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


#define MAX_HEIGHT 600
#define MAX_WIDTH 400

int main(int argc, char ** argv){

    FILE *file = fopen("", "r");

    if(file == NULL){
        fprintf(stderr, "File is not valid");
        return 0;
    }
    else {
        struct PPM *newPPM = getPPM(file);
        return 0;
    }
}

struct PPM {
    char format[2]; //PPM format code
    int height, width; //image pixel height and width
    int max; //max rgb colour value

};

struct PPM_Pixel {
    //Create variables to hold the rgb pixel values
    int red, green, blue;
};

struct PPM * getPPM(FILE * fd){

    struct PPM *image;
    char format[16];
    int c;
    fd = fopen(fd, "r");

    //checks if the file being opened is valid/the correct file
    if(fd == NULL){
        return NULL;
    }

    if(!fgets(format, sizeOf(format), fd)){
        exit(1);
    }

    //checks the format of the ppm file is correct
    if(format[0] != 'P' || format[1] != '3'){
        fprintf(stderr, "Invalid image format! \n");
        exit(1);
    }

    //allocate memory for the image
    image = ((PPM *)malloc(sizeof(PPM)));
    if(!image){
        fprintf(stderr, "Cannot allocate memory");
        exit(1);
    }

    //checks whether the next character is a comment and store it in a linked list
    c = getc(fd);
    while(c == '#'){
        while(getc(fd) != '\n'){
        c = getc(fd);
        }
    }

    if(fscaf(fd, "%d %d", &image->height, &image->width)!= 2){
        fprintf(stderr, "Size of image is invalid");
        exit(1);
    }

    fclose(fd);
    return image;
};

showPPM(struct PPM * image){

    //two-dimensional array to show the rows and columns of pixels.



};

char * decode(struct ppm * image1, struct PPM * image2){
}