package xpto;

import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.logging.Logger;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import javax.xml.bind.DatatypeConverter;
import javax.xml.datatype.DatatypeFactory;

import org.apache.commons.io.IOUtils;

/**
 * utilitário de criptografia
 *
 * dę o caminho do arquivo, năo importa muito qual, e ele vai gerar um arquivo
 * de mexmo exato nome, adiionando .cryp no final
 *
 * ex:
 *
 * e: foto1.jpg
 *
 * s: foto1.jpg.cryp
 *
 * a chave de criptografia está no classpath.
 *
 * ou ainda descriptografa, caso o arquivo .cryp gerado tenha sido criado pela
 * mesma chave que este componente conhece.
 *
 * caso năo tenha uma chave, gere uma AES que tá tudo certo.
 *
 * @author leonardo
 *
 */
public class CryptoUtil {

    private static final Logger LOG = Logger.getLogger("CryptoUtil");

    private static byte[] sKey;

    static {
        try {
            sKey = IOUtils.toByteArray(CryptoUtil.class
                    .getResourceAsStream("secret.key"));
        } catch (IOException e) {
            LOG.severe(e.getMessage());
            e.printStackTrace();
        }
    }

    public void genKey() throws Exception {
        KeyGenerator kgen = KeyGenerator.getInstance("AES");
        kgen.init(128);
        SecretKey key = kgen.generateKey();
        Files.write(Paths.get("secret.key"), key.getEncoded());

    }

    public void encrypt(InputStream in, OutputStream out) throws Exception {
        SecretKey key = new SecretKeySpec(sKey, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        try (OutputStream cout = new CipherOutputStream(out, cipher)) {
            IOUtils.copy(in, cout);
        }
    }

    public void decrypt(InputStream in, OutputStream out) throws Exception {
        SecretKey key = new SecretKeySpec(sKey, "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, key);
        try (InputStream cin = new CipherInputStream(in, cipher)) {
            IOUtils.copy(cin, out);
        }
    }

    public void encrypt(Path in, Path out) throws Exception {
        try (InputStream fin = Files.newInputStream(in)) {
            try (OutputStream fout = Files.newOutputStream(out)) {
                encrypt(fin, fout);
            }
        }
    }

    public void decrypt(Path in, Path out) throws Exception {
        try (InputStream fin = Files.newInputStream(in)) {
            try (OutputStream fout = Files.newOutputStream(out)) {
                decrypt(fin, fout);
            }
        }
    }

    public void encrypt(String in, String out) throws Exception {
        // if (!out.endsWith(".crypt"))
        // out += ".crypt";
        try (InputStream fin = new FileInputStream(in)) {
            try (OutputStream fout = new FileOutputStream(out)) {
                decrypt(fin, fout);
            }
        }
    }

    public void decrypt(String in, String out) throws Exception {
        // if (!in.endsWith(".crypt"))
        // in += ".crypt";
        try (InputStream fin = new FileInputStream(in)) {
            try (OutputStream fout = new FileOutputStream(out)) {
                decrypt(fin, fout);
            }
        }
    }

    public byte[] encrypt(InputStream in) throws Exception {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        decrypt(in, out);
        return out.toByteArray();
    }

    public byte[] decrypt(InputStream in) throws Exception {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        decrypt(in, out);
        return out.toByteArray();
    }

    public byte[] decrypt(Path pin) throws Exception {
        return decrypt(Files.newInputStream(pin));
    }

    public static void main(String[] args) throws Exception {
//      new CryptoUtil().genKey();
        byte[]b = new CryptoUtil().decrypt(Paths.get("msg.txt"));
        String s = DatatypeConverter.printBase64Binary(b);
        System.out.println(s);
    }
}