#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "studlist04.h"

int main(int argc, char *argv[])
{
  char filename[40], mode;
  FILE *fp;
  Record r;

  /* open input file */
  if (argc >= 2) strcpy(filename, argv[1]);
  else strcpy(filename, "Student.txt");

  if ((fp = fopen(filename, "r")) == NULL) {
    fprintf(stderr, "Cannot open %s!\n", filename);
    exit(2);
  }

  /* initialize */
  head = make_1node(r, NULL);

  /* sort mode : Descending/Ascending */
  printf("Enter sort mode (d:descending / a:ascending) -> ");
  scanf( " %c", &mode );
  if (!(mode == 'd' || mode == 'a')) {
    printf("Enter d or a\n");  
    exit(1);
  }

  /* read data from file */
  while (fscanf(fp, "%d %s %s %d", &r.id, r.surname, r.givenname, &r.age) != EOF) {
    if(insert_sort(r, mode) == NULL) printf("Error: %d appears twice in the file.\n", r.id);   /* ここのメッセージは適当。なくてもよい */
  }
  fclose(fp);
  listprint();

  /* insert list member */
  /* CTL+D to escape this loop */
  while (1) {
    printf("Insert new student data: (ID Surname Givenname Age) -> ");
    if (scanf("%d %s %s %d", &r.id, r.surname, r.givenname, &r.age) != 4) {
      printf("\n");
      break;
    }
    if (insert_sort(r,mode) == NULL) {
      printf("ID %d is already on the list!\n", r.id);
    }
    listprint();
  }
  return 0;
}


/* insert one node in descending or ascending order */
/* return pos(inserted), NULL(already exist)        */
/* mode-> d:descending / a:ascending                */ 
NodePointer insert_sort(Record r, char mode)
{
  NodePointer n, newnode;

  if (finditem(r.id) != NULL) return NULL;

  for(n = head; n->next != NULL; n = n->next) {
    if (mode == 'd') {
      if ( n->next->data.id <= r.id ) break;
    }
    else { /* mode == 'a' */
      if ( n->next->data.id >= r.id ) break;
    }
  }

  newnode = make_1node(r,n->next);
  n->next = newnode;
  return newnode;
}

/* print all items in the list from head to tail */
void listprint(void)
{
  NodePointer n;
  int count = 0;

  printf("Head - \n");
  for(n = head->next; n != NULL; n = n->next){
    printf("  %7d %-12s %-12s %d\n", n->data.id, n->data.surname, n->data.givenname, n->data.age);
    count++;
  }
  printf("%d nodes exist in the list.\n", count);
  printf("\n");
}

/* find item id_data with given ID                      */
/*   if found, return the address of the previous node. */
/*   otherwise, return NULL                             */
NodePointer finditem(int sid)
{
  NodePointer n;
  
  for(n = head; n->next != NULL; n = n->next) {
    if(n->next->data.id == sid) return n;
  }
  return NULL;
}

NodePointer make_1node(Record r, NodePointer p)
{
  NodePointer n;

  if ((n = (NodePointer) malloc(sizeof(struct node))) == NULL) {
    printf("Error in memory allocation\n");
    exit(8);
  }

  n->data = r;
  n->next = p;
  return n;
}