#include <stdio.h>
#include <errno.h>

struct                  /* struct to hold CGI name/value pairs */
{
  char name[128];
  char val[128];
} elements[16];

struct phonebook_entry  /* struct of each phone entry  */
{
  char name[41];        /* HTML form variable size + 1 */
  char phone[11];       /* HTML form variable size + 1 */
} entry;

extern int errno;

/***************************************************/
/* Function to add an entry to the phonebook       */
/***************************************************/
void phonebook_add()
{
  FILE *fp;

  if (strlen(elements[0].val) == 0 )
    {
     printf("Name is required!\n");
     exit(0);
    }
  if ((fp = fopen("C_phone.dat", "a"))==NULL)
    {
      printf("Unable to open C_phone.dat.\nContact Webmaster.\n");
      exit(1);
    }
  strcpy(entry.name, elements[0].val);
  strcpy(entry.phone, elements[1].val);
  fwrite(&entry, sizeof(entry), 1, fp);
  fclose(fp);
  printf("Entry added successfully!\n");
}

/***************************************************/
/* Function to delete an entry to the phonebook    */
/***************************************************/
void phonebook_delete()
{
  FILE *fp, *tempfp;
  int found = 0;

  if (rename("C_phone.dat", "C_phone.tmp") != 0 )
    {
      printf("Unable to rename C_phone.dat to C_phone.tmp.\n");
      printf("Contact Webmaster.\n");
      exit(1);
    }
  if ((tempfp = fopen("C_phone.tmp", "r"))==NULL)
    {
      printf("Unable to open C_phone.tmp. Contact Webmaster.\n");
      exit(1);
    }
  if ((fp = fopen("C_phone.dat", "w")) == NULL)
    {
      printf("Unable to open C_phone.dat. Contact Webmaster. \n");
      fclose(tempfp);
      exit(1);
    }

  /* copy all entries from C_phone.tmp to C_phone.dat */
  /* except the one to be deleted.                    */
  while (!feof(tempfp))
    {
      if (fread(&entry, sizeof(entry), 1, tempfp) ==1 )
	{
	  if (strcmp(entry.name, elements[0].val) != 0)
	    fwrite(&entry, sizeof(entry), 1, fp);
	  else
	    found = 1;       /* found name to be deleted */
	}
      else
	break;               /* no more records to read */
    }

  if (found)
    printf("Entry successfully deleted!\n");
  else
    printf("Entry not found!\n");
  fclose(fp);
  fclose(tempfp);
}

/***************************************************/
/* Function to search for an entry in the phonebook*/
/***************************************************/
void phonebook_search()
{
  FILE *fp;
  int found = 0;

  if ((fp=fopen("C_phone.dat", "r")) == NULL)
    {
      printf("Unable to open C_phone.dat. Contact Webmaster.\n");
      exit(1);
    }
  while (!feof(fp))
    {
      if (fread(&entry, sizeof(entry), 1, fp) == 1)
		  {
		  if (strcmp(entry.name, elements[0].val) == 0)
			  {
			  printf("Name\t= %s\nPhone\t= %s\n", entry.name, entry.phone);
			  found = 1;
			  break;
		      }
          }
      else
	     break;         /* no more entries in phone book */
    }
  fclose(fp);

  if(!found)
    printf("Entry not found in the phonebook.\n");
}


main()
{
  char * cgistr;
  char *content_len;
  int len, i, rc;

  /* send the MIME header first */
  printf("Content-type: text/plain\n\n");

  /* get the length of the cgi content */
  content_len = getenv("CONTENT_LENGTH");
  if (content_len==NULL)
    {
      printf("content-length is undefined!\n");
      exit(1);
    }
  if ((len = atoi(content_len))==0)
    {
      printf("content-length is zero\n");
      exit(1);
    }

  /* allocate memory for the cgi content */
  if ((cgistr = malloc(len + 1))==NULL)
    {
      printf("cannot allocate memory, contact the webmaster\n");
      exit(1);
    }

  /* read the cgi content from STDIN */
  if ((rc = fread(cgistr, len, 1, stdin))!=1)
    {
      printf("cannot read the input stream (%d)! Contact the webmaster\n", rc);
      exit(1);
    }
  cgistr[len]='\0';

  /* extract the contents of the form from cgistr */
  for(i=0; cgistr[0] != '\0'; i++)
    {
      /* first split cgistr using the '&' as separator */
      splitword(elements[i].val, cgistr, '&');

      /*decode the string */
      unescape_url(elements[i].val);

      /*now split the string into name and value using
       the '=' as separator */
      splitword(elements[i].name, elements[i].val, '=');
    }

  /* call appropriate subrouting depending on the button,*/
  /* the user pressed on the form.                       */
  if (strcmp(elements[2].val, "ADD") == 0)
    phonebook_add();
  else if (strcmp(elements[2].val, "DELETE") == 0)
    phonebook_delete();
  else /* else it is SEARCH */
    phonebook_search();
}