package com.five_ten_sg.connectbot.service;

import java.io.IOException;
import java.security.SecureRandom;
import java.security.KeyPair;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.interfaces.DSAPrivateKey;
import java.security.interfaces.DSAPublicKey;
import java.security.interfaces.ECPrivateKey;
import java.security.interfaces.ECPublicKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

import com.five_ten_sg.connectbot.service.TerminalManager;
import com.five_ten_sg.connectbot.service.TerminalManager.KeyHolder;
import android.app.Service;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.IBinder;
import android.os.RemoteException;
import android.util.Log;

import com.madgag.ssh.android.authagent.AndroidAuthAgent;
import com.trilead.ssh2.signature.DSASHA1Verify;
import com.trilead.ssh2.signature.ECDSASHA2Verify;
import com.trilead.ssh2.signature.RSASHA1Verify;

public class AuthAgentService extends Service {
    private static final String TAG = "ConnectBot.AuthAgentService";
    protected TerminalManager manager;
    final Lock lock = new ReentrantLock();
    final Condition managerReady = lock.newCondition();

    private ServiceConnection connection = new ServiceConnection() {
        public void onServiceConnected(ComponentName className, IBinder service) {
            Log.d(TAG, "Terminal manager available! Hurrah");
            manager = ((TerminalManager.TerminalBinder) service).getService();
            lock.lock();

            try {
                managerReady.signal();
            }
            finally {
                lock.unlock();
            }
        }
        public void onServiceDisconnected(ComponentName className) {
            manager = null;
            Log.d(TAG, "Terminal manager gone...");
        }
    };

    @Override
    public IBinder onBind(Intent intent) {
        Log.d(TAG, "onBind() called");
        bindService(new Intent(this, TerminalManager.class), connection, BIND_AUTO_CREATE);
        return mBinder;
    }

    private final AndroidAuthAgent.Stub mBinder = new AndroidAuthAgent.Stub() {
        public Map getIdentities() throws RemoteException {
            Log.d(TAG, "getIdentities() called");
            waitForTerminalManager();
            Log.d(TAG, "getIdentities() manager.loadedKeypairs : " + manager.loadedKeypairs);
            return sshEncodedPubKeysFrom(manager.loadedKeypairs);
        }
        public byte[] sign(byte[] publicKey, byte[] data) throws RemoteException {
            Log.d(TAG, "sign() called");
            waitForTerminalManager();
            KeyPair pair = keyPairFor(publicKey);
            Log.d(TAG, "sign() - signing keypair found : " + pair);

            if (pair == null) {
                return null;
            }

            PrivateKey privKey = pair.getPrivate();

            if (privKey instanceof RSAPrivateKey) {
                return sshEncodedSignatureFor(data, (RSAPrivateKey) privKey);
            }
            else if (privKey instanceof DSAPrivateKey) {
                return sshEncodedSignatureFor(data, (DSAPrivateKey) privKey);
            }

            return null;
        }
        private void waitForTerminalManager() throws RemoteException {
            lock.lock();

            try {
                while (manager == null) {
                    Log.d(TAG, "Waiting for TerminalManager...");
                    managerReady.await();
                }
            }
            catch (InterruptedException e) {
                throw new RemoteException();
            }
            finally {
                lock.unlock();
            }

            Log.d(TAG, "Got TerminalManager : " + manager);
        }
        private Map<String, byte[]> sshEncodedPubKeysFrom(Map<String, KeyHolder> keypairs) {
            Map<String, byte[]> pubkeys = new HashMap<String, byte[]> (keypairs.size());

            for (Entry<String, KeyHolder> entry : keypairs.entrySet()) {
                byte[] encodedKey = sshEncodedPubKeyFrom(entry.getValue().pair);

                if (encodedKey != null) {
                    pubkeys.put(entry.getKey(), encodedKey);
                }
            }

            return pubkeys;
        }
        private byte[] sshEncodedPubKeyFrom(KeyPair pair) {
            try {
                PrivateKey privKey = pair.getPrivate();

                if (privKey instanceof RSAPrivateKey) {
                    RSAPublicKey pubkey = (RSAPublicKey)pair.getPublic();
                    return RSASHA1Verify.encodeSSHRSAPublicKey(pubkey);
                }
                else if (privKey instanceof DSAPrivateKey) {
                    DSAPublicKey pubkey = (DSAPublicKey)pair.getPublic();
                    return DSASHA1Verify.encodeSSHDSAPublicKey(pubkey);
                }
            }
            catch (IOException e) {
                Log.e(TAG, "Couldn't encode " + pair, e);
            }

            return null;
        }
        private byte[] sshEncodedSignatureFor(byte[] data, RSAPrivateKey privKey) {
            try {
                byte[] signature = RSASHA1Verify.generateSignature(data, privKey);
                return RSASHA1Verify.encodeSSHRSASignature(signature);
            }
            catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        private byte[] sshEncodedSignatureFor(byte[] data, DSAPrivateKey privKey) {
            try {
                byte[] signature = DSASHA1Verify.generateSignature(data, privKey, new SecureRandom());
                return DSASHA1Verify.encodeSSHDSASignature(signature);
            }
            catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        private KeyPair keyPairFor(byte[] publicKey) {
            String nickname = manager.getKeyNickname(publicKey);

            if (nickname == null) {
                Log.w(TAG, "No key-pair found for public-key.");
                return null;
            }

            // check manager.loadedKeypairs.get(nickname).bean.isConfirmUse() and promptForPubkeyUse(nickname) ?
            return manager.getKey(nickname);
        }
    };
}