//File ISBN Validation System.cpp
//Purpose:
//	Program to identify and validate an ISBN number.

#include <iostream>
#include <iomanip>
using namespace std;

int main()
{
	char one = 0; // variable that is always a number
	char two = 0; // variable that can either be a variable or a hyphen
	char three = 0; // variable that can either be a variable or a hyphen
	char four = 0; // variable that can either be a variable or a hyphen
	char five = 0; // variable that can either be a variable or a hyphen
	char six = 0; // variable that can either be a variable or a hyphen
	char seven = 0; // variable that can either be a variable or a hyphen
	char eight = 0; // variable that can either be a variable or a hyphen
	char nine = 0; // variable that can either be a variable or a hyphen
	char ten = 0; // variable that can either be a variable or a hyphen
	char eleven = 0; // variable that can either be a variable or a hyphen
	char twelve = 0; // variable that is always a hyphen
	char thirteen = 0; // variable that is always a number
	int sum = 0; // sum of the first nine characters
	int remainder = 0; // remainder variable used to check validation
	
	cout << "                 ISBN Validation System"<< endl << endl;
	cout << "Enter ISBN number: "; // Where the ISBN number is entered
	cin >> one >> two >> three >> four >> five >> six >> seven >> eight >> nine >> ten >> eleven >> twelve >> thirteen; // Where character variables will get their value 

	switch (one) // corrects if invalid character is entered for each variable
	{
	case '0':
		one = '0';
		break;
	case '1':
		one = 1;
		break;
	case '2':
		one = '2';
		break;
	case '3':
		one = '3';
		break;
	case '4':
		one = '4';
		break;
	case '5':
		one = '5';
		break;
	case '6':
		one = '6';
		break;
	case '7':
		one = '7';
		break;
	case '8':
		one = '8';
		break;
	case '9':
		one = '9';
		break;
	default:
		cout << "Wrong character entered for first number, please try again" << endl;
	}
	switch (two)
	{
	case '0':
		two = '0';
		break;
	case '1':
		two = '1';
		break;
	case '2':
		two = '2';
		break;
	case '3':
		two = '3';
		break;
	case '4':
		two = '4';
		break;
	case '5':
		two = '5';
		break;
	case '6':
		two = '6';
		break;
	case '7':
		two = '7';
		break;
	case '8':
		two = '8';
		break;
	case '9':
		two = '9';
		break;
	case '-':
		two = '-';
		break;
	default:
		cout << "Wrong character entered for second number, please try again" << endl;
	}
	switch (three)
	{
	case '0':
		three = '0';
		break;
	case '1':
		three = '1';
		break;
	case '2':
		three = '2';
		break;
	case '3':
		three = '3';
		break;
	case '4':
		three = '4';
		break;
	case '5':
		three = '5';
		break;
	case '6':
		three = '6';
		break;
	case '7':
		three = '7';
		break;
	case '8':
		three = '8';
		break;
	case '9':
		three = '9';
		break;
	case '-':
		three = '-';
		break;
	default:
		cout << "Wrong character entered for third number, please try again" << endl;
	}
	switch (four)
	{
	case '0':
		four = '0';
		break;
	case '1':
		four = '1';
		break;
	case '2':
		four = '2';
		break;
	case '3':
		four = '3';
		break;
	case '4':
		four = '4';
		break;
	case '5':
		four = '5';
		break;
	case '6':
		four = '6';
		break;
	case '7':
		four = '7';
		break;
	case '8':
		four = '8';
		break;
	case '9':
		four = '9';
		break;
	case '-':
		four = '-';
		break;
	default:
		cout << "Wrong character entered for fourth number, please try again" << endl;
	}
	switch (five)
	{
	case '0':
		five = '0';
		break;
	case '1':
		five = '1';
		break;
	case '2':
		five = '2';
		break;
	case '3':
		five = '3';
		break;
	case '4':
		five = '4';
		break;
	case '5':
		five = '5';
		break;
	case '6':
		five = '6';
		break;
	case '7':
		five = '7';
		break;
	case '8':
		five = '8';
		break;
	case '9':
		five = '9';
		break;
	case '-':
		five = '-';
		break;
	default:
		cout << "Wrong character entered for fifth number, please try again" << endl;
	}
	switch (six)
	{
	case '0':
		six = '0';
		break;
	case '1':
		six = '1';
		break;
	case '2':
		six = '2';
		break;
	case '3':
		six = '3';
		break;
	case '4':
		six = '4';
		break;
	case '5':
		six = '5';
		break;
	case '6':
		six = '6';
		break;
	case '7':
		six = '7';
		break;
	case '8':
		six = '8';
		break;
	case '9':
		six = '9';
		break;
	case '-':
		six = '-';
		break;
	default:
		cout << "Wrong character entered for sixth number, please try again" << endl;
	}
	switch (seven)
	{
	case '0':
		seven = '0';
		break;
	case '1':
		seven = '1';
		break;
	case '2':
		seven = '2';
		break;
	case '3':
		seven = '3';
		break;
	case '4':
		seven = '4';
		break;
	case '5':
		seven = '5';
		break;
	case '6':
		seven = '6';
		break;
	case '7':
		seven = '7';
		break;
	case '8':
		seven = '8';
		break;
	case '9':
		seven = '9';
		break;
	case '-':
		seven = '-';
		break;
	default:
		cout << "Wrong character entered for seventh number, please try again" << endl;
	}
	switch (eight)
	{
	case '0':
		eight = '0';
		break;
	case '1':
		eight = '1';
		break;
	case '2':
		eight = '2';
		break;
	case '3':
		eight = '3';
		break;
	case '4':
		eight = '4';
		break;
	case '5':
		eight = '5';
		break;
	case '6':
		eight = '6';
		break;
	case '7':
		eight = '7';
		break;
	case '8':
		eight = '8';
		break;
	case '9':
		eight = '9';
		break;
	case '-':
		eight = '-';
		break;
	default:
		cout << "Wrong character entered for eighth number, please try again" << endl;
	}
	switch (nine)
	{
	case '0':
		nine = '0';
		break;
	case '1':
		nine = '1';
		break;
	case '2':
		nine = '2';
		break;
	case '3':
		nine = '3';
		break;
	case '4':
		nine = '4';
		break;
	case '5':
		nine = '5';
		break;
	case '6':
		nine = '6';
		break;
	case '7':
		nine = '7';
		break;
	case '8':
		nine = '8';
		break;
	case '9':
		nine = '9';
		break;
	case '-':
		nine = '-';
		break;
	default:
		cout << "Wrong character entered for ninth number, please try again" << endl;
	}
	switch (ten)
	{
	case '0':
		ten = '0';
		break;
	case '1':
		ten = '1';
		break;
	case '2':
		ten = '2';
		break;
	case '3':
		ten = '3';
		break;
	case '4':
		ten = '4';
		break;
	case '5':
		ten = '5';
		break;
	case '6':
		ten = '6';
		break;
	case '7':
		ten = '7';
		break;
	case '8':
		ten = '8';
		break;
	case '9':
		ten = '9';
		break;
	case '-':
		ten = '-';
		break;
	default:
		cout << "Wrong character entered for tenth number, please try again" << endl;
	}
	switch (eleven)
	{
	case '0':
		eleven = '0';
		break;
	case '1':
		eleven = '1';
		break;
	case '2':
		eleven = '2';
		break;
	case '3':
		eleven = '3';
		break;
	case '4':
		eleven = '4';
		break;
	case '5':
		eleven = '5';
		break;
	case '6':
		eleven = '6';
		break;
	case '7':
		eleven = '7';
		break;
	case '8':
		eleven = '8';
		break;
	case '9':
		eleven = '9';
		break;
	case '-':
		eleven = '-';
		break;
	default:
		cout << "Wrong character entered for tenth number, please try again" << endl;
	}
	switch (eleven)
	{
	case '0':
		eleven = '0';
		break;
	case '1':
		eleven = '1';
		break;
	case '2':
		eleven = '2';
		break;
	case '3':
		eleven = '3';
		break;
	case '4':
		eleven = '4';
		break;
	case '5':
		eleven = '5';
		break;
	case '6':
		eleven = '6';
		break;
	case '7':
		eleven = '7';
		break;
	case '8':
		eleven = '8';
		break;
	case '9':
		eleven = '9';
		break;
	default:
		cout << "Wrong character entered for eleventh number, please try again" << endl;
	}
	switch (twelve)
	{
	case '-':
		twelve = '-';
		break;
	default:
		cout << "Wrong character entered for twelvth number, please try again" << endl;
	}
	switch (thirteen)
	{
	case '0':
		thirteen = '0';
		break;
	case '1':
		thirteen = '1';
		break;
	case '2':
		thirteen = '2';
		break;
	case '3':
		thirteen = '3';
		break;
	case '4':
		thirteen = '4';
		break;
	case '5':
		thirteen = '5';
		break;
	case '6':
		thirteen = '6';
		break;
	case '7':
		thirteen = '7';
		break;
	case '8':
		thirteen = '8';
		break;
	case '9':
		thirteen = '9';
		break;
	default:
		cout << "Wrong character entered for thirteenth number, please try again" << endl;
	} // corrects if invalid character is entered 
	if(two != '-'){ // picks which equation to use
		if(three != '-'){
			if(four != '-'){
				if(five != '-'){
					if(six != '-'){
						if(seven != '-'){
							sum = (one + 2*two + 3*three + 4*four + 5*five + 6*six + 7*seven + 8*nine + 9*eleven - 2160);}
	
						else if(nine != '-'){
							sum = (one + 2*two + 3*three + 4*four + 5*five + 6*six + 7*eight + 8*nine + 9*eleven - 2160);}
							else 
								sum = (one + 2*two + 3*three + 4*four + 5*five + 6*six + 7*eight + 8*ten + 9*eleven - 2160);
						}
					else if(eight != '-'){
							if(nine != '-'){
								sum = (one + 2*two + 3*three + 4*four + 5*five + 6*seven + 7*eight + 8*nine + 9*eleven - 2160);}
							else
								sum = (one + 2*two + 3*three + 4*four + 5*five + 6*seven + 7*eight + 8*ten + 9*eleven - 2160);}
						else
							sum = (one + 2*two + 3*three + 4*four + 5*five + 6*seven + 7*nine + 8*ten + 9*eleven - 2160);
					}
				else if(seven != '-'){
						if(eight != '-'){
							if(nine != '-'){
								sum = (one + 2*two + 3*three + 4*four + 5*six + 6*seven + 7*eight + 8*nine + 9*eleven - 2160);}
							else 
								sum = (one + 2*two + 3*three + 4*four + 5*six + 6*seven + 7*eight + 8*ten + 9*eleven - 2160);}
						else
							sum = (one + 2*two + 3*three + 4*four + 5*six + 6*seven + 7*nine + 8*ten + 9*eleven - 2160);}
					else
						sum = (one + 2*two + 3*three + 4*four + 5*six + 6*eight + 7*nine + 8*ten + 9*eleven - 2160);
				}
			else if(six != '-'){
					if(seven != '-'){
						if(eight != '-'){
							if(nine != '-'){
								sum = (one + 2*two + 3*three + 4*five + 5*six + 6*seven + 7*eight + 8*nine + 9*eleven - 2160);}
							else 
								sum = (one + 2*two + 3*three + 4*five + 5*six + 6*seven + 7*eight + 8*ten + 9*eleven - 2160);}
						else
							sum = (one + 2*two + 3*three + 4*five + 5*six + 6*seven + 7*nine + 8*ten + 9*eleven - 2160);}
					else
						sum = (one + 2*two + 3*three + 4*five + 5*six + 6*eight + 7*nine + 8*ten + 9*eleven - 2160);}
				else
					sum = (one + 2*two + 3*three + 4*five + 5*seven + 6*eight + 7*nine + 8*ten + 9*eleven - 2160);
			}
		else if(five != '-'){
				if(six != '-'){
					if(seven != '-'){
						if(eight != '-'){
							if(nine != '-'){
								sum = (one + 2*two + 3*four + 4*five + 5*six + 6*seven + 7*eight + 8*nine + 9*eleven - 2160);}
							else
								sum = (one + 2*two + 3*four + 4*five + 5*six + 6*seven + 7*eight + 8*ten + 9*eleven - 2160);}
						else 
							sum = (one + 2*two + 3*four + 4*five + 5*six + 6*seven + 7*nine + 8*ten + 9*eleven - 2160);}
					else
						sum = (one + 2*two + 3*four + 4*five + 5*six + 6*eight + 7*nine + 8*ten + 9*eleven - 2160);}
				else 
					sum = (one + 2*two + 3*four + 4*five + 5*seven + 6*eight + 7*nine + 8*ten + 9*eleven - 2160);}
			else 
				sum = (one + 2*two + 3*four + 4*six + 5*seven + 6*eight + 7*nine + 8*ten + 9*eleven - 2160);
		}
	else if(four != '-'){
			if(five != '-'){
				if(six != '-'){
					if(seven != '-'){
						if(eight != '-'){
							if(nine != '-'){
								sum = (one + 2*three + 3*four + 4*five + 5*six + 6*seven + 7*eight + 8*nine + 9*eleven - 2160);}
							else 
								sum = (one + 2*three + 3*four + 4*five + 5*six + 6*seven + 7*eight + 8*ten + 9*eleven - 2160);}
						else 
							sum = (one + 2*three + 3*four + 4*five + 5*six + 6*seven + 7*nine + 8*ten + 9*eleven - 2160);}
					else 
						sum = (one + 2*three + 3*four + 4*five + 5*six + 6*eight + 7*nine + 8*ten + 9*eleven - 2160);}
				else 
					sum = (one + 2*three + 3*four + 4*five + 5*seven + 6*eight + 7*nine + 8*ten + 9*eleven - 2160);}
			else 
				sum = (one + 2*three + 3*four + 4*six + 5*seven + 6*eight + 7*nine + 8*ten + 9*eleven - 2160);}
		else 
			sum = (one + 2*three + 3*five + 4*six + 5*seven + 6*eight + 7*nine + 8*ten + 9*eleven - 2160);
	
		
	remainder = (sum%11) + 48; // finds the remainder of the sum

	if(thirteen == remainder) // validates ISBN number by thirteenth character
		cout << endl << "The ISBN number, " << one << two << three << four << five << six << seven << eight << nine << ten << eleven <<twelve << thirteen << " is VALID." << endl << endl; // If ISBN number is valid
	else 
		cout << endl << "The ISBN number, " << one << two << three << four << five << six << seven << eight << nine << ten << eleven << twelve << thirteen << " is INVALID. Check digit is invalid" << endl << endl; // if ISBN number is invalid
	
return 0; // end program

}