/* Program to sort a file, "lst11-1.old", into a new file, "lst11-1.new".
   Files contain employee data records (max 100).  Records have four lines:
   (1) Surname (20 chars), Given names (50 chars)
   (2) Address line 1 (60 chars)
   (3) Address line 2 (60 chars)
   (4) Position title (40 chars), Payroll no. (long), age (int),
       Sex (char, M or F), salary (double), Department no. (int).
   File to be sorted on: surnames, then given names, then payroll no.
   (Uses a structure to encapsulate all data belonging to one employee.)
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define MAX_STAFF (50)

#define ADDRESS_SIZE (61)
#define SURNAME_SIZE (21)
#define GIVEN_NAME_SIZE (51)
#define TITLE_SIZE (41)

/* The following are format strings used in function "load_data".
   If the above #define sizes are altered, these must also be changed. */

#define address_format "%60[^\n]%*c"   /* meaning: read up to 60 chars, */
                                       /* stopping at a newline, then */
                                       /* read and discard the newline. */
#define name_format "%20[^\n]%50[^\n]%*c"
#define title_format "%40[^\n]%ld%d %c%lf%d%*c"

/**** staff_data: The main structure used to store employee data. ****/

typedef struct {
    char   surname[SURNAME_SIZE];
    char   given_names[GIVEN_NAME_SIZE];
    char   address1[ADDRESS_SIZE];
    char   address2[ADDRESS_SIZE];
    char   title[TITLE_SIZE];
    long   payroll_no;
    int    age;
    int    department;
    double salary;
    char   sex;
} staff_data;

/* Function Declarations: */

FILE *file_open(char name[], char access_mode[]);   /* See listing 10-7 */
int load_data(staff_data staff[]);
void sort_data(staff_data *staff[], int numb_staff);
void write_data(staff_data *staff[], int numb_staff);

/******* The functions themselves: *******/

main() {
    staff_data staff[MAX_STAFF];
    staff_data *pstaff[MAX_STAFF]; /* array of pointers to staff_datas */
    int numb_staff;                /* How many employee records are read */

    /* Set up pointers: */
    for (numb_staff=0; numb_staff<MAX_STAFF; numb_staff++) {
        pstaff[numb_staff] = &staff[numb_staff];
    }

    numb_staff = load_data(staff);
    sort_data(pstaff, numb_staff);
    write_data(pstaff, numb_staff);
    return 0;
}

/* load_data: Fills the array with data from lst11-1.old, until MAX_SIZE
              items read or EOF.
              Returns a count of the number of employee records input.
              If an input error (except for EOF) occurs, a message is
              printed and the program terminates.
*/
int load_data(staff_data staff[]) {
    int number=0;         /* How many employee records are read */
    int status;           /* result of fscanf call */
    FILE *inf;

    inf = file_open("lst11-1.old", "r");            /* See listing 10-7 */
    do {                    /* Load one record at a time until failure */
        status = fscanf (
            inf, name_format, staff[number].surname,
            staff[number].given_names
        );
        if (status >= 0) {      /* EOF not detected on first fscanf */
            if (
                status < 2
            ||
                fscanf(inf, address_format, staff[number].address1) < 1
            ||
                fscanf(inf, address_format, staff[number].address2) < 1
            ||
                fscanf (
                    inf, title_format, staff[number].title,
                    &staff[number].payroll_no, &staff[number].age,
                    &staff[number].sex, &staff[number].salary,
                    &staff[number].department
                ) < 6
            ) {
                /* This branch is selected on error in any of the fscanf
                   calls, and on EOF in any call except the first one.
                */
                fprintf(stderr, "Error in input file, record %d\n", number);
                exit(EXIT_FAILURE);
            }
        }
        number++;
    } while (number<MAX_STAFF && status>=0);
    fclose(inf);
    return number - 1;          /* The loop counted one too many. */
}

int in_wrong_order(staff_data *pstaff[], int which);
   /* Compares items at indices which & which+1, tells if disordered. */

void sort_data(staff_data *pstaff[], int numb_staff) {
    staff_data *temp_ptr;
    int i, j;

    for (i=numb_staff-1; i>0; i--) { /* scan numb_staff-1 times */
        for (j=1; j<=i; j++) {   /* Scan the elements still unsorted. */
            if (in_wrong_order(pstaff,j-1)) {
                temp_ptr = pstaff[j-1];       /* Swap elements */
                pstaff[j-1] = pstaff[j];
                pstaff[j] = temp_ptr;
            }
        }
    }
}

int in_wrong_order(staff_data *pstaff[], int which) {
    /* Compares items at indices which & which+1, tells if disordered.
       Do three tests, stop at the first where the items differ.
    */
    int order;  /* will be <0 for less, 0 for ==, >0 for greater */
    order = strcmp(pstaff[which]->surname, pstaff[which+1]->surname);
    if (order==0) {      /* surnames ==, must compare given names. */
        order = strcmp(
            pstaff[which]->given_names, pstaff[which+1]->given_names
        );
        if (order==0) {      /* given names ==, must compare payroll. */
            return (pstaff[which]->payroll_no>pstaff[which+1]->payroll_no);
        }
    }
    return (order>0); /* Since (order>0) means they are wrongly ordered. */
}

void write_data(staff_data *pstaff[], int numb_staff) {
    FILE *outf;
    int i;

    outf = file_open("lst11-1.new", "w");           /* See listing 10-7 */

    for (i=0; i<numb_staff; i++) {
        fprintf (
            outf, "%-*s%-s\n%-s\n%-s\n%-*s%ld %d%c %4.2f %d\n",
            SURNAME_SIZE-1, pstaff[i]->surname, pstaff[i]->given_names,
            pstaff[i]->address1, pstaff[i]->address2, TITLE_SIZE-1,
            pstaff[i]->title, pstaff[i]->payroll_no, pstaff[i]->age,
            pstaff[i]->sex, pstaff[i]->salary, pstaff[i]->department
        );
    }
    fclose(outf);
}

/* The following #ifdef includes the file_open function; if you have
   it in a personal function library, you may wish to delete these lines
   and link the two files separately.
*/
#ifdef __cplusplus
    #include "lst10-7.cpp"    /* or maybe "lst10-7.cxx" */
#else
    #include "lst10-7.c"
#endif