
 *     02/19/2015 - Rick Curtis  
 *       - 458877 : Add national character support
 *****************************************************************************/  
package org.eclipse.persistence.platform.database;

import java.io.*;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.SQLException;
import java.util.*;

import org.eclipse.persistence.exceptions.*;
import org.eclipse.persistence.internal.databaseaccess.FieldTypeDefinition;
import org.eclipse.persistence.internal.helper.*;
import org.eclipse.persistence.queries.*;
import org.eclipse.persistence.tools.schemaframework.FieldDefinition;

/**
 *    <p><b>Purpose</b>: Provides Informix specific behavior.
 *    <p><b>Responsibilities</b>:<ul>
 *    <li> Types for schema creation.
 *    <li> Native sequencing using @@SERIAL.
 *    </ul>
 *
 * @since TOPLink/Java 1.0.1
 */
public class InformixPlatform extends org.eclipse.persistence.platform.database.DatabasePlatform {

    
    @Override
    public void initializeConnectionData(Connection connection) throws SQLException {
        DatabaseMetaData dmd = connection.getMetaData();

        // Wasn't able to find a driver that would support passing unicode values
        this.driverSupportsNationalCharacterVarying = false;
    }
    
    /**
     * Answer a platform correct string representation of a Date, suitable for SQL generation.
     * Native format: 'yyyy-mm-dd
     */
    @Override
    protected void appendDate(java.sql.Date date, Writer writer) throws IOException {
        if (usesNativeSQL()) {
            writer.write("'");
            writer.write(Helper.printDate(date));
            writer.write("'");
        } else {
            super.appendDate(date, writer);
        }
    }

    /**
     * Write a timestamp in Informix specific format (yyyy-mm-dd hh:mm:ss.fff).
     */
    protected void appendInformixTimestamp(java.sql.Timestamp timestamp, Writer writer) throws IOException {
        writer.write("'");
        writer.write(Helper.printTimestampWithoutNanos(timestamp));
        writer.write('.');

        // Must truncate the nanos to three decimal places,
        // it is actually a complex algorithm...
        String nanoString = Integer.toString(timestamp.getNanos());
        int numberOfZeros = 0;
        for (int num = Math.min(9 - nanoString.length(), 3); num > 0; num--) {
            writer.write('0');
            numberOfZeros++;
        }
        if ((nanoString.length() + numberOfZeros) > 3) {
            nanoString = nanoString.substring(0, (3 - numberOfZeros));
        }
        writer.write(nanoString);
        writer.write("'");
    }

    /**
     * Answer a platform correct string representation of a Calendar, suitable for SQL generation.
     * The date is printed in the ODBC platform independent format {d'YYYY-MM-DD'}.
     */
    @Override
    protected void appendCalendar(Calendar calendar, Writer writer) throws IOException {
        if (usesNativeSQL()) {
            appendInformixCalendar(calendar, writer);
        } else {
            super.appendCalendar(calendar, writer);
        }
    }

    /**
     * Write a timestamp in Informix specific format ( yyyy-mm-dd hh:mm:ss.fff)
     */
    protected void appendInformixCalendar(Calendar calendar, Writer writer) throws IOException {
        writer.write("'");
        writer.write(Helper.printCalendar(calendar));
        writer.write("'");
    }

    /**
     * Answer a platform correct string representation of a Time, suitable for SQL generation.
     * The time is printed in the ODBC platform independent format {t'hh:mm:ss'}.
     */
    @Override
    protected void appendTime(java.sql.Time time, Writer writer) throws IOException {
        if (usesNativeSQL()) {
            writer.write("'");
            writer.write(Helper.printTime(time));
            writer.write("'");
        } else {
            super.appendTime(time, writer);
        }
    }

    /**
     * Answer a platform correct string representation of a Timestamp, suitable for SQL generation.
     * The date is printed in the ODBC platform independent format {d'YYYY-MM-DD'}.
     */
    @Override
    protected void appendTimestamp(java.sql.Timestamp timestamp, Writer writer) throws IOException {
        if (usesNativeSQL()) {
            appendInformixTimestamp(timestamp, writer);
        } else {
            super.appendTimestamp(timestamp, writer);
        }
    }

    @Override
    protected Hashtable buildFieldTypes() {
        Hashtable fieldTypeMapping;

        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("NUMERIC", 19));
        fieldTypeMapping.put(Float.class, new FieldTypeDefinition("FLOAT(16)", false));
        // Bug 218183: Informix 11 FLOAT precision max is 16 - substitute DECIMAL(32) for FLOAT(32)
        fieldTypeMapping.put(Double.class, new FieldTypeDefinition("DECIMAL(32)", 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("DECIMAL", 32));
        fieldTypeMapping.put(java.math.BigDecimal.class, new FieldTypeDefinition("DECIMAL", 32).setLimits(32, -19, 19));
        fieldTypeMapping.put(Number.class, new FieldTypeDefinition("DECIMAL", 32).setLimits(32, -19, 19));

        if (getUseNationalCharacterVaryingTypeForString()) {
            fieldTypeMapping.put(String.class, new FieldTypeDefinition("NVARCHAR", DEFAULT_VARCHAR_SIZE));
        } else {
            fieldTypeMapping.put(String.class, new FieldTypeDefinition("VARCHAR", DEFAULT_VARCHAR_SIZE));
        }
        fieldTypeMapping.put(Character.class, new FieldTypeDefinition("CHAR", 1));
        
        fieldTypeMapping.put(Byte[].class, new FieldTypeDefinition("BYTE", false));
        fieldTypeMapping.put(Character[].class, new FieldTypeDefinition("TEXT", false));
        fieldTypeMapping.put(byte[].class, new FieldTypeDefinition("BYTE", false));
        fieldTypeMapping.put(char[].class, new FieldTypeDefinition("TEXT", false));
        fieldTypeMapping.put(java.sql.Blob.class, new FieldTypeDefinition("BYTE", false));
        fieldTypeMapping.put(java.sql.Clob.class, new FieldTypeDefinition("TEXT", false));        

        fieldTypeMapping.put(java.sql.Date.class, new FieldTypeDefinition("DATE", false));
        fieldTypeMapping.put(java.sql.Time.class, new FieldTypeDefinition("DATETIME HOUR TO SECOND", false));
        fieldTypeMapping.put(java.sql.Timestamp.class, new FieldTypeDefinition("DATETIME YEAR TO FRACTION(5)", false));

        return fieldTypeMapping;
    }

    /**
     * INTERNAL:
     * Build the identity query for native sequencing.
     */
    @Override
    public ValueReadQuery buildSelectQueryForIdentity() {
        ValueReadQuery selectQuery = new ValueReadQuery();
        StringWriter writer = new StringWriter();
        writer.write("SELECT DISTINCT(DBINFO('sqlca.sqlerrd1')) FROM systables");
        selectQuery.setSQLString(writer.toString());
        return selectQuery;
    }

    /**
     * INTERNAL:
     * returns the maximum number of characters that can be used in a field
     * name on this platform.
     */
    @Override
    public int getMaxFieldNameSize() {
        return 18;
    }

    /**
     * Informix seems to like this syntax instead of the OF * syntax.
     */
    @Override
    public String getSelectForUpdateString() {
        return " FOR UPDATE";
    }

    @Override
    public boolean isInformix() {
        return true;
    }

    /**
     * Some database require outer joins to be given in the where clause, others require it in the from clause.
     * Informix requires it in the from clause with no ON expression.
     */
    @Override
    public boolean isInformixOuterJoin() {
        return true;
    }
    
    /**
     * Informix seemed to require this at some point.
     * Not sure if it still does.
     */
    @Override
    public boolean shouldSelectIncludeOrderBy() {
        return true;
    }

    /**
     * Builds a table of maximum numeric values keyed on java class. This is used for type testing but
     * might also be useful to end users attempting to sanitize values.
     * <p><b>NOTE</b>: BigInteger {@literal &} BigDecimal maximums are dependent upon their precision {@literal &} Scale
     */
    @Override
    public Hashtable maximumNumericValues() {
        Hashtable values = new Hashtable();

        values.put(Integer.class, Integer.valueOf(Integer.MAX_VALUE));
        values.put(Long.class, Long.valueOf(Long.MAX_VALUE));
        values.put(Double.class, Double.valueOf(Float.MAX_VALUE));
        values.put(Short.class, Short.valueOf(Short.MAX_VALUE));
        values.put(Byte.class, Byte.valueOf(Byte.MAX_VALUE));
        values.put(Float.class, Float.valueOf(Float.MAX_VALUE));
        values.put(java.math.BigInteger.class, new java.math.BigInteger("99999999999999999999999999999999999999"));
        values.put(java.math.BigDecimal.class, new java.math.BigDecimal("9999999999999999999.9999999999999999999"));
        return values;
    }

    /**
     * Builds a table of minimum numeric values keyed on java class. This is used for type testing but
     * might also be useful to end users attempting to sanitize values.
     * <p><b>NOTE</b>: BigInteger {@literal &} BigDecimal minimums are dependent upon their precision {@literal &} Scale
     */
    @Override
    public Hashtable minimumNumericValues() {
        Hashtable values = new Hashtable();

        values.put(Integer.class, Integer.valueOf(Integer.MIN_VALUE));
        values.put(Long.class, Long.valueOf(Long.MIN_VALUE));
        values.put(Double.class, Double.valueOf(1.4012984643247149E-44));// The double values are weird. They lose precision at E-45
        values.put(Short.class, Short.valueOf(Short.MIN_VALUE));
        values.put(Byte.class, Byte.valueOf(Byte.MIN_VALUE));
        values.put(Float.class, Float.valueOf(Float.MIN_VALUE));
        values.put(java.math.BigInteger.class, new java.math.BigInteger("-99999999999999999999999999999999999999"));
        values.put(java.math.BigDecimal.class, new java.math.BigDecimal("-9999999999999999999.9999999999999999999"));
        return values;
    }

    /**
     * Append the field type to a writer unless the field uses an Identity strategy to generate its value.
     * In this case, the field type 'SERIAL' will be appended later.  
     */
    @Override
    public void printFieldTypeSize(Writer writer, FieldDefinition field, 
            FieldTypeDefinition fieldType, boolean shouldPrintFieldIdentityClause) throws IOException {
        if (!shouldPrintFieldIdentityClause)
            printFieldTypeSize(writer, field, fieldType);
    }
    
    /**
     * Append the receiver's field serial constraint clause to a writer.
     */
    @Override
    public void printFieldIdentityClause(Writer writer) throws ValidationException {
        try {
            writer.write(" SERIAL");
        } catch (IOException ioException) {
            throw ValidationException.fileError(ioException);
        }
    }

    /**
     * Used for sp calls.
     */
    @Override
    public boolean requiresProcedureCallBrackets() {
        return false;
    }

    /**
     * Some Platforms want the constraint name after the constraint definition.
     */
    @Override
    public boolean shouldPrintConstraintNameAfter() {
        return true;
    }


    /**
     *  INTERNAL:
     *  Indicates whether the platform supports identity.
     *  Informix does this through SERIAL field types.
     *  This method is to be used *ONLY* by sequencing classes
     */
    @Override
    public boolean supportsIdentity() {
        return true;
    }

    /**
     *  INTERNAL:
     *  Indicates whether the platform supports sequence objects.
     *  This method is to be used *ONLY* by sequencing classes
     */
    @Override
    public boolean supportsSequenceObjects() {
        return true;
    }
    
    /**
     * INTERNAL:
     * Returns query used to read value generated by sequence object (like Oracle sequence).
     * This method is called when sequence object NativeSequence is connected,
     * the returned query used until the sequence is disconnected.
     * If the platform supportsSequenceObjects then (at least) one of buildSelectQueryForSequenceObject
     * methods should return non-null query.
     */
    @Override
    public ValueReadQuery buildSelectQueryForSequenceObject(String qualifiedSeqName, Integer size) {
        return new ValueReadQuery("select " + qualifiedSeqName + ".nextval from systables where tabid = 1");
    }
 
    /**
     * INTERNAL:
     * Override this method if the platform supports sequence objects
     * and it's possible to alter sequence object's increment in the database.
     */
    @Override
    public boolean isAlterSequenceObjectSupported() {
        return true;
    }
}