Green DAO Migrate Helper class

GreenDAOMigrateHelper

/**
 * Created by umesh0492 on 15/02/16.
 */

public class GreenDAOMigrateHelper {
    private static final String CONVERSION_CLASS_NOT_FOUND_EXCEPTION = "MIGRATION HELPER - CLASS DOESN'T MATCH WITH THE CURRENT PARAMETERS";
    private static GreenDAOMigrateHelper instance;

    public static GreenDAOMigrateHelper getInstance () {
        if (instance == null) {
            instance = new GreenDAOMigrateHelper ();
        }
        return instance;
    }

    public void migrate (Database db, Context context) {
        DaoMaster.dropAllTables (db, true);
        DaoMaster.createAllTables (db, false);

        SharedPreferences prefs =
                PreferenceManager.getDefaultSharedPreferences (context);
        prefs.edit ().clear ().commit ();

    }

    public void migrateLatest (Database db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        generateTempTables (db, daoClasses);
        DaoMaster.dropAllTables (db, true);
        DaoMaster.createAllTables (db, false);
        restoreData (db, daoClasses);
    }

    //generate AND copy values
    private void generateTempTables (Database db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        for (int i = 0; i < daoClasses.length; i++) {
            DaoConfig daoConfig = new DaoConfig (db, daoClasses[i]);

            String divider = "";
            String tableName = daoConfig.tablename;
            String tempTableName = daoConfig.tablename.concat ("_TEMP");
            ArrayList<String> properties = new ArrayList<> ();

            StringBuilder createTableStringBuilder = new StringBuilder ();

            createTableStringBuilder.append ("CREATE TABLE ").append (tempTableName).append (" (");

            for (int j = 0; j < daoConfig.properties.length; j++) {
                String columnName = daoConfig.properties[j].columnName;
                if (getColumns (db, tableName).contains (columnName)) {
                    properties.add (columnName);

                    String type = null;

                    try {
                        type = getTypeByClass (daoConfig.properties[j].type);
                    } catch (Exception exception) {
                        //Sentry.captureException (exception);
                    }

                    createTableStringBuilder.append (divider).append (columnName).append (" ").append (type);

                    if (daoConfig.properties[j].primaryKey) {
                        createTableStringBuilder.append (" PRIMARY KEY");
                    }

                    divider = ",";
                }
            }
            createTableStringBuilder.append (");");

            Log.e ("Table statement", createTableStringBuilder.toString ());

            db.execSQL (createTableStringBuilder.toString ());

            StringBuilder insertTableStringBuilder = new StringBuilder ();

            insertTableStringBuilder.append ("INSERT INTO ").append (tempTableName).append (" (");
            insertTableStringBuilder.append (TextUtils.join (",", properties));
            insertTableStringBuilder.append (") SELECT ");
            insertTableStringBuilder.append (TextUtils.join (",", properties));
            insertTableStringBuilder.append (" FROM ").append (tableName).append (";");

            db.execSQL (insertTableStringBuilder.toString ());
        }
    }

    private void restoreData (Database db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        for (int i = 0; i < daoClasses.length; i++) {
            DaoConfig daoConfig = new DaoConfig (db, daoClasses[i]);

            String tableName = daoConfig.tablename;
            String tempTableName = daoConfig.tablename.concat ("_TEMP");
            ArrayList<String> properties = new ArrayList ();

            for (int j = 0; j < daoConfig.properties.length; j++) {
                String columnName = daoConfig.properties[j].columnName;

                if (getColumns (db, tempTableName).contains (columnName)) {
                    properties.add (columnName);
                }
            }

            StringBuilder insertTableStringBuilder = new StringBuilder ();

            insertTableStringBuilder.append ("INSERT INTO ").append (tableName).append (" (");
            insertTableStringBuilder.append (TextUtils.join (",", properties));
            insertTableStringBuilder.append (") SELECT ");
            insertTableStringBuilder.append (TextUtils.join (",", properties));
            insertTableStringBuilder.append (" FROM ").append (tempTableName).append (";");

            StringBuilder dropTableStringBuilder = new StringBuilder ();

            dropTableStringBuilder.append ("DROP TABLE ").append (tempTableName);

            db.execSQL (insertTableStringBuilder.toString ());
            db.execSQL (dropTableStringBuilder.toString ());
        }
    }

    private static List<String> getColumns (Database db, String tableName) {
        List<String> columns = new ArrayList<> ();
        Cursor cursor = null;
        try {
            cursor = db.rawQuery ("SELECT * FROM " + tableName + " limit 1", null);
            if (cursor != null) {
                columns = new ArrayList<> (Arrays.asList (cursor.getColumnNames ()));
            }
        } catch (Exception e) {
            Log.v (tableName, e.getMessage (), e);
            //Sentry.captureException (e);
            e.printStackTrace ();
        } finally {
            if (cursor != null) {
                cursor.close ();
            }
        }
        return columns;
    }

    private String getTypeByClass (Class<?> type) throws Exception {
        if (type.equals (String.class)) {
            return "TEXT";
        }
        if (type.equals (Long.class) || type.equals (Integer.class)
                || type.equals (int.class) || type.equals (long.class)) {
            return "INTEGER";
        }
        if (type.equals (Boolean.class) || type.equals (boolean.class)) {
            return "BOOLEAN";
        }

        Exception exception = new Exception (CONVERSION_CLASS_NOT_FOUND_EXCEPTION.concat (" - Class: ").concat (type.toString ()));
        //Sentry.captureException (exception);
        throw exception;
    }


}