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

#include "error.h"
#include "message.h"

#define MAX_NO_RECORD 1000

RECORD data[MAX_NO_RECORD];
int no_account;
    
void write_data_file();

int fd;
int TOTAL=0;

main(argc, argv)
int argc;
char *argv[];
{
    char data_file_name[40] ;
    char Machine[32],ShortHost[32];
    if (argc != 2) {
     fprintf(stderr,"Form: add_data <Department>\n");
     exit(1);
    }
    strcpy(data_file_name,"DATA.");
    strcat(data_file_name,argv[1]);
    strcat(data_file_name,".");
    gethostname(Machine,32);
    strcpy(ShortHost,strtok(Machine,"."));
    strcat(data_file_name,Machine);
    fprintf(stderr,"Opening: %s\n",data_file_name);    
    printf("\nWhen you want to stop the input,");
    printf(" INTERRUPT the program.\n\n");
    fd = open(data_file_name, O_RDWR | O_CREAT, 0600);
    if(signal(SIGINT, write_data_file) == SIG_ERR)
/*    if(signal(SIGINT, write_data_file) == BAD_SIGNAL) */
    	perror("signal");
    read_data_file();
    while(query(&data[no_account++]))    
    { }
}

/* return 999 if succeed */
query(rec)
RECORD *rec;
{
    printf("Input the bar code.\n");
    scanf("%d", &(rec->bar_code));
    printf("Input the unit price.\n");
    scanf("%f", &(rec->unit_price));
    printf("Input the quantity.\n");
    scanf("%d", &(rec->quantity));
    TOTAL += rec->quantity;
    
    printf("Input a short description\n");
    while(getchar() != '\n') { }
    
    if(gets(rec->description) == NULL)
    {
	printf("The description reading is wrong.\n");
	exit(1);
    }
}

read_data_file()
{   int i, read_byte;
    
    if((read_byte=read(fd, &no_account, sizeof(int)))<=0)
    {   no_account = 0;
	if(read_byte==0)
	    fprintf(stderr, "The file DATA is currently empty.\n");
	else
	    perror("READ ERROR");
    }
    else if(no_account>0)
    {   printf("Current no. of item = %d \n", no_account);
	read_byte = sizeof(RECORD)*no_account;
	
	if(read(fd, data, read_byte) != read_byte)
	{
	    fprintf(stderr, "The file DATA has wrong format\n");
	    exit(2);
	}
	for(i=0; i<no_account; i++)
	    printf("%4d: bar_code = %5d, quantity = %5d, %s\n",
		   (i+1), data[i].bar_code, data[i].quantity, data[i].description);
	if(read(fd, &TOTAL, sizeof(int)) != sizeof(int))
	{
	    fprintf(stderr, "The file DATA has wrong format\n");
	    exit(2);
	}
    } 
}



void write_data_file()
{
    int i, write_byte;

    no_account--;
    lseek(fd, 0, 0);
    write_byte = sizeof(RECORD)*no_account;

    for(i=0; i<no_account; i++)
    {
	printf("%4d: Bar Code = %5d, Price = %10.2f, Quantity = %6d\n",
	       (i+1), data[i].bar_code, data[i].unit_price, data[i].quantity);
	puts(data[i].description);
    }
    
    
    if(write(fd, &no_account, sizeof(int)) != sizeof(int) ||
       write(fd, data, write_byte) != write_byte ||
       write(fd, (char *) &TOTAL, sizeof(int)) != sizeof(int)) 
	perror("WRITE data ERROR");

    close(fd);
    exit(0);
}