//CipherStreamJava/src/main/java/com/mattrixwv/cipherstream/polysubstitution/LargePolybiusSquare.java
//Mattrixwv
// Created: 04-21-23
// Modified: 08-11-24
/*
	Copyright (C) 2024  Mattrixwv

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Lesser General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/
package com.mattrixwv.cipherstream.polysubstitution;


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.InvalidKeywordException;


/**
 * Represents the Polybius square cipher encryption and decryption.
 * The Polybius square cipher is a classical encryption method that uses a 6x6 grid
 * to encode and decode messages based on the positions of letters and numbers in the grid.
 */
public final class LargePolybiusSquare extends PolybiusSquare{
	private static final Logger logger = LoggerFactory.getLogger(LargePolybiusSquare.class);


	/**
	 * Creates the grid from the keyword.
	 */
	@Override
	protected void createGrid(){
		logger.debug("Creating grid");

		for(int row = 0;row < 6;++row){
			for(int col = 0;col < 6;++col){
				char letter = keyword.charAt((6 * row) + col);
				grid[row][col] = letter;
			}
		}
	}
	/**
	 * Strips invalid characters from the string that needs encoding/decoding.
	 *
	 * @param inputString the input string to be cleaned
	 * @throws InvalidCharacterException if an invalid character is found
	 * @throws InvalidInputException if the input string is invalid
	 */
	@Override
	protected void setInputStringEncode(String inputString) throws InvalidCharacterException, InvalidInputException{
		if(inputString == null){
			throw new InvalidInputException("Input cannot be null");
		}

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

		//Change to upper case
		inputString = inputString.toUpperCase();

		//Remove any whitespace if selected
		if(!preserveWhitespace){
			logger.debug("Removing whitespace");

			inputString = inputString.replaceAll("\\s", "");
		}

		//Remove any symbols if selected
		if(!preserveSymbols){
			logger.debug("Removing symbols");

			inputString = inputString.replaceAll("[^a-zA-Z0-9\\s]", "");
		}

		if(!preserveWhitespace && !preserveSymbols){
			//Add whitespace after every character for the default look
			StringJoiner spacedString = new StringJoiner(" ");
			for(int cnt = 0;cnt < inputString.length();++cnt){
				spacedString.add(Character.toString(inputString.charAt(cnt)));
			}
			inputString = spacedString.toString();
		}

		//Save the string
		this.inputString = inputString;

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

		if(this.inputString.isBlank() || getPreparedInputStringEncode().isBlank()){
			throw new InvalidInputException("Input must contain at least 1 letter");
		}
	}
	/**
	 * Returns the input string ready for encoding.
	 *
	 * @return the prepared input string
	 */
	@Override
	protected String getPreparedInputStringEncode(){
		logger.debug("Preparing input string for encoding");

		String cleanString = inputString.toUpperCase();
		cleanString = cleanString.replaceAll("[^A-Z0-9]", "");

		logger.debug("Prepared input string '{}'", cleanString);

		return cleanString;
	}
	/**
	 * Strips invalid characters from the keyword and creates the grid.
	 *
	 * @param keyword the keyword to be processed
	 */
	@Override
	protected void setKeyword(String keyword) throws InvalidKeywordException{
		if(keyword == null){
			throw new InvalidKeywordException("Keyword cannot be null");
		}

		logger.debug("Original keyword '{}'", keyword);

		//Change everything to uppercase
		keyword = keyword.toUpperCase();

		//Remove everything except capital letters and numbers
		keyword = keyword.replaceAll("[^A-Z0-9]", "");

		//Add all letters in the alphabet to the key
		keyword += "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

		//Remove all duplicate characters
		StringBuilder uniqueKey = new StringBuilder();
		keyword.chars().distinct().forEach(c -> uniqueKey.append((char)c));
		keyword = uniqueKey.toString();

		logger.debug("Cleaned keyword '{}'", keyword);
		this.keyword = keyword;

		//Create the grid from the sanitized keyword
		createGrid();
	}
	/**
	 * Adds characters that aren't letters to the output during encoding.
	 *
	 * @param cleanString the cleaned string to be formatted
	 */
	@Override
	protected void addCharactersToCleanStringEncode(String cleanString){
		logger.debug("Formatting output string");

		int outputCnt = 0;
		StringBuilder fullOutput = new StringBuilder();
		for(int inputCnt = 0;inputCnt < inputString.length();++inputCnt){
			logger.debug("Current character {}", inputString.charAt(inputCnt));

			//Add both numbers of any letters to the output
			if(Character.isAlphabetic(inputString.charAt(inputCnt)) || Character.isDigit(inputString.charAt(inputCnt))){
				logger.debug("Appending character");

				fullOutput.append(cleanString.charAt(outputCnt++));
				fullOutput.append(cleanString.charAt(outputCnt++));
			}
			//Add any other characters that appear to the output
			else{
				logger.debug("Appending symbol");

				fullOutput.append(inputString.charAt(inputCnt));
			}
		}

		outputString = fullOutput.toString();
		logger.debug("Saving output string {}", outputString);
	}
	/**
	 * Adds characters that aren't letters to the output during decoding.
	 *
	 * @param cleanString the cleaned string to be formatted
	 */
	@Override
	protected void addCharactersToCleanStringDecode(String cleanString){
		logger.debug("Formatting output string");

		int outputCnt = 0;
		StringBuilder fullOutput = new StringBuilder();
		for(int inputCnt = 0;inputCnt < inputString.length();++inputCnt){
			logger.debug("Current character {}", inputString.charAt(inputCnt));

			//Add the letter to the output and skip the second number
			if(Character.isDigit(inputString.charAt(inputCnt)) || Character.isAlphabetic(inputString.charAt(inputCnt))){
				logger.debug("Appending character");

				fullOutput.append(cleanString.charAt(outputCnt++));
				++inputCnt;
			}
			//Add any other characters that appear to the output
			else{
				logger.debug("Appending symbol");

				fullOutput.append(inputString.charAt(inputCnt));
			}
		}

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

	/**
	 * Resets all variables to their default values.
	 */
	@Override
	public void reset(){
		logger.debug("Resetting");

		grid = new char[6][6];
		inputString = "";
		outputString = "";
		keyword = "";
	}

	//?Constructors
	/**
	 * Constructs a PolybiusSquare cipher instance with default settings.
	 *
	 * @throws InvalidCharacterException if default characters are invalid
	 */
	public LargePolybiusSquare() throws InvalidCharacterException{
		super();
		reset();
	}
	/**
	 * Constructs a PolybiusSquare cipher instance with specified settings.
	 *
	 * @param preserveWhitespace whether to preserve whitespace
	 * @param preserveSymbols whether to preserve symbols
	 * @throws InvalidCharacterException if default characters are invalid
	 */
	public LargePolybiusSquare(boolean preserveWhitespace, boolean preserveSymbols) throws InvalidCharacterException{
		super(preserveWhitespace, preserveSymbols);
		reset();
	}
}