/*
 * Copyright (C) Volition, Inc. 1999.  All rights reserved.
 *
 * All source code herein is the property of Volition, Inc. You may not sell 
 * or otherwise commercially exploit the source or things you created based on the 
 * source.
 *
*/



#include <stdio.h>
#include <string.h>
#include <setjmp.h>

#include "jpeglib.h"

#undef LOCAL // fix from a jpeg header, pstypes.h will define it again

#include "globalincs/pstypes.h"
#include "jpgutils/jpgutils.h"
#include "cfile/cfile.h"
#include "bmpman/bmpman.h"
#include "palman/palman.h"
#include "graphics/2d.h"


// forward declarations
void jpeg_cfile_src(j_decompress_ptr cinfo, CFILE *cfp);

// structs
typedef struct {
  struct jpeg_source_mgr pub;	// public fields

  CFILE *infile;		// source stream
  JOCTET *buffer;		// start of buffer
  boolean start_of_file;	// have we gotten any data yet?
} cfile_source_mgr;

typedef cfile_source_mgr *cfile_src_ptr;
struct jpeg_decompress_struct jpeg_info;
struct jpeg_error_mgr jpeg_err;

#define INPUT_BUF_SIZE  4096	// choose an efficiently read'able size

static int jpeg_error_code;

// set current error
#define Jpeg_Set_Error(x)	{ jpeg_error_code = x; }

// error handler stuff, rather than the default, which will screw us
//
jmp_buf FSJpegError;

// error (exit) handler
void jpg_error_exit(j_common_ptr cinfo)
{
	// give an error message that isn't just generic
	(*cinfo->err->output_message) (cinfo);

	// do cleanup since we won't get the chance otherwise
	jpeg_destroy(cinfo);

	// set the error code, pretty much always going to be a read error
	Jpeg_Set_Error(JPEG_ERROR_READING);

	// bail
	longjmp(FSJpegError, 1);
}

// message handler for errors
void jpg_output_message(j_common_ptr cinfo)
{
	// JMSG_LENGTH_MAX should be 200, DO NOT change from this define so
	// that we don't risk overruns from the jpeg lib
	char buffer[JMSG_LENGTH_MAX];

	// Create the message 
	(*cinfo->err->format_message) (cinfo, buffer);

	// don't actually output anything unless we are a debug build, let bmpman
	// give any errors instead for release builds
#ifndef NDEBUG
	Warning(LOCATION, "%s %s", "JPEG Error:", buffer);
#endif
}



// Reads header information from the JPEG file into the bitmap pointer
// 
// filename - name of the JPEG bitmap file
// w - (output) width of the bitmap
// h - (output) height of the bitmap
// bpp - (output) bits per pixel of the bitmap
//
// returns - JPEG_ERROR_NONE if successful, otherwise error code
//
int jpeg_read_header(char *real_filename, CFILE *img_cfp, int *w, int *h, int *bpp, ubyte *palette)
{
	CFILE *jpeg_file = NULL;
	char filename[MAX_FILENAME_LEN];

	if (img_cfp == NULL) {
		strcpy_s( filename, real_filename );

		char *p = strchr( filename, '.' );

		if ( p )
			*p = 0;

		strcat_s( filename, ".jpg" );

		jpeg_file = cfopen( filename , "rb" );

		if ( !jpeg_file ) {
			return JPEG_ERROR_READING;
		}
	} else {
		jpeg_file = img_cfp;
	}

	Assert( jpeg_file != NULL );

	if (jpeg_file == NULL)
		return JPEG_ERROR_READING;

	// set the basic/default error code
	Jpeg_Set_Error(JPEG_ERROR_NONE);

	// initialize error message handler and decompression struct
	jpeg_info.err = jpeg_std_error(&jpeg_err);
	jpeg_err.error_exit = jpg_error_exit;
	jpeg_err.output_message = jpg_output_message;

	jpeg_create_decompress(&jpeg_info);

	// setup to read data via CFILE
	jpeg_cfile_src(&jpeg_info, jpeg_file);

	jpeg_read_header(&jpeg_info, TRUE);

	// send the info back out
	if (w) *w = jpeg_info.image_width;
	if (h) *h = jpeg_info.image_height;
	if (bpp) *bpp = (jpeg_info.num_components * 8);

	// cleanup
	jpeg_destroy_decompress(&jpeg_info);

	if (img_cfp == NULL) {
		cfclose(jpeg_file);
		jpeg_file = NULL;
	}

	return jpeg_error_code;
}


// Loads a JPEG image
// 
// filename - name of the targa file to load
// image_data - allocated storage for the bitmap
//
// returns - true if succesful, false otherwise
//
int jpeg_read_bitmap(char *real_filename, ubyte *image_data, ubyte *palette, int dest_size, int cf_type)
{
	char filename[MAX_FILENAME_LEN];
	CFILE *img_cfp = NULL;
	JSAMPARRAY buffer = NULL;

	strcpy_s( filename, real_filename );
	char *p = strchr( filename, '.' );
	if ( p ) *p = 0;
	strcat_s( filename, ".jpg" );


	img_cfp = cfopen(filename, "rb", CFILE_NORMAL, cf_type);

	if (img_cfp == NULL)
		return JPEG_ERROR_READING;

	// set the basic error code
	Jpeg_Set_Error(JPEG_ERROR_NONE);

	// initialize error message handler
	jpeg_info.err = jpeg_std_error(&jpeg_err);
	jpeg_err.error_exit = jpg_error_exit;
	jpeg_err.output_message = jpg_output_message;

	// SPECIAL NOTE: we've already allocated memory on the basis of original height, width and bpp
	// of the image from the header.  DO NOT change any settings that affect output variables here
	// or we risk needed more memory than we have available in "image_data".  The only exception is
	// bpp since 'dest_size' should already indicate what we want to end up with.

	if ( setjmp( FSJpegError ) == 0) {
		// initialize decompression struct
		jpeg_create_decompress(&jpeg_info);

		// setup to read data via CFILE
		jpeg_cfile_src(&jpeg_info, img_cfp);

		jpeg_read_header(&jpeg_info, TRUE);

		// memory for the storage of each scanline
		jpeg_calc_output_dimensions(&jpeg_info);

		// set the output components to be 'dest_size' (so we can support 16/24/32-bit images with this one function)
		// NOTE: only 24-bit is actually supported right now, we don't currently up/down sample at all
		jpeg_info.output_components = dest_size;
		jpeg_info.out_color_components = dest_size;	// may need/have to match above

		// multiplying by rec_outbuf_height isn't required but is more efficient
		int size = jpeg_info.output_width * jpeg_info.output_components * jpeg_info.rec_outbuf_height;
		// a standard malloc doesn't appear to work properly here (debug vm_malloc??), crashes in lib
		buffer = (*jpeg_info.mem->alloc_sarray)((j_common_ptr) &jpeg_info, JPOOL_IMAGE, size, 1); // DON'T free() THIS! jpeg lib does it

		// begin decompression process --
		jpeg_start_decompress(&jpeg_info);

		// read each scanline and output to previously allocated 'image_data'
		while (jpeg_info.output_scanline < jpeg_info.output_height) {
			jpeg_read_scanlines(&jpeg_info, buffer, 1);

			// niffiwan: swap some bytes (FSO uses BGR, not RGB) so that libjpeg
			// code is used in its original state
			// NOTE: assumes only one scanline is being read at a time. If
			// multiple lines are read this needs updating
			// also note that this doesn't deal with jpegs that are greyscale
			JSAMPLE tmp;
			for (int k = 2; k < size; k += 3) {
				tmp = buffer[0][k - 2];
				buffer[0][k - 2] = buffer[0][k];
				buffer[0][k] = tmp;
			}

			memcpy(image_data, *buffer, size);
			image_data += size;
		}

		// -- done with decompression process
		jpeg_finish_decompress(&jpeg_info);

		// cleanup
		jpeg_destroy_decompress(&jpeg_info);
	}

	cfclose(img_cfp);


	return jpeg_error_code;
}




// --------------------- handlers for reading of files -------------------------
// ---- basic copy of source from jdatasrc.c, originally:
//		Copyright (C) 1994-1996, Thomas G. Lane.

void jpeg_cf_init_source(j_decompress_ptr cinfo)
{
	cfile_src_ptr src = (cfile_src_ptr) cinfo->src;

	// We reset the empty-input-file flag for each image,
	// but we don't clear the input buffer.
	// This is correct behavior for reading a series of images from one source.
	src->start_of_file = TRUE;
}

boolean jpeg_cf_fill_input_buffer(j_decompress_ptr cinfo)
{
	cfile_src_ptr src = (cfile_src_ptr) cinfo->src;
	size_t nbytes;

	nbytes = cfread(src->buffer, 1, INPUT_BUF_SIZE, src->infile);

	if (nbytes <= 0) {
		if (src->start_of_file) {	// Treat empty input file as fatal error
			Jpeg_Set_Error(JPEG_ERROR_READING);
		}

		// Insert a fake EOI marker
		src->buffer[0] = (JOCTET) 0xFF;
		src->buffer[1] = (JOCTET) JPEG_EOI;
		nbytes = 2;

		return FALSE;
	}

	src->pub.next_input_byte = src->buffer;
	src->pub.bytes_in_buffer = nbytes;
	src->start_of_file = FALSE;

	return TRUE;
}

void jpeg_cf_skip_input_data(j_decompress_ptr cinfo, long num_bytes)
{
	cfile_src_ptr src = (cfile_src_ptr) cinfo->src;

	if (num_bytes > 0) {
		while (num_bytes > (long) src->pub.bytes_in_buffer) {
			num_bytes -= (long) src->pub.bytes_in_buffer;

			if (!jpeg_cf_fill_input_buffer(cinfo))
				return;
		}

		src->pub.next_input_byte += (size_t) num_bytes;
		src->pub.bytes_in_buffer -= (size_t) num_bytes;
	}
}

void jpeg_cf_term_source(j_decompress_ptr cinfo)
{
	// no work necessary here
}

void jpeg_cfile_src(j_decompress_ptr cinfo, CFILE *cfp)
{
	cfile_src_ptr src;

	if (cinfo->src == NULL) {	// first time for this JPEG object?
		cinfo->src = (struct jpeg_source_mgr *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, sizeof(cfile_source_mgr));
		src = (cfile_src_ptr) cinfo->src;
		src->buffer = (JOCTET *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, INPUT_BUF_SIZE * sizeof(JOCTET));
	}

	src = (cfile_src_ptr) cinfo->src;
	src->pub.init_source = jpeg_cf_init_source;
	src->pub.fill_input_buffer = jpeg_cf_fill_input_buffer;
	src->pub.skip_input_data = jpeg_cf_skip_input_data;
	src->pub.resync_to_restart = jpeg_resync_to_restart; // use default method
	src->pub.term_source = jpeg_cf_term_source;
	src->infile = cfp;
	src->pub.bytes_in_buffer = 0; // forces fill_input_buffer on first read
	src->pub.next_input_byte = NULL; // until buffer loaded
}