#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
struct obr_pgm{
    unsigned short int h, w, maxval;
    unsigned short int **dane;
};
void free_img(struct obr_pgm **img){
    int i;
    if(*img==NULL) return;
    if((*img)->dane!=NULL){
        for(i=0;i<(*img)->h;i++){
            free((*img)->dane[i]);
        }
        free((*img)->dane);
        free(*img);
        *img=NULL;
    }
}
struct obr_pgm *createImg(unsigned short int w, unsigned short int h, unsigned short int maxval){
    struct obr_pgm *retImg;
    int i;
    retImg=(struct obr_pgm*)calloc(1,sizeof(struct obr_pgm));
    if(retImg=NULL) return NULL;
    printf("%d \n%d \n%d \n",w,h,maxval);
    retImg->w=w;
    retImg->h=h;
    retImg->maxval=maxval;
    retImg->dane=(unsigned short int**)calloc(h,sizeof(unsigned short int*));
    if(retImg->dane==NULL){
        free_img(&retImg);
        return NULL;
    }
    for(i=0;i<h;i++){
        retImg->dane[i]=(unsigned short int*)malloc(w*sizeof(unsigned short int));
        if(retImg->dane[i]==NULL){
            free_img(&retImg);
            return NULL;
        }
    }
    return retImg;
}
void SkipCom(FILE *f){
    char zn, buff[255];
    zn=fgetc(f);
    do{
        if(zn=='#') fgets(buff,sizeof(buff),f);
        zn=getc(f);
    }while(!isdigit(zn));
    ungetc(zn,f);
}
struct obr_pgm *LoadImg(char *path){
    FILE *f;
    char buff[255];
    int w,h,maxval,x,y;
    struct obr_pgm *ptr;
    f=fopen(path,"rt");
    if(f==NULL) return NULL;
    if(fscanf(f,"%2s",buff)!=1){
        fclose(f);
        return NULL;
    }
    if(buff[0]!='P' || (buff[1]!='2' && buff[2]!='5')){
        fclose(f);
        return NULL;
    }
    SkipCom(f);
    if(fscanf(f,"%d %d", &w, &h)!=2){
        fclose(f);
        return NULL;
    }
    SkipCom(f);
    if(fscanf(f,"%d",&maxval)!=1){
        fclose(f);
        return NULL;
    }
    ptr=createImg(w,h,maxval);
    if(ptr==NULL){
        fclose(f);
        return NULL;
    }
    for(y=0;y<h;y++){
        SkipCom(f);
        for(x=0;x<w;x++){
            if(fscanf(f,"%d",&(ptr->dane[y][x]))!=1){
                free(&ptr);
                fclose(f);
                return NULL;
            }
        }
    }
    fclose(f);
    return ptr;
}
struct obr_pgm *zapis(struct obr_pgm *ptr, char *path){
    FILE *f;
    int x,y;
    f=fopen(path,"wt");
    if(f==NULL) return NULL;
    fprintf(f, "P2\n");
    fprintf(f, "%d %d\n%d\n", ptr->w, ptr->h, ptr->maxval);
    for(y=0;y<ptr->h;y++){
        for(x=0;x<ptr->w;x++){
            fprintf(f,"%d ",&(ptr->dane[y][x]));
        }
        fprintf(f,"\n");
    }
    fclose(f);

}
struct obr_pgm *inwersja(struct obr_pgm *img){
    struct obr_pgm *ptr;
    int x,y;
    if(img==NULL) return NULL;
    ptr=createImg(img->w, img->h,img->maxval);
    if(ptr==NULL) return NULL;
    for(y=0;y<img->h;y++){
        for(x=0;x<img->w;x++){
            ptr->dane[y][x]=img->maxval-(img->dane[y][x]);
        }
    }
    return ptr;
}
int main(){
    struct obr_pgm *ptr;
    ptr=LoadImg("bird.pgm");
    inwersja(ptr);
    zapis(ptr,"obrazek.pgm");
    free_img(&ptr);
    return 0;
}