package org.hwo.image.tiff;

import java.awt.image.BufferedImage;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import org.hwo.Unsigned;
import org.hwo.image.UnsupportedFormatException;

class IFD
{
	final TiffFile tiffFile;

	boolean decoded;
	
	Short numEntries;
	HashMap<Short, IFDEntry> entries;
	
	BufferedImage bufferedImage;
	
	protected IFD(TiffFile tiffFile)
	{
		this.tiffFile = tiffFile;
		decoded = false;
		entries = new HashMap<Short, IFDEntry>();
		bufferedImage = null;
		
		numEntries = this.tiffFile.sourceBuffer.getShort();
		System.err.println(String.format("readIFD(): reading %d entries",numEntries));

		for (int i=0;i<numEntries;i++)
		{
			IFDEntry entry = IFDEntry.read(this);
			if (entry != null)
				entries.put(entry.tag, entry);
		}
		
		Integer nextIFD = this.tiffFile.sourceBuffer.getInt();
		if (nextIFD != 0)
		{
			this.tiffFile.sourceBuffer.position(nextIFD);
			this.tiffFile.ifds.add(0,new IFD(this.tiffFile));
		}
	}
	protected IFD(TiffFile tiffFile, BufferedImage image)
	{
		this.tiffFile = tiffFile;
		decoded = true;
		bufferedImage = image;
		numEntries = 0;
		entries = new HashMap<Short, IFDEntry>();
	}
	
	public boolean isDecoded()
	{
		return decoded;
	}
	
	private BufferedImage decode()
	{
		System.err.println("TiffFile: Decoding...");
		if (isDecoded())
			return bufferedImage;
		
		int 	width = getWidth(),
				height = getHeight();
		
		Short	compression = getCompression();
		
		short[] bitsPerSample = getBitsPerSample();
		PHOTOMETRIC photometric = getPhotometric();
		short samplesPerPixel = getSamplesPerPixel();
		
		System.err.println(String.format("Size: %dx%d TYPE: %s COMP: %d BPS: %s",width,height,photometric.toString(),compression,Arrays.toString(bitsPerSample)));

		BufferedImage image = new BufferedImage(width, height, getJImageType(photometric, bitsPerSample));
		
		int rowsPerStrip = getRowsPerStrip();
		int[] stripOffsets = getStripOffsets();
		int[] stripByteCounts = getStripByteCounts();
		
		if (stripOffsets.length != stripByteCounts.length)
			throw new UnsupportedFormatException("StripOffset.length != StripbyteCount.length");
		
		if ((stripOffsets.length * rowsPerStrip) < height)
			throw new UnsupportedFormatException("stripped lines < scanlines");
		
		ArrayList<Strip> strips = new ArrayList<Strip>();
		
		for (int i=0;i<stripOffsets.length;i++)
			strips.add(new Strip(this, stripOffsets[i], stripByteCounts[i], rowsPerStrip));

		switch (photometric)
		{
		case BLACK:
		case WHITE:
			decodeGray(image,strips);
			break;
		case RGB:
			decodeRGB(image,strips);
			break;
		default:
			throw new UnsupportedFormatException("unsupported pixel format");
		}		
		return image;
	}
	
	private void decodeGray(BufferedImage image,List<Strip> strips)
	{
		PHOTOMETRIC photometric = getPhotometric();

		int 	width = getWidth(),
				height = getHeight();

		short[] bitsPerSample = getBitsPerSample();
		short samplesPerPixel = getSamplesPerPixel();
		
		
		
		switch (bitsPerSample[0])
		{
		case 1:
		case 4:
		case 8:
			break;
		default:
			throw new UnsupportedFormatException();
		}

		int y = 0;
		short predictor = getPredictor();
		
		for (Strip strip:strips)
		{
			ByteBuffer buffer = strip.getBuffer();
			int p = 0;
			
			for (int row=0; (row < strip.rowcount) && (y + row < height); row++)
			{
				int[] lastPixel = new int[0];
				
				for (int column = 0; column < width ; column++)
				{
					int[] pixel = new int[1];
					
					pixel[0] = Unsigned.byte2short(buffer.get(p));
					if (predictor == 2 && column > 0)
						pixel[0] += lastPixel[0];
					 						
					image.getRaster().setPixel(column, y + row, pixel);
					
					p += samplesPerPixel;
					lastPixel = pixel;
				}
			}
			y += strip.rowcount;
		}
		
		
		
	}
	
	private void decodeRGB(BufferedImage image,List<Strip> strips)
	{
		int 	width = getWidth(),
				height = getHeight();

		short[] bitsPerSample = getBitsPerSample();
		short samplesPerPixel = getSamplesPerPixel();
		
		switch (samplesPerPixel)
		{
		case 3:
			break;
		case 4:
			break;
		default:
			throw new UnsupportedFormatException();
		}
		
		for (int i=0;i<samplesPerPixel;i++)
			if (bitsPerSample[i] != 8)
				throw new UnsupportedFormatException();
		
		int y = 0;
		
		short predictor = getPredictor();
		
		for (Strip strip:strips)
		{
			ByteBuffer buffer = strip.getBuffer();
			int p = 0;
			
			for (int row=0; (row < strip.rowcount) && (y + row < height); row++)
			{
				int[] lastPixel = new int[0];
				
				for (int column = 0; column < width ; column++)
				{
					byte r,g,b,a;
					
					int[] pixel = new int[samplesPerPixel];
					
					for (int n=0;n<samplesPerPixel;n++)
					{
						pixel[n] = Unsigned.byte2short(buffer.get(p + n));
						if (predictor == 2 && column > 0)
						{
							pixel[n] += lastPixel[n];
						}
					}
					 						
					image.getRaster().setPixel(column, y + row, pixel);
					
					p += samplesPerPixel;
					lastPixel = pixel;
				}
			}
			y += strip.rowcount;
		}
	}
	
	public BufferedImage getBufferedImage()
	{
		if (bufferedImage == null)
			bufferedImage = decode();
		return bufferedImage;
	}
	
	int getJImageType(PHOTOMETRIC p,short[] bitsPerSample)
	{
		switch (p)
		{
		case WHITE:
		case BLACK:
			return BufferedImage.TYPE_BYTE_GRAY;
		case RGB:
			switch (bitsPerSample.length)
			{
			case 3:
				return BufferedImage.TYPE_3BYTE_BGR;
			case 4:
				return BufferedImage.TYPE_4BYTE_ABGR;
			}
			break;
		case PALETTE:
			return BufferedImage.TYPE_3BYTE_BGR;
		}
		throw new UnsupportedFormatException();
	}
	
	IFDEntry getEntry(short tag)
	{
		if (entries.containsKey(tag))
			return entries.get(tag);
		return null;
	}
	
	int getWidth()
	{
		IFDEntry e = getEntry((short)256);
		if (e == null)
			throw new UnsupportedFormatException("missing width tag");
		return ((NumericEntry)e).getInteger();
	}
	
	int getHeight()
	{
		IFDEntry e = getEntry((short)257);
		if (e == null)
			throw new UnsupportedFormatException("missing width tag");
		return ((NumericEntry)e).getInteger();		
	}
	
	short getPageNumber()
	{
		ShortEntry e = (ShortEntry)entries.get((short)297);
		if (e == null)
			return -1;
		return e.getShort();
	}
	
	
	PHOTOMETRIC getPhotometric()
	{
		ShortEntry e = (ShortEntry)entries.get((short)262);
		if (e == null)
			return PHOTOMETRIC.WHITE;
		return PHOTOMETRIC.fromCode(e.getShort());
	}
	
	short[] getBitsPerSample()
	{
		ShortEntry e = (ShortEntry)entries.get((short)258);
		if (e == null)
			return new short[]{1};
		return e.getShortArray();
	}
	Integer getRowsPerStrip()
	{
		NumericEntry e = (NumericEntry)entries.get((short)278);
		if (e == null)
			return 0;
		return e.getInteger();
	}
	short getSamplesPerPixel()
	{
		ShortEntry e = (ShortEntry)entries.get((short)277);
		if (e == null)
			return 1;
		return e.getShort();
	}
	int[] getStripOffsets()
	{
		NumericEntry e = (NumericEntry)entries.get((short)273);
		if (e == null)
			return new int[0];
		return e.getIntArray();
	}
	int[] getStripByteCounts()
	{
		NumericEntry e = (NumericEntry)entries.get((short)279);
		if (e == null)
			return new int[0];
		return e.getIntArray();			
	}
	short getCompression()
	{
		ShortEntry e = (ShortEntry)entries.get((short)259);
		if (e == null)
			return 1;
		return e.getShort();
	}
	short getPredictor()
	{
		ShortEntry e = (ShortEntry)entries.get((short)317);
		if (e == null)
			return 1;
		return e.getShort();
	}
	short getFillOrder()
	{
		ShortEntry e = (ShortEntry)entries.get((short)266);
		if (e == null)
			return 1;
		return e.getShort();
	}
	
	
}