/*******************************************************************************
 * Copyright (c) 2000, 2011 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.internal.image;

import java.io.*;
import java.util.zip.*;

import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;

final class PngEncoder extends Object {

	static final byte SIGNATURE[] = {(byte) '\211', (byte) 'P', (byte) 'N', (byte) 'G', (byte) '\r', (byte) '\n', (byte) '\032', (byte) '\n'};
	static final byte TAG_IHDR[] = {(byte) 'I', (byte) 'H', (byte) 'D', (byte) 'R'};
	static final byte TAG_PLTE[] = {(byte) 'P', (byte) 'L', (byte) 'T', (byte) 'E'};
	static final byte TAG_TRNS[] = {(byte) 't', (byte) 'R', (byte) 'N', (byte) 'S'};
	static final byte TAG_IDAT[] = {(byte) 'I', (byte) 'D', (byte) 'A', (byte) 'T'};
	static final byte TAG_IEND[] = {(byte) 'I', (byte) 'E', (byte) 'N', (byte) 'D'};

	static final int NO_COMPRESSION = 0;
	static final int BEST_SPEED = 1;
	static final int BEST_COMPRESSION = 9;
	static final int DEFAULT_COMPRESSION = -1;

	ByteArrayOutputStream bytes = new ByteArrayOutputStream(1024);
	PngChunk chunk;

	ImageLoader loader;
	ImageData data;
	int transparencyType;

	int width, height, bitDepth, colorType;

	int compressionMethod = 0;
	int filterMethod = 0;
	int interlaceMethod = 0;

public PngEncoder(ImageLoader loader) {

	this.loader = loader;
	this.data = loader.data[0];
	this.transparencyType = data.getTransparencyType();

	this.width = data.width;
	this.height = data.height;

	this.bitDepth = 8;

	this.colorType = 2;

	if (data.palette.isDirect) {
		if (transparencyType == SWT.TRANSPARENCY_ALPHA) {
			this.colorType = 6;
		}
	}
	else {
		this.colorType = 3;
	}

	if (!(colorType == 2 || colorType == 3 || colorType == 6)) SWT.error(SWT.ERROR_INVALID_IMAGE);

}

void writeShort(ByteArrayOutputStream baos, int theShort) {

	byte byte1 = (byte) ((theShort >> 8) & 0xff);
	byte byte2 = (byte) (theShort & 0xff);
	byte[] temp = {byte1, byte2};
	baos.write(temp, 0, 2);

}

void writeInt(ByteArrayOutputStream baos, int theInt) {

	byte byte1 = (byte) ((theInt >> 24) & 0xff);
	byte byte2 = (byte) ((theInt >> 16) & 0xff);
	byte byte3 = (byte) ((theInt >> 8) & 0xff);
	byte byte4 = (byte) (theInt & 0xff);
	byte[] temp = {byte1, byte2, byte3, byte4};
	baos.write(temp, 0, 4);

}

void writeChunk(byte[] tag, byte[] buffer) {

	int bufferLength = (buffer != null) ? buffer.length : 0;

	chunk = new PngChunk(bufferLength);

	writeInt(bytes, bufferLength);
	bytes.write(tag, 0, 4);
	chunk.setType(tag);
	if (bufferLength != 0) {
		bytes.write(buffer, 0, bufferLength);
		chunk.setData(buffer);
	}
	else {
		chunk.setCRC(chunk.computeCRC());
	}
	writeInt(bytes, chunk.getCRC());

}

void writeSignature() {

	bytes.write(SIGNATURE, 0, 8);

}

void writeHeader() {

	ByteArrayOutputStream baos = new ByteArrayOutputStream(13);

	writeInt(baos, width);
	writeInt(baos, height);
	baos.write(bitDepth);
	baos.write(colorType);
	baos.write(compressionMethod);
	baos.write(filterMethod);
	baos.write(interlaceMethod);

	writeChunk(TAG_IHDR, baos.toByteArray());

}

void writePalette() {

	RGB[] RGBs = data.palette.getRGBs();

	if (RGBs.length > 256) SWT.error(SWT.ERROR_INVALID_IMAGE);

	ByteArrayOutputStream baos = new ByteArrayOutputStream(RGBs.length);

	for (RGB rgb : RGBs) {

		baos.write((byte) rgb.red);
		baos.write((byte) rgb.green);
		baos.write((byte) rgb.blue);

	}

	writeChunk(TAG_PLTE, baos.toByteArray());

}

void writeTransparency() {

	ByteArrayOutputStream baos = new ByteArrayOutputStream();

	switch (transparencyType) {

		case SWT.TRANSPARENCY_ALPHA:

			int pixelValue, alphaValue;

			byte[] alphas = new byte[data.palette.getRGBs().length];

			for (int y = 0; y < height; y++) {

				for (int x = 0; x < width; x++) {

					pixelValue = data.getPixel(x, y);
					alphaValue = data.getAlpha(x, y);

					alphas[pixelValue] = (byte) alphaValue;

				}

			}

			baos.write(alphas, 0, alphas.length);

			break;

		case SWT.TRANSPARENCY_PIXEL:

			int pixel = data.transparentPixel;

			if (colorType == 2) {

				int redMask = data.palette.redMask;
				int redShift = data.palette.redShift;
				int greenMask = data.palette.greenMask;
				int greenShift = data.palette.greenShift;
				int blueShift = data.palette.blueShift;
				int blueMask = data.palette.blueMask;

				int r = pixel & redMask;
				r = (redShift < 0) ? r >>> -redShift : r << redShift;
				int g = pixel & greenMask;
				g = (greenShift < 0) ? g >>> -greenShift : g << greenShift;
				int b = pixel & blueMask;
				b = (blueShift < 0) ? b >>> -blueShift : b << blueShift;

				writeShort(baos, r);
				writeShort(baos, g);
				writeShort(baos, b);

			}

			if (colorType == 3) {

				byte[] padding = new byte[pixel + 1];

				for (int i = 0; i < pixel; i++) {

					padding[i] = (byte) 255;

				}

				padding[pixel] = (byte) 0;

				baos.write(padding, 0, padding.length);

			}

			break;

	}

	writeChunk(TAG_TRNS, baos.toByteArray());

}

void writeImageData() throws IOException {

	ByteArrayOutputStream baos = new ByteArrayOutputStream(1024);
	OutputStream os = new DeflaterOutputStream(baos, new Deflater(switch (loader.compression) {
	case 0 -> NO_COMPRESSION;
	case 1 -> BEST_SPEED;
	case 3 -> BEST_COMPRESSION;
	default -> DEFAULT_COMPRESSION;
	}));

	if (colorType == 3) {

		byte[] lineData = new byte[width];

		for (int y = 0; y < height; y++) {

			int filter = 0;
			os.write(filter);

			data.getPixels(0, y, width, lineData, 0);

			os.write(lineData);

		}

	}

	else {

		int[] lineData = new int[width];
		byte[] alphaData = null;
		if (colorType == 6) {
			alphaData = new byte[width];
		}

		int redMask = data.palette.redMask;
		int redShift = data.palette.redShift;
		int greenMask = data.palette.greenMask;
		int greenShift = data.palette.greenShift;
		int blueShift = data.palette.blueShift;
		int blueMask = data.palette.blueMask;

		byte[] lineBytes = new byte[width * (colorType == 6 ? 4 : 3)];

		for (int y = 0; y < height; y++) {

			int filter = 0;
			os.write(filter);

			data.getPixels(0, y, width, lineData, 0);

			if (colorType == 6) {
				data.getAlphas(0, y, width, alphaData, 0);
			}

			int offset = 0;
			for (int x = 0; x < lineData.length; x++) {

				int pixel = lineData[x];

				int r = pixel & redMask;
				lineBytes[offset++] = (byte) ((redShift < 0) ? r >>> -redShift
						: r << redShift);
				int g = pixel & greenMask;
				lineBytes[offset++] = (byte) ((greenShift < 0) ? g >>> -greenShift
						: g << greenShift);
				int b = pixel & blueMask;
				lineBytes[offset++] = (byte) ((blueShift < 0) ? b >>> -blueShift
						: b << blueShift);

				if (colorType == 6) {
					lineBytes[offset++] = alphaData[x];
				}

			}

			os.write(lineBytes);

		}

	}

	os.flush();
	os.close();

	writeChunk(TAG_IDAT, baos.toByteArray());

}

void writeEnd() {

	writeChunk(TAG_IEND, null);

}

public void encode(LEDataOutputStream outputStream) {

	try {

		writeSignature();
		writeHeader();

		if (colorType == 3) {
			writePalette();
		}

		boolean transparencyAlpha = (transparencyType == SWT.TRANSPARENCY_ALPHA);
		boolean transparencyPixel = (transparencyType == SWT.TRANSPARENCY_PIXEL);
		boolean type2Transparency = (colorType == 2 && transparencyPixel);
		boolean type3Transparency = (colorType == 3 && (transparencyAlpha || transparencyPixel));

		if (type2Transparency || type3Transparency) {
			writeTransparency();
		}

		writeImageData();
		writeEnd();

		outputStream.write(bytes.toByteArray());

	}

	catch (IOException e) {

		SWT.error(SWT.ERROR_IO, e);

	}

}

}
