/*

   Derby - Class org.apache.derby.iapi.types.SQLSmallint

   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to you 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 org.apache.derby.iapi.types;

import org.apache.derby.iapi.reference.SQLState;

import org.apache.derby.iapi.services.io.StoredFormatIds;
import org.apache.derby.iapi.services.io.Storable;

import org.apache.derby.iapi.error.StandardException;
import org.apache.derby.shared.common.sanity.SanityManager;

import org.apache.derby.iapi.services.cache.ClassSize;

import java.io.ObjectOutput;
import java.io.ObjectInput;
import java.io.IOException;

import java.sql.ResultSet;
import java.sql.PreparedStatement;
import java.sql.SQLException;

/**
 * SQLSmallint satisfies the DataValueDescriptor
 * interfaces (i.e., OrderableDataType). It implements a smallint column, 
 * e.g. for storing a column value; it can be specified
 * when constructed to not allow nulls. Nullability cannot be changed
 * after construction, as it affects the storage size and mechanism.
 * <p>
 * Because OrderableDataType is a subtype of ValueColumn,
 * SQLSmallint can play a role in either a ValueColumn/Row
 * or a OrderableDataType/Row, interchangeably.
 * <p>
 * We assume the store has a flag for nullness of the value,
 * and simply return a 0-length array for the stored form
 * when the value is null.
 * <p>
 * PERFORMANCE: There are likely alot of performance improvements
 * possible for this implementation -- it new's Short
 * more than it probably wants to.
 */
public final class SQLSmallint
	extends NumberDataType
{
	/*
	 * DataValueDescriptor interface
	 * (mostly implemented in DataType)
	 */


        // JDBC is lax in what it permits and what it
	// returns, so we are similarly lax

	/** 
	 * @see DataValueDescriptor#getInt 
	 */
	public int	getInt()
	{
		return (int) value;
	}

	/** 
	 * @exception StandardException thrown on failure to convert
	 * @see DataValueDescriptor#getByte 
	 */
	public byte	getByte() throws StandardException
	{
		if (value > Byte.MAX_VALUE || value < Byte.MIN_VALUE)
			throw StandardException.newException(SQLState.LANG_OUTSIDE_RANGE_FOR_DATATYPE, "TINYINT");
		return (byte) value;
	}

	/** 
	 * @see DataValueDescriptor#getShort 
	 */
	public short	getShort()
	{
		return value;
	}

	/** 
	 * @see DataValueDescriptor#getLong 
	 */
	public long	getLong()
	{
		return (long) value;
	}

	/** 
	 * @see DataValueDescriptor#getFloat 
	 */
	public float	getFloat()
	{
		return (float) value;
	}

	/** 
	 * @see DataValueDescriptor#getDouble 
	 */
	public double	getDouble()
	{
		return (double) value;
	}

    // for lack of a specification: 0 or null is false,
    // all else is true
	/** 
	 * @see DataValueDescriptor#getBoolean 
	 */
	public boolean	getBoolean()
	{
		return (value != 0);
	}

	/** 
	 * @see DataValueDescriptor#getString 
	 */
	public String	getString()
	{
		if (isNull())
			return null;
		else
			return Short.toString(value);
	}

	/** 
	 * @see DataValueDescriptor#getLength 
	 */
	public int	getLength()
	{
		return SMALLINT_LENGTH;
	}

	/** 
	 * @see DataValueDescriptor#getObject 
	 */
	public Object	getObject() 
	{
		if (isNull())
			return null;
		else
          return (int) value;
	}

	// this is for DataType's error generator
	public String getTypeName()
	{
		return TypeId.SMALLINT_NAME;
	}

	/*
	 * Storable interface, implies Externalizable, TypedFormat
	 */


	/**
		Return my format identifier.

		@see org.apache.derby.iapi.services.io.TypedFormat#getTypeFormatId
	*/
	public int getTypeFormatId() {
		return StoredFormatIds.SQL_SMALLINT_ID;
	}

	/**
	 * always false for non-nullable columns
	 @see Storable#isNull
	*/
	public boolean isNull()
	{
		return isnull;
	}

	public void writeExternal(ObjectOutput out) throws IOException {

		// never called when value is null
		if (SanityManager.DEBUG)
			SanityManager.ASSERT(! isNull());

		out.writeShort(value);
	}

	/** @see java.io.Externalizable#readExternal */
	public void readExternal(ObjectInput in) throws IOException {

		value = in.readShort();
		isnull = false;
	}

	/**
	 * @see Storable#restoreToNull
	 *
	 */
	public void restoreToNull()
	{
		value = 0;
		isnull = true;
	}


	/** @exception StandardException		Thrown on error */
	protected int typeCompare(DataValueDescriptor arg) throws StandardException
	{
		/* neither are null, get the value */

		/* Do comparisons with ints to avoid overflow problems */
		int thisValue = this.getInt();
		int otherValue = arg.getInt();
		if (thisValue == otherValue)
			return 0;
		else if (thisValue > otherValue)
			return 1;
		else
			return -1;
	}

	/*
	 * DataValueDescriptor interface
	 */

	/** @see DataValueDescriptor#cloneValue */
	public DataValueDescriptor cloneValue(boolean forceMaterialization)
	{
		return new SQLSmallint(value, isnull);
	}

	/**
	 * @see DataValueDescriptor#getNewNull
	 */
	public DataValueDescriptor getNewNull()
	{
		return new SQLSmallint();
	}

	/** 
	 * @see DataValueDescriptor#setValueFromResultSet 
	 *
	 * @exception SQLException		Thrown on error
	 */
	public void setValueFromResultSet(ResultSet resultSet, int colNumber,
									  boolean isNullable)
		throws SQLException
	{
		try {
			value = resultSet.getShort(colNumber);
			isnull = (isNullable && resultSet.wasNull());
		} catch (SQLException selq) {
			int i = resultSet.getInt(colNumber);
			value = (short) i;
			isnull = false;

		}
	}
	/**
		Set the value into a PreparedStatement.

		@exception SQLException Error setting value in PreparedStatement
	*/
	public final void setInto(PreparedStatement ps, int position) throws SQLException {

		if (isNull()) {
			ps.setNull(position, java.sql.Types.SMALLINT);
			return;
		}

		ps.setShort(position, value);
	}
	/**
		Set this value into a ResultSet for a subsequent ResultSet.insertRow
		or ResultSet.updateRow. This method will only be called for non-null values.

		@exception SQLException thrown by the ResultSet object
		@exception StandardException thrown by me accessing my value.
	*/
	public final void setInto(ResultSet rs, int position) throws SQLException, StandardException {
		rs.updateShort(position, value);
	}


	/*
	 * class interface
	 */

	/*
	 * constructors
	 */

	/**
		No-arg constructor, required by Formattable.
    // This constructor also gets used when we are
    // allocating space for a short.
	*/
	public SQLSmallint() 
	{
		isnull = true;
	}

	public SQLSmallint(short val)
	{
		value = val;
	}

	/* This constructor gets used for the cloneValue() method */
	private SQLSmallint(short val, boolean isnull) {
		value = val;
		this.isnull = isnull;
	}

	public SQLSmallint(Short obj) {
		if (isnull = (obj == null))
			;
		else
			value = obj.shortValue();
	}

	/**
		@exception StandardException thrown if string not accepted
	 */
	public void setValue(String theValue)
		throws StandardException
	{
		if (theValue == null)
		{
			value = 0;
			isnull = true;
		}
		else
		{
		    try {
		        value = Short.valueOf(theValue.trim()).shortValue();
			} catch (NumberFormatException nfe) {
			    throw invalidFormat();
			}
			isnull = false;
		}

	}

	public void setValue(short theValue)
	{
		value = theValue;
		isnull = false;
	}

	public void setValue(byte theValue)
	{
		value = theValue;
		isnull = false;
	}

	/**
		@exception StandardException if outsideRangeForSmallint
	 */
	public void setValue(int theValue) throws StandardException
	{
		if (theValue > Short.MAX_VALUE || theValue < Short.MIN_VALUE)
			throw StandardException.newException(SQLState.LANG_OUTSIDE_RANGE_FOR_DATATYPE, "SMALLINT");
		value = (short)theValue;
		isnull = false;
	}

	/**
		@exception StandardException if outsideRangeForSmallint
	 */
	public void setValue(long theValue) throws StandardException
	{
		if (theValue > Short.MAX_VALUE || theValue < Short.MIN_VALUE)
			throw StandardException.newException(SQLState.LANG_OUTSIDE_RANGE_FOR_DATATYPE, "SMALLINT");
		value = (short)theValue;
		isnull = false;
	}

	/**
	 * @see NumberDataValue#setValue
	 *
	 * @exception StandardException		Thrown on error
	 */
	public void setValue(float theValue) throws StandardException
	{
		theValue = NumberDataType.normalizeREAL(theValue);

		if (theValue > Short.MAX_VALUE || theValue < Short.MIN_VALUE)
			throw StandardException.newException(SQLState.LANG_OUTSIDE_RANGE_FOR_DATATYPE, "SMALLINT");

		float floorValue = (float)Math.floor(theValue);

		value = (short)floorValue;
		isnull = false;
	}

	/**
	 * @see NumberDataValue#setValue
	 *
	 * @exception StandardException		Thrown on error
	 */
	public void setValue(double theValue) throws StandardException
	{
		theValue = NumberDataType.normalizeDOUBLE(theValue);

		if (theValue > Short.MAX_VALUE || theValue < Short.MIN_VALUE)
			throw StandardException.newException(SQLState.LANG_OUTSIDE_RANGE_FOR_DATATYPE, "SMALLINT");

		double floorValue = Math.floor(theValue);

		value = (short)floorValue;
		isnull = false;
	}

	/**
	 * @see NumberDataValue#setValue
	 *
	 */
	public void setValue(boolean theValue)
	{
		value = theValue?(short)1:(short)0;
		isnull = false;
	}

	protected void setFrom(DataValueDescriptor theValue) throws StandardException {

		setValue(theValue.getShort());
	}

	/*
	 * DataValueDescriptor interface
	 */

	/** @see DataValueDescriptor#typePrecedence */
	public int typePrecedence()
	{
		return TypeId.SMALLINT_PRECEDENCE;
	}


	/*
	** SQL Operators
	*/

	/**
	 * The = operator as called from the language module, as opposed to
	 * the storage module.
	 *
	 * @param left			The value on the left side of the =
	 * @param right			The value on the right side of the =
	 *
	 * @return	A SQL boolean value telling whether the two parameters are equal
	 *
	 * @exception StandardException		Thrown on error
	 */

	public BooleanDataValue equals(DataValueDescriptor left,
							DataValueDescriptor right)
			throws StandardException
	{
		return SQLBoolean.truthValue(left,
									 right,
									 left.getShort() == right.getShort());
	}

	/**
	 * The &lt;&gt; operator as called from the language module, as opposed to
	 * the storage module.
	 *
	 * @param left			The value on the left side of the operator
	 * @param right			The value on the right side of the operator
	 *
	 * @return	A SQL boolean value telling whether the two parameters
	 *			are not equal
	 *
	 * @exception StandardException		Thrown on error
	 */

	public BooleanDataValue notEquals(DataValueDescriptor left,
							DataValueDescriptor right)
			throws StandardException
	{
		return SQLBoolean.truthValue(left,
									 right,
									 left.getShort() != right.getShort());
	}

	/**
	 * The &lt; operator as called from the language module, as opposed to
	 * the storage module.
	 *
	 * @param left			The value on the left side of the operator
	 * @param right			The value on the right side of the operator
	 *						is not.
	 *
	 * @return	A SQL boolean value telling whether the first operand is less
	 *			than the second operand
	 *
	 * @exception StandardException		Thrown on error
	 */

	public BooleanDataValue lessThan(DataValueDescriptor left,
							DataValueDescriptor right)
			throws StandardException
	{
		return SQLBoolean.truthValue(left,
									 right,
									 left.getShort() < right.getShort());
	}

	/**
	 * The &gt; operator as called from the language module, as opposed to
	 * the storage module.
	 *
	 * @param left			The value on the left side of the operator
	 * @param right			The value on the right side of the operator
	 *
	 * @return	A SQL boolean value telling whether the first operand is greater
	 *			than the second operand
	 *
	 * @exception StandardException		Thrown on error
	 */

	public BooleanDataValue greaterThan(DataValueDescriptor left,
							DataValueDescriptor right)
			throws StandardException
	{
		return SQLBoolean.truthValue(left,
									 right,
									 left.getShort() > right.getShort());
	}

	/**
	 * The &lt;= operator as called from the language module, as opposed to
	 * the storage module.
	 *
	 * @param left			The value on the left side of the operator
	 * @param right			The value on the right side of the operator
	 *
	 * @return	A SQL boolean value telling whether the first operand is less
	 *			than or equal to the second operand
	 *
	 * @exception StandardException		Thrown on error
	 */

	public BooleanDataValue lessOrEquals(DataValueDescriptor left,
							DataValueDescriptor right)
			throws StandardException
	{
		return SQLBoolean.truthValue(left,
									 right,
									 left.getShort() <= right.getShort());
	}

	/**
	 * The &gt;= operator as called from the language module, as opposed to
	 * the storage module.
	 *
	 * @param left			The value on the left side of the operator
	 * @param right			The value on the right side of the operator
	 *
	 * @return	A SQL boolean value telling whether the first operand is greater
	 *			than or equal to the second operand
	 *
	 * @exception StandardException		Thrown on error
	 */

	public BooleanDataValue greaterOrEquals(DataValueDescriptor left,
							DataValueDescriptor right)
			throws StandardException
	{
		return SQLBoolean.truthValue(left,
									 right,
									 left.getShort() >= right.getShort());
	}




	/**
	 * This method implements the * operator for "smallint * smallint".
	 *
	 * @param left	The first value to be multiplied
	 * @param right	The second value to be multiplied
	 * @param result	The result of a previous call to this method, null
	 *					if not called yet
	 *
	 * @return	A SQLSmallint containing the result of the multiplication
	 *
	 * @exception StandardException		Thrown on error
	 */

	public NumberDataValue times(NumberDataValue left,
							NumberDataValue right,
							NumberDataValue result)
				throws StandardException
	{
		if (result == null)
		{
			result = new SQLSmallint();
		}

		if (left.isNull() || right.isNull())
		{
			result.setToNull();
			return result;
		}

		/*
		** Java does not check for overflow with integral types. We have to
		** check the result ourselves.
		**
			The setValue(int) will perform the overflow check.
		*/
		int product = left.getShort() * right.getShort();
		result.setValue(product);
		return result;
	}


	/**
		mod(smallint, smallint)
	*/
	public NumberDataValue mod(NumberDataValue dividend,
							 NumberDataValue divisor,
							 NumberDataValue result)
				throws StandardException
	{
		if (result == null)
		{
			result = new SQLSmallint();
		}

		if (dividend.isNull() || divisor.isNull())
		{
			result.setToNull();
			return result;
		}

		/* Catch divide by 0 */
		short shortDivisor = divisor.getShort();
		if (shortDivisor == 0)
		{
			throw StandardException.newException(SQLState.LANG_DIVIDE_BY_ZERO);
		}

		result.setValue(dividend.getShort() % shortDivisor);
		return result;
	}
	/**
	 * This method implements the unary minus operator for smallint.
	 *
	 * @param result	The result of a previous call to this method, null
	 *					if not called yet
	 *
	 * @return	A SQLSmalllint containing the result of the division
	 *
	 * @exception StandardException		Thrown on error
	 */

	public NumberDataValue minus(NumberDataValue result)
									throws StandardException
	{
		if (result == null)
		{
			result = new SQLSmallint();
		}

		if (this.isNull())
		{
			result.setToNull();
			return result;
		}

		int operandValue = this.getShort();

		result.setValue(-operandValue);
		return result;
	}

    /**
     * This method implements the isNegative method.
     *
     * @return  A boolean.  If this.value is negative, return true.
     *          For positive values or null, return false.
     */

    protected boolean isNegative()
    {
        return !isNull() && value < 0;
    }

	/*
	 * String display of value
	 */

	public String toString()
	{
		if (isNull())
			return "NULL";
		else
			return Short.toString(value);
	}

	/*
	 * Hash code
	 */
	public int hashCode()
	{
		return (int) value;
	}

	/*
	 * useful constants...
	 */
	static final int SMALLINT_LENGTH = 2;

    private static final int BASE_MEMORY_USAGE = ClassSize.estimateBaseFromCatalog( SQLSmallint.class);

    public int estimateMemoryUsage()
    {
        return BASE_MEMORY_USAGE;
    }

	/*
	 * object state
	 */
	private short value;
	private boolean isnull;
}
