package org.expeditee.encryption;

import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Arrays;
import java.util.Base64;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import org.expeditee.auth.AuthenticatorBrowser;
import org.expeditee.gui.DisplayController;
import org.expeditee.gui.Frame;
import org.expeditee.gui.FrameIO;
import org.expeditee.items.Item;
import org.expeditee.items.Text;
import org.expeditee.settings.UserSettings;

import com.codahale.shamir.Scheme;

public class Actions implements CryptographyConstants {
	
	public static void TestSurrogate(Item primary) {
		System.out.println("Test surrogates: ");
	}
	
	public static Text GenerateSecret(String label) {
		return AuthGenerateSecret(label);
	}
	
	public static Text SplitSecret(Text key) {
		return AuthSplitSecret(key);
	}
	
	public static Text JoinSecret(Text key) {
		return AuthJoinSecret(key);
	}
	
	public static void Encrypt(Text labelWithKey) {
		AuthEncrypt(labelWithKey);
	}
	
	public static void Decrypt(Text labelWithKey) {
		AuthDecrypt(labelWithKey);
	}
	
	public static Text AuthGenerateSecret(String label) {
		// Generate AES Key
		Random rand = new SecureRandom();
		byte[] keyBytes = new byte[16];
		rand.nextBytes(keyBytes);
		String key = Base64.getEncoder().encodeToString(keyBytes);
		
		Text text = new Text(label);
		text.setData(key);
		text.setPosition(DisplayController.getMousePosition());
		return text;
	}

	public static Text AuthSplitSecret(Text key) {
		// Retrieve secret
		String secret = key.getData().get(0);
		byte[] secretBytes = Base64.getDecoder().decode(secret);
		
		// Obtain parameters for shamir
		String[] arguments = key.getText().split(" ");
		int requiredShares = Integer.parseInt(arguments[1]);
		int totalShares = arguments.length - 2;
		
		// Create shares
		Scheme scheme = new Scheme(new SecureRandom(), totalShares, requiredShares);
		Map<Integer, byte[]> split = scheme.split(secretBytes);
		
		// Add shares to key
		List<String> data = key.getData();
		for (Integer i: split.keySet()) {
			data.add("{" + i + "}" + Base64.getEncoder().encodeToString(split.get(i)));
		}
		key.setData(data);
		
		return key;
	}
	
	public static Text AuthJoinSecret(Text key) {
		Map<Integer, byte[]> contributingParts = new HashMap<Integer, byte[]>();
		
		// Retrieve splits
		List<String> data = key.getData();
		for (String d: data) {
			if (d.startsWith("{")) {
				String[] split = d.split("}");
				Integer k = Integer.parseInt(split[0].replace("{", ""));
				byte[] v = Base64.getDecoder().decode(split[1]);
				contributingParts.put(k, v);
			}
		}
		
		// Obtain parameters for shamir
		String[] arguments = key.getText().split(" ");
		int totalShares = Integer.parseInt(arguments[2]);
		int requiredShares = Integer.parseInt(arguments[1]);
		
		// Perform join
		Scheme scheme = new Scheme(new SecureRandom(), totalShares, requiredShares);
		byte[] join = scheme.join(contributingParts);
		
		data.clear();
		data.add(Base64.getEncoder().encodeToString(join));
		
		return key;
	}
	
	public static void AuthEncrypt(Text labelWithKey) {
		// Obtain encryption key
		String keyEncoded = labelWithKey.getData().get(0);
		byte[] keyDecoded = Base64.getDecoder().decode(keyEncoded);
		SecretKey key = new SecretKeySpec(keyDecoded, SymmetricAlgorithm);
		
		// Perform encryption
		Frame toEncrypt = FrameIO.LoadFrame(labelWithKey.getLink());
		Collection<Text> textItems = toEncrypt.getTextItems();
		for (Text t: textItems) {
			byte[] encrypted = EncryptSymmetric(t.getText().getBytes(), key);
			t.setText(Base64.getEncoder().encodeToString(encrypted));
		}
		
		// Save changes
		FrameIO.SaveFrame(toEncrypt);
	}
	
	public static void AuthDecrypt(Text labelWithKey) {
		// Obtain encryption key
		String keyEncoded = labelWithKey.getData().get(0);
		byte[] keyDecoded = Base64.getDecoder().decode(keyEncoded);
		SecretKey key = new SecretKeySpec(keyDecoded, SymmetricAlgorithm);
		
		// Perform decryption
		Frame toDecrypt = FrameIO.LoadFrame(labelWithKey.getLink());
		Collection<Text> textItems = toDecrypt.getTextItems();
		for (Text t: textItems) {
			byte[] decrypted = DecryptSymmetric(Base64.getDecoder().decode(t.getText().getBytes()), key);
			t.setText(new String(decrypted));
		}
		
		// Save changes
		FrameIO.SaveFrame(toDecrypt);
	}
	
	public static byte[] EncryptSymmetric(final byte[] toEncrypt, final SecretKey key) {
		// toEncrypt = Base64.getDecoder().decode(toEncrypt);
		try {
			final Cipher cipher = Cipher.getInstance(SymmetricAlgorithm + SymmetricAlgorithmParameters);
			cipher.init(Cipher.ENCRYPT_MODE, key);
			//could use modulus
			final int length = (int) ((Math.ceil(toEncrypt.length / 16f)) * 16);
			final byte[] toEncryptSizeAdjusted = Arrays.copyOf(toEncrypt, length);
			//System.err.println("(" + toEncryptSizeAdjusted.length + ")" + "Before Encryption Data: "
			//		+ Arrays.toString(toEncryptSizeAdjusted));
			final byte[] result = cipher.doFinal(toEncryptSizeAdjusted);
			//System.err.println("(" + result.length + ")" + "Encrypted Data: " + Arrays.toString(result));
			return result;
		} catch (final NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException
				| IllegalBlockSizeException | BadPaddingException e) {
			e.printStackTrace();
			return null;
		}
	}

	public static byte[] DecryptSymmetric(final byte[] toDecrypt, final SecretKey key) {
		try {
			final Cipher cipher = Cipher.getInstance(SymmetricAlgorithm + SymmetricAlgorithmParameters);
			cipher.init(Cipher.DECRYPT_MODE, key);
			final byte[] decryptedBytes = cipher.doFinal(toDecrypt);
			int indexOfZero = decryptedBytes.length - 1;
			for (int i = decryptedBytes.length - 1; i >= 0; i--) {
				if (decryptedBytes[i] != (byte) 0) {
					indexOfZero = i + 1;
					break;
				}
			}
			return Arrays.copyOf(decryptedBytes, indexOfZero);
		} catch (final NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException
				| IllegalBlockSizeException | BadPaddingException e) {
			e.printStackTrace();
			return null;
		}
	}

	public static void AuthAddSecretKey(String name, String data) {
		Frame secretsFrame = FrameIO.LoadFrame(UserSettings.UserName.get() + AuthenticatorBrowser.SECRETS_FRAME);
		secretsFrame.addText(500, 500, name, null).addToData(data);
	}
}