#include <stdio.h>
#include "readline.h"

#define NAME_LEN 25
#define MAX_PARTS 100

struct part {
  int number;
  char name[NAME_LEN+1];
  int on_hand;
};

int find_part(int number, const struct part inv[], int np);
void insert(struct part inv[], int *np);
void search(const struct part inv[], int np);
void update(struct part inv[], int np);
void print(const struct part inv[], int np);

/**********************************************************
 * main: Prompts the user to enter an operation code,     *
 *       then calls a function to perform the requested   *
 *       action. Repeats until the user enters the        *
 *       command 'q'. Prints an error message if the user *
 *       enters an illegal code.                          *
 **********************************************************/
int main(void)
{
  char code;
  struct part inventory[MAX_PARTS];
  int num_parts = 0;

  for (;;) {
    printf("Enter operation code: ");
    scanf(" %c", &code);
    while (getchar() != '\n')   /* skips to end of line */
      ;
    switch (code) {
      case 'i': insert(inventory, &num_parts);
                break;
      case 's': search(inventory, num_parts);
                break;
      case 'u': update(inventory, num_parts);
                break;
      case 'p': print(inventory, num_parts);
                break;
      case 'q': return 0;
      default:  printf("Illegal code\n");
    }
    printf("\n");
  }
}

/**********************************************************
 * find_part: Looks up a part number in the inv array.    *
 *            Returns the array index if the part number  *
 *            is found; otherwise, returns -1.            *
 **********************************************************/
int find_part(int number, const struct part inv[], int np)
{
  int i;

  for (i = 0; i < np; i++)
    if (inv[i].number == number)
      return i;
  return -1;
}

/**********************************************************
 * insert: Prompts the user for information about a new   *
 *         part and then inserts the part into the inv    *
 *         array. Prints an error message and returns     *
 *         prematurely if the part already exists or the  *
 *         array is full.                                 *
 **********************************************************/
void insert(struct part inv[], int *np)
{
  int part_number;

  if (*np == MAX_PARTS) {
    printf("Database is full; can't add more parts.\n");
    return;
  }

  printf("Enter part number: ");
  scanf("%d", &part_number);
  if (find_part(part_number, inv, *np) >= 0) {
    printf("Part already exists.\n");
    return;
  }

  inv[*np].number = part_number;
  printf("Enter part name: ");
  read_line(inv[*np].name, NAME_LEN);
  printf("Enter quantity on hand: ");
  scanf("%d", &inv[*np].on_hand);
  (*np)++;
}

/**********************************************************
 * search: Prompts the user to enter a part number, then  *
 *         looks up the part in the inv array. If the     *
 *         part exists, prints the name and quantity on   *
 *         hand; if not, prints an error message.         *
 **********************************************************/
void search(const struct part inv[], int np)
{
  int i, number;

  printf("Enter part number: ");
  scanf("%d", &number);
  i = find_part(number, inv, np);
  if (i >= 0) {
    printf("Part name: %s\n", inv[i].name);
    printf("Quantity on hand: %d\n", inv[i].on_hand);
  } else
    printf("Part not found.\n");
}

/**********************************************************
 * update: Prompts the user to enter a part number.       *
 *         Prints an error message if the part can't be   *
 *         found in the inv array; otherwise, prompts the *
 *         user to enter change in quantity on hand and   *
 *         updates the array.                             *
 **********************************************************/
void update(struct part inv[], int np)
{
  int i, number, change;

  printf("Enter part number: ");
  scanf("%d", &number);
  i = find_part(number, inv, np);
  if (i >= 0) {
    printf("Enter change in quantity on hand: ");
    scanf("%d", &change);
    inv[i].on_hand += change;
  } else
    printf("Part not found.\n");
}

/**********************************************************
 * print: Prints a listing of all parts in the inv array, *
 *        showing the part number, part name, and         *
 *        quantity on hand. Parts are printed in the      *
 *        order in which they were entered into the       *
 *        array.                                          *
 **********************************************************/
void print(const struct part inv[], int np)
{
  int i;

  printf("Part Number   Part Name                  "
         "Quantity on Hand\n");
  for (i = 0; i < np; i++)
    printf("%7d       %-25s%11d\n", inv[i].number,
           inv[i].name, inv[i].on_hand);
}