#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;
const char * axis;
const char * direction;
double times;

JSAMPARRAY row_pointers = NULL;

JDIMENSION width;
JDIMENSION height;
int num_components;
int quality = 75;
J_COLOR_SPACE color_space;

void flip(){
    int x, y, c;
    if (axis != NULL && strcmp(axis, "x") == 0) {
        for (y = 0; y < height / 2; y++) {
            JSAMPROW temp = row_pointers[y];
            row_pointers[y] = row_pointers[height - 1 - y];
            row_pointers[height - 1 - y] = temp;
        }
    } else if (axis != NULL && strcmp(axis, "y") == 0) {
        for (y = 0; y < height; y++) {
            for (x = 0; x < width / 2; x++) {
                for (c = 0; c < num_components; c++) {
                    unsigned char temp = row_pointers[y][x * num_components + c];
                    row_pointers[y][x * num_components + c] = row_pointers[y][(width - 1 - x) * num_components + c];
                    row_pointers[y][(width - 1 - x) * num_components + c] = temp;
                }
            }
        }
    }
}    

void rotate(){
    int x, y, c;
    JDIMENSION new_width = height;
    JDIMENSION new_height = width;
    JSAMPARRAY new_row_pointers = (JSAMPARRAY) malloc(sizeof(j_common_ptr) * new_height);
    size_t rowbytes = new_width * num_components;
    
    if (direction != NULL && strcmp(direction, "right") == 0) {
        for (y = 0; y < new_height; y++) {
            new_row_pointers[y] = (JSAMPROW) malloc(rowbytes);
            for (x = 0; x < new_width; x++) {
                for (c = 0; c < num_components; c++) {
                    new_row_pointers[y][x * num_components + c] = row_pointers[height - 1 - x][y * num_components + c];
                }
            }
        }
    } else if (direction != NULL && strcmp(direction, "left") == 0) {
        for (y = 0; y < new_height; y++) {
            new_row_pointers[y] = (JSAMPROW) malloc(rowbytes);
            for (x = 0; x < new_width; x++) {
                for (c = 0; c < num_components; c++) {
                    new_row_pointers[y][x * num_components + c] = row_pointers[x][(width - 1 - y) * num_components + c];
                }
            }
        }
    }
    
    for (y = 0; y < height; y++) {
        free(row_pointers[y]);
    }
    free(row_pointers);
    row_pointers = new_row_pointers;
    width = new_width;
    height = new_height;
}

void process_file(){
    if(strcmp(filter, "flip") == 0 ){
        flip();
    } else if(strcmp(filter, "rotate") == 0 ){
        rotate();
    }
}

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

void read_jpeg_file( const char *filename )
{
    struct jpeg_decompress_struct cinfo;
    struct jpeg_error_mgr jerr;
    int y;
    
    FILE *infile = fopen( filename, "rb" );
    
    if ( !infile )
    {
        abort_("Error opening input jpeg file %s!\n", filename);
    }
    cinfo.err = jpeg_std_error( &jerr );
    jpeg_create_decompress( &cinfo );
    jpeg_stdio_src( &cinfo, infile );
    jpeg_read_header( &cinfo, TRUE );

    jpeg_start_decompress( &cinfo );
    width = cinfo.output_width;
    height = cinfo.output_height;
    num_components = cinfo.out_color_components;
    color_space = cinfo.out_color_space;
    
    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);
    }

    y=0;
    JSAMPARRAY tmp = row_pointers;
    while( cinfo.output_scanline < cinfo.image_height )
    {
        y = jpeg_read_scanlines( &cinfo, tmp, 1 );
        tmp +=y;
    }
    jpeg_finish_decompress( &cinfo );
    jpeg_destroy_decompress( &cinfo );
    fclose( infile );
}

void write_jpeg_file( const char *filename )
{
    struct jpeg_compress_struct cinfo;
    struct jpeg_error_mgr jerr;
    int y;
    JSAMPARRAY tmp;

    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);

    cinfo.image_width = width;	
    cinfo.image_height = height;
    cinfo.input_components = num_components;
    cinfo.in_color_space = color_space;
    jpeg_set_defaults( &cinfo );
    jpeg_set_quality (&cinfo, quality, TRUE);
    jpeg_start_compress( &cinfo, TRUE );
    tmp = row_pointers;
    while( cinfo.next_scanline < cinfo.image_height )
    {
        y = jpeg_write_scanlines( &cinfo, tmp, 1 );
        tmp +=y;
    }
    jpeg_finish_compress( &cinfo );
    jpeg_destroy_compress( &cinfo );
    fclose( outfile );
    
    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("i", "in-file", "<input>", "Input JPEG File");
    struct arg_file *output_file_arg = arg_file1("o", "out-file" , "<output>", "Output JPEG File");
    struct arg_str *filter_arg = arg_str1("f", "filter" , "<filter>", "Filter");
    struct arg_str *axis_arg = arg_str0("a", "axis", "<axis>", "Axis to flip");
    struct arg_str *direction_arg = arg_str0("d", "direction", "<direction>", "Direction to rotate");
    struct arg_dbl *times_arg = arg_dbl0("t", "times" , "<times>", "Multiplyer");
    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, axis_arg, direction_arg, times_arg, help, end};
  
    if (arg_nullcheck(argtable) != 0) printf("error: insufficient memory\n");
  
    times_arg->dval[0] = 1;
    axis_arg->sval[0] = "";
    direction_arg->sval[0] = "";
  
    nerrors = arg_parse(argc, argv, argtable);
  
    if (help->count > 0){
        printf("Usage: geometry");
        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];
        axis = axis_arg->sval[0];
        direction = direction_arg->sval[0];
        times = times_arg->dval[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;
}