package eu.siacs.conversations.services;

import android.content.Context;
import android.os.PowerManager;
import android.os.SystemClock;
import android.util.Log;

import org.bouncycastle.crypto.engines.AESEngine;
import org.bouncycastle.crypto.io.CipherInputStream;
import org.bouncycastle.crypto.io.CipherOutputStream;
import org.bouncycastle.crypto.modes.AEADBlockCipher;
import org.bouncycastle.crypto.modes.GCMBlockCipher;
import org.bouncycastle.crypto.params.AEADParameters;
import org.bouncycastle.crypto.params.KeyParameter;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.util.concurrent.atomic.AtomicLong;

import javax.crypto.NoSuchPaddingException;

import eu.siacs.conversations.Config;
import eu.siacs.conversations.R;
import eu.siacs.conversations.entities.DownloadableFile;
import eu.siacs.conversations.utils.Compatibility;

import static eu.siacs.conversations.entities.Transferable.VALID_CRYPTO_EXTENSIONS;

public class AbstractConnectionManager {

    private static final int UI_REFRESH_THRESHOLD = 250;
    private static final AtomicLong LAST_UI_UPDATE_CALL = new AtomicLong(0);
    protected XmppConnectionService mXmppConnectionService;

    public AbstractConnectionManager(XmppConnectionService service) {
        this.mXmppConnectionService = service;
    }

    public static InputStream upgrade(DownloadableFile file, InputStream is) throws InvalidAlgorithmParameterException, NoSuchAlgorithmException, InvalidKeyException, NoSuchPaddingException, NoSuchProviderException {
        if (file.getKey() != null && file.getIv() != null) {
            AEADBlockCipher cipher = new GCMBlockCipher(new AESEngine());
            cipher.init(true, new AEADParameters(new KeyParameter(file.getKey()), 128, file.getIv()));
            return new CipherInputStream(is, cipher);
        } else {
            return is;
        }
    }

    public static OutputStream createOutputStream(DownloadableFile file, boolean append, boolean decrypt) {
        FileOutputStream os;
        try {
            os = new FileOutputStream(file, append);
            if (file.getKey() == null || !decrypt) {
                return os;
            }
        } catch (FileNotFoundException e) {
            Log.d(Config.LOGTAG, "unable to create output stream", e);
            return null;
        }
        try {
            AEADBlockCipher cipher = new GCMBlockCipher(new AESEngine());
            cipher.init(false, new AEADParameters(new KeyParameter(file.getKey()), 128, file.getIv()));
            return new CipherOutputStream(os, cipher);
        } catch (Exception e) {
            Log.d(Config.LOGTAG, "unable to create cipher output stream", e);
            return null;
        }
    }

    public XmppConnectionService getXmppConnectionService() {
        return this.mXmppConnectionService;
    }

    public long getAutoAcceptFileSize() {
        return this.mXmppConnectionService.getLongPreference("auto_accept_file_size", R.integer.auto_accept_filesize);
    }

    public boolean hasStoragePermission() {
        return Compatibility.hasStoragePermission(mXmppConnectionService);
    }

    public void updateConversationUi(boolean force) {
        synchronized (LAST_UI_UPDATE_CALL) {
            if (force || SystemClock.elapsedRealtime() - LAST_UI_UPDATE_CALL.get() >= UI_REFRESH_THRESHOLD) {
                LAST_UI_UPDATE_CALL.set(SystemClock.elapsedRealtime());
                mXmppConnectionService.updateConversationUi();
            }
        }
    }

    public PowerManager.WakeLock createWakeLock(String name) {
        PowerManager powerManager = (PowerManager) mXmppConnectionService.getSystemService(Context.POWER_SERVICE);
        return powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, name);
    }

    public static class Extension {
        public final String main;
        public final String secondary;

        private Extension(String main, String secondary) {
            this.main = main;
            this.secondary = secondary;
        }

        public String getExtension() {
            if (VALID_CRYPTO_EXTENSIONS.contains(main)) {
                return secondary;
            } else {
                return main;
            }
        }

        public static Extension of(String path) {
            final int pos = path.lastIndexOf('/');
            final String filename = path.substring(pos + 1).toLowerCase();
            final String[] parts = filename.split("\\.");
            final String main = parts.length >= 2 ? parts[parts.length - 1] : null;
            final String secondary = parts.length >= 3 ? parts[parts.length - 2] : null;
            return new Extension(main, secondary);
        }
    }
}