/*
Author  : Michael Robinson
Program : structs.c
Purpose : To present strucs in C 
Updated : April 5, 2011
*/


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

#define STRSIZE 10

FILE  *inp;  // pointer to the file inp 
FILE  *outp; // pointer to the file outp


typedef struct   //this is a template to create multiple structures with diff names
{                //it does NOT allocate memory  
	char   name[STRSIZE];
	double diameter;      //equatorial diameter in km
        int    moons;         //number of moons
	double orbit_time;    //years to orbit sun once
 	double rotation_time; //hours to complete one revolution on axis
}planet_t;


typedef struct //this is a hierarchical struct b/c it contains another struct inside
{
	double    diameter;
	planet_t  planets[9];  //note this is another structure, an array of planet_t structures
 	char      galaxy[STRSIZE];
}solar_sys_t;


void pause()
{
    printf( "Press any key to continue" );
    getchar();
}



void printPlanet( planet_t pl )
{
    printf("\n Planet's name: %s\n", pl.name);
    printf("   Equatorial diameter is %.1f km.\n", pl.diameter); 
    printf("   Number of moons        %d\n", pl.moons); 
    printf("   Time to complete one orbit of the sun %.2f\n", pl.orbit_time); 
    printf("   Time to complete one rotation on axis %.4f\n", pl.rotation_time); 
}


int compareStructures( planet_t one, planet_t two )
{   //page 414
    return( strcmp(one.name, two.name) == 0        &&  
            one.diameter      == two.diameter      &&
            one.moons         == two.moons         &&
            one.orbit_time    == two.orbit_time    &&
            one.rotation_time == two.rotation_time    ); 
}


void writeStructDataToDisk( planet_t one )
{
   outp = fopen("struct.txt", "w");
 
   printf("\nWritting struct to disk file struct.txt\n");
   fprintf(outp, "name          : %s\n", one.name);
   fprintf(outp, "diameter      : %f\n", one.diameter);
   fprintf(outp, "moons         : %d\n", one.moons);
   fprintf(outp, "orbit_time    : %f\n", one.orbit_time);
   fprintf(outp, "rotation_time : %f\n", one.rotation_time);


   printf( "\nname          : %s\n", one.name);
   printf( "diameter      : %f\n", one.diameter);
   printf( "moons         : %d\n", one.moons);
   printf( "orbit_time    : %f\n", one.orbit_time);
   printf( "rotation_time : %f\n", one.rotation_time);

   fclose(outp); 

}


void readStructDataFromDisk()
{
   char record[100]; 
   int  totalRecords = 0;
   int  x = 0;
   int  y = 0;  

   inp  = fopen("struct.txt", "r");

   printf("\nGetting struct data from disk file struct.txt\n");

   for(x=0; x < 5; x++)
   {
      printf("Record %d = ", totalRecords++ );
      fgets (record , 100 , inp); 
      printf("%s",  record);
   }
   printf("\n");

   fclose(inp);

} 



int main()
{
    //create structs from struct prototypes 
    planet_t currentPlanet;
    planet_t previousPlanet;
    planet_t blankPlanet = {"blank", 0, 0, 0, 0}; //has been initialized with this data

    //load data into currentPlanet structure
    strcpy(currentPlanet.name, "Jupiter");
    currentPlanet.diameter      = 142980;
    currentPlanet.moons         = 16;
    currentPlanet.orbit_time    = 11.9;
    currentPlanet.rotation_time = 9.925;

    printf("\n currentPlanet:  %s's equatorial diameter is %.1f km.\n", 
               currentPlanet.name, currentPlanet.diameter);
    pause(); 

    printf(" previousPlanet: %s's equatorial diameter is %.1f km.\n", 
             previousPlanet.name, previousPlanet.diameter);
    pause(); 
    
    
    //assign one struct to another
    printf("\n Assigning: previousPlanet = currentPlanet\n");
    previousPlanet = currentPlanet;  
    printf(" currentPlanet  %s's equatorial diameter is %.1f km.\n", 
             currentPlanet.name, currentPlanet.diameter);
    pause(); 
    
    printf(" previousPlanet %s's equatorial diameter is %.1f km.\n", 
             previousPlanet.name, previousPlanet.diameter);
    pause(); 
    
    //print planets statistics
    printPlanet( currentPlanet );
    printPlanet( previousPlanet );
    printPlanet( blankPlanet );

    int result = compareStructures( currentPlanet, previousPlanet );

    if( result == 1 )
    {
           printf("\n currentPlanet and previousPlanet Planets are equivalent\n");
    }    
    else
    {
           printf("\n currentPlanet and previousPlanet Planets are NOT equivalent\n");
    }    

    writeStructDataToDisk( currentPlanet );
    readStructDataFromDisk(); 


    exit(0);
}//end int main()