#include <stdio.h>	// This defines the standard IO functions
#include <stdlib.h> // This is for atoi
#include <unistd.h> // This is for sleep
#include <string.h> // This is for strlen
#include "atm.h"	// This defines the account structure

struct	account accounts[MAXACCTS];	// Array of account structures

/*
 * Declare functions used in the program.
 * This is REQUIRED for functions which return non-integer values.
 */
int	load_account_data();
int	save_account_data();
struct account *validate_account();

// This is the entry point for the atm program.
int
main(int argc, char **argv)
{
	// Declare local variables
	int		acct_in;			// User account number
	float	amount;				// User amount for deposit or withdraw
	int		fields;				// Number of fields processed by scanf
	int		error;				// Function returns error code, 0 = OK
	char	input[80];			// Data from the keyboard
	int		keep_going;			// Flag - keep the loops going
	struct	account *my_acct;	// Struct pointer for the current record
	int		pin_in;				// User PIN
	
	// 1) Call load_account_data with the structure to load
	error = load_account_data(accounts);
	if (error) {
		printf("Error: Can not open the bank database file.\n");
		return 1;
	}	else if (error >= 2) {
		printf("Error: Problems with bank database file.\n");
		return 2;
	}
	
	for (;;) {			// person loop
		system("cls");	// clears the screen.  "clear" replaces "cls" in Linux/UNIX
		printf("Welcome to the ATM Machine!\n\n");
		for (keep_going = 1; keep_going;) {			// account loop
			printf("Please enter your account number: ");
			fgets(input, sizeof(input), stdin);
			if(input[0] == '0') return 0;
			if(input[0] == 'x') return 0;
			acct_in = atoi(input);
			
			printf("Please enter your PIN: ");
			fgets(input, sizeof(input), stdin);
			if(input[0] == '0') return 0;
			if(input[0] == 'x') return 0;
			pin_in = atoi(input);
			
			// validate the account and PIN against the bank data
			my_acct = validate_account(accounts, acct_in, pin_in);
			if (my_acct == NULL) {
				printf("Invalid account or PIN.\n");
				printf("Please try again.\n");
			} else {
				input[0] = '\0';	// Set for the first time through
				for (; keep_going;) {	// transaction loop
					system("cls");		// Windows clear screen command
					printf("Welcome %s %s!\n\n",
						my_acct->first_name, my_acct->last_name);
					printf("Please choose from the following options:\n\n");
					printf("\tB - Balance\n");
					printf("\tD - Deposit\n");
					printf("\tW - Withdraw\n");
					printf("\tE - Exit\n\n");
					switch(input[0]) {
					case '\0':	// This handles the first time through
							break;
					case 'B':
					case 'b':	// Balance Logic
							printf("Your balance is $%.2f\n",
								my_acct->balance);
							break;
					case 'D':
					case 'd':	// Deposit logic
							printf("Amount: $");
							fgets(input, sizeof(input), stdin);
							fields = sscanf(input, "%f", &amount);
							if (fields <= 0)
								printf("Error: Non-numeric amount\n");
							else if (amount < 0)
										printf("Error: Can NOT transact negative numbers.\n");
							else if (amount > 100000)
										printf("Error: Can not transact more than $100,000.\n");
							else {
										my_acct->balance += amount;
										printf("Your new balance is $%.2f\n",
											my_acct->balance);
							}
							break;
					case 'W':
					case 'w':	// Withdraw logic
							printf("Amount: $");
							fgets(input, sizeof(input), stdin);
							fields = sscanf(input, "%f", &amount);
							if (fields <= 0)
								printf("Error: Non-numeric amount\n");
							else if (amount < 0)
										printf("Error: Can NOT transact negative numbers.\n");
							else if (amount > 100000)
										printf("Error: Can not transact more than $100,000.\n");
							else if (amount > my_acct->balance)
										printf("Error: Insufficient funds.\n");
							else {
										my_acct->balance -= amount;
										printf("Your new balance is $%.2f\n\n",
											my_acct->balance);
							}
							break;
					case 'E':
					case 'e':
					case 'X':
					case 'x':	// Exit logic
							printf("Thank you for using the ATM machine.\n\n");
							// terminate the transaction and account loops
							keep_going = 0;
							error = save_account_data(accounts);
							if (error >= 1) {
								printf("Can not save the database file.\n");
								return 1;
							}
							// This is 2000 milliseconds, not seconds
							sleep(2000);	// Wait for the user to see the previous message
							break;
					default:
							printf("Unknown command %c", input[0]);
					}	// switch
					if (keep_going) {	// Don't ask for input for exit
					printf("\nPlease enter your transaction: ");
					fgets(input, sizeof(input), stdin);
					}
				}	// Transaction loop
			}	// If-else
		}  // Account loop
	}	// Person loop
}	// Main

/*
 * Read in the accounts.data file into a structure
 * which is passed in as an argument.
 */
int
load_account_data(struct account *acct)
{
	// Define local variables
	int		fields;
	FILE	*file_in;
	
	// Open the data file
	file_in = fopen("accounts.data", "r");
	if (file_in == NULL) return 1;

	// loop through all the records
	for (;; acct++) {
		// Read one record into variables
		fields = fscanf(file_in, "%s %s %d %d %f", 
			acct->last_name, acct->first_name, 
			&acct->acct_number, &acct->pin,
			&acct->balance);
		// If End Of File, break out of loop
		if (fields == EOF) break;
		// check for non processed fields
		if (fields < 5) return 2;
		// check for garbage numbers
		// || = logical OR
		if (acct->acct_number <= 0 ||
			acct->pin <= 0 ||
			acct->balance <= 0) return 3;
		// check for garbage names
		if (strlen(acct->last_name) == 0 ||
			strlen(acct->first_name) == 0) return 4;
	}
	// Mark end of data
	acct->pin = 0;
	// Close the data file
	fclose(file_in);
	// Return to the calling function
	return 0;
}

/*
 * Save all the data in the account structure
 * which is passed in as an argument.
 */
int
save_account_data(struct account *acct)
{
	FILE	*file_in;
	
	// Open the data file
	file_in = fopen("accounts.data", "w");
	if (file_in == NULL) return 1;

	// loop through all the records
	for (; acct->pin; acct++) {
		// Read one record into variables
		fprintf(file_in, "%s %s %d %d %6.2f\n", 
			acct->last_name, acct->first_name, 
			acct->acct_number, acct->pin,
			acct->balance);
	}
	// Close the data file
	fclose(file_in);
	// Return to the calling function
	return 0;
}

/* 
 * Check each member of the bank data to see if the acct and PIN match
 * Return the structure address for a match
 * Return NULL for no match
 */
struct account *
validate_account(struct account *acct, int acct_in, int pin_in)
{
	// loop through all the records
	for (; acct->pin; acct++) {
		if (acct->acct_number == acct_in &&
			acct->pin == pin_in) return(acct);
	}
	return(NULL);
}