package com.xagasoft.gats;

import java.io.InputStream;
import java.io.DataInputStream;
import java.io.OutputStream;
import java.io.ByteArrayOutputStream;

import java.lang.Math;

/**
 * Represents a simple java double value.  This does not represent an arbitrary
 * precision floating point number, a class to handle that is forthcoming.
 */
public class GatsFloat extends GatsObject
{
	double dValue = 0.0;

	public GatsFloat()
	{
	}

	public GatsFloat( double dValue )
	{
		this.dValue = dValue;
	}

	public double getValue()
	{
		return dValue;
	}

	public void setValue( double dValue )
	{
		this.dValue = dValue;
	}

	public String toString()
	{
		return "" + dValue;
	}

	public int getType()
	{
		return GatsObject.FLOAT;
	}

	void read( InputStream is, char cType ) throws java.io.IOException
	{
		if( cType == 'F' )
		{
			char cSubType = (char)is.read();
			switch( cSubType )
			{
				case 'N': dValue = -Double.NaN;					break;
				case 'n': dValue = Double.NaN;					break;
				case 'I': dValue = Double.NEGATIVE_INFINITY;	break;
				case 'i': dValue = Double.POSITIVE_INFINITY;	break;
				case 'Z': dValue = -0.0;						break;
				case 'z': dValue = 0.0;							break;
			}
		}
		else if( cType == 'f' )
		{
			int iStr = (int)GatsInteger.readPackedInt( is );
			boolean bNeg = false;
			if( iStr < 0 )
			{
				bNeg = true;
				iStr = -iStr;
			}
			int aBuf[] = new int[iStr];
			DataInputStream dis = new DataInputStream( is );
			for( int j = 0; j < iStr; j++ )
			{
				aBuf[j] = dis.readUnsignedByte();
			}
			dValue = 0.0;
			for( int j = iStr-1; j > 0; j-- )
			{
				dValue = (dValue+(double)aBuf[j])*0x1p-8;
			}
			dValue += aBuf[0];
			long iScale = GatsInteger.readPackedInt( is );
			dValue *= Math.pow( 256.0, iScale );
			if( bNeg )
				dValue = -dValue;
		}
	}

	void write( OutputStream os ) throws java.io.IOException
	{
		if( dValue == 0.0 )
		{
			os.write( (int)'F' );
			os.write( (int)'z' );
		}
		else if( Double.isInfinite( dValue ) )
		{
			os.write( (int)'F' );
			if( dValue < 0 )
				os.write( (int)'I' );
			else
				os.write( (int)'i' );
		}
		else if( Double.isNaN( dValue ) )
		{
			os.write( (int)'F' );
			os.write( (int)'n' );
		}
		else
		{
			os.write( (int)'f' );
			double d = dValue;
			boolean bNeg = false;
			if( d < 0.0 )
			{
				bNeg = true;
				d = -d;
			}
			
			ByteArrayOutputStream oTmp = new ByteArrayOutputStream();
			long iScale = (long)(Math.log( d ) / 0x1.62e42fefa39efp+2);
			if( iScale < 0 ) iScale--;
			d /= Math.pow( 256.0, iScale );
			oTmp.write( (int)d );
			d -= (int)d;
			for( int j = 0; j < 150 && d != 0.0; j++ )
			{
				d = d*256.0;
				oTmp.write( (int)d );
				d -= (int)d;
			}
			if( bNeg )
				GatsInteger.writePackedInt( os, -oTmp.size() );
			else
				GatsInteger.writePackedInt( os, oTmp.size() );
			os.write( oTmp.toByteArray() );
			GatsInteger.writePackedInt( os, iScale );
		}
	}
};