/************************************************************************************************************************************************************************
* Encoder/Decoder
* Charles Wood-Henderson
* To encrypt strings and decrypt them.
* Acknowledgements: none
************************************************************************************************************************************************************************/

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

/***********************************************************************************************************************************************************************
* cipher()
* none
* class
* To encode/decode strings.
************************************************************************************************************************************************************************/
class cipher {
private:
	string line;
	int shift_key;
	bool encoder;
public:
	cipher() : shift_key(0)
	{    }
	void get_shift_key();
	void print();
	void encode();
	void decode();
};

/***********************************************************************************************************************************************************************
* main()
* none
* int
* Required to run the program.
***********************************************************************************************************************************************************************/

int main() {
	cipher cipher1;  // creating a class
	string do_what; // creating a string to see what the user wants to do
	bool repeat = true;
	while(repeat == true) {
		cout << "Welcome to the Caesar Encoder/Decoder!\n" << "Would you like to encode or decode or quit? ";
		cin >> do_what;
		if(do_what == "encode") {
			cipher1.encode(); // seeing what the user wants to do
		}
		else if(do_what == "decode") {
			cipher1.decode(); // seeing what the user wants to do
		}
		else if(do_what == "quit") { // seeing what the user wants to do
			return 0;
		}
	}
}

void cipher::encode() {
	encoder = true;
	bool uppercase = false;
	cout << "Please enter a string that you would like to encode: \n(Please end your string with a ~ symbol and then press the enter key)\n";
	getline(cin, line, '~');
	get_shift_key();
	int length = line.length();
	for(int j = 0; j < length; j++) {
		if(line[j] >= 'A' && line[j] <= 'Z' || line[j] >= 'a' && line[j] <= 'z') {
			if(line[j] < 'a')
				uppercase = true;
			else
				uppercase = false;
			line.at(j) = line.at(j) + shift_key; // shifting the letter how many places the user asked for
			if(line.at(j) > 'z' && uppercase == false) { 
				int k = line.at(j) - 'z'; // checking if the places shifted goes over z when its lowercase
				line.at(j) = 'a' + k - 1;
			}
			if(line.at(j) > 'Z' && uppercase == true) {
				int k = line.at(j) - 'Z'; // checking if the places shifted goes over Z when its uppercase
				line.at(j) = 'A' + k - 1;
			}
		}
	}
	print();
	cout << endl;
}

void cipher::decode() {
	encoder = false;
	bool uppercase = false;
	cout << "Please enter a string that you would like to encode: \n(Please end your string with a ~ symbol and then press the enter key)\n";
	getline(cin, line, '~');
	get_shift_key();
	int length = line.length();
	for(int j = 0; j < length; j++) {
		if(line[j] >= 'A' && line[j] <= 'Z' || line[j] >= 'a' && line[j] <= 'z') {
			if(line.at(j) < 'a')
				uppercase = true;
			else					// checking if the letter is uppercase or lowercase
				uppercase = false;
			line.at(j) = line.at(j) - shift_key;
			if(line.at(j) < 'a' && uppercase == false) {
				int k = 'a' - line.at(j); //	checking that the places needed to go backwards goes less than a in lowercase
				line.at(j) = 'z' - k + 1;
			}
			if(line.at(j) < 'A' && uppercase == true) {
				int k = 'A' - line.at(j);//		checking that the places needed to go backwards goes less than a in uppercase
				line.at(j) = 'Z' - k + 1;
			}
		}
	}
	print();
}

void cipher::print() {
	if(encoder == true) 
		cout << "Your encoded string is: " << line << endl;
	else
		cout << "Your decoded string is: " << line << endl;
}

void cipher::get_shift_key() {
	cout << "What integer cipher shift key will you use? (1-20) ";
	cin >> shift_key;
}