package com.meo.shrimp.meo;

import android.Manifest;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import com.nbsp.materialfilepicker.MaterialFilePicker;
import com.nbsp.materialfilepicker.ui.FilePickerActivity;

import org.encryptor4j.Encryptor;
import org.encryptor4j.factory.KeyFactory;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.util.regex.Pattern;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;


public class cryptActivity extends AppCompatActivity {

    String key = "Bar12345Bar12345"; // 128 bit key
    String initVector = "RandomInitVector"; // 16 bytes IV

    Button selectBtn;
    Button cryptBtn;
    Button decryptBtn;
    TextView pathView;
    TextView textView;

    String path;
    String buffer;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_crypt);
        setTitle("AES Crypt/Decrypt");

        selectBtn = (Button) findViewById(R.id.selectBtn);
        cryptBtn = (Button) findViewById(R.id.cryptBtn);
        decryptBtn = (Button) findViewById(R.id.decryptBtn);
        pathView = (TextView) findViewById(R.id.pathView);
        textView = (TextView) findViewById(R.id.textView);

        if(Build.VERSION.SDK_INT > Build.VERSION_CODES.M && checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE)
                != PackageManager.PERMISSION_GRANTED){
            requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1001);
        }

        cryptBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                try {
                    newEncrypt(path, key, initVector);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });

        decryptBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                try {
                    newDecrypt(path, key, initVector);
                } catch (Exception e) {
                e.printStackTrace();
            }
            }
        });

    }

    public void encrypt() throws Exception{
        if(path.length() !=0) {
            String out = encrypt(key, initVector, readFile(path));

            Toast.makeText(this, "зашифровано", Toast.LENGTH_SHORT).show();
            createFile(this, "encrypted.txt", out);
        }else{
            Toast.makeText(this, "файл не выбран", Toast.LENGTH_SHORT).show();
        }
    }

    public void decrypt() throws Exception{
        if(path.length() !=0) {
            String out = decrypt(key, initVector, readFile(path));

            Toast.makeText(this, out, Toast.LENGTH_SHORT).show();
            createFile(this, "decrypted.txt", out);
        }else{
            Toast.makeText(this, "файл не выбран", Toast.LENGTH_SHORT).show();
        }
    }

    public void newEncrypt(String fPath, String nKey, String niv) throws Exception{

        SecretKeySpec secretKeySpec = new SecretKeySpec(nKey.getBytes("UTF-8"), "AES");

        Encryptor encryptor = new Encryptor(secretKeySpec, "AES/CBC/PKCS5PADDING", 16);

        InputStream is = null;
        OutputStream os = null;
        try {
            is = new FileInputStream(fPath);
            os = encryptor.wrapOutputStream(new FileOutputStream("encrypted.txt"));
            byte[] buffer = new byte[4096];
            int nRead;
            while((nRead = is.read(buffer)) != -1) {
                os.write(buffer, 0, nRead);
            }
            os.flush();
            Toast.makeText(this, "зашифровано", Toast.LENGTH_SHORT).show();
        } finally {
            if(is != null) {
                is.close();
            }
            if(os != null) {
                os.close();
            }
        }
    }

    public void newDecrypt(String fPath, String nKey, String niv) throws Exception{
        SecretKeySpec secretKeySpec = new SecretKeySpec(nKey.getBytes("UTF-8"), "AES");

        Encryptor encryptor = new Encryptor(secretKeySpec, "AES/CBC/PKCS5PADDING", 16);

        InputStream is = null;
        OutputStream os = null;

        try {
            is = encryptor.wrapInputStream(new FileInputStream(fPath));
            os = new FileOutputStream("decrypted.txt");
            byte[] buffer = new byte[4096];
            int nRead;
            while((nRead = is.read(buffer)) != -1) {
                os.write(buffer, 0, nRead);
            }
            os.flush();
            Toast.makeText(this, "расшифровано", Toast.LENGTH_SHORT).show();
        } finally {
            if(is != null) {
                is.close();
            }
            if(os != null) {
                os.close();
            }
        }
    }

    public void select(View v){
        new MaterialFilePicker()
                .withActivity(cryptActivity.this)
                .withRequestCode(1000)
                .withFilter(Pattern.compile(".*\\.txt$")) // Filtering files and directories by file name using regexp
                //.withFilterDirectories(true) // Set directories filterable (false by default)
                .withHiddenFiles(true) // Show hidden files and folders
                .start();
    }


    public static String readFile (String filePath) throws Exception {
        File fl = new File(filePath);
        FileInputStream fin = new FileInputStream(fl);
        String ret = convertStreamToString(fin);
        //Make sure you close all streams.
        fin.close();
        return ret;
    }

    public static String convertStreamToString(InputStream is) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
        StringBuilder sb = new StringBuilder();
        String line = null;
        while ((line = reader.readLine()) != null) {
            sb.append(line).append("\n");
        }
        reader.close();
        return sb.toString();
    }


    public static String encrypt(String key, String initVector, String value) {
        try {
            IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
            SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");

            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
            cipher.init(Cipher.ENCRYPT_MODE, skeySpec);

            byte[] encrypted = cipher.doFinal(value.getBytes());
            String str = new String(encrypted);

            return str;
        } catch (Exception ex) {
            ex.printStackTrace();
        }

        return null;
    }

    public static String decrypt(String key, String initVector, String encrypted) {
        try {
            IvParameterSpec iv = new IvParameterSpec(initVector.getBytes("UTF-8"));
            SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");

            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
            cipher.init(Cipher.DECRYPT_MODE, skeySpec);

            byte[] decrypted = cipher.doFinal(encrypted.getBytes());
            String str = new String(decrypted);

            return str;
        } catch (Exception ex) {
            ex.printStackTrace();
        }

        return null;
    }

    public void createFile(Context context, String sFileName, String sBody) {
        try {
            File root = new File(Environment.getExternalStorageDirectory(), ".aNotes");
            if (!root.exists()) {
                root.mkdirs();
            }
            File gpxfile = new File(root, sFileName);
            FileWriter writer = new FileWriter(gpxfile);
            writer.append(sBody);
            writer.flush();
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (requestCode == 1000 && resultCode == RESULT_OK) {
            String filePath = data.getStringExtra(FilePickerActivity.RESULT_FILE_PATH);
            path = filePath;
            pathView.setText(path);
            try {
                textView.setText(readFile(filePath));
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode) {
            case 1001:{
                if(grantResults[0] == PackageManager.PERMISSION_GRANTED){
                    Toast.makeText(this, "Permission granted!", Toast.LENGTH_SHORT).show();
                }else{
                    Toast.makeText(this, "Permission not granted!", Toast.LENGTH_SHORT).show();
                    finish();
                }
            }
        }
    }
}