package de.pixart.messenger.crypto.axolotl;

import android.util.Log;
import android.util.LruCache;

import org.whispersystems.libsignal.IdentityKey;
import org.whispersystems.libsignal.IdentityKeyPair;
import org.whispersystems.libsignal.InvalidKeyIdException;
import org.whispersystems.libsignal.SignalProtocolAddress;
import org.whispersystems.libsignal.ecc.Curve;
import org.whispersystems.libsignal.ecc.ECKeyPair;
import org.whispersystems.libsignal.state.PreKeyRecord;
import org.whispersystems.libsignal.state.SessionRecord;
import org.whispersystems.libsignal.state.SignalProtocolStore;
import org.whispersystems.libsignal.state.SignedPreKeyRecord;
import org.whispersystems.libsignal.util.KeyHelper;

import java.security.cert.X509Certificate;
import java.util.List;
import java.util.Set;

import de.pixart.messenger.Config;
import de.pixart.messenger.entities.Account;
import de.pixart.messenger.services.XmppConnectionService;
import de.pixart.messenger.utils.CryptoHelper;

public class SQLiteAxolotlStore implements SignalProtocolStore {

    public static final String PREKEY_TABLENAME = "prekeys";
    public static final String SIGNED_PREKEY_TABLENAME = "signed_prekeys";
    public static final String SESSION_TABLENAME = "sessions";
    public static final String IDENTITIES_TABLENAME = "identities";
    public static final String ACCOUNT = "account";
    public static final String DEVICE_ID = "device_id";
    public static final String ID = "id";
    public static final String KEY = "key";
    public static final String FINGERPRINT = "fingerprint";
    public static final String NAME = "name";
    public static final String TRUSTED = "trusted"; //no longer used
    public static final String TRUST = "trust";
    public static final String ACTIVE = "active";
    public static final String LAST_ACTIVATION = "last_activation";
    public static final String OWN = "ownkey";
    public static final String CERTIFICATE = "certificate";

    public static final String JSONKEY_REGISTRATION_ID = "axolotl_reg_id";
    public static final String JSONKEY_CURRENT_PREKEY_ID = "axolotl_cur_prekey_id";

    private static final int NUM_TRUSTS_TO_CACHE = 100;

    private final Account account;
    private final XmppConnectionService mXmppConnectionService;

    private IdentityKeyPair identityKeyPair;
    private int localRegistrationId;
    private int currentPreKeyId = 0;

    private final LruCache<String, FingerprintStatus> trustCache =
            new LruCache<String, FingerprintStatus>(NUM_TRUSTS_TO_CACHE) {
                @Override
                protected FingerprintStatus create(String fingerprint) {
                    return mXmppConnectionService.databaseBackend.getFingerprintStatus(account, fingerprint);
                }
            };

    private static IdentityKeyPair generateIdentityKeyPair() {
        Log.i(Config.LOGTAG, AxolotlService.LOGPREFIX + " : " + "Generating axolotl IdentityKeyPair...");
        ECKeyPair identityKeyPairKeys = Curve.generateKeyPair();
        return new IdentityKeyPair(new IdentityKey(identityKeyPairKeys.getPublicKey()),
                identityKeyPairKeys.getPrivateKey());
    }

    private static int generateRegistrationId() {
        Log.i(Config.LOGTAG, AxolotlService.LOGPREFIX + " : " + "Generating axolotl registration ID...");
        return KeyHelper.generateRegistrationId(true);
    }

    public SQLiteAxolotlStore(Account account, XmppConnectionService service) {
        this.account = account;
        this.mXmppConnectionService = service;
        this.localRegistrationId = loadRegistrationId();
        this.currentPreKeyId = loadCurrentPreKeyId();
    }

    public int getCurrentPreKeyId() {
        return currentPreKeyId;
    }

    // --------------------------------------
    // IdentityKeyStore
    // --------------------------------------

    private IdentityKeyPair loadIdentityKeyPair() {
        synchronized (mXmppConnectionService) {
            IdentityKeyPair ownKey = mXmppConnectionService.databaseBackend.loadOwnIdentityKeyPair(account);

            if (ownKey != null) {
                return ownKey;
            } else {
                Log.i(Config.LOGTAG, AxolotlService.getLogprefix(account) + "Could not retrieve own IdentityKeyPair");
                ownKey = generateIdentityKeyPair();
                mXmppConnectionService.databaseBackend.storeOwnIdentityKeyPair(account, ownKey);
            }
            return ownKey;
        }
    }

    private int loadRegistrationId() {
        return loadRegistrationId(false);
    }

    private int loadRegistrationId(boolean regenerate) {
        String regIdString = this.account.getKey(JSONKEY_REGISTRATION_ID);
        int reg_id;
        if (!regenerate && regIdString != null) {
            reg_id = Integer.valueOf(regIdString);
        } else {
            Log.i(Config.LOGTAG, AxolotlService.getLogprefix(account) + "Could not retrieve axolotl registration id for account " + account.getJid());
            reg_id = generateRegistrationId();
            boolean success = this.account.setKey(JSONKEY_REGISTRATION_ID, Integer.toString(reg_id));
            if (success) {
                mXmppConnectionService.databaseBackend.updateAccount(account);
            } else {
                Log.e(Config.LOGTAG, AxolotlService.getLogprefix(account) + "Failed to write new key to the database!");
            }
        }
        return reg_id;
    }

    private int loadCurrentPreKeyId() {
        String prekeyIdString = this.account.getKey(JSONKEY_CURRENT_PREKEY_ID);
        int prekey_id;
        if (prekeyIdString != null) {
            prekey_id = Integer.valueOf(prekeyIdString);
        } else {
            Log.w(Config.LOGTAG, AxolotlService.getLogprefix(account) + "Could not retrieve current prekey id for account " + account.getJid());
            prekey_id = 0;
        }
        return prekey_id;
    }

    public void regenerate() {
        mXmppConnectionService.databaseBackend.wipeAxolotlDb(account);
        trustCache.evictAll();
        account.setKey(JSONKEY_CURRENT_PREKEY_ID, Integer.toString(0));
        identityKeyPair = loadIdentityKeyPair();
        localRegistrationId = loadRegistrationId(true);
        currentPreKeyId = 0;
        mXmppConnectionService.updateAccountUi();
    }

    /**
     * Get the local client's identity key pair.
     *
     * @return The local client's persistent identity key pair.
     */
    @Override
    public IdentityKeyPair getIdentityKeyPair() {
        if (identityKeyPair == null) {
            identityKeyPair = loadIdentityKeyPair();
        }
        return identityKeyPair;
    }

    /**
     * Return the local client's registration ID.
     * <p/>
     * Clients should maintain a registration ID, a random number
     * between 1 and 16380 that's generated once at install time.
     *
     * @return the local client's registration ID.
     */
    @Override
    public int getLocalRegistrationId() {
        return localRegistrationId;
    }

    /**
     * Save a remote client's identity key
     * <p/>
     * Store a remote client's identity key as trusted.
     *
     * @param address        The address of the remote client.
     * @param identityKey The remote client's identity key.
     * @return true on success
     */
    @Override
    public boolean saveIdentity(SignalProtocolAddress address, IdentityKey identityKey) {
        if (!mXmppConnectionService.databaseBackend.loadIdentityKeys(account, address.getName()).contains(identityKey)) {
            String fingerprint = CryptoHelper.bytesToHex(identityKey.getPublicKey().serialize());
            FingerprintStatus status = getFingerprintStatus(fingerprint);
            if (status == null) {
                if (mXmppConnectionService.blindTrustBeforeVerification() && !account.getAxolotlService().hasVerifiedKeys(address.getName())) {
                    Log.d(Config.LOGTAG, account.getJid().toBareJid() + ": blindly trusted " + fingerprint + " of " + address.getName());
                    status = FingerprintStatus.createActiveTrusted();
                } else {
                    status = FingerprintStatus.createActiveUndecided();
                }
            } else {
                status = status.toActive();
            }
            mXmppConnectionService.databaseBackend.storeIdentityKey(account, address.getName(), identityKey, status);
            trustCache.remove(fingerprint);
        }
        return true;
    }

    /**
     * Verify a remote client's identity key.
     * <p/>
     * Determine whether a remote client's identity is trusted.  Convention is
     * that the TextSecure protocol is 'trust on first use.'  This means that
     * an identity key is considered 'trusted' if there is no entry for the recipient
     * in the local store, or if it matches the saved key for a recipient in the local
     * store.  Only if it mismatches an entry in the local store is it considered
     * 'untrusted.'
     *
     * @param name        The name of the remote client.
     * @param identityKey The identity key to verify.
     * @return true if trusted, false if untrusted.
     */
    @Override
    public boolean isTrustedIdentity(SignalProtocolAddress address, IdentityKey identityKey, Direction direction) {
        return true;
    }

    public FingerprintStatus getFingerprintStatus(String fingerprint) {
        return (fingerprint == null) ? null : trustCache.get(fingerprint);
    }

    public void setFingerprintStatus(String fingerprint, FingerprintStatus status) {
        mXmppConnectionService.databaseBackend.setIdentityKeyTrust(account, fingerprint, status);
        trustCache.remove(fingerprint);
    }

    public void setFingerprintCertificate(String fingerprint, X509Certificate x509Certificate) {
        mXmppConnectionService.databaseBackend.setIdentityKeyCertificate(account, fingerprint, x509Certificate);
    }

    public X509Certificate getFingerprintCertificate(String fingerprint) {
        return mXmppConnectionService.databaseBackend.getIdentityKeyCertifcate(account, fingerprint);
    }

    public Set<IdentityKey> getContactKeysWithTrust(String bareJid, FingerprintStatus status) {
        return mXmppConnectionService.databaseBackend.loadIdentityKeys(account, bareJid, status);
    }

    public long getContactNumTrustedKeys(String bareJid) {
        return mXmppConnectionService.databaseBackend.numTrustedKeys(account, bareJid);
    }

    // --------------------------------------
    // SessionStore
    // --------------------------------------

    /**
     * Returns a copy of the {@link SessionRecord} corresponding to the recipientId + deviceId tuple,
     * or a new SessionRecord if one does not currently exist.
     * <p/>
     * It is important that implementations return a copy of the current durable information.  The
     * returned SessionRecord may be modified, but those changes should not have an effect on the
     * durable session state (what is returned by subsequent calls to this method) without the
     * store method being called here first.
     *
     * @param address The name and device ID of the remote client.
     * @return a copy of the SessionRecord corresponding to the recipientId + deviceId tuple, or
     * a new SessionRecord if one does not currently exist.
     */
    @Override
    public SessionRecord loadSession(SignalProtocolAddress address) {
        SessionRecord session = mXmppConnectionService.databaseBackend.loadSession(this.account, address);
        return (session != null) ? session : new SessionRecord();
    }

    /**
     * Returns all known devices with active sessions for a recipient
     *
     * @param name the name of the client.
     * @return all known sub-devices with active sessions.
     */
    @Override
    public List<Integer> getSubDeviceSessions(String name) {
        return mXmppConnectionService.databaseBackend.getSubDeviceSessions(account,
                new SignalProtocolAddress(name, 0));
    }

    public List<String> getKnownAddresses() {
        return mXmppConnectionService.databaseBackend.getKnownSignalAddresses(account);
    }

    /**
     * Commit to storage the {@link SessionRecord} for a given recipientId + deviceId tuple.
     *
     * @param address the address of the remote client.
     * @param record  the current SessionRecord for the remote client.
     */
    @Override
    public void storeSession(SignalProtocolAddress address, SessionRecord record) {
        mXmppConnectionService.databaseBackend.storeSession(account, address, record);
    }

    /**
     * Determine whether there is a committed {@link SessionRecord} for a recipientId + deviceId tuple.
     *
     * @param address the address of the remote client.
     * @return true if a {@link SessionRecord} exists, false otherwise.
     */
    @Override
    public boolean containsSession(SignalProtocolAddress address) {
        return mXmppConnectionService.databaseBackend.containsSession(account, address);
    }

    /**
     * Remove a {@link SessionRecord} for a recipientId + deviceId tuple.
     *
     * @param address the address of the remote client.
     */
    @Override
    public void deleteSession(SignalProtocolAddress address) {
        mXmppConnectionService.databaseBackend.deleteSession(account, address);
    }

    /**
     * Remove the {@link SessionRecord}s corresponding to all devices of a recipientId.
     *
     * @param name the name of the remote client.
     */
    @Override
    public void deleteAllSessions(String name) {
        SignalProtocolAddress address = new SignalProtocolAddress(name, 0);
        mXmppConnectionService.databaseBackend.deleteAllSessions(account,
                address);
    }

    // --------------------------------------
    // PreKeyStore
    // --------------------------------------

    /**
     * Load a local PreKeyRecord.
     *
     * @param preKeyId the ID of the local PreKeyRecord.
     * @return the corresponding PreKeyRecord.
     * @throws InvalidKeyIdException when there is no corresponding PreKeyRecord.
     */
    @Override
    public PreKeyRecord loadPreKey(int preKeyId) throws InvalidKeyIdException {
        PreKeyRecord record = mXmppConnectionService.databaseBackend.loadPreKey(account, preKeyId);
        if (record == null) {
            throw new InvalidKeyIdException("No such PreKeyRecord: " + preKeyId);
        }
        return record;
    }

    /**
     * Store a local PreKeyRecord.
     *
     * @param preKeyId the ID of the PreKeyRecord to store.
     * @param record   the PreKeyRecord.
     */
    @Override
    public void storePreKey(int preKeyId, PreKeyRecord record) {
        mXmppConnectionService.databaseBackend.storePreKey(account, record);
        currentPreKeyId = preKeyId;
        boolean success = this.account.setKey(JSONKEY_CURRENT_PREKEY_ID, Integer.toString(preKeyId));
        if (success) {
            mXmppConnectionService.databaseBackend.updateAccount(account);
        } else {
            Log.e(Config.LOGTAG, AxolotlService.getLogprefix(account) + "Failed to write new prekey id to the database!");
        }
    }

    /**
     * @param preKeyId A PreKeyRecord ID.
     * @return true if the store has a record for the preKeyId, otherwise false.
     */
    @Override
    public boolean containsPreKey(int preKeyId) {
        return mXmppConnectionService.databaseBackend.containsPreKey(account, preKeyId);
    }

    /**
     * Delete a PreKeyRecord from local storage.
     *
     * @param preKeyId The ID of the PreKeyRecord to remove.
     */
    @Override
    public void removePreKey(int preKeyId) {
        mXmppConnectionService.databaseBackend.deletePreKey(account, preKeyId);
    }

    // --------------------------------------
    // SignedPreKeyStore
    // --------------------------------------

    /**
     * Load a local SignedPreKeyRecord.
     *
     * @param signedPreKeyId the ID of the local SignedPreKeyRecord.
     * @return the corresponding SignedPreKeyRecord.
     * @throws InvalidKeyIdException when there is no corresponding SignedPreKeyRecord.
     */
    @Override
    public SignedPreKeyRecord loadSignedPreKey(int signedPreKeyId) throws InvalidKeyIdException {
        SignedPreKeyRecord record = mXmppConnectionService.databaseBackend.loadSignedPreKey(account, signedPreKeyId);
        if (record == null) {
            throw new InvalidKeyIdException("No such SignedPreKeyRecord: " + signedPreKeyId);
        }
        return record;
    }

    /**
     * Load all local SignedPreKeyRecords.
     *
     * @return All stored SignedPreKeyRecords.
     */
    @Override
    public List<SignedPreKeyRecord> loadSignedPreKeys() {
        return mXmppConnectionService.databaseBackend.loadSignedPreKeys(account);
    }

    public int getSignedPreKeysCount() {
        return mXmppConnectionService.databaseBackend.getSignedPreKeysCount(account);
    }

    /**
     * Store a local SignedPreKeyRecord.
     *
     * @param signedPreKeyId the ID of the SignedPreKeyRecord to store.
     * @param record         the SignedPreKeyRecord.
     */
    @Override
    public void storeSignedPreKey(int signedPreKeyId, SignedPreKeyRecord record) {
        mXmppConnectionService.databaseBackend.storeSignedPreKey(account, record);
    }

    /**
     * @param signedPreKeyId A SignedPreKeyRecord ID.
     * @return true if the store has a record for the signedPreKeyId, otherwise false.
     */
    @Override
    public boolean containsSignedPreKey(int signedPreKeyId) {
        return mXmppConnectionService.databaseBackend.containsSignedPreKey(account, signedPreKeyId);
    }

    /**
     * Delete a SignedPreKeyRecord from local storage.
     *
     * @param signedPreKeyId The ID of the SignedPreKeyRecord to remove.
     */
    @Override
    public void removeSignedPreKey(int signedPreKeyId) {
        mXmppConnectionService.databaseBackend.deleteSignedPreKey(account, signedPreKeyId);
    }

    public void preVerifyFingerprint(Account account, String name, String fingerprint) {
        mXmppConnectionService.databaseBackend.storePreVerification(account, name, fingerprint, FingerprintStatus.createInactiveVerified());
    }
}