//CipherStreamJava/src/main/java/com/mattrixwv/CipherStreamJava/monoSubstitution/BaseX.java
//Mattrixwv
// Created: 01-08-22
//Modified: 07-09-22
package com.mattrixwv.cipherstream.monosubstitution;


import java.util.StringJoiner;

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

import com.mattrixwv.cipherstream.exceptions.InvalidCharacterException;
import com.mattrixwv.cipherstream.exceptions.InvalidInputException;
import com.mattrixwv.cipherstream.exceptions.InvalidBaseException;


public class BaseX{
	private static final Logger logger = LoggerFactory.getLogger(BaseX.class);

	private String inputString;		//The string that needs encoded/decoded
	private String outputString;	//The encoded/decoded string
	private int base;	//The base that the number will be encoded at

	//Sets the input string
	private void setInputStringEncode(String inputString) throws InvalidInputException{
		if(inputString == null){
			throw new NullPointerException("Input cannot be null");
		}

		logger.debug("Setting input string for encoding '{}'", inputString);

		this.inputString = inputString;

		if(this.inputString.isBlank()){
			throw new InvalidInputException("Input must contain at least 1 letter");
		}
	}
	private void setInputStringDecode(String inputString) throws InvalidCharacterException, InvalidInputException{
		if(inputString == null){
			throw new NullPointerException("Input cannot be null");
		}

		logger.debug("Setting input string for decoding '{}'", inputString);

		//Create a string of valid 'numbers'
		logger.debug("Creating string of valid 'numbers'");
		StringBuilder validNumbers = new StringBuilder();
		for(int cnt = 0;cnt < base;++cnt){
			String number = Integer.toString(cnt, base).toUpperCase();
			logger.debug("Current number {}, converted {}", cnt, number);
			validNumbers.append(number);
		}

		//Remove all invalid characters
		logger.debug("Checking for invalid characters");
		this.inputString = inputString.replaceAll("[^" + validNumbers.toString() + "\\s]", "");
		//Throw an exception if there were any invalid characters
		if(!this.inputString.equals(inputString)){
			throw new InvalidCharacterException("inputString cannot contain anything except numbers 0-" + Integer.toString(base - 1, base) + ", and whitespace");
		}

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

		if(this.inputString.isBlank()){
			throw new InvalidInputException("Input must contain at least 1 letter");
		}
	}
	//Sets the numeric base
	private void setBase(int base) throws InvalidBaseException{
		if(base <= 0){
			throw new InvalidBaseException("Base cannot be a negative number");
		}

		logger.debug("Setting base {}", base);

		this.base = base;
	}
	//Encode inputString, store it in outputString, and return it
	private String encode(){
		logger.debug("Encoding");

		//Encode every character in inputString
		StringJoiner output = new StringJoiner(" ");
		for(int cnt = 0;cnt < inputString.length();++cnt){
			//Get the next character
			char ch = inputString.charAt(cnt);
			logger.debug("Working number {}", ch);

			//Encode the character to binary and add it to the output
			String convertedNum = Integer.toString(ch, base);
			output.add(convertedNum);
			logger.debug("Converted number {}", convertedNum);
		}

		//Save the output
		outputString = output.toString().toUpperCase();
		logger.debug("Saving output string '{}'", outputString);

		//Return the output
		return outputString;
	}
	//Decode inputString, store it in outputString, and return it
	private String decode() throws InvalidCharacterException{
		logger.debug("Decoding");

		//Decode every binary number in the string
		StringBuilder output = new StringBuilder();
		for(String baseXString : inputString.split(" ")){
			logger.debug("Current number {}", baseXString);

			//Decode the current binary number
			int num = Integer.valueOf(baseXString, base);
			logger.debug("Decoded number {}", num);

			//Make sure it is in a valid range
			if((num < 0) && (num > 255)){
				throw new InvalidCharacterException("The base" + base + " string '" + baseXString + "' is not a valid character");
			}

			//Convert the int to a char and save it
			output.append((char)num);
		}

		//Save the output
		logger.debug("Saving output string '{}'", output);
		outputString = output.toString();

		//Return the output
		return outputString;
	}

	//Constructor
	public BaseX() throws InvalidBaseException{
		reset();
		setBase(2);
	}
	public BaseX(int base) throws InvalidBaseException{
		reset();
		setBase(base);
	}
	//Returns the inputString
	public String getInputString(){
		return inputString;
	}
	//Returns the outputString
	public String getOutputString(){
		return outputString;
	}
	//Returns the base
	public int getBase(){
		return base;
	}
	//Sets the inputString and encodes the message
	public String encode(String inputString) throws InvalidInputException{
		reset();
		setInputStringEncode(inputString);
		return encode();
	}
	public String encode(int base, String inputString) throws InvalidBaseException, InvalidInputException{
		reset();
		setBase(base);
		setInputStringEncode(inputString);
		return encode();
	}
	//Sets the inputString and decodes the message
	public String decode(String inputString) throws InvalidCharacterException, InvalidInputException{
		reset();
		setInputStringDecode(inputString);
		return decode();
	}
	public String decode(int base, String inputString) throws InvalidBaseException, InvalidCharacterException, InvalidInputException{
		reset();
		setBase(base);
		setInputStringDecode(inputString);
		return decode();
	}
	//Makes sure all of the variables are empty
	public void reset(){
		logger.debug("Resetting fields");

		inputString = "";
		outputString = "";
	}
}