//CipherStreamJava/src/main/java/com/mattrixwv/CipherStreamJava/monoSubstitution/Caesar.java
//Matthew Ellison
// Created: 07-25-21
//Modified: 04-16-23
package com.mattrixwv.cipherstream.monosubstitution;


import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.mattrixwv.cipherstream.exceptions.InvalidInputException;


public class Caesar{
	protected static Logger logger = LoggerFactory.getLogger(Caesar.class);

	//Fields
	protected String inputString;	//The string that needs encoded/decoded
	protected String outputString;	//The encoded/decoded string
	protected int shift;	//The amount that you need to shift each letter
	protected boolean preserveCapitals;	//Whether to respect capitals in the output string
	protected boolean preserveWhitespace;	//Whether to respect whitespace in the output string
	protected boolean preserveSymbols;	//Whether to respect symbols in the output string

	//Sets shift and makes sure it is within the propper bounds
	protected void setShift(int shiftAmount){
		logger.debug("Setting shift {}", shiftAmount);

		//If you shift more than 26 you will just be wrapping back around again
		shift = shiftAmount % 26;

		logger.debug("Cleaned shift {}", shift);
	}
	//Sets the input string
	protected void setInputString(String inputString) throws InvalidInputException{
		if(inputString == null){
			throw new InvalidInputException("Input cannot be null");
		}

		logger.debug("Original input string '{}'", inputString);

		if(!preserveCapitals){
			logger.debug("Removing case");

			inputString = inputString.toLowerCase();
		}
		if(!preserveWhitespace){
			logger.debug("Removing whitespace");

			inputString = inputString.replaceAll("\\s", "");
		}
		if(!preserveSymbols){
			logger.debug("Removing symbols");

			inputString = inputString.replaceAll("[^a-zA-Z\\s]", "");
		}

		logger.debug("Cleaned input string '{}'", inputString);
		this.inputString = inputString;

		if(this.inputString.isBlank()){
			throw new InvalidInputException("Input must contain at least 1 letter");
		}
	}
	//Encodes the inputString and stores the result in outputString
	protected String encode(){
		logger.debug("Encoding");

		StringBuilder output = new StringBuilder();
		for(int cnt = 0;cnt < inputString.length();++cnt){
			char currentChar = inputString.charAt(cnt);	//A temperary holder for the current working character
			logger.debug("Working character {}", currentChar);

			//If it is an upper case letter shift it and wrap if necessary
			if(Character.isUpperCase(currentChar)){
				logger.debug("Encoding uppercase");

				currentChar += shift;
				//Wrap around if the letter is now out of bounds
				if(currentChar < 'A'){
					logger.debug("Wrapping around to Z");
					currentChar += 26;
				}
				else if(currentChar > 'Z'){
					logger.debug("Wrapping around to A");
					currentChar -= 26;
				}
			}
			//If it is a lower case letter shift it and wrap if necessary
			else if(Character.isLowerCase(currentChar)){
				logger.debug("Encoding lowercase");

				currentChar += shift;
				//Wrap around if the letter is now out of bounds
				if(currentChar < 'a'){
					logger.debug("Wrapping around to z");
					currentChar += 26;
				}
				else if(currentChar > 'z'){
					logger.debug("Wrapping around to a");
					currentChar -= 26;
				}
			}
			//If it is whitespace, number, or punctuation just let it pass through
			//Add it to the output string
			logger.debug("Encoded character {}", currentChar);
			output.append(currentChar);
		}

		outputString = output.toString();
		logger.debug("Saving encoded string '{}'", outputString);
		return outputString;
	}
	//Decodes the inputString and stores the result in outputString
	protected String decode(){
		logger.debug("Decoding");

		StringBuilder output = new StringBuilder();
		for(int cnt = 0;cnt < inputString.length();++cnt){
			char currentChar = inputString.charAt(cnt);	//A temperary holder for the current working character
			logger.debug("Working character {}", currentChar);

			//If it is an upper case letter shift it and wrap if necessary
			if(Character.isUpperCase(currentChar)){
				logger.debug("Decoding uppercase");

				currentChar -= shift;
				//Wrap around if the letter is now out of bounds
				if(currentChar < 'A'){
					logger.debug("Wrapping around to Z");

					currentChar += 26;
				}
				else if(currentChar > 'Z'){
					logger.debug("Wrapping around to A");

					currentChar -= 26;
				}
			}
			//If it is a lower case letter shift it and wrap if necessary
			else if(Character.isLowerCase(currentChar)){
				logger.debug("Decoding lowercase");

				currentChar -= shift;
				//Wrap around if the letter is now out of bounds
				if(currentChar < 'a'){
					logger.debug("Wrapping around to z");

					currentChar += 26;
				}
				else if(currentChar > 'z'){
					logger.debug("Wrapping around to a");

					currentChar -= 26;
				}
			}
			//If it is whitespace, number, or punctuation just let it pass through
			//Add it to the output string
			logger.debug("Decoded character {}", currentChar);
			output.append(currentChar);
		}

		outputString = output.toString();
		logger.debug("Saving decoded string '{}'", outputString);
		return outputString;
	}

	//Constructor
	public Caesar(){
		reset();
		preserveCapitals = false;
		preserveWhitespace = false;
		preserveSymbols = false;
	}
	public Caesar(boolean preserveCapitals, boolean preserveWhitespace, boolean preserveSymbols){
		reset();
		this.preserveCapitals = preserveCapitals;
		this.preserveWhitespace = preserveWhitespace;
		this.preserveSymbols = preserveSymbols;
	}

	//Sets the shift and inputString and encodes the message
	public String encode(int shiftAmount, String inputString) throws InvalidInputException{
		reset();
		setShift(shiftAmount);
		setInputString(inputString);
		return encode();
	}
	//Sets the shift and inputString and decodes the message
	public String decode(int shiftAmount, String inputString) throws InvalidInputException{
		reset();
		setShift(shiftAmount);
		setInputString(inputString);
		return decode();
	}

	//Returns the inputString
	public String getInputString(){
		return inputString;
	}
	//Returns shift
	public int getShift(){
		return shift;
	}
	//Returns the outputString
	public String getOutputString(){
		return outputString;
	}
	//Makes sure all of the variables are empty
	public void reset(){
		logger.debug("Resetting fields");

		inputString = "";
		outputString = "";
		shift = 0;
	}
}