/*         ______   ___    ___
 *        /\  _  \ /\_ \  /\_ \
 *        \ \ \L\ \\//\ \ \//\ \      __     __   _ __   ___
 *         \ \  __ \ \ \ \  \ \ \   /'__`\ /'_ `\/\`'__\/ __`\
 *          \ \ \/\ \ \_\ \_ \_\ \_/\  __//\ \L\ \ \ \//\ \L\ \
 *           \ \_\ \_\/\____\/\____\ \____\ \____ \ \_\\ \____/
 *            \/_/\/_/\/____/\/____/\/____/\/___L\ \/_/ \/___/
 *                                           /\____/
 *                                           \_/__/
 *      By Shawn Hargreaves
 *      shawn@talula.demon.co.uk
 *      http://www.talula.demon.co.uk/allegro/
 *
 *      BMP reader by Seymour Shlien.
 *      OS/2 BMP support and BMP save function by Jonas Petersen.
 *
 *      See readme.txt for copyright information.
 */


#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <limits.h>

#include "internal.h"


#define BI_RGB          0
#define BI_RLE8         1
#define BI_RLE4         2
#define BI_BITFIELDS    3

#define OS2INFOHEADERSIZE  12
#define WININFOHEADERSIZE  40


typedef struct BITMAPFILEHEADER
{
   unsigned long  bfType;
   unsigned long  bfSize;
   unsigned short bfReserved1;
   unsigned short bfReserved2;
   unsigned long  bfOffBits;
} BITMAPFILEHEADER;


/* Used for both OS/2 and Windows BMP. 
 * Contains only the parameters needed to load the image 
 */
typedef struct BITMAPINFOHEADER
{
   unsigned long  biWidth;
   unsigned long  biHeight;
   unsigned short biBitCount;
   unsigned long  biCompression;
} BITMAPINFOHEADER;


typedef struct WINBMPINFOHEADER  /* size: 40 */
{
   unsigned long  biWidth;
   unsigned long  biHeight;
   unsigned short biPlanes;
   unsigned short biBitCount;
   unsigned long  biCompression;
   unsigned long  biSizeImage;
   unsigned long  biXPelsPerMeter;
   unsigned long  biYPelsPerMeter;
   unsigned long  biClrUsed;
   unsigned long  biClrImportant;
} WINBMPINFOHEADER;


typedef struct OS2BMPINFOHEADER  /* size: 12 */
{
   unsigned short biWidth;
   unsigned short biHeight;
   unsigned short biPlanes;
   unsigned short biBitCount;
} OS2BMPINFOHEADER;



/* read_bmfileheader:
 *  Reads a BMP file header and check that it has the BMP magic number.
 */
static int read_bmfileheader(PACKFILE *f, BITMAPFILEHEADER *fileheader)
{
   fileheader->bfType = pack_igetw(f);
   fileheader->bfSize= pack_igetl(f);
   fileheader->bfReserved1= pack_igetw(f);
   fileheader->bfReserved2= pack_igetw(f);
   fileheader->bfOffBits= pack_igetl(f);

   if (fileheader->bfType != 19778)
      return -1;

   return 0;
}



/* read_win_bminfoheader:
 *  Reads information from a BMP file header.
 */
static int read_win_bminfoheader(PACKFILE *f, BITMAPINFOHEADER *infoheader)
{
   WINBMPINFOHEADER win_infoheader;

   win_infoheader.biWidth = pack_igetl(f);
   win_infoheader.biHeight = pack_igetl(f);
   win_infoheader.biPlanes = pack_igetw(f);
   win_infoheader.biBitCount = pack_igetw(f);
   win_infoheader.biCompression = pack_igetl(f);
   win_infoheader.biSizeImage = pack_igetl(f);
   win_infoheader.biXPelsPerMeter = pack_igetl(f);
   win_infoheader.biYPelsPerMeter = pack_igetl(f);
   win_infoheader.biClrUsed = pack_igetl(f);
   win_infoheader.biClrImportant = pack_igetl(f);

   infoheader->biWidth = win_infoheader.biWidth;
   infoheader->biHeight = win_infoheader.biHeight;
   infoheader->biBitCount = win_infoheader.biBitCount;
   infoheader->biCompression = win_infoheader.biCompression;

   return 0;
}



/* read_os2_bminfoheader:
 *  Reads information from an OS/2 format BMP file header.
 */
static int read_os2_bminfoheader(PACKFILE *f, BITMAPINFOHEADER *infoheader)
{
   OS2BMPINFOHEADER os2_infoheader;

   os2_infoheader.biWidth = pack_igetw(f);
   os2_infoheader.biHeight = pack_igetw(f);
   os2_infoheader.biPlanes = pack_igetw(f);
   os2_infoheader.biBitCount = pack_igetw(f);

   infoheader->biWidth = os2_infoheader.biWidth;
   infoheader->biHeight = os2_infoheader.biHeight;
   infoheader->biBitCount = os2_infoheader.biBitCount;
   infoheader->biCompression = 0;

   return 0;
}



/* read_bmicolors:
 *  Loads the color pallete for 1,4,8 bit formats.
 */
static void read_bmicolors(int ncols, RGB *pal, PACKFILE *f,int win_flag)
{
   int i;

   for (i=0; i<ncols; i++) {
      pal[i].b = pack_getc(f) / 4;
      pal[i].g = pack_getc(f) / 4;
      pal[i].r = pack_getc(f) / 4;
      if (win_flag)
	 pack_getc(f);
   }
}



/* read_1bit_line:
 *  Support function for reading the 1 bit bitmap file format.
 */
static void read_1bit_line(int length, PACKFILE *f, BITMAP *bmp, int line)
{
   unsigned char b[32];
   unsigned long n;
   int i, j, k;
   int pix;

   for (i=0; i<length; i++) {
      j = i % 32;
      if (j == 0) {
	 n = pack_mgetl(f);
	 for (k=0; k<32; k++) {
	    b[31-k] = n & 1;
	    n = n >> 1;
	 }
      }
      pix = b[j];
      bmp->line[line][i] = pix;
   }
}



/* read_4bit_line:
 *  Support function for reading the 4 bit bitmap file format.
 */
static void read_4bit_line(int length, PACKFILE *f, BITMAP *bmp, int line)
{
   unsigned char b[8];
   unsigned long n;
   int i, j, k;
   int temp;
   int pix;

   for (i=0; i<length; i++) {
      j = i % 8;
      if (j == 0) {
	 n = pack_igetl(f);
	 for (k=0; k<4; k++) {
	    temp = n & 255;
	    b[k*2+1] = temp & 15;
	    temp = temp >> 4;
	    b[k*2] = temp & 15;
	    n = n >> 8;
	 }
      }
      pix = b[j];
      bmp->line[line][i] = pix;
   }
}



/* read_8bit_line:
 *  Support function for reading the 8 bit bitmap file format.
 */
static void read_8bit_line(int length, PACKFILE *f, BITMAP *bmp, int line)
{
   unsigned char b[4];
   unsigned long n;
   int i, j, k;
   int pix;

   for (i=0; i<length; i++) {
      j = i % 4;
      if (j == 0) {
	 n = pack_igetl(f);
	 for (k=0; k<4; k++) {
	    b[k] = n & 255;
	    n = n >> 8;
	 }
      }
      pix = b[j];
      bmp->line[line][i] = pix;
   }
}



/* read_24bit_line:
 *  Support function for reading the 24 bit bitmap file format, doing
 *  our best to convert it down to a 256 color pallete.
 */
static void read_24bit_line(int length, PACKFILE *f, BITMAP *bmp, int line)
{
   int i, nbytes;
   RGB c;

   nbytes=0;

   for (i=0; i<length; i++) {
      c.b = pack_getc(f);
      c.g = pack_getc(f);
      c.r = pack_getc(f);
      bmp->line[line][i*3+_rgb_r_shift_24/8] = c.r;
      bmp->line[line][i*3+_rgb_g_shift_24/8] = c.g;
      bmp->line[line][i*3+_rgb_b_shift_24/8] = c.b;
      nbytes += 3;
   }

   nbytes = nbytes % 4;
   if (nbytes != 0)
      for (i=nbytes; i<4; i++)
	 pack_getc(f);
}



/* read_image:
 *  For reading the noncompressed BMP image format.
 */
static void read_image(PACKFILE *f, BITMAP *bmp, BITMAPINFOHEADER *infoheader)
{
   int i, line;

   for (i=0; i<(int)infoheader->biHeight; i++) {
      line = i;

      switch (infoheader->biBitCount) {

	 case 1:
	    read_1bit_line(infoheader->biWidth, f, bmp, infoheader->biHeight-i-1);
	    break;

	 case 4:
	    read_4bit_line(infoheader->biWidth, f, bmp, infoheader->biHeight-i-1);
	    break;

	 case 8:
	    read_8bit_line(infoheader->biWidth, f, bmp, infoheader->biHeight-i-1);
	    break;

	 case 24:
	    read_24bit_line(infoheader->biWidth, f, bmp, infoheader->biHeight-i-1);
	    break;
      }
   }
}



/* read_RLE8_compressed_image:
 *  For reading the 8 bit RLE compressed BMP image format.
 */
static void read_RLE8_compressed_image(PACKFILE *f, BITMAP *bmp, BITMAPINFOHEADER *infoheader)
{
   unsigned char count, val, val0;
   int j, pos, line;
   int eolflag, eopicflag;

   eopicflag = 0;
   line = infoheader->biHeight - 1;

   while (eopicflag == 0) {
      pos = 0;                               /* x position in bitmap */
      eolflag = 0;                           /* end of line flag */

      while ((eolflag == 0) && (eopicflag == 0)) {
	 count = pack_getc(f);
	 val = pack_getc(f);

	 if (count > 0) {                    /* repeat pixel count times */
	    for (j=0;j<count;j++) {
	       bmp->line[line][pos] = val;
	       pos++;
	    }
	 }
	 else {
	    switch (val) {

	       case 0:                       /* end of line flag */
		  eolflag=1;
		  break;

	       case 1:                       /* end of picture flag */
		  eopicflag=1;
		  break;

	       case 2:                       /* displace picture */
		  count = pack_getc(f);
		  val = pack_getc(f);
		  pos += count;
		  line -= val;
		  break;

	       default:                      /* read in absolute mode */
		  for (j=0; j<val; j++) {
		     val0 = pack_getc(f);
		     bmp->line[line][pos] = val0;
		     pos++;
		  }

		  if (j%2 == 1)
		     val0 = pack_getc(f);    /* align on word boundary */
		  break;

	    }
	 }

	 if (pos > (int)infoheader->biWidth)
	    eolflag=1;
      }

      line--;
      if (line < 0)
	 eopicflag = 1;
   }
}



/* read_RLE4_compressed_image:
 *  For reading the 4 bit RLE compressed BMP image format.
 */
static void read_RLE4_compressed_image(PACKFILE *f, BITMAP *bmp, BITMAPINFOHEADER *infoheader)
{
   unsigned char b[8];
   unsigned char count;
   unsigned short val0, val;
   int j, k, pos, line;
   int eolflag, eopicflag;

   eopicflag = 0;                            /* end of picture flag */
   line = infoheader->biHeight - 1;

   while (eopicflag == 0) {
      pos = 0;
      eolflag = 0;                           /* end of line flag */

      while ((eolflag == 0) && (eopicflag == 0)) {
	 count = pack_getc(f);
	 val = pack_getc(f);

	 if (count > 0) {                    /* repeat pixels count times */
	    b[1] = val & 15;
	    b[0] = (val >> 4) & 15;
	    for (j=0; j<count; j++) {
	       bmp->line[line][pos] = b[j%2];
	       pos++;
	    }
	 }
	 else {
	    switch (val) {

	       case 0:                       /* end of line */
		  eolflag=1;
		  break;

	       case 1:                       /* end of picture */
		  eopicflag=1;
		  break;

	       case 2:                       /* displace image */
		  count = pack_getc(f);
		  val = pack_getc(f);
		  pos += count;
		  line -= val;
		  break;

	       default:                      /* read in absolute mode */
		  for (j=0; j<val; j++) {
		     if ((j%4) == 0) {
			val0 = pack_igetw(f);
			for (k=0; k<2; k++) {
			   b[2*k+1] = val0 & 15;
			   val0 = val0 >> 4;
			   b[2*k] = val0 & 15;
			   val0 = val0 >> 4;
			}
		     }
		     bmp->line[line][pos] = b[j%4];
		     pos++;
		  }
		  break;
	    }
	 }

	 if (pos > (int)infoheader->biWidth)
	    eolflag=1;
      }

      line--;
      if (line < 0)
	 eopicflag = 1;
   }
}



/* load_bmp:
 *  Loads a Windows BMP file, returning a bitmap structure and storing
 *  the pallete data in the specified pallete (this should be an array of
 *  at least 256 RGB structures).
 *
 *  Thanks to Seymour Shlien for contributing this function.
 */
BITMAP *load_bmp(char *filename, RGB *pal)
{
   BITMAPFILEHEADER fileheader;
   BITMAPINFOHEADER infoheader;
   PACKFILE *f;
   BITMAP *bmp;
   int ncol;
   unsigned long biSize;
   int bpp, dest_depth;

   f = pack_fopen(filename, F_READ);
   if (!f)
      return NULL;

   if (read_bmfileheader(f, &fileheader) != 0) {
      pack_fclose(f);
      return NULL;
   }

   biSize = pack_igetl(f);

   if (biSize == WININFOHEADERSIZE) {
      if (read_win_bminfoheader(f, &infoheader) != 0) {
	 pack_fclose(f);
	 return NULL;
      }
      /* compute number of colors recorded */
      ncol = (fileheader.bfOffBits - 54) / 4;
      read_bmicolors(ncol, pal, f, 1);
   }
   else if (biSize == OS2INFOHEADERSIZE) {
      if (read_os2_bminfoheader(f, &infoheader) != 0) {
	 pack_fclose(f);
	 return NULL;
      }
      /* compute number of colors recorded */
      ncol = (fileheader.bfOffBits - 26) / 3;
      read_bmicolors(ncol, pal, f, 0);
   }
   else {
      pack_fclose(f);
      return NULL;
   }

   /* if 24 bit format then we use whatever pallete is currently
    * active and try our best to represent the image with this
    * color pallete.
    */
   if (infoheader.biBitCount == 24) {
    #ifdef ALLEGRO_COLOR24
      bpp = 24;
      generate_332_palette(pal);
    #else
      pack_fclose(f);
      return NULL;
    #endif
   }
   else
      bpp = 8;

   dest_depth = _color_load_depth(bpp);

   bmp = create_bitmap_ex(bpp, infoheader.biWidth, infoheader.biHeight);
   if (!bmp) {
      pack_fclose(f);
      return NULL;
   }

   clear(bmp);

   switch (infoheader.biCompression) {

      case BI_RGB:
	 read_image(f, bmp, &infoheader);
	 break;

      case BI_RLE8:
	 read_RLE8_compressed_image(f, bmp, &infoheader);
	 break;

      case BI_RLE4:
	 read_RLE4_compressed_image(f, bmp, &infoheader);
	 break;

      default:
	 destroy_bitmap(bmp);
	 bmp = NULL;
   }

   if (dest_depth != bpp)
      bmp = _fixup_loaded_bitmap(bmp, pal, dest_depth);

   pack_fclose(f);
   return bmp;
}



/* save_bmp:
 *  Writes a bitmap into a BMP file, using the specified pallete (this
 *  should be an array of at least 256 RGB structures).
 */
int save_bmp(char *filename, BITMAP *bmp, RGB *pal) 
{
   PACKFILE *f;
   int bfSize;
   int depth = bitmap_color_depth(bmp);
   int bpp = (depth == 8) ? 8 : 24;
   int filler = 3 - ((bmp->w*(bpp/8)-1) & 3);
   int c, i, j;

   if (bpp == 8) {
      bfSize = 54                      /* header */
	       +256*4                  /* palette */
	       +bmp->w*bmp->h;         /* image data */
   }
   else {
      bfSize = 54                      /* header */
	       +bmp->w*bmp->h*3;       /* image data */
   }

   f = pack_fopen(filename, F_WRITE);
   if (!f) 
      return errno;

   /* file_header */
   pack_iputw(0x4D42, f);              /* bfType ("BM") */
   pack_iputl(bfSize, f);              /* bfSize */
   pack_iputw(0, f);                   /* bfReserved1 */
   pack_iputw(0, f);                   /* bfReserved2 */

   if (bpp == 8)                       /* bfOffBits */
      pack_iputl(54+256*4, f); 
   else
      pack_iputl(54, f); 

   /* info_header */
   bfSize = bmp->w * bmp->h * bpp/8;

   pack_iputl(40, f);                  /* biSize */
   pack_iputl(bmp->w, f);              /* biWidth */
   pack_iputl(bmp->h, f);              /* biHeight */
   pack_iputw(1, f);                   /* biPlanes */
   pack_iputw(bpp, f);                 /* biBitCount */
   pack_iputl(0, f);                   /* biCompression */
   pack_iputl(bfSize, f);              /* biSizeImage */
   pack_iputl(0, f);                   /* biXPelsPerMeter */
   pack_iputl(0, f);                   /* biYPelsPerMeter */

   if (bpp == 8) {
      pack_iputl(256, f);              /* biClrUsed */
      pack_iputl(256, f);              /* biClrImportant */

      /* palette */
      for (i=0; i<256; i++) {
	 pack_putc(_rgb_scale_6[pal[i].b], f);
	 pack_putc(_rgb_scale_6[pal[i].g], f);
	 pack_putc(_rgb_scale_6[pal[i].r], f);
	 pack_putc(0, f);
      }
   }
   else {
      pack_iputl(0, f);                /* biClrUsed */
      pack_iputl(0, f);                /* biClrImportant */
   }

   /* image data */
   for (i=bmp->h-1; i>=0; i--) {
      for (j=0; j<bmp->w; j++) {
	 if (bpp == 8) {
	    pack_putc(getpixel(bmp, j, i), f);
	 }
	 else {
	    c = getpixel(bmp, j, i);
	    pack_putc(getb_depth(depth, c), f);
	    pack_putc(getg_depth(depth, c), f);
	    pack_putc(getr_depth(depth, c), f);
	 }
      }

      for (j=0; j<filler; j++)
	 pack_putc(0, f);
   }

   pack_fclose(f);
   return errno;
}