#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

void clearInput(void);
void addNewAccount(void);
void listAll(void);
void deleteAccount(void);
void modifyAccount(void);
int prompt(void);

struct account {
    int number;
    char lastname[15];
    char firstname[15];
    float balance;
    struct account *next;
};
struct account *firsta,*currenta,*newa;
int anum = 0;

int main()
{
    char ch;
    firsta = NULL;

    do
    {
	clearInput();
        puts("\nA - Add a new account");
	puts("D - Delete account");
	puts("L - List all accounts");
	puts("M - Modify account");
        puts("Q - Quit this program\n");
        printf("\tYour choice:");
        ch = getchar();
	ch = toupper(ch);
        switch(ch)
        {
            case 'A':
                puts("Add new account\n");
		clearInput();
                addNewAccount();
                break;
	    case 'D':
		puts("Delete account\n");
		deleteAccount();
		break;
	    case 'L':
		puts("List all accounts\n");
		listAll();
		break;
	    case 'M':
		puts("Modify an account\n");
		modifyAccount();
		break;
            case 'Q':
                puts("Quit\n");
            default:
                break;
        }
    }
    while(ch != 'Q');

    return(0);
}

/*
 * This function clears any text from the input stream
 */

void clearInput(void)
{
	fflush(stdin);			/* fpurge(stdin) */
}

void addNewAccount(void)
{
    newa = (struct account *)malloc(sizeof(struct account));

/*
 * Check to see if this is the first record
 * If so, then initialize all the pointers to this,
 * first structure in the database
 */

    if(firsta==NULL)
        firsta = currenta = newa;

/* 
 * Otherwise, you must find the end of the structure list
 * (Easily spotted by the NULL pointer) and add on the
 * new structure you just allocated memory for
 */

    else
    {
        currenta = firsta;      /* make the first record the current one */
                                /* and loop through all records: */

        while(currenta->next != NULL)
            currenta = currenta->next;
				/* the last record is found */
        currenta->next = newa;  /* save the address of new */
        currenta = newa;        /* make current record the new one */
    }

/* Now, you just fill in the new structure */

    anum++;
    printf("%27s: %5i\n","Account number",anum);
    currenta->number = anum;

    printf("%27s: ","Enter customer's last name");
    gets(currenta->lastname);

    printf("%27s: ","Enter customer's first name");
    gets(currenta->firstname);

    printf("%27s: $","Enter account balance");
    scanf("%f",&currenta->balance);

/* 
 * Finally, cap the new record with a NULL pointer
 * so that you know it's the last record:
 */

    currenta->next = NULL;
}

void listAll(void)
{
    if(firsta==NULL)
        puts("There are no records to print!");
    else
    {
	printf("%6s %-15s %-15s %11s\n","Acct#","Last","First","Balance");
        currenta=firsta;
        do
        {
            printf("%5d: %-15s %-15s $%8.2f\n",
                currenta->number,
                currenta->lastname,
                currenta->firstname,
                currenta->balance);
        }
        while((currenta=currenta->next) != NULL);
    }
}

void deleteAccount(void)
{
    int record;
    struct account *previousa;

    if(firsta==NULL)
    {
        puts("There are no records to delete!");
	return;
    }
    
    listAll();		/* show all records first */
    printf("Enter account number to delete: ");
    scanf("%d",&record);

    currenta = firsta;
    while(currenta != NULL)
    {
        if(currenta->number == record)
	{
	    if(currenta == firsta)	/* special condition */
		firsta=currenta->next;
	    else
		previousa->next = currenta->next;
            free(currenta);
	    printf("Acount %d deleted!\n",record);
	    return;
	}
	else
	{
            previousa = currenta;
	    currenta = currenta->next;
	}
    }
    printf("Account %d was not found!\n",record);
    puts("Nothing deleted.");
}

void modifyAccount(void)
{
    int record;

    if(firsta==NULL)
    {
        puts("There are no records to modify!");
	return;
    }
    
    listAll();		/* show all records first */
    printf("Enter account number to modify or change: ");
    scanf("%d",&record);

    currenta = firsta;
    while(currenta != NULL)
    {
        if(currenta->number == record)
	{
	    printf("Account $%d:\n",currenta->number);
	    printf("Last name: %s\n",currenta->lastname);
	    if(prompt())
		    gets(currenta->lastname);
	    printf("First name: %s\n",currenta->firstname);
	    if(prompt())
		    gets(currenta->firstname);
	    printf("Balance %8.2f\n",currenta->balance);
	    if(prompt())
		    scanf("%f",&currenta->balance);
	    return;
	}
	else
	{
	    currenta = currenta->next;
	}
    }
    printf("Account %d was not found!\n",record);
}

int prompt(void)
{
	char ch;

	clearInput();
	printf("Update?");
	ch = getchar();
	ch = toupper(ch);
	clearInput();
	if(ch == 'Y')
	{
		printf("Enter new: ");
		return(1);
	}
	else
		return(0);
}