package de.pixart.messenger.persistance;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.DatabaseUtils;
import android.database.sqlite.SQLiteCantOpenDatabaseException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Base64;
import android.util.Log;
import android.util.Pair;

import org.json.JSONException;
import org.json.JSONObject;
import org.whispersystems.libaxolotl.AxolotlAddress;
import org.whispersystems.libaxolotl.IdentityKey;
import org.whispersystems.libaxolotl.IdentityKeyPair;
import org.whispersystems.libaxolotl.InvalidKeyException;
import org.whispersystems.libaxolotl.state.PreKeyRecord;
import org.whispersystems.libaxolotl.state.SessionRecord;
import org.whispersystems.libaxolotl.state.SignedPreKeyRecord;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.security.cert.CertificateEncodingException;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArrayList;

import de.pixart.messenger.Config;
import de.pixart.messenger.crypto.axolotl.AxolotlService;
import de.pixart.messenger.crypto.axolotl.FingerprintStatus;
import de.pixart.messenger.crypto.axolotl.SQLiteAxolotlStore;
import de.pixart.messenger.entities.Account;
import de.pixart.messenger.entities.Contact;
import de.pixart.messenger.entities.Conversation;
import de.pixart.messenger.entities.Message;
import de.pixart.messenger.entities.PresenceTemplate;
import de.pixart.messenger.entities.Roster;
import de.pixart.messenger.entities.ServiceDiscoveryResult;
import de.pixart.messenger.xmpp.jid.InvalidJidException;
import de.pixart.messenger.xmpp.jid.Jid;

public class DatabaseBackend extends SQLiteOpenHelper {

    private static DatabaseBackend instance = null;

    public static final String DATABASE_NAME = "history";
    public static final int DATABASE_VERSION = 34;

    private static String CREATE_CONTATCS_STATEMENT = "create table "
            + Contact.TABLENAME + "(" + Contact.ACCOUNT + " TEXT, "
            + Contact.SERVERNAME + " TEXT, " + Contact.SYSTEMNAME + " TEXT,"
            + Contact.JID + " TEXT," + Contact.KEYS + " TEXT,"
            + Contact.PHOTOURI + " TEXT," + Contact.OPTIONS + " NUMBER,"
            + Contact.SYSTEMACCOUNT + " NUMBER, " + Contact.AVATAR + " TEXT, "
            + Contact.LAST_PRESENCE + " TEXT, " + Contact.LAST_TIME + " NUMBER, "
            + Contact.GROUPS + " TEXT, FOREIGN KEY(" + Contact.ACCOUNT + ") REFERENCES "
            + Account.TABLENAME + "(" + Account.UUID
            + ") ON DELETE CASCADE, UNIQUE(" + Contact.ACCOUNT + ", "
            + Contact.JID + ") ON CONFLICT REPLACE);";

    private static String CREATE_DISCOVERY_RESULTS_STATEMENT = "create table "
            + ServiceDiscoveryResult.TABLENAME + "("
            + ServiceDiscoveryResult.HASH + " TEXT, "
            + ServiceDiscoveryResult.VER + " TEXT, "
            + ServiceDiscoveryResult.RESULT + " TEXT, "
            + "UNIQUE(" + ServiceDiscoveryResult.HASH + ", "
            + ServiceDiscoveryResult.VER + ") ON CONFLICT REPLACE);";

    private static String CREATE_PRESENCE_TEMPLATES_STATEMENT = "CREATE TABLE "
            + PresenceTemplate.TABELNAME + "("
            + PresenceTemplate.UUID + " TEXT, "
            + PresenceTemplate.LAST_USED + " NUMBER,"
            + PresenceTemplate.MESSAGE + " TEXT,"
            + PresenceTemplate.STATUS + " TEXT,"
            + "UNIQUE(" + PresenceTemplate.MESSAGE + "," + PresenceTemplate.STATUS + ") ON CONFLICT REPLACE);";

    private static String CREATE_PREKEYS_STATEMENT = "CREATE TABLE "
            + SQLiteAxolotlStore.PREKEY_TABLENAME + "("
            + SQLiteAxolotlStore.ACCOUNT + " TEXT,  "
            + SQLiteAxolotlStore.ID + " INTEGER, "
            + SQLiteAxolotlStore.KEY + " TEXT, FOREIGN KEY("
            + SQLiteAxolotlStore.ACCOUNT
            + ") REFERENCES " + Account.TABLENAME + "(" + Account.UUID + ") ON DELETE CASCADE, "
            + "UNIQUE( " + SQLiteAxolotlStore.ACCOUNT + ", "
            + SQLiteAxolotlStore.ID
            + ") ON CONFLICT REPLACE"
            + ");";

    private static String CREATE_SIGNED_PREKEYS_STATEMENT = "CREATE TABLE "
            + SQLiteAxolotlStore.SIGNED_PREKEY_TABLENAME + "("
            + SQLiteAxolotlStore.ACCOUNT + " TEXT,  "
            + SQLiteAxolotlStore.ID + " INTEGER, "
            + SQLiteAxolotlStore.KEY + " TEXT, FOREIGN KEY("
            + SQLiteAxolotlStore.ACCOUNT
            + ") REFERENCES " + Account.TABLENAME + "(" + Account.UUID + ") ON DELETE CASCADE, "
            + "UNIQUE( " + SQLiteAxolotlStore.ACCOUNT + ", "
            + SQLiteAxolotlStore.ID
            + ") ON CONFLICT REPLACE" +
            ");";

    private static String CREATE_SESSIONS_STATEMENT = "CREATE TABLE "
            + SQLiteAxolotlStore.SESSION_TABLENAME + "("
            + SQLiteAxolotlStore.ACCOUNT + " TEXT,  "
            + SQLiteAxolotlStore.NAME + " TEXT, "
            + SQLiteAxolotlStore.DEVICE_ID + " INTEGER, "
            + SQLiteAxolotlStore.KEY + " TEXT, FOREIGN KEY("
            + SQLiteAxolotlStore.ACCOUNT
            + ") REFERENCES " + Account.TABLENAME + "(" + Account.UUID + ") ON DELETE CASCADE, "
            + "UNIQUE( " + SQLiteAxolotlStore.ACCOUNT + ", "
            + SQLiteAxolotlStore.NAME + ", "
            + SQLiteAxolotlStore.DEVICE_ID
            + ") ON CONFLICT REPLACE"
            + ");";

    private static String CREATE_IDENTITIES_STATEMENT = "CREATE TABLE "
            + SQLiteAxolotlStore.IDENTITIES_TABLENAME + "("
            + SQLiteAxolotlStore.ACCOUNT + " TEXT,  "
            + SQLiteAxolotlStore.NAME + " TEXT, "
            + SQLiteAxolotlStore.OWN + " INTEGER, "
            + SQLiteAxolotlStore.FINGERPRINT + " TEXT, "
            + SQLiteAxolotlStore.CERTIFICATE + " BLOB, "
            + SQLiteAxolotlStore.TRUST + " TEXT, "
            + SQLiteAxolotlStore.ACTIVE + " NUMBER, "
            + SQLiteAxolotlStore.LAST_ACTIVATION + " NUMBER,"
            + SQLiteAxolotlStore.KEY + " TEXT, FOREIGN KEY("
            + SQLiteAxolotlStore.ACCOUNT
            + ") REFERENCES " + Account.TABLENAME + "(" + Account.UUID + ") ON DELETE CASCADE, "
            + "UNIQUE( " + SQLiteAxolotlStore.ACCOUNT + ", "
            + SQLiteAxolotlStore.NAME + ", "
            + SQLiteAxolotlStore.FINGERPRINT
            + ") ON CONFLICT IGNORE"
            + ");";

    private static String START_TIMES_TABLE = "start_times";
    private static String CREATE_START_TIMES_TABLE = "create table " + START_TIMES_TABLE + " (timestamp NUMBER);";
    private static String CREATE_MESSAGE_TIME_INDEX = "create INDEX message_time_index ON " + Message.TABLENAME + "(" + Message.TIME_SENT + ")";

    private DatabaseBackend(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("PRAGMA foreign_keys=ON;");
        db.execSQL("create table " + Account.TABLENAME + "(" + Account.UUID + " TEXT PRIMARY KEY,"
                + Account.USERNAME + " TEXT,"
                + Account.SERVER + " TEXT,"
                + Account.PASSWORD + " TEXT,"
                + Account.DISPLAY_NAME + " TEXT, "
                + Account.STATUS + " TEXT,"
                + Account.STATUS_MESSAGE + " TEXT,"
                + Account.ROSTERVERSION + " TEXT,"
                + Account.OPTIONS + " NUMBER, "
                + Account.AVATAR + " TEXT, "
                + Account.KEYS + " TEXT, "
                + Account.HOSTNAME + " TEXT, "
                + Account.PORT + " NUMBER DEFAULT 5222)");
        db.execSQL("create table " + Conversation.TABLENAME + " ("
                + Conversation.UUID + " TEXT PRIMARY KEY, " + Conversation.NAME
                + " TEXT, " + Conversation.CONTACT + " TEXT, "
                + Conversation.ACCOUNT + " TEXT, " + Conversation.CONTACTJID
                + " TEXT, " + Conversation.CREATED + " NUMBER, "
                + Conversation.STATUS + " NUMBER, " + Conversation.MODE
                + " NUMBER, " + Conversation.ATTRIBUTES + " TEXT, FOREIGN KEY("
                + Conversation.ACCOUNT + ") REFERENCES " + Account.TABLENAME
                + "(" + Account.UUID + ") ON DELETE CASCADE);");
        db.execSQL("create table " + Message.TABLENAME + "( " + Message.UUID
                + " TEXT PRIMARY KEY, " + Message.CONVERSATION + " TEXT, "
                + Message.TIME_SENT + " NUMBER, " + Message.COUNTERPART
                + " TEXT, " + Message.TRUE_COUNTERPART + " TEXT,"
                + Message.BODY + " TEXT, " + Message.ENCRYPTION + " NUMBER, "
                + Message.STATUS + " NUMBER," + Message.TYPE + " NUMBER, "
                + Message.RELATIVE_FILE_PATH + " TEXT, "
                + Message.SERVER_MSG_ID + " TEXT, "
                + Message.FINGERPRINT + " TEXT, "
                + Message.CARBON + " INTEGER, "
                + Message.EDITED + " TEXT, "
                + Message.READ + " NUMBER DEFAULT 1, "
                + Message.OOB + " INTEGER, "
                + Message.ERROR_MESSAGE + " TEXT,"
                + Message.REMOTE_MSG_ID + " TEXT, FOREIGN KEY("
                + Message.CONVERSATION + ") REFERENCES "
                + Conversation.TABLENAME + "(" + Conversation.UUID
                + ") ON DELETE CASCADE);");

        db.execSQL(CREATE_MESSAGE_TIME_INDEX);
        db.execSQL(CREATE_CONTATCS_STATEMENT);
        db.execSQL(CREATE_DISCOVERY_RESULTS_STATEMENT);
        db.execSQL(CREATE_SESSIONS_STATEMENT);
        db.execSQL(CREATE_PREKEYS_STATEMENT);
        db.execSQL(CREATE_SIGNED_PREKEYS_STATEMENT);
        db.execSQL(CREATE_IDENTITIES_STATEMENT);
        db.execSQL(CREATE_PRESENCE_TEMPLATES_STATEMENT);
        db.execSQL(CREATE_START_TIMES_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        if (oldVersion < 2 && newVersion >= 2) {
            db.execSQL("update " + Account.TABLENAME + " set "
                    + Account.OPTIONS + " = " + Account.OPTIONS + " | 8");
        }
        if (oldVersion < 3 && newVersion >= 3) {
            db.execSQL("ALTER TABLE " + Message.TABLENAME + " ADD COLUMN "
                    + Message.TYPE + " NUMBER");
        }
        if (oldVersion < 5 && newVersion >= 5) {
            db.execSQL("DROP TABLE " + Contact.TABLENAME);
            db.execSQL(CREATE_CONTATCS_STATEMENT);
            db.execSQL("UPDATE " + Account.TABLENAME + " SET "
                    + Account.ROSTERVERSION + " = NULL");
        }
        if (oldVersion < 6 && newVersion >= 6) {
            db.execSQL("ALTER TABLE " + Message.TABLENAME + " ADD COLUMN "
                    + Message.TRUE_COUNTERPART + " TEXT");
        }
        if (oldVersion < 7 && newVersion >= 7) {
            db.execSQL("ALTER TABLE " + Message.TABLENAME + " ADD COLUMN "
                    + Message.REMOTE_MSG_ID + " TEXT");
            db.execSQL("ALTER TABLE " + Contact.TABLENAME + " ADD COLUMN "
                    + Contact.AVATAR + " TEXT");
            db.execSQL("ALTER TABLE " + Account.TABLENAME + " ADD COLUMN "
                    + Account.AVATAR + " TEXT");
        }
        if (oldVersion < 8 && newVersion >= 8) {
            db.execSQL("ALTER TABLE " + Conversation.TABLENAME + " ADD COLUMN "
                    + Conversation.ATTRIBUTES + " TEXT");
        }
        if (oldVersion < 9 && newVersion >= 9) {
            db.execSQL("ALTER TABLE " + Contact.TABLENAME + " ADD COLUMN "
                    + Contact.LAST_TIME + " NUMBER");
            db.execSQL("ALTER TABLE " + Contact.TABLENAME + " ADD COLUMN "
                    + Contact.LAST_PRESENCE + " TEXT");
        }
        if (oldVersion < 10 && newVersion >= 10) {
            db.execSQL("ALTER TABLE " + Message.TABLENAME + " ADD COLUMN "
                    + Message.RELATIVE_FILE_PATH + " TEXT");
        }
        if (oldVersion < 11 && newVersion >= 11) {
            db.execSQL("ALTER TABLE " + Contact.TABLENAME + " ADD COLUMN "
                    + Contact.GROUPS + " TEXT");
            db.execSQL("delete from " + Contact.TABLENAME);
            db.execSQL("update " + Account.TABLENAME + " set " + Account.ROSTERVERSION + " = NULL");
        }
        if (oldVersion < 12 && newVersion >= 12) {
            db.execSQL("ALTER TABLE " + Message.TABLENAME + " ADD COLUMN "
                    + Message.SERVER_MSG_ID + " TEXT");
        }
        if (oldVersion < 13 && newVersion >= 13) {
            db.execSQL("delete from " + Contact.TABLENAME);
            db.execSQL("update " + Account.TABLENAME + " set " + Account.ROSTERVERSION + " = NULL");
        }
        if (oldVersion < 14 && newVersion >= 14) {
            canonicalizeJids(db);
        }
        if (oldVersion < 15 && newVersion >= 15) {
            recreateAxolotlDb(db);
            db.execSQL("ALTER TABLE " + Message.TABLENAME + " ADD COLUMN "
                    + Message.FINGERPRINT + " TEXT");
        } else if (oldVersion < 22 && newVersion >= 22) {
            db.execSQL("ALTER TABLE " + SQLiteAxolotlStore.IDENTITIES_TABLENAME + " ADD COLUMN " + SQLiteAxolotlStore.CERTIFICATE);
        }
        if (oldVersion < 16 && newVersion >= 16) {
            db.execSQL("ALTER TABLE " + Message.TABLENAME + " ADD COLUMN "
                    + Message.CARBON + " INTEGER");
        }
        if (oldVersion < 19 && newVersion >= 19) {
            db.execSQL("ALTER TABLE " + Account.TABLENAME + " ADD COLUMN " + Account.DISPLAY_NAME + " TEXT");
        }
        if (oldVersion < 20 && newVersion >= 20) {
            db.execSQL("ALTER TABLE " + Account.TABLENAME + " ADD COLUMN " + Account.HOSTNAME + " TEXT");
            db.execSQL("ALTER TABLE " + Account.TABLENAME + " ADD COLUMN " + Account.PORT + " NUMBER DEFAULT 5222");
        }
        if (oldVersion < 26 && newVersion >= 26) {
            db.execSQL("ALTER TABLE " + Account.TABLENAME + " ADD COLUMN " + Account.STATUS + " TEXT");
            db.execSQL("ALTER TABLE " + Account.TABLENAME + " ADD COLUMN " + Account.STATUS_MESSAGE + " TEXT");
        }
        /* Any migrations that alter the Account table need to happen BEFORE this migration, as it
		 * depends on account de-serialization.
		 */
        if (oldVersion < 17 && newVersion >= 17) {
            List<Account> accounts = getAccounts(db);
            for (Account account : accounts) {
                String ownDeviceIdString = account.getKey(SQLiteAxolotlStore.JSONKEY_REGISTRATION_ID);
                if (ownDeviceIdString == null) {
                    continue;
                }
                int ownDeviceId = Integer.valueOf(ownDeviceIdString);
                AxolotlAddress ownAddress = new AxolotlAddress(account.getJid().toBareJid().toPreppedString(), ownDeviceId);
                deleteSession(db, account, ownAddress);
                IdentityKeyPair identityKeyPair = loadOwnIdentityKeyPair(db, account);
                if (identityKeyPair != null) {
                    String[] selectionArgs = {
                            account.getUuid(),
                            identityKeyPair.getPublicKey().getFingerprint().replaceAll("\\s", "")
                    };
                    ContentValues values = new ContentValues();
                    values.put(SQLiteAxolotlStore.TRUSTED, 2);
                    db.update(SQLiteAxolotlStore.IDENTITIES_TABLENAME, values,
                            SQLiteAxolotlStore.ACCOUNT + " = ? AND "
                                    + SQLiteAxolotlStore.FINGERPRINT + " = ? ",
                            selectionArgs);
                } else {
                    Log.d(Config.LOGTAG, account.getJid().toBareJid() + ": could not load own identity key pair");
                }
            }
        }
        if (oldVersion < 18 && newVersion >= 18) {
            db.execSQL("ALTER TABLE " + Message.TABLENAME + " ADD COLUMN " + Message.READ + " NUMBER DEFAULT 1");
        }

        if (oldVersion < 21 && newVersion >= 21) {
            List<Account> accounts = getAccounts(db);
            for (Account account : accounts) {
                account.unsetPgpSignature();
                db.update(Account.TABLENAME, account.getContentValues(), Account.UUID
                        + "=?", new String[]{account.getUuid()});
            }
        }

        if (oldVersion < 23 && newVersion >= 23) {
            db.execSQL(CREATE_DISCOVERY_RESULTS_STATEMENT);
        }

        if (oldVersion < 24 && newVersion >= 24) {
            db.execSQL("ALTER TABLE " + Message.TABLENAME + " ADD COLUMN " + Message.EDITED + " TEXT");
        }

        if (oldVersion < 25 && newVersion >= 25) {
            db.execSQL("ALTER TABLE " + Message.TABLENAME + " ADD COLUMN " + Message.OOB + " INTEGER");
        }

        if (oldVersion < 26 && newVersion >= 26) {
            db.execSQL(CREATE_PRESENCE_TEMPLATES_STATEMENT);
        }

        if (oldVersion < 27 && newVersion >= 27) {
            db.execSQL("DELETE FROM " + ServiceDiscoveryResult.TABLENAME);
        }

        if (oldVersion < 28 && newVersion >= 28) {
            canonicalizeJids(db);
        }

        if (oldVersion < 29 && newVersion >= 29) {
            db.execSQL("ALTER TABLE " + Message.TABLENAME + " ADD COLUMN " + Message.ERROR_MESSAGE + " TEXT");
        }

        if (oldVersion < 30 && newVersion >= 30) {
            db.execSQL(CREATE_START_TIMES_TABLE);
        }
        if (oldVersion < 31 && newVersion >= 31) {
            db.execSQL("ALTER TABLE " + SQLiteAxolotlStore.IDENTITIES_TABLENAME + " ADD COLUMN " + SQLiteAxolotlStore.TRUST + " TEXT");
            db.execSQL("ALTER TABLE " + SQLiteAxolotlStore.IDENTITIES_TABLENAME + " ADD COLUMN " + SQLiteAxolotlStore.ACTIVE + " NUMBER");
            HashMap<Integer, ContentValues> migration = new HashMap<>();
            migration.put(0, createFingerprintStatusContentValues(FingerprintStatus.Trust.TRUSTED, true));
            migration.put(1, createFingerprintStatusContentValues(FingerprintStatus.Trust.TRUSTED, true));
            migration.put(2, createFingerprintStatusContentValues(FingerprintStatus.Trust.UNTRUSTED, true));
            migration.put(3, createFingerprintStatusContentValues(FingerprintStatus.Trust.COMPROMISED, false));
            migration.put(4, createFingerprintStatusContentValues(FingerprintStatus.Trust.TRUSTED, false));
            migration.put(5, createFingerprintStatusContentValues(FingerprintStatus.Trust.TRUSTED, false));
            migration.put(6, createFingerprintStatusContentValues(FingerprintStatus.Trust.UNTRUSTED, false));
            migration.put(7, createFingerprintStatusContentValues(FingerprintStatus.Trust.VERIFIED_X509, true));
            migration.put(8, createFingerprintStatusContentValues(FingerprintStatus.Trust.VERIFIED_X509, false));
            for (Map.Entry<Integer, ContentValues> entry : migration.entrySet()) {
                String whereClause = SQLiteAxolotlStore.TRUSTED + "=?";
                String[] where = {String.valueOf(entry.getKey())};
                db.update(SQLiteAxolotlStore.IDENTITIES_TABLENAME, entry.getValue(), whereClause, where);
            }
        }
        if (oldVersion < 32 && newVersion >= 32) {
            db.execSQL("ALTER TABLE "+ SQLiteAxolotlStore.IDENTITIES_TABLENAME + " ADD COLUMN "+SQLiteAxolotlStore.LAST_ACTIVATION + " NUMBER");
            ContentValues defaults = new ContentValues();
            defaults.put(SQLiteAxolotlStore.LAST_ACTIVATION,System.currentTimeMillis());
            db.update(SQLiteAxolotlStore.IDENTITIES_TABLENAME,defaults,null,null);
        }
        if (oldVersion < 33 && newVersion >= 33) {
            String whereClause = SQLiteAxolotlStore.OWN+"=1";
            db.update(SQLiteAxolotlStore.IDENTITIES_TABLENAME,createFingerprintStatusContentValues(FingerprintStatus.Trust.VERIFIED,true),whereClause,null);
        }
        if (oldVersion < 34 && newVersion >= 34) {
            db.execSQL(CREATE_MESSAGE_TIME_INDEX);
            // do nothing else at this point because we have seperated videos, images, audios and other files in different directories
        }
    }

    private static ContentValues createFingerprintStatusContentValues(FingerprintStatus.Trust trust, boolean active) {
        ContentValues values = new ContentValues();
        values.put(SQLiteAxolotlStore.TRUST, trust.toString());
        values.put(SQLiteAxolotlStore.ACTIVE, active ? 1 : 0);
        return values;
    }

    private void canonicalizeJids(SQLiteDatabase db) {
        // migrate db to new, canonicalized JID domainpart representation

        // Conversation table
        Cursor cursor = db.rawQuery("select * from " + Conversation.TABLENAME, new String[0]);
        while (cursor.moveToNext()) {
            String newJid;
            try {
                newJid = Jid.fromString(
                        cursor.getString(cursor.getColumnIndex(Conversation.CONTACTJID))
                ).toPreppedString();
            } catch (InvalidJidException ignored) {
                Log.e(Config.LOGTAG, "Failed to migrate Conversation CONTACTJID "
                        + cursor.getString(cursor.getColumnIndex(Conversation.CONTACTJID))
                        + ": " + ignored + ". Skipping...");
                continue;
            }

            String updateArgs[] = {
                    newJid,
                    cursor.getString(cursor.getColumnIndex(Conversation.UUID)),
            };
            db.execSQL("update " + Conversation.TABLENAME
                    + " set " + Conversation.CONTACTJID + " = ? "
                    + " where " + Conversation.UUID + " = ?", updateArgs);
        }
        cursor.close();

        // Contact table
        cursor = db.rawQuery("select * from " + Contact.TABLENAME, new String[0]);
        while (cursor.moveToNext()) {
            String newJid;
            try {
                newJid = Jid.fromString(
                        cursor.getString(cursor.getColumnIndex(Contact.JID))
                ).toPreppedString();
            } catch (InvalidJidException ignored) {
                Log.e(Config.LOGTAG, "Failed to migrate Contact JID "
                        + cursor.getString(cursor.getColumnIndex(Contact.JID))
                        + ": " + ignored + ". Skipping...");
                continue;
            }

            String updateArgs[] = {
                    newJid,
                    cursor.getString(cursor.getColumnIndex(Contact.ACCOUNT)),
                    cursor.getString(cursor.getColumnIndex(Contact.JID)),
            };
            db.execSQL("update " + Contact.TABLENAME
                    + " set " + Contact.JID + " = ? "
                    + " where " + Contact.ACCOUNT + " = ? "
                    + " AND " + Contact.JID + " = ?", updateArgs);
        }
        cursor.close();

        // Account table
        cursor = db.rawQuery("select * from " + Account.TABLENAME, new String[0]);
        while (cursor.moveToNext()) {
            String newServer;
            try {
                newServer = Jid.fromParts(
                        cursor.getString(cursor.getColumnIndex(Account.USERNAME)),
                        cursor.getString(cursor.getColumnIndex(Account.SERVER)),
                        "mobile"
                ).getDomainpart();
            } catch (InvalidJidException ignored) {
                Log.e(Config.LOGTAG, "Failed to migrate Account SERVER "
                        + cursor.getString(cursor.getColumnIndex(Account.SERVER))
                        + ": " + ignored + ". Skipping...");
                continue;
            }

            String updateArgs[] = {
                    newServer,
                    cursor.getString(cursor.getColumnIndex(Account.UUID)),
            };
            db.execSQL("update " + Account.TABLENAME
                    + " set " + Account.SERVER + " = ? "
                    + " where " + Account.UUID + " = ?", updateArgs);
        }
        cursor.close();
    }

    public static synchronized DatabaseBackend getInstance(Context context) {
        if (instance == null) {
            instance = new DatabaseBackend(context);
        }
        return instance;
    }

    public void createConversation(Conversation conversation) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.insert(Conversation.TABLENAME, null, conversation.getContentValues());
    }

    public void createMessage(Message message) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.insert(Message.TABLENAME, null, message.getContentValues());
    }

    public void createAccount(Account account) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.insert(Account.TABLENAME, null, account.getContentValues());
    }

    public void insertDiscoveryResult(ServiceDiscoveryResult result) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.insert(ServiceDiscoveryResult.TABLENAME, null, result.getContentValues());
    }

    public ServiceDiscoveryResult findDiscoveryResult(final String hash, final String ver) {
        SQLiteDatabase db = this.getReadableDatabase();
        String[] selectionArgs = {hash, ver};
        Cursor cursor = db.query(ServiceDiscoveryResult.TABLENAME, null,
                ServiceDiscoveryResult.HASH + "=? AND " + ServiceDiscoveryResult.VER + "=?",
                selectionArgs, null, null, null);
        if (cursor.getCount() == 0) {
            cursor.close();
            return null;
        }
        cursor.moveToFirst();

        ServiceDiscoveryResult result = null;
        try {
            result = new ServiceDiscoveryResult(cursor);
        } catch (JSONException e) { /* result is still null */ }

        cursor.close();
        return result;
    }

    public void insertPresenceTemplate(PresenceTemplate template) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.insert(PresenceTemplate.TABELNAME, null, template.getContentValues());
    }

    public List<PresenceTemplate> getPresenceTemplates() {
        ArrayList<PresenceTemplate> templates = new ArrayList<>();
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.query(PresenceTemplate.TABELNAME, null, null, null, null, null, PresenceTemplate.LAST_USED + " desc");
        while (cursor.moveToNext()) {
            templates.add(PresenceTemplate.fromCursor(cursor));
        }
        cursor.close();
        return templates;
    }

    public void deletePresenceTemplate(PresenceTemplate template) {
        Log.d(Config.LOGTAG, "deleting presence template with uuid " + template.getUuid());
        SQLiteDatabase db = this.getWritableDatabase();
        String where = PresenceTemplate.UUID + "=?";
        String[] whereArgs = {template.getUuid()};
        db.delete(PresenceTemplate.TABELNAME, where, whereArgs);
    }

    public CopyOnWriteArrayList<Conversation> getConversations(int status) {
        CopyOnWriteArrayList<Conversation> list = new CopyOnWriteArrayList<>();
        SQLiteDatabase db = this.getReadableDatabase();
        String[] selectionArgs = {Integer.toString(status)};
        Cursor cursor = db.rawQuery("select * from " + Conversation.TABLENAME
                + " where " + Conversation.STATUS + " = ? order by "
                + Conversation.CREATED + " desc", selectionArgs);
        while (cursor.moveToNext()) {
            list.add(Conversation.fromCursor(cursor));
        }
        cursor.close();
        return list;
    }

    public ArrayList<Message> getMessages(Conversation conversations, int limit) {
        return getMessages(conversations, limit, -1);
    }

    public ArrayList<Message> getMessages(Conversation conversation, int limit,
                                          long timestamp) {
        ArrayList<Message> list = new ArrayList<>();
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor;
        if (timestamp == -1) {
            String[] selectionArgs = {conversation.getUuid()};
            cursor = db.query(Message.TABLENAME, null, Message.CONVERSATION
                    + "=?", selectionArgs, null, null, Message.TIME_SENT
                    + " DESC", String.valueOf(limit));
        } else {
            String[] selectionArgs = {conversation.getUuid(),
                    Long.toString(timestamp)};
            cursor = db.query(Message.TABLENAME, null, Message.CONVERSATION
                            + "=? and " + Message.TIME_SENT + "<?", selectionArgs,
                    null, null, Message.TIME_SENT + " DESC",
                    String.valueOf(limit));
        }
        if (cursor.getCount() > 0) {
            cursor.moveToLast();
            do {
                Message message = Message.fromCursor(cursor);
                message.setConversation(conversation);
                list.add(message);
            } while (cursor.moveToPrevious());
        }
        cursor.close();
        return list;
    }

    public Iterable<Message> getMessagesIterable(final Conversation conversation) {
        return new Iterable<Message>() {
            @Override
            public Iterator<Message> iterator() {
                class MessageIterator implements Iterator<Message> {
                    SQLiteDatabase db = getReadableDatabase();
                    String[] selectionArgs = {conversation.getUuid()};
                    Cursor cursor = db.query(Message.TABLENAME, null, Message.CONVERSATION
                            + "=?", selectionArgs, null, null, Message.TIME_SENT
                            + " ASC", null);

                    public MessageIterator() {
                        cursor.moveToFirst();
                    }

                    @Override
                    public boolean hasNext() {
                        return !cursor.isAfterLast();
                    }

                    @Override
                    public Message next() {
                        Message message = Message.fromCursor(cursor);
                        cursor.moveToNext();
                        return message;
                    }

                    @Override
                    public void remove() {
                        throw new UnsupportedOperationException();
                    }
                }
                return new MessageIterator();
            }
        };
    }

    public Conversation findConversation(final Account account, final Jid contactJid) {
        SQLiteDatabase db = this.getReadableDatabase();
        String[] selectionArgs = {account.getUuid(),
                contactJid.toBareJid().toPreppedString() + "/%",
                contactJid.toBareJid().toPreppedString()
        };
        Cursor cursor = db.query(Conversation.TABLENAME, null,
                Conversation.ACCOUNT + "=? AND (" + Conversation.CONTACTJID
                        + " like ? OR " + Conversation.CONTACTJID + "=?)", selectionArgs, null, null, null);
        if (cursor.getCount() == 0) {
            cursor.close();
            return null;
        }
        cursor.moveToFirst();
        Conversation conversation = Conversation.fromCursor(cursor);
        cursor.close();
        return conversation;
    }

    public void updateConversation(final Conversation conversation) {
        final SQLiteDatabase db = this.getWritableDatabase();
        final String[] args = {conversation.getUuid()};
        db.update(Conversation.TABLENAME, conversation.getContentValues(),
                Conversation.UUID + "=?", args);
    }

    public List<Account> getAccounts() {
        SQLiteDatabase db = this.getReadableDatabase();
        return getAccounts(db);
    }

    private List<Account> getAccounts(SQLiteDatabase db) {
        List<Account> list = new ArrayList<>();
        Cursor cursor = db.query(Account.TABLENAME, null, null, null, null,
                null, null);
        while (cursor.moveToNext()) {
            list.add(Account.fromCursor(cursor));
        }
        cursor.close();
        return list;
    }

    public boolean updateAccount(Account account) {
        SQLiteDatabase db = this.getWritableDatabase();
        String[] args = {account.getUuid()};
        final int rows = db.update(Account.TABLENAME, account.getContentValues(), Account.UUID + "=?", args);
        return rows == 1;
    }

    public boolean deleteAccount(Account account) {
        SQLiteDatabase db = this.getWritableDatabase();
        String[] args = {account.getUuid()};
        final int rows = db.delete(Account.TABLENAME, Account.UUID + "=?", args);
        return rows == 1;
    }

    public boolean hasEnabledAccounts() {
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery("select count(" + Account.UUID + ")  from "
                + Account.TABLENAME + " where not options & (1 <<1)", null);
        try {
            cursor.moveToFirst();
            int count = cursor.getInt(0);
            return (count > 0);
        } catch (SQLiteCantOpenDatabaseException e) {
            return true; // better safe than sorry
        } catch (RuntimeException e) {
            return true; // better safe than sorry
        } finally {
            if (cursor != null) {
                cursor.close();
            }
        }
    }

    @Override
    public SQLiteDatabase getWritableDatabase() {
        SQLiteDatabase db = super.getWritableDatabase();
        db.execSQL("PRAGMA foreign_keys=ON;");
        return db;
    }

    public void updateMessage(Message message) {
        SQLiteDatabase db = this.getWritableDatabase();
        String[] args = {message.getUuid()};
        db.update(Message.TABLENAME, message.getContentValues(), Message.UUID
                + "=?", args);
    }

    public void updateMessage(Message message, String uuid) {
        SQLiteDatabase db = this.getWritableDatabase();
        String[] args = {uuid};
        db.update(Message.TABLENAME, message.getContentValues(), Message.UUID
                + "=?", args);
    }

    public void readRoster(Roster roster) {
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor;
        String args[] = {roster.getAccount().getUuid()};
        cursor = db.query(Contact.TABLENAME, null, Contact.ACCOUNT + "=?", args, null, null, null);
        while (cursor.moveToNext()) {
            roster.initContact(Contact.fromCursor(cursor));
        }
        cursor.close();
    }

    public void writeRoster(final Roster roster) {
        final Account account = roster.getAccount();
        final SQLiteDatabase db = this.getWritableDatabase();
        db.beginTransaction();
        for (Contact contact : roster.getContacts()) {
            if (contact.getOption(Contact.Options.IN_ROSTER)) {
                db.insert(Contact.TABLENAME, null, contact.getContentValues());
            } else {
                String where = Contact.ACCOUNT + "=? AND " + Contact.JID + "=?";
                String[] whereArgs = {account.getUuid(), contact.getJid().toPreppedString()};
                db.delete(Contact.TABLENAME, where, whereArgs);
            }
        }
        db.setTransactionSuccessful();
        db.endTransaction();
        account.setRosterVersion(roster.getVersion());
        updateAccount(account);
    }

    public void deleteMessagesInConversation(Conversation conversation) {
        SQLiteDatabase db = this.getWritableDatabase();
        String[] args = {conversation.getUuid()};
        db.delete(Message.TABLENAME, Message.CONVERSATION + "=?", args);
    }

    public boolean expireOldMessages(long timestamp) {
        String where = Message.TIME_SENT + "<?";
        String[] whereArgs = {String.valueOf(timestamp)};
        SQLiteDatabase db = this.getReadableDatabase();
        return db.delete(Message.TABLENAME, where, whereArgs) > 0;
    }

    public Pair<Long, String> getLastMessageReceived(Account account) {
        Cursor cursor = null;
        try {
            SQLiteDatabase db = this.getReadableDatabase();
            String sql = "select messages.timeSent,messages.serverMsgId from accounts join conversations on accounts.uuid=conversations.accountUuid join messages on conversations.uuid=messages.conversationUuid where accounts.uuid=? and (messages.status=0 or messages.carbon=1 or messages.serverMsgId not null) order by messages.timesent desc limit 1";
            String[] args = {account.getUuid()};
            cursor = db.rawQuery(sql, args);
            if (cursor.getCount() == 0) {
                return null;
            } else {
                cursor.moveToFirst();
                return new Pair<>(cursor.getLong(0), cursor.getString(1));
            }
        } catch (Exception e) {
            return null;
        } finally {
            if (cursor != null) {
                cursor.close();
            }
        }
    }

    public long getLastTimeFingerprintUsed(Account account, String fingerprint) {
        String SQL = "select messages.timeSent from accounts join conversations on accounts.uuid=conversations.accountUuid join messages on conversations.uuid=messages.conversationUuid where accounts.uuid=? and messages.axolotl_fingerprint=? order by messages.timesent desc limit 1";
        String[] args = {account.getUuid(), fingerprint};
        Cursor cursor = getReadableDatabase().rawQuery(SQL,args);
        long time;
        if (cursor.moveToFirst()) {
            time = cursor.getLong(0);
        } else {
            time = 0;
        }
        cursor.close();
        return time;
    }

    public Pair<Long, String> getLastClearDate(Account account) {
        SQLiteDatabase db = this.getReadableDatabase();
        String[] columns = {Conversation.ATTRIBUTES};
        String selection = Conversation.ACCOUNT + "=?";
        String[] args = {account.getUuid()};
        Cursor cursor = db.query(Conversation.TABLENAME, columns, selection, args, null, null, null);
        long maxClearDate = 0;
        while (cursor.moveToNext()) {
            try {
                final JSONObject jsonObject = new JSONObject(cursor.getString(0));
                maxClearDate = Math.max(maxClearDate, jsonObject.getLong(Conversation.ATTRIBUTE_LAST_CLEAR_HISTORY));
            } catch (Exception e) {
                //ignored
            }
        }
        cursor.close();
        return new Pair<>(maxClearDate, null);
    }

    private Cursor getCursorForSession(Account account, AxolotlAddress contact) {
        final SQLiteDatabase db = this.getReadableDatabase();
        String[] selectionArgs = {account.getUuid(),
                contact.getName(),
                Integer.toString(contact.getDeviceId())};
        return db.query(SQLiteAxolotlStore.SESSION_TABLENAME,
                null,
                SQLiteAxolotlStore.ACCOUNT + " = ? AND "
                        + SQLiteAxolotlStore.NAME + " = ? AND "
                        + SQLiteAxolotlStore.DEVICE_ID + " = ? ",
                selectionArgs,
                null, null, null);
    }

    public SessionRecord loadSession(Account account, AxolotlAddress contact) {
        SessionRecord session = null;
        Cursor cursor = getCursorForSession(account, contact);
        if (cursor.getCount() != 0) {
            cursor.moveToFirst();
            try {
                session = new SessionRecord(Base64.decode(cursor.getString(cursor.getColumnIndex(SQLiteAxolotlStore.KEY)), Base64.DEFAULT));
            } catch (IOException e) {
                cursor.close();
                throw new AssertionError(e);
            }
        }
        cursor.close();
        return session;
    }

    public List<Integer> getSubDeviceSessions(Account account, AxolotlAddress contact) {
        final SQLiteDatabase db = this.getReadableDatabase();
        return getSubDeviceSessions(db, account, contact);
    }

    private List<Integer> getSubDeviceSessions(SQLiteDatabase db, Account account, AxolotlAddress contact) {
        List<Integer> devices = new ArrayList<>();
        String[] columns = {SQLiteAxolotlStore.DEVICE_ID};
        String[] selectionArgs = {account.getUuid(),
                contact.getName()};
        Cursor cursor = db.query(SQLiteAxolotlStore.SESSION_TABLENAME,
                columns,
                SQLiteAxolotlStore.ACCOUNT + " = ? AND "
                        + SQLiteAxolotlStore.NAME + " = ?",
                selectionArgs,
                null, null, null);

        while (cursor.moveToNext()) {
            devices.add(cursor.getInt(
                    cursor.getColumnIndex(SQLiteAxolotlStore.DEVICE_ID)));
        }

        cursor.close();
        return devices;
    }

    public boolean containsSession(Account account, AxolotlAddress contact) {
        Cursor cursor = getCursorForSession(account, contact);
        int count = cursor.getCount();
        cursor.close();
        return count != 0;
    }

    public void storeSession(Account account, AxolotlAddress contact, SessionRecord session) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(SQLiteAxolotlStore.NAME, contact.getName());
        values.put(SQLiteAxolotlStore.DEVICE_ID, contact.getDeviceId());
        values.put(SQLiteAxolotlStore.KEY, Base64.encodeToString(session.serialize(), Base64.DEFAULT));
        values.put(SQLiteAxolotlStore.ACCOUNT, account.getUuid());
        db.insert(SQLiteAxolotlStore.SESSION_TABLENAME, null, values);
    }

    public void deleteSession(Account account, AxolotlAddress contact) {
        SQLiteDatabase db = this.getWritableDatabase();
        deleteSession(db, account, contact);
    }

    private void deleteSession(SQLiteDatabase db, Account account, AxolotlAddress contact) {
        String[] args = {account.getUuid(),
                contact.getName(),
                Integer.toString(contact.getDeviceId())};
        db.delete(SQLiteAxolotlStore.SESSION_TABLENAME,
                SQLiteAxolotlStore.ACCOUNT + " = ? AND "
                        + SQLiteAxolotlStore.NAME + " = ? AND "
                        + SQLiteAxolotlStore.DEVICE_ID + " = ? ",
                args);
    }

    public void deleteAllSessions(Account account, AxolotlAddress contact) {
        SQLiteDatabase db = this.getWritableDatabase();
        String[] args = {account.getUuid(), contact.getName()};
        db.delete(SQLiteAxolotlStore.SESSION_TABLENAME,
                SQLiteAxolotlStore.ACCOUNT + "=? AND "
                        + SQLiteAxolotlStore.NAME + " = ?",
                args);
    }

    private Cursor getCursorForPreKey(Account account, int preKeyId) {
        SQLiteDatabase db = this.getReadableDatabase();
        String[] columns = {SQLiteAxolotlStore.KEY};
        String[] selectionArgs = {account.getUuid(), Integer.toString(preKeyId)};
        Cursor cursor = db.query(SQLiteAxolotlStore.PREKEY_TABLENAME,
                columns,
                SQLiteAxolotlStore.ACCOUNT + "=? AND "
                        + SQLiteAxolotlStore.ID + "=?",
                selectionArgs,
                null, null, null);

        return cursor;
    }

    public PreKeyRecord loadPreKey(Account account, int preKeyId) {
        PreKeyRecord record = null;
        Cursor cursor = getCursorForPreKey(account, preKeyId);
        if (cursor.getCount() != 0) {
            cursor.moveToFirst();
            try {
                record = new PreKeyRecord(Base64.decode(cursor.getString(cursor.getColumnIndex(SQLiteAxolotlStore.KEY)), Base64.DEFAULT));
            } catch (IOException e) {
                throw new AssertionError(e);
            }
        }
        cursor.close();
        return record;
    }

    public boolean containsPreKey(Account account, int preKeyId) {
        Cursor cursor = getCursorForPreKey(account, preKeyId);
        int count = cursor.getCount();
        cursor.close();
        return count != 0;
    }

    public void storePreKey(Account account, PreKeyRecord record) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(SQLiteAxolotlStore.ID, record.getId());
        values.put(SQLiteAxolotlStore.KEY, Base64.encodeToString(record.serialize(), Base64.DEFAULT));
        values.put(SQLiteAxolotlStore.ACCOUNT, account.getUuid());
        db.insert(SQLiteAxolotlStore.PREKEY_TABLENAME, null, values);
    }

    public void deletePreKey(Account account, int preKeyId) {
        SQLiteDatabase db = this.getWritableDatabase();
        String[] args = {account.getUuid(), Integer.toString(preKeyId)};
        db.delete(SQLiteAxolotlStore.PREKEY_TABLENAME,
                SQLiteAxolotlStore.ACCOUNT + "=? AND "
                        + SQLiteAxolotlStore.ID + "=?",
                args);
    }

    private Cursor getCursorForSignedPreKey(Account account, int signedPreKeyId) {
        SQLiteDatabase db = this.getReadableDatabase();
        String[] columns = {SQLiteAxolotlStore.KEY};
        String[] selectionArgs = {account.getUuid(), Integer.toString(signedPreKeyId)};
        Cursor cursor = db.query(SQLiteAxolotlStore.SIGNED_PREKEY_TABLENAME,
                columns,
                SQLiteAxolotlStore.ACCOUNT + "=? AND " + SQLiteAxolotlStore.ID + "=?",
                selectionArgs,
                null, null, null);

        return cursor;
    }

    public SignedPreKeyRecord loadSignedPreKey(Account account, int signedPreKeyId) {
        SignedPreKeyRecord record = null;
        Cursor cursor = getCursorForSignedPreKey(account, signedPreKeyId);
        if (cursor.getCount() != 0) {
            cursor.moveToFirst();
            try {
                record = new SignedPreKeyRecord(Base64.decode(cursor.getString(cursor.getColumnIndex(SQLiteAxolotlStore.KEY)), Base64.DEFAULT));
            } catch (IOException e) {
                throw new AssertionError(e);
            }
        }
        cursor.close();
        return record;
    }

    public List<SignedPreKeyRecord> loadSignedPreKeys(Account account) {
        List<SignedPreKeyRecord> prekeys = new ArrayList<>();
        SQLiteDatabase db = this.getReadableDatabase();
        String[] columns = {SQLiteAxolotlStore.KEY};
        String[] selectionArgs = {account.getUuid()};
        Cursor cursor = db.query(SQLiteAxolotlStore.SIGNED_PREKEY_TABLENAME,
                columns,
                SQLiteAxolotlStore.ACCOUNT + "=?",
                selectionArgs,
                null, null, null);

        while (cursor.moveToNext()) {
            try {
                prekeys.add(new SignedPreKeyRecord(Base64.decode(cursor.getString(cursor.getColumnIndex(SQLiteAxolotlStore.KEY)), Base64.DEFAULT)));
            } catch (IOException ignored) {
            }
        }
        cursor.close();
        return prekeys;
    }

    public boolean containsSignedPreKey(Account account, int signedPreKeyId) {
        Cursor cursor = getCursorForPreKey(account, signedPreKeyId);
        int count = cursor.getCount();
        cursor.close();
        return count != 0;
    }

    public void storeSignedPreKey(Account account, SignedPreKeyRecord record) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(SQLiteAxolotlStore.ID, record.getId());
        values.put(SQLiteAxolotlStore.KEY, Base64.encodeToString(record.serialize(), Base64.DEFAULT));
        values.put(SQLiteAxolotlStore.ACCOUNT, account.getUuid());
        db.insert(SQLiteAxolotlStore.SIGNED_PREKEY_TABLENAME, null, values);
    }

    public void deleteSignedPreKey(Account account, int signedPreKeyId) {
        SQLiteDatabase db = this.getWritableDatabase();
        String[] args = {account.getUuid(), Integer.toString(signedPreKeyId)};
        db.delete(SQLiteAxolotlStore.SIGNED_PREKEY_TABLENAME,
                SQLiteAxolotlStore.ACCOUNT + "=? AND "
                        + SQLiteAxolotlStore.ID + "=?",
                args);
    }

    private Cursor getIdentityKeyCursor(Account account, String name, boolean own) {
        final SQLiteDatabase db = this.getReadableDatabase();
        return getIdentityKeyCursor(db, account, name, own);
    }

    private Cursor getIdentityKeyCursor(SQLiteDatabase db, Account account, String name, boolean own) {
        return getIdentityKeyCursor(db, account, name, own, null);
    }

    private Cursor getIdentityKeyCursor(Account account, String fingerprint) {
        final SQLiteDatabase db = this.getReadableDatabase();
        return getIdentityKeyCursor(db, account, fingerprint);
    }

    private Cursor getIdentityKeyCursor(SQLiteDatabase db, Account account, String fingerprint) {
        return getIdentityKeyCursor(db, account, null, null, fingerprint);
    }

    private Cursor getIdentityKeyCursor(SQLiteDatabase db, Account account, String name, Boolean own, String fingerprint) {
        String[] columns = {SQLiteAxolotlStore.TRUST,
                SQLiteAxolotlStore.ACTIVE,
                SQLiteAxolotlStore.LAST_ACTIVATION,
                SQLiteAxolotlStore.KEY};
        ArrayList<String> selectionArgs = new ArrayList<>(4);
        selectionArgs.add(account.getUuid());
        String selectionString = SQLiteAxolotlStore.ACCOUNT + " = ?";
        if (name != null) {
            selectionArgs.add(name);
            selectionString += " AND " + SQLiteAxolotlStore.NAME + " = ?";
        }
        if (fingerprint != null) {
            selectionArgs.add(fingerprint);
            selectionString += " AND " + SQLiteAxolotlStore.FINGERPRINT + " = ?";
        }
        if (own != null) {
            selectionArgs.add(own ? "1" : "0");
            selectionString += " AND " + SQLiteAxolotlStore.OWN + " = ?";
        }
        Cursor cursor = db.query(SQLiteAxolotlStore.IDENTITIES_TABLENAME,
                columns,
                selectionString,
                selectionArgs.toArray(new String[selectionArgs.size()]),
                null, null, null);

        return cursor;
    }

    public IdentityKeyPair loadOwnIdentityKeyPair(Account account) {
        SQLiteDatabase db = getReadableDatabase();
        return loadOwnIdentityKeyPair(db, account);
    }

    private IdentityKeyPair loadOwnIdentityKeyPair(SQLiteDatabase db, Account account) {
        String name = account.getJid().toBareJid().toPreppedString();
        IdentityKeyPair identityKeyPair = null;
        Cursor cursor = getIdentityKeyCursor(db, account, name, true);
        if (cursor.getCount() != 0) {
            cursor.moveToFirst();
            try {
                identityKeyPair = new IdentityKeyPair(Base64.decode(cursor.getString(cursor.getColumnIndex(SQLiteAxolotlStore.KEY)), Base64.DEFAULT));
            } catch (InvalidKeyException e) {
                Log.d(Config.LOGTAG, AxolotlService.getLogprefix(account) + "Encountered invalid IdentityKey in database for account" + account.getJid().toBareJid() + ", address: " + name);
            }
        }
        cursor.close();

        return identityKeyPair;
    }

    public Set<IdentityKey> loadIdentityKeys(Account account, String name) {
        return loadIdentityKeys(account, name, null);
    }

    public Set<IdentityKey> loadIdentityKeys(Account account, String name, FingerprintStatus status) {
        Set<IdentityKey> identityKeys = new HashSet<>();
        Cursor cursor = getIdentityKeyCursor(account, name, false);

        while (cursor.moveToNext()) {
            if (status != null && !FingerprintStatus.fromCursor(cursor).equals(status)) {
                continue;
            }
            try {
                String key = cursor.getString(cursor.getColumnIndex(SQLiteAxolotlStore.KEY));
                if (key != null) {
                    identityKeys.add(new IdentityKey(Base64.decode(key, Base64.DEFAULT), 0));
                } else {
                    Log.d(Config.LOGTAG, AxolotlService.getLogprefix(account) + "Missing key (possibly preverified) in database for account" + account.getJid().toBareJid() + ", address: " + name);
                }
            } catch (InvalidKeyException e) {
                Log.d(Config.LOGTAG, AxolotlService.getLogprefix(account) + "Encountered invalid IdentityKey in database for account" + account.getJid().toBareJid() + ", address: " + name);
            }
        }
        cursor.close();

        return identityKeys;
    }

    public long numTrustedKeys(Account account, String name) {
        SQLiteDatabase db = getReadableDatabase();
        String[] args = {
                account.getUuid(),
                name,
                FingerprintStatus.Trust.TRUSTED.toString(),
                FingerprintStatus.Trust.VERIFIED.toString(),
                FingerprintStatus.Trust.VERIFIED_X509.toString()
        };
        return DatabaseUtils.queryNumEntries(db, SQLiteAxolotlStore.IDENTITIES_TABLENAME,
                SQLiteAxolotlStore.ACCOUNT + " = ?"
                        + " AND " + SQLiteAxolotlStore.NAME + " = ?"
                        + " AND (" + SQLiteAxolotlStore.TRUST + " = ? OR " + SQLiteAxolotlStore.TRUST + " = ? OR " + SQLiteAxolotlStore.TRUST + " = ?)"
                        + " AND " + SQLiteAxolotlStore.ACTIVE + " > 0",
                args
        );
    }

    private void storeIdentityKey(Account account, String name, boolean own, String fingerprint, String base64Serialized, FingerprintStatus status) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(SQLiteAxolotlStore.ACCOUNT, account.getUuid());
        values.put(SQLiteAxolotlStore.NAME, name);
        values.put(SQLiteAxolotlStore.OWN, own ? 1 : 0);
        values.put(SQLiteAxolotlStore.FINGERPRINT, fingerprint);
        values.put(SQLiteAxolotlStore.KEY, base64Serialized);
        values.putAll(status.toContentValues());
        String where = SQLiteAxolotlStore.ACCOUNT + "=? AND " + SQLiteAxolotlStore.NAME + "=? AND " + SQLiteAxolotlStore.FINGERPRINT + " =?";
        String[] whereArgs = {account.getUuid(), name, fingerprint};
        int rows = db.update(SQLiteAxolotlStore.IDENTITIES_TABLENAME, values, where, whereArgs);
        if (rows == 0) {
            db.insert(SQLiteAxolotlStore.IDENTITIES_TABLENAME, null, values);
        }
    }

    public void storePreVerification(Account account, String name, String fingerprint, FingerprintStatus status) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(SQLiteAxolotlStore.ACCOUNT, account.getUuid());
        values.put(SQLiteAxolotlStore.NAME, name);
        values.put(SQLiteAxolotlStore.OWN, 0);
        values.put(SQLiteAxolotlStore.FINGERPRINT, fingerprint);
        values.putAll(status.toContentValues());
        db.insert(SQLiteAxolotlStore.IDENTITIES_TABLENAME, null, values);
    }

    public FingerprintStatus getFingerprintStatus(Account account, String fingerprint) {
        Cursor cursor = getIdentityKeyCursor(account, fingerprint);
        final FingerprintStatus status;
        if (cursor.getCount() > 0) {
            cursor.moveToFirst();
            status = FingerprintStatus.fromCursor(cursor);
        } else {
            status = null;
        }
        cursor.close();
        return status;
    }

    public boolean setIdentityKeyTrust(Account account, String fingerprint, FingerprintStatus fingerprintStatus) {
        SQLiteDatabase db = this.getWritableDatabase();
        return setIdentityKeyTrust(db, account, fingerprint, fingerprintStatus);
    }

    private boolean setIdentityKeyTrust(SQLiteDatabase db, Account account, String fingerprint, FingerprintStatus status) {
        String[] selectionArgs = {
                account.getUuid(),
                fingerprint
        };
        int rows = db.update(SQLiteAxolotlStore.IDENTITIES_TABLENAME, status.toContentValues(),
                SQLiteAxolotlStore.ACCOUNT + " = ? AND "
                        + SQLiteAxolotlStore.FINGERPRINT + " = ? ",
                selectionArgs);
        return rows == 1;
    }

    public boolean setIdentityKeyCertificate(Account account, String fingerprint, X509Certificate x509Certificate) {
        SQLiteDatabase db = this.getWritableDatabase();
        String[] selectionArgs = {
                account.getUuid(),
                fingerprint
        };
        try {
            ContentValues values = new ContentValues();
            values.put(SQLiteAxolotlStore.CERTIFICATE, x509Certificate.getEncoded());
            return db.update(SQLiteAxolotlStore.IDENTITIES_TABLENAME, values,
                    SQLiteAxolotlStore.ACCOUNT + " = ? AND "
                            + SQLiteAxolotlStore.FINGERPRINT + " = ? ",
                    selectionArgs) == 1;
        } catch (CertificateEncodingException e) {
            Log.d(Config.LOGTAG, "could not encode certificate");
            return false;
        }
    }

    public X509Certificate getIdentityKeyCertifcate(Account account, String fingerprint) {
        SQLiteDatabase db = this.getReadableDatabase();
        String[] selectionArgs = {
                account.getUuid(),
                fingerprint
        };
        String[] colums = {SQLiteAxolotlStore.CERTIFICATE};
        String selection = SQLiteAxolotlStore.ACCOUNT + " = ? AND " + SQLiteAxolotlStore.FINGERPRINT + " = ? ";
        Cursor cursor = db.query(SQLiteAxolotlStore.IDENTITIES_TABLENAME, colums, selection, selectionArgs, null, null, null);
        if (cursor.getCount() < 1) {
            return null;
        } else {
            cursor.moveToFirst();
            byte[] certificate = cursor.getBlob(cursor.getColumnIndex(SQLiteAxolotlStore.CERTIFICATE));
            cursor.close();
            if (certificate == null || certificate.length == 0) {
                return null;
            }
            try {
                CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
                return (X509Certificate) certificateFactory.generateCertificate(new ByteArrayInputStream(certificate));
            } catch (CertificateException e) {
                Log.d(Config.LOGTAG, "certificate exception " + e.getMessage());
                return null;
            }
        }
    }

    public void storeIdentityKey(Account account, String name, IdentityKey identityKey, FingerprintStatus status) {
        storeIdentityKey(account, name, false, identityKey.getFingerprint().replaceAll("\\s", ""), Base64.encodeToString(identityKey.serialize(), Base64.DEFAULT), status);
    }

    public void storeOwnIdentityKeyPair(Account account, IdentityKeyPair identityKeyPair) {
        storeIdentityKey(account, account.getJid().toBareJid().toPreppedString(), true, identityKeyPair.getPublicKey().getFingerprint().replaceAll("\\s", ""), Base64.encodeToString(identityKeyPair.serialize(), Base64.DEFAULT), FingerprintStatus.createActiveVerified(false));
    }

    public void recreateAxolotlDb(SQLiteDatabase db) {
        Log.d(Config.LOGTAG, AxolotlService.LOGPREFIX + " : " + ">>> (RE)CREATING AXOLOTL DATABASE <<<");
        db.execSQL("DROP TABLE IF EXISTS " + SQLiteAxolotlStore.SESSION_TABLENAME);
        db.execSQL(CREATE_SESSIONS_STATEMENT);
        db.execSQL("DROP TABLE IF EXISTS " + SQLiteAxolotlStore.PREKEY_TABLENAME);
        db.execSQL(CREATE_PREKEYS_STATEMENT);
        db.execSQL("DROP TABLE IF EXISTS " + SQLiteAxolotlStore.SIGNED_PREKEY_TABLENAME);
        db.execSQL(CREATE_SIGNED_PREKEYS_STATEMENT);
        db.execSQL("DROP TABLE IF EXISTS " + SQLiteAxolotlStore.IDENTITIES_TABLENAME);
        db.execSQL(CREATE_IDENTITIES_STATEMENT);
    }

    public void wipeAxolotlDb(Account account) {
        String accountName = account.getUuid();
        Log.d(Config.LOGTAG, AxolotlService.getLogprefix(account) + ">>> WIPING AXOLOTL DATABASE FOR ACCOUNT " + accountName + " <<<");
        SQLiteDatabase db = this.getWritableDatabase();
        String[] deleteArgs = {
                accountName
        };
        db.delete(SQLiteAxolotlStore.SESSION_TABLENAME,
                SQLiteAxolotlStore.ACCOUNT + " = ?",
                deleteArgs);
        db.delete(SQLiteAxolotlStore.PREKEY_TABLENAME,
                SQLiteAxolotlStore.ACCOUNT + " = ?",
                deleteArgs);
        db.delete(SQLiteAxolotlStore.SIGNED_PREKEY_TABLENAME,
                SQLiteAxolotlStore.ACCOUNT + " = ?",
                deleteArgs);
        db.delete(SQLiteAxolotlStore.IDENTITIES_TABLENAME,
                SQLiteAxolotlStore.ACCOUNT + " = ?",
                deleteArgs);
    }

    public boolean startTimeCountExceedsThreshold() {
        SQLiteDatabase db = this.getWritableDatabase();
        long cleanBeforeTimestamp = System.currentTimeMillis() - Config.FREQUENT_RESTARTS_DETECTION_WINDOW;
        db.execSQL("delete from " + START_TIMES_TABLE + " where timestamp < " + cleanBeforeTimestamp);
        ContentValues values = new ContentValues();
        values.put("timestamp", System.currentTimeMillis());
        db.insert(START_TIMES_TABLE, null, values);
        String[] columns = new String[]{"count(timestamp)"};
        Cursor cursor = db.query(START_TIMES_TABLE, columns, null, null, null, null, null);
        int count;
        if (cursor.moveToFirst()) {
            count = cursor.getInt(0);
        } else {
            count = 0;
        }
        cursor.close();
        Log.d(Config.LOGTAG, "start time counter reached " + count);
        return count >= Config.FREQUENT_RESTARTS_THRESHOLD;
    }

    public void clearStartTimeCounter(boolean justOne) {
        SQLiteDatabase db = this.getWritableDatabase();
        if (justOne) {
            db.execSQL("delete from "+START_TIMES_TABLE+" where timestamp in (select timestamp from "+START_TIMES_TABLE+" order by timestamp desc limit 1)");
            Log.d(Config.LOGTAG,"do not count start up after being swiped away");
        } else {
            Log.d(Config.LOGTAG,"resetting start time counter");
            db.execSQL("delete from " + START_TIMES_TABLE);
        }
    }
}