#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>

#include <jpeglib.h>
#include <argtable2.h>
#include <string.h>

const char * input_file;
const char * output_file;
const char * filter;
double times;
int percent;

/* we will be using this uninitialized pointer later to store raw, uncompressd image */
JSAMPARRAY row_pointers = NULL;

/* dimensions of the image we want to write */
JDIMENSION width;
JDIMENSION height;
int num_components;
int quality = 75;
J_COLOR_SPACE color_space;

unsigned char clamp(double value) {
    if (value < 0.0) return 0;
    if (value > 255.0) return 255;
    return (unsigned char)value;
}

void negate(){
  int x, y;
  if (color_space != JCS_RGB)  return;

  for (y=0; y<height; y++) {
    JSAMPROW row = row_pointers[y];
    for (x=0; x<width; x++) {
      JSAMPROW ptr = &(row[x*3]);
      
      ptr[0] = clamp(255.0 - ptr[0]);
      ptr[1] = clamp(255.0 - ptr[1]);
      ptr[2] = clamp(255.0 - ptr[2]);
    }
  }
}    

void brightness(){
  int x, y;
  if (color_space != JCS_RGB) return;
  double k = percent / 100.0;

  for (y=0; y<height; y++) {
    JSAMPROW row = row_pointers[y];
    for (x=0; x<width; x++) {
      JSAMPROW ptr = &(row[x*3]);
      
      ptr[0] = clamp(ptr[0] + (ptr[0] * k));
      ptr[1] = clamp(ptr[1] + (ptr[1] * k));
      ptr[2] = clamp(ptr[2] + (ptr[2] * k));
    }
  }
}

void contrast(){
  int x, y;
  if (color_space != JCS_RGB) return;

  for (y=0; y<height; y++) {
    JSAMPROW row = row_pointers[y];
    for (x=0; x<width; x++) {
      JSAMPROW ptr = &(row[x*3]);
      
      ptr[0] = clamp(times * (ptr[0] - 127.0) + 127.0);
      ptr[1] = clamp(times * (ptr[1] - 127.0) + 127.0);
      ptr[2] = clamp(times * (ptr[2] - 127.0) + 127.0);
    }
  }
}

void sepia(){
  int x, y;
  if (color_space != JCS_RGB) return;

  for (y=0; y<height; y++) {
    JSAMPROW row = row_pointers[y];
    for (x=0; x<width; x++) {
      JSAMPROW ptr = &(row[x*3]);
      
      unsigned char r = ptr[0];
      unsigned char g = ptr[1];
      unsigned char b = ptr[2];

      ptr[0] = clamp(0.393 * r + 0.769 * g + 0.189 * b);
      ptr[1] = clamp(0.349 * r + 0.686 * g + 0.168 * b);
      ptr[2] = clamp(0.272 * r + 0.534 * g + 0.131 * b);
    }
  }
}

void process_file(){
    if(strcmp(filter, "negate") == 0){
        negate();
    }
    else if(strcmp(filter, "brightness") == 0){
        brightness();
    }
    else if(strcmp(filter, "contrast") == 0){
        contrast();
    }
    else if(strcmp(filter, "sepia") == 0){
        sepia();
    }
}

void abort_(const char * s, ...)
{
    va_list args;
    va_start(args, s);
    vfprintf(stderr, s, args);
    fprintf(stderr, "\n");
    va_end(args);
    abort();
}

/**
 * read_jpeg_file Reads from a jpeg file on disk specified by filename and saves into the 
 * raw_image buffer in an uncompressed format.
 * 
 * \returns positive integer if successful, -1 otherwise
 * \param *filename char string specifying the file name to read from
 *
 */
void read_jpeg_file( const char *filename )
{
    /* these are standard libjpeg structures for reading(decompression) */
    struct jpeg_decompress_struct cinfo;
    struct jpeg_error_mgr jerr;
    /* libjpeg data structure for storing one row, that is, scanline of an image */
    int y;
    
    FILE *infile = fopen( filename, "rb" );
    
    if ( !infile )
    {
        abort_("Error opening input jpeg file %s!\n", filename);
    }
    /* here we set up the standard libjpeg error handler */
    cinfo.err = jpeg_std_error( &jerr );
    jpeg_create_decompress( &cinfo );
    /* this makes the library read from infile */
    jpeg_stdio_src( &cinfo, infile );
    /* reading the image header which contains image information */
    jpeg_read_header( &cinfo, TRUE );

    /* Start decompression jpeg here */
    jpeg_start_decompress( &cinfo );
    width = cinfo.output_width;
    height = cinfo.output_height;
    num_components = cinfo.out_color_components;
    color_space = cinfo.out_color_space;
    
    /* allocate memory to hold the uncompressed image */
    size_t rowbytes = width * num_components;
    row_pointers = (JSAMPARRAY) malloc(sizeof(j_common_ptr) * height);
    for (y=0; y<height; y++){
        row_pointers[y] = (JSAMPROW) malloc(rowbytes);
    }
    
    /* read one scan line at a time */
    y=0;
    JSAMPARRAY tmp = row_pointers;
    while( cinfo.output_scanline < cinfo.image_height )
    {
        y = jpeg_read_scanlines( &cinfo, tmp, 1 );
        tmp +=y;
    }
    /* wrap up decompression, destroy objects, free pointers and close open files */
    jpeg_finish_decompress( &cinfo );
    jpeg_destroy_decompress( &cinfo );
    fclose( infile );
    /* yup, we succeeded! */
}

/**
 * write_jpeg_file Writes the raw image data stored in the raw_image buffer
 * to a jpeg image with default compression and smoothing options in the file
 * specified by *filename.
 *
 * \returns positive integer if successful, -1 otherwise
 * \param *filename char string specifying the file name to save to
 *
 */
void write_jpeg_file( const char *filename )
{
    struct jpeg_compress_struct cinfo;
    struct jpeg_error_mgr jerr;
    int y;
    JSAMPARRAY tmp;
    
    /* this is a pointer to one row of image data */
    FILE *outfile = fopen( filename, "wb" );
    
    if ( !outfile ) {
        abort_("Error opening output jpeg file %s!\n", filename );
    }
    cinfo.err = jpeg_std_error( &jerr );
    jpeg_create_compress(&cinfo);
    jpeg_stdio_dest(&cinfo, outfile);

    /* Setting the parameters of the output file here */
    cinfo.image_width = width;  
    cinfo.image_height = height;
    cinfo.input_components = num_components;
    cinfo.in_color_space = color_space;
    /* default compression parameters, we shouldn't be worried about these */
    jpeg_set_defaults( &cinfo );
    jpeg_set_quality (&cinfo, quality, TRUE);
    /* Now do the compression .. */
    jpeg_start_compress( &cinfo, TRUE );
    /* like reading a file, this time write one row at a time */
    tmp = row_pointers;
    while( cinfo.next_scanline < cinfo.image_height )
    {
        y = jpeg_write_scanlines( &cinfo, tmp, 1 );
        tmp +=y;
    }
    /* similar to read file, clean up after we're done compressing */
    jpeg_finish_compress( &cinfo );
    jpeg_destroy_compress( &cinfo );
    fclose( outfile );
    
        /* cleanup heap allocation */
    for (y=0; y<height; y++){
        free(row_pointers[y]);
    }
    free(row_pointers);
}

int main(int argc, char **argv){   
  struct arg_file *input_file_arg = arg_file1(NULL, "in-file", "<input>", "Input JPEG File");
  struct arg_file *output_file_arg = arg_file1(NULL, "out-file" , "<output>", "Output JPEG File");
  struct arg_str *filter_arg = arg_str1(NULL, "filter" , "<filter>", "Filter");
  struct arg_dbl *times_arg = arg_dbl0(NULL, "times" , "<times>", "Multiplyer");
  struct arg_int *percent_arg = arg_int0(NULL, "percent" , "<percent>", "Percent");
  struct arg_lit *help = arg_lit0("h","help", "print this help and exit");
  struct arg_end *end = arg_end(10); 
  
  int nerrors;
  
  void *argtable[] = {input_file_arg, output_file_arg, filter_arg, times_arg, percent_arg, help, end};
  
  if (arg_nullcheck(argtable) != 0) printf("error: insufficient memory\n");
  
  times_arg->dval[0] = 1.0;
  percent_arg->ival[0] = 0;
  
  nerrors = arg_parse(argc, argv, argtable);

  if (help->count > 0){
     printf("Usage: point");
     arg_print_syntax(stdout, argtable,"\n");
     arg_print_glossary(stdout, argtable,"  %-25s %s\n");
     arg_freetable(argtable, sizeof(argtable)/sizeof(argtable[0]));
     return 0;
  }
  
  if (nerrors==0){
     input_file = input_file_arg->filename[0];
     output_file = output_file_arg->filename[0];
     filter = filter_arg->sval[0];
     times = times_arg->dval[0];
     percent = percent_arg->ival[0];
  }
  else{
     arg_print_errors(stderr, end, "point");
     arg_print_glossary(stderr, argtable, " %-25s %s\n");
     arg_freetable(argtable, sizeof(argtable)/sizeof(argtable[0]));
     return 1;
  }

   read_jpeg_file(input_file);
   process_file();
   write_jpeg_file(output_file);
   arg_freetable(argtable, sizeof(argtable)/sizeof(argtable[0]));
   return 0;
}