// Copyright (C) 2002-2012 Nikolaus Gebhardt
// This file is part of the "Irrlicht Engine".
// For conditions of distribution and use, see copyright notice in irrlicht.h

#include "CImageLoaderJPG.h"

#include "IReadFile.h"
#include "CImage.h"
#include "coreutil.h"
#include "os.h"
#include "irrString.h"
#include <csetjmp>

namespace irr
{
namespace video
{

//! constructor
CImageLoaderJPG::CImageLoaderJPG()
{
}

//! destructor
CImageLoaderJPG::~CImageLoaderJPG()
{
}

//! returns true if the file maybe is able to be loaded by this class
//! based on the file extension (e.g. ".tga")
bool CImageLoaderJPG::isALoadableFileExtension(const io::path &filename) const
{
	return core::hasFileExtension(filename, "jpg", "jpeg");
}

// struct for handling jpeg errors
struct irr_jpeg_error_mgr
{
	// public jpeg error fields
	struct jpeg_error_mgr pub;

	// for longjmp, to return to caller on a fatal error
	jmp_buf setjmp_buffer;

	// for having access to the filename when printing the error messages
	core::stringc *filename;
};

void CImageLoaderJPG::init_source(j_decompress_ptr cinfo)
{
	// DO NOTHING
}

boolean CImageLoaderJPG::fill_input_buffer(j_decompress_ptr cinfo)
{
	// DO NOTHING
	return TRUE;
}

void CImageLoaderJPG::skip_input_data(j_decompress_ptr cinfo, long count)
{
	jpeg_source_mgr *src = cinfo->src;
	if (count > 0) {
		src->bytes_in_buffer -= count;
		src->next_input_byte += count;
	}
}

void CImageLoaderJPG::term_source(j_decompress_ptr cinfo)
{
	// DO NOTHING
}

void CImageLoaderJPG::error_exit(j_common_ptr cinfo)
{
	// unfortunately we need to use a goto rather than throwing an exception
	// as gcc crashes under linux crashes when using throw from within
	// extern c code

	// Always display the message
	(*cinfo->err->output_message)(cinfo);

	// cinfo->err really points to a irr_error_mgr struct
	irr_jpeg_error_mgr *myerr = (irr_jpeg_error_mgr *)cinfo->err;

	longjmp(myerr->setjmp_buffer, 1);
}

void CImageLoaderJPG::output_message(j_common_ptr cinfo)
{
	// display the error message.
	c8 temp1[JMSG_LENGTH_MAX];
	(*cinfo->err->format_message)(cinfo, temp1);
	core::stringc errMsg("JPEG FATAL ERROR in ");

	irr_jpeg_error_mgr *myerr = (irr_jpeg_error_mgr *)cinfo->err;
	errMsg += *myerr->filename;
	os::Printer::log(errMsg.c_str(), temp1, ELL_ERROR);
}

//! returns true if the file maybe is able to be loaded by this class
bool CImageLoaderJPG::isALoadableFileFormat(io::IReadFile *file) const
{
	if (!(file && file->seek(0)))
		return false;
	unsigned char header[3];
	size_t headerLen = file->read(header, sizeof(header));
	return headerLen >= 3 && !memcmp(header, "\xFF\xD8\xFF", 3);
}

//! creates a surface from the file
IImage *CImageLoaderJPG::loadImage(io::IReadFile *file) const
{
	if (!file)
		return 0;

	core::stringc filename = file->getFileName();

	u8 **rowPtr = 0;
	u8 *input = new u8[file->getSize()];
	file->read(input, file->getSize());

	// allocate and initialize JPEG decompression object
	struct jpeg_decompress_struct cinfo;
	struct irr_jpeg_error_mgr jerr;

	// We have to set up the error handler first, in case the initialization
	// step fails.  (Unlikely, but it could happen if you are out of memory.)
	// This routine fills in the contents of struct jerr, and returns jerr's
	// address which we place into the link field in cinfo.

	cinfo.err = jpeg_std_error(&jerr.pub);
	cinfo.err->error_exit = error_exit;
	cinfo.err->output_message = output_message;
	jerr.filename = &filename;

	// compatibility fudge:
	// we need to use setjmp/longjmp for error handling as gcc-linux
	// crashes when throwing within external c code
	if (setjmp(jerr.setjmp_buffer)) {
		// If we get here, the JPEG code has signaled an error.
		// We need to clean up the JPEG object and return.

		jpeg_destroy_decompress(&cinfo);

		delete[] input;
		delete[] rowPtr;

		// return null pointer
		return 0;
	}

	// Now we can initialize the JPEG decompression object.
	jpeg_create_decompress(&cinfo);

	// specify data source
	jpeg_source_mgr jsrc;

	// Set up data pointer
	jsrc.bytes_in_buffer = file->getSize();
	jsrc.next_input_byte = (JOCTET *)input;
	cinfo.src = &jsrc;

	jsrc.init_source = init_source;
	jsrc.fill_input_buffer = fill_input_buffer;
	jsrc.skip_input_data = skip_input_data;
	jsrc.resync_to_restart = jpeg_resync_to_restart;
	jsrc.term_source = term_source;

	// Decodes JPG input from whatever source
	// Does everything AFTER jpeg_create_decompress
	// and BEFORE jpeg_destroy_decompress
	// Caller is responsible for arranging these + setting up cinfo

	// read file parameters with jpeg_read_header()
	jpeg_read_header(&cinfo, TRUE);

	bool useCMYK = false;
	if (cinfo.jpeg_color_space == JCS_CMYK) {
		cinfo.out_color_space = JCS_CMYK;
		cinfo.out_color_components = 4;
		useCMYK = true;
	} else {
		cinfo.out_color_space = JCS_RGB;
		cinfo.out_color_components = 3;
	}
	cinfo.output_gamma = 2.2;
	cinfo.do_fancy_upsampling = FALSE;

	// reject unreasonable sizes
	if (!checkImageDimensions(cinfo.image_width, cinfo.image_height))
		longjmp(jerr.setjmp_buffer, 1);

	// Start decompressor
	jpeg_start_decompress(&cinfo);

	// Get image data
	u32 rowspan = cinfo.image_width * cinfo.out_color_components;
	u32 width = cinfo.image_width;
	u32 height = cinfo.image_height;

	// Allocate memory for buffer
	u8 *output = new u8[rowspan * height];

	// Here we use the library's state variable cinfo.output_scanline as the
	// loop counter, so that we don't have to keep track ourselves.
	// Create array of row pointers for lib
	rowPtr = new u8 *[height];

	for (u32 i = 0; i < height; i++)
		rowPtr[i] = &output[i * rowspan];

	u32 rowsRead = 0;

	while (cinfo.output_scanline < cinfo.output_height)
		rowsRead += jpeg_read_scanlines(&cinfo, &rowPtr[rowsRead], cinfo.output_height - rowsRead);

	delete[] rowPtr;
	// Finish decompression

	jpeg_finish_decompress(&cinfo);

	// Release JPEG decompression object
	// This is an important step since it will release a good deal of memory.
	jpeg_destroy_decompress(&cinfo);

	// convert image
	IImage *image = 0;
	if (useCMYK) {
		image = new CImage(ECF_R8G8B8,
				core::dimension2d<u32>(width, height));
		const u32 size = 3 * width * height;
		u8 *data = (u8 *)image->getData();
		if (data) {
			for (u32 i = 0, j = 0; i < size; i += 3, j += 4) {
				// Also works without K, but has more contrast with K multiplied in
				//				data[i+0] = output[j+2];
				//				data[i+1] = output[j+1];
				//				data[i+2] = output[j+0];
				data[i + 0] = (char)(output[j + 2] * (output[j + 3] / 255.f));
				data[i + 1] = (char)(output[j + 1] * (output[j + 3] / 255.f));
				data[i + 2] = (char)(output[j + 0] * (output[j + 3] / 255.f));
			}
		}
		delete[] output;
	} else
		image = new CImage(ECF_R8G8B8,
				core::dimension2d<u32>(width, height), output);

	delete[] input;

	return image;
}

//! creates a loader which is able to load jpeg images
IImageLoader *createImageLoaderJPG()
{
	return new CImageLoaderJPG();
}

} // end namespace video
} // end namespace irr
