// Author: Isak Andersson
// License: Public Domain

import java.io.File;
import java.io.FileNotFoundException;
import java.util.HashMap;
import java.util.Scanner;

import javax.swing.JFileChooser;
import javax.swing.JOptionPane;
import javax.swing.filechooser.FileNameExtensionFilter;


public class IsaKrypt {

    private JFileChooser chooser;
    private FileNameExtensionFilter filter;
    private HashMap<char [], String> encryptionDict;

    private String key;

    public IsaKrypt() {
        chooser = new JFileChooser();
        filter = new FileNameExtensionFilter("Supported files", "txt", "isakrypt");
        chooser.setFileFilter(filter);
        encryptionDict = initDictionary();
    }

    public void start() throws Exception {
        String filepath = pickFile();

        if (getFileExtension(filepath).equals("txt")) {
            System.out.println("It is a .txt file! Let's encrypt!");
            encypt(filepath);
        }
        else if (getFileExtension(filepath).equals("isakrypt")) {
            System.out.println("It is a .isakrypt file! Let's decrypt!");
            decrypt(filepath);
        }
        else {
            throw new Exception("Unsupported file format. Isakrypt only accepts .txt and .isakrypt");
        }
    }

    private String pickFile() throws Exception {
        int dialogVal = chooser.showOpenDialog(null);
        String fp = "";

        if (dialogVal == JFileChooser.APPROVE_OPTION) {
            System.out.println("File to use: " + chooser.getSelectedFile().getName());
            System.out.println("Absolute path: " + chooser.getSelectedFile().getAbsolutePath());
            fp = chooser.getSelectedFile().getAbsolutePath();
        }
        else {
            throw new Exception("No file was selected");
        }

        return fp;
    }

    private String getFileExtension(String fp) throws Exception {
        String ext = "";

        System.out.println("Entering for loop.... filepath length is: "+fp.length());

        for (int index = fp.length()-1; index >= 0; index--) {
            System.out.println("Index: "+index);
            if (fp.charAt(index) == '.') {
                ext = fp.substring(index+1);
                break;
            }
        }

//      if (ext.equals("")) {
//          throw new Exception("No file extension was found");
//      }

        return ext;
    }

    private String read(String filepath) throws Exception {
        StringBuilder builder = new StringBuilder();
        String txt = "";

        try {
            Scanner mrscanner = new Scanner(new File(filepath));
            while(mrscanner.hasNext()) {
                builder.append(mrscanner.nextLine());
                builder.append("\n");
            }
            txt = builder.toString();

            if (txt.equals("")) {
                throw new Exception("Empty string, SOMETHING is wrong, file empty?");
            }

        } catch (FileNotFoundException e) {
            System.err.println("File could not be read");
            e.printStackTrace();
        }

        return txt;
    }

    // Kallas om filen har .txt extension
    private void encypt(String fp) throws Exception {
        String filecontent = read(fp);
        String kryptedVersion = "";
        StringBuilder cryptBuilder = new StringBuilder();

        System.out.println("File content: "+filecontent);

        key = JOptionPane.showInputDialog(null, "Enter your encryption key");
        char[] valueOnIndex;

        for (int index = 0; index < filecontent.length(); index++) {
            System.out.println(String.valueOf(String.valueOf(filecontent.charAt(index)).toCharArray())); // Prints correctly I know it is converting more than necessary, I just wanted to emulate what's below
            valueOnIndex = String.valueOf(filecontent.charAt(index)).toCharArray();
            if (encryptionDict.containsKey(valueOnIndex)) {
                // Append to string
                cryptBuilder.append(encryptionDict.get(valueOnIndex));
            }
            else {
                // If a character is not in the map, just add it as it is
                cryptBuilder.append(valueOnIndex);
            }
        }

        System.out.println("Encrypted version: \n" + cryptBuilder.toString());
    }

    // Kallas om filen hap .isakrypt extension
    private void decrypt(String fp) throws Exception {
        String filecontent = read(fp);
    }

    private HashMap<char [], String> initDictionary() {
        HashMap<char [], String> d = new HashMap<char [], String>();

        d.put("a".toCharArray(), "!\"#¤");
        d.put("b".toCharArray(), "¤#\"!");
        d.put("c".toCharArray(), "\"#¤%");
        d.put("d".toCharArray(), "%¤#\"");
        d.put("e".toCharArray(), "#¤%&");
        d.put("f".toCharArray(), "&%¤#");
        d.put("g".toCharArray(), "¤%&/");
        d.put("h".toCharArray(), "/&%¤");
        d.put("i".toCharArray(), "%&/(");
        d.put("j".toCharArray(), "(/&%");
        d.put("k".toCharArray(), "&/()");
        d.put("l".toCharArray(), ")(/&");
        d.put("m".toCharArray(), "/()=");
        d.put("n".toCharArray(), "=)(/");
        d.put("o".toCharArray(), "()=?");
        d.put("p".toCharArray(), "?=)(");
        d.put("q".toCharArray(), ")=?!");
        d.put("r".toCharArray(), "!?=)");
        d.put("s".toCharArray(), "=?!\"");
        d.put("t".toCharArray(), "\"!?=");
        d.put("u".toCharArray(), "?!\"#");
        d.put("v".toCharArray(), "#\"!?");
        d.put("w".toCharArray(), ";:*^");
        d.put("x".toCharArray(), "^*:;");
        d.put("y".toCharArray(), ":*^>");
        d.put("z".toCharArray(), ">^*:");

        d.put("A".toCharArray(), "¶¡@£");
        d.put("B".toCharArray(), "£@¡¶");
        d.put("C".toCharArray(), "¡@£$");
        d.put("D".toCharArray(), "$£@¡");
        d.put("E".toCharArray(), "@£$€");
        d.put("F".toCharArray(), "€$£@");
        d.put("G".toCharArray(), "£$€¥");
        d.put("H".toCharArray(), "¥€$£");
        d.put("I".toCharArray(), "$€¥{");
        d.put("J".toCharArray(), "{¥€$");
        d.put("K".toCharArray(), "€¥{[");
        d.put("L".toCharArray(), "[{¥€");
        d.put("M".toCharArray(), "¥{[]");
        d.put("N".toCharArray(), "][{¥");
        d.put("O".toCharArray(), "{[]}");
        d.put("P".toCharArray(), "}][{");
        d.put("Q".toCharArray(), "[]}\\");
        d.put("R".toCharArray(), "\\}][");
        d.put("S".toCharArray(), "]}\\±");
        d.put("T".toCharArray(), "±\\}]");
        d.put("U".toCharArray(), "}\\±¶");
        d.put("V".toCharArray(), "¶±\\}");
        d.put("W".toCharArray(), "\\±¶¡");
        d.put("X".toCharArray(), "¡¶±\\");
        d.put("Y".toCharArray(), "±¶¡@");
        d.put("Z".toCharArray(), "@¡¶±");

        d.put("0".toCharArray(), "¶±¡\\");
        d.put("1".toCharArray(), "\\¡±¶");
        d.put("2".toCharArray(), "¡\\@}");
        d.put("3".toCharArray(), "}@\\¡");
        d.put("4".toCharArray(), "@}£]");
        d.put("5".toCharArray(), "]£}@");
        d.put("6".toCharArray(), "£]$[");
        d.put("7".toCharArray(), "[$]£");
        d.put("8".toCharArray(), "$[€{");
        d.put("9".toCharArray(), "[€]$");

        d.put(" ".toCharArray(), "_/|\\_");

        return d;
    }

    public static void main(String[] args) throws Exception {
        IsaKrypt p = new IsaKrypt();
        p.start();
    }
}