package com.mattrixwv.cipherstream.combination;


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;
import com.mattrixwv.cipherstream.polysubstitution.Columnar;
import com.mattrixwv.cipherstream.polysubstitution.PolybiusSquare;


/**
 * Implements the ADFGX cipher, which is a combination of a Polybius square and a columnar transposition cipher.
 * This class provides methods to encode and decode strings using the ADFGX cipher.
 *
 * <p>
 * The cipher involves two main steps:
 * </p>
 * <ol>
 * 	<li>Encoding/decoding with a Polybius square (PolybiusSquare)</li>
 * 	<li>Encoding/decoding with a columnar transposition cipher (Columnar)</li>
 * </ol>
 */
public final class ADFGX{
	private static final Logger logger = LoggerFactory.getLogger(ADFGX.class);

	//?Internal fields
	/** The string that needs encoded/decoded */
	protected String inputString;
	/** The string that is output after encoding/decoding */
	protected String outputString;
	/** The keyword used in the Polybius Square */
	protected String squareKeyword;
	/** The keyword used in the Columnar cipher */
	protected String keyword;
	//?Settings
	/** Persist capitals in the output string */
	protected boolean preserveCapitals;
	/** Persist whitespace in the output string */
	protected boolean preserveWhitespace;
	/** Persist symbols in the output string */
	protected boolean preserveSymbols;
	//?Internal ciphers
	/** The first step in encoding */
	protected PolybiusSquare polybiusSquare;
	/** The second step in encoding */
	protected Columnar columnar;


	/**
	 * Sets the Polybius square keyword and validates it.
	 *
	 * @param squareKeyword the keyword for the Polybius square
	 * @throws InvalidKeywordException if the keyword is null
	 */
	protected void setSquareKeyword(String squareKeyword) throws InvalidKeywordException{
		if(squareKeyword == null){
			throw new InvalidKeywordException("Square keyword cannot be null");
		}

		logger.debug("Square keyword '{}'", squareKeyword);
		this.squareKeyword = squareKeyword;
	}
	/**
	 * Sets the columnar cipher keyword and validates it.
	 *
	 * @param keyword the keyword for the columnar cipher
	 * @throws InvalidKeywordException if the keyword is null
	 */
	protected void setKeyword(String keyword) throws InvalidKeywordException{
		if(keyword == null){
			throw new InvalidKeywordException("Keyword cannot be null");
		}

		logger.debug("Keyword '{}'", keyword);
		this.keyword = keyword;
	}
	/**
	 * Sets and sanitizes the input string according to the preservation settings.
	 *
	 * @param inputString the string to be processed
	 * @throws InvalidInputException if the input string is null or blank after processing
	 */
	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 capitals");

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

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

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

		this.inputString = inputString;

		logger.debug("Cleaned input string '{}'", inputString);
		if(this.inputString.isBlank()){
			throw new InvalidInputException("Input cannot be blank");
		}
	}
	/**
	 * Formats the output string to match the original input string when encoding.
	 */
	protected void formatOutputStringEncode(){
		logger.debug("Formatting output string to match input string");

		StringBuilder output = new StringBuilder();
		int outputLocation = 0;
		for(char ch : inputString.toCharArray()){
			logger.debug("Input character {}", ch);
			if(Character.isUpperCase(ch)){
				logger.debug("Converting output to uppercase");

				output.append(Character.toUpperCase(outputString.charAt(outputLocation++)));
				output.append(Character.toUpperCase(outputString.charAt(outputLocation++)));
			}
			else if(Character.isLowerCase(ch)){
				logger.debug("Converting output to lowercase");

				output.append(Character.toLowerCase(outputString.charAt(outputLocation++)));
				output.append(Character.toLowerCase(outputString.charAt(outputLocation++)));
			}
			else{
				logger.debug("Appending symbol to output");

				output.append(ch);
			}
		}

		outputString = output.toString();
		logger.debug("Saving output string '{}'", outputString);
	}
	/**
	 * Formats the output string to match the original input string when decoding.
	 */
	protected void formatOutputStringDecode(){
		logger.debug("Formatting output string to match input string");
		StringBuilder output = new StringBuilder();
		int outputLocation = 0;
		for(int inputLocation = 0;inputLocation < inputString.length();++inputLocation){
			char ch = inputString.charAt(inputLocation);
			logger.debug("Input character {}", ch);
			if(Character.isUpperCase(ch)){
				logger.debug("Converting output to uppercase");

				output.append(Character.toUpperCase(outputString.charAt(outputLocation++)));
				++inputLocation;
			}
			else if(Character.isLowerCase(ch)){
				logger.debug("Converting output to lowercase");

				output.append(Character.toLowerCase(outputString.charAt(outputLocation++)));
				++inputLocation;
			}
			else{
				logger.debug("Appending symbol to output");

				output.append(ch);
			}
		}

		outputString = output.toString();
		logger.debug("Saving output string '{}'", outputString);
	}
	/**
	 * Encodes the input string using the Polybius square and columnar cipher.
	 *
	 * @throws InvalidCharacterException	if there are invalid characters in the ciphers
	 * @throws InvalidInputException		if the input string is invalid
	 * @throws InvalidKeywordException		if any of the keywords are invalid
	 */
	protected void encode() throws InvalidCharacterException, InvalidInputException, InvalidKeywordException{
		//Encode the input with polybius
		logger.debug("Encoding using Polybius Square");
		String polybiusOutput = polybiusSquare.encode(squareKeyword, inputString);
		squareKeyword = polybiusSquare.getKeyword();
		//Change polybius to use the correct symbols
		logger.debug("Replacing coordinates with letters");
		polybiusOutput = polybiusOutput.replace("1", "A").replace("2", "D").replace("3", "F").replace("4", "G").replace("5", "X");

		//Encode polybius's output with columnar
		logger.debug("Encoding using columnar");
		String columnarOutput = columnar.encode(keyword, polybiusOutput);
		keyword = columnar.getKeyword();
		outputString = columnarOutput;

		//Add whatever is needed to the output string
		formatOutputStringEncode();
	}
	/**
	 * Decodes the input string using the columnar cipher and Polybius square.
	 *
	 * @throws InvalidKeywordException		if any of the keywords are invalid
	 * @throws InvalidCharacterException	if there are invalid characters in the ciphers
	 * @throws InvalidInputException		if the input string is invalid
	 */
	protected void decode() throws InvalidKeywordException, InvalidCharacterException, InvalidInputException{
		//Decode the input with columnar
		logger.debug("Decoding using columnar");
		String columnarOutput = columnar.decode(keyword, inputString);
		keyword = columnar.getKeyword();

		//Change the symbols to the correct ones for polybius
		logger.debug("Replacing letters with coordinates");
		columnarOutput = columnarOutput.replace("A", "1").replace("D", "2").replace("F", "3").replace("G", "4").replace("X", "5");
		//Decode with polybius
		logger.debug("Decoding using Polybius Square");
		String polybiusOutput = polybiusSquare.decode(squareKeyword, columnarOutput);
		squareKeyword = polybiusSquare.getKeyword();
		outputString = polybiusOutput;

		//Add whatever is needed to the output string
		formatOutputStringDecode();
	}


	//?Constructor
	/**
	 * Constructs a new {@code ADFGX} instance with default settings:
	 * capitals, whitespace, and symbols are not preserved.
	 *
	 * @throws InvalidCharacterException if there are invalid characters in the ciphers
	 */
	public ADFGX() throws InvalidCharacterException{
		preserveCapitals = false;
		preserveWhitespace = false;
		preserveSymbols = false;
		reset();
	}
	/**
	 * Constructs a new {@code ADFGX} instance with specified settings for preserving capitals, whitespace, and symbols.
	 *
	 * @param preserveCapitals		whether to preserve capital letters in the output
	 * @param preserveWhitespace	whether to preserve whitespace in the output
	 * @param preserveSymbols		whether to preserve symbols in the output
	 * @throws InvalidCharacterException if there are invalid characters in the ciphers
	 */
	public ADFGX(boolean preserveCapitals, boolean preserveWhitespace, boolean preserveSymbols) throws InvalidCharacterException{
		this.preserveCapitals = preserveCapitals;
		this.preserveWhitespace = preserveWhitespace;
		this.preserveSymbols = preserveSymbols;
		reset();
	}

	/**
	 * Encodes the provided input string using the specified keywords and returns the encoded result.
	 *
	 * @param squareKeyword	the keyword for the Polybius square
	 * @param keyword		the keyword for the columnar cipher
	 * @param inputString	the string to be encoded
	 * @return the encoded string
	 * @throws InvalidKeywordException if any of the keywords are invalid
	 * @throws InvalidInputException   if the input string is invalid
	 * @throws InvalidCharacterException if the input contains invalid characters
	 */
	public String encode(String squareKeyword, String keyword, String inputString) throws InvalidKeywordException, InvalidInputException, InvalidCharacterException{
		setSquareKeyword(squareKeyword);
		setKeyword(keyword);
		setInputString(inputString);
		encode();
		return outputString;
	}
	/**
	 * Decodes the provided input string using the specified keywords and returns the decoded result.
	 *
	 * @param squareKeyword	the keyword for the Polybius square
	 * @param keyword		the keyword for the columnar cipher
	 * @param inputString	the string to be decoded
	 * @return the decoded string
	 * @throws InvalidKeywordException if any of the keywords are invalid
	 * @throws InvalidInputException   if the input string is invalid
	 * @throws InvalidCharacterException if the input contains invalid characters
	 */
	public String decode(String squareKeyword, String keyword, String inputString) throws InvalidKeywordException, InvalidInputException, InvalidCharacterException{
		setSquareKeyword(squareKeyword);
		setKeyword(keyword);
		setInputString(inputString);
		decode();
		return outputString;
	}

	//?Getters
	/**
	 * Returns the current input string.
	 *
	 * @return the input string
	 */
	public String getInputString(){
		return inputString;
	}
	/**
	 * Returns the current output string.
	 *
	 * @return the output string
	 */
	public String getOutputString(){
		return outputString;
	}
	/**
	 * Returns the current Polybius square keyword.
	 *
	 * @return the Polybius square keyword
	 */
	public String getSquareKeyword(){
		return squareKeyword;
	}
	/**
	 * Returns the current columnar cipher keyword.
	 *
	 * @return the columnar cipher keyword
	 */
	public String getKeyword(){
		return keyword;
	}
	/**
	 * Resets all fields to their default values and reinitializes the internal ciphers.
	 *
	 * @throws InvalidCharacterException if there are invalid characters in the ciphers
	 */
	public void reset() throws InvalidCharacterException{
		logger.debug("Resetting fields");

		polybiusSquare = new PolybiusSquare(false, false);
		columnar = new Columnar(false, false, false, true, 'B');
		inputString = "";
		outputString = "";
		squareKeyword = "";
		keyword = "";
	}
}