public class DbHelper extends SQLiteOpenHelper{

// private static final String TAG = DbHelper.class.getSimpleName();
//declaration of database version
private static final int DATABASE_VERSION = 1;
//declare databsse
private static final String DATABASE_NAME = "salesPortal.db";
//declare table name
private static final String TABLE_NAME = "tbl_user";
//declareing table columns
private static final String COLUMN_USER_ID ="user_id";
private static final String COLUMN_NAME_NAME = "user_name";
private static final String COLUMN_NAME_PASSWORD = "user_password";
private static final String COLUMN_NAME_EMAIL = "user_email";

 //===========login==================================
//creating database tables
private String CREATE_USER_TABLE = "CREATE TABLE " + TABLE_NAME + "("
        + COLUMN_USER_ID + " INTEGER PRIMARY KEY AUTOINCREMENT," + COLUMN_NAME_NAME + " TEXT,"
        + COLUMN_NAME_PASSWORD + " TEXT," + COLUMN_NAME_EMAIL + " TEXT" + ")";
//if availabele drop the schema
private  String DROP_USER_TABLE = "DROP TABLE IF EXISTS " +TABLE_NAME;
private Users users;

/**
 *Constructor
 *
 *@param context
 */
public DbHelper(Context context){

    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
    //create tb execution method
    sqLiteDatabase.execSQL(CREATE_USER_TABLE);
    sqLiteDatabase.execSQL(CREATE_MILEAGE_TABLE);
    sqLiteDatabase.execSQL(CREATE_SHOPSLIST_TABLE);
    sqLiteDatabase.execSQL(CREATE_STOCK_TABLE);
    Log.e("DATABASE OPERATION","table created successfully");
    }

@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int oldVersion, int newVersion) {
    //drop table if availablr execution method
    sqLiteDatabase.execSQL(DROP_USER_TABLE);
    sqLiteDatabase.execSQL(DROP_MILEAGE_TABLE);
    sqLiteDatabase.execSQL(DROP_SALES_TABLE);
    String DROP_STOCK_TABLE = "DROP TABLE IF EXISTS " +tbName ;
    //drop table if available exercuion method
    sqLiteDatabase.execSQL(DROP_STOCK_TABLE);
    //calling on creating method
    onCreate(sqLiteDatabase);

     }
/**
 * creating user records
 *
 * @param newUser
  */
public void addUser(Users newUser){
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put(COLUMN_NAME_NAME,newUser.getName());
    values.put(COLUMN_NAME_PASSWORD,newUser.getPassword());
    values.put(COLUMN_NAME_EMAIL,newUser.getEmail());
    db.insert(TABLE_NAME,null,values);
    db.close();

}

/**
 * fletch as alist user records
 *
 * @return list
 */
public List<Users> getUsers() {
    // array of columns to fetch
    String[] columns = {
            COLUMN_USER_ID,
            COLUMN_NAME_EMAIL,
            COLUMN_NAME_NAME,
            COLUMN_NAME_PASSWORD
    };
    // sorting orders
    String sortOrder =
            COLUMN_NAME_NAME + " ASC";
    List<Users> userList = new ArrayList<Users>();

    SQLiteDatabase db = this.getReadableDatabase();

    // query the user table
    /**
     * Here query function is used to fetch records from user table this function works like we use sql query.
     * SQL query equivalent to this query function is
     * SELECT user_id,user_name,user_email,user_password FROM user ORDER BY user_name;
     */
    Cursor cursor = db.query(TABLE_NAME, //Table to query
            columns,    //columns to return
            null,        //columns for the WHERE clause
            null,        //The values for the WHERE clause
            null,       //group the rows
            null,       //filter by row groups
            sortOrder); //The sort order


    // Traversing through all rows and adding to list
    if (cursor.moveToFirst()) {
        do {
            Users user = new Users();
            user.setUserId(Integer.parseInt(cursor.getString(cursor.getColumnIndex(COLUMN_USER_ID))));
            user.setName(cursor.getString(cursor.getColumnIndex(COLUMN_NAME_NAME)));
            user.setEmail(cursor.getString(cursor.getColumnIndex(COLUMN_NAME_EMAIL)));
            user.setPassword(cursor.getString(cursor.getColumnIndex(COLUMN_NAME_PASSWORD)));
            // Adding user record to list
            userList.add(user);
        } while (cursor.moveToNext());
    }
    cursor.close();
    db.close();

    // return user list
    return userList;
}
/**
 * This method to update user record
 *
 * @param users
 */
public void updateUser(Users users){
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put(COLUMN_NAME_NAME,users.getName());
    values.put(COLUMN_NAME_PASSWORD,users.getPassword());
    values.put(COLUMN_NAME_EMAIL,users.getEmail());
    db.update(TABLE_NAME,values,COLUMN_USER_ID + "=?"
            ,new String[]{String.valueOf(users.getUserId())});
    db.close();
}
/**
 * This method is to delete user record
 *
 * @param user
 */
public boolean deleteUser(Users user){
    SQLiteDatabase db = this.getWritableDatabase();
    db.delete(TABLE_NAME,COLUMN_USER_ID + "=?",
            new String[]{String.valueOf(user.getUserId())});
    db.close();
    return true;
}

/**
 * This method to check user exist or not
 *
 * @param email
 * @param password
 * @return true/false
 */

public Users checkUser(String email,String password){
    Users users =null;
    try {
        SQLiteDatabase db = getReadableDatabase();
        Cursor cursor = db.rawQuery("SELECT * FROM " + TABLE_NAME + " WHERE user_email = ? AND user_password = ?" ,new String[]{email,password} );
            if (cursor.moveToFirst()){
               users = new Users();
               users.setUserId(cursor.getInt(0));
                users.setName(cursor.getString(1));
                users.setPassword(cursor.getString(2));
                users.setEmail(cursor.getString(3));
            }
    }catch (Exception e){
        users=null;
    }
    return users;

}

public boolean checkUser(String email) {

    // array of columns to fetch
    String[] columns = {
            COLUMN_USER_ID
    };
    SQLiteDatabase db = this.getReadableDatabase();

    // selection criteria
    String selection = COLUMN_NAME_EMAIL + " = ?";

    // selection argument
    String[] selectionArgs = {email};

    // query user table with condition
    /**
     *
     */

    Cursor cursor = db.query(TABLE_NAME,columns,selection, selectionArgs,null,null,null);
    int cursorCount = cursor.getCount();
    cursor.close();
    db.close();

    if (cursorCount > 0) {
        return true;
    }

    return false;
}

public boolean checkWithOldPassword(String OldPassword) {

    // array of columns to fetch
    String[] columns = {
            COLUMN_USER_ID
    };
    SQLiteDatabase db = this.getReadableDatabase();

    // selection criteria
    String selection = COLUMN_NAME_PASSWORD + " = ?";

    // selection argument
    String[] selectionArgs = {OldPassword};

    // query user table with condition
    /**
     *
     */

    Cursor cursor = db.query(TABLE_NAME,columns,selection, selectionArgs,null,null,null);
    int cursorCount = cursor.getCount();
    cursor.close();
    db.close();

    if (cursorCount > 0) {
        return true;
    }

    return false;
}

public class LoginActivity extends AppCompatActivity implements
View.OnClickListener{
private final AppCompatActivity activity = LoginActivity.this;
private RelativeLayout relativeLayout;


private TextInputLayout textInputLayoutEmail;
private  TextInputLayout textInputLayoutPassword;

private TextInputEditText textInputEditTextEmail;
private TextInputEditText textInputEditTextPassword;

private AppCompatButton appCompatButtonLogin;
private AppCompatTextView textViewLinkRegister;

private Validation validations;
private DbHelper dbHelper;
private Users users;



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);



    initViews();
    initListeners();
    initObjects();


}
//intializing all objects that are used on application login
private void initObjects() {
   dbHelper = new DbHelper(activity);
   validations =  new Validation(activity);
   users = new Users();

}
 //intializing all listerners
private void initListeners() {
    appCompatButtonLogin.setOnClickListener(this);
    textViewLinkRegister.setOnClickListener(this);
}

//intializing all views on login
private void initViews() {
    relativeLayout = findViewById(R.id.relativeLayout);

    textInputLayoutEmail = findViewById(R.id.textInputLayoutEmail);
    textInputLayoutPassword = findViewById(R.id.textInputLayoutPassword);

    textInputEditTextPassword = findViewById(R.id.textInputEditTextPassword);
    textInputEditTextEmail = findViewById(R.id.textInputEditTextEmail);

    appCompatButtonLogin = findViewById(R.id.appCompatButtonLogin);
    textViewLinkRegister = findViewById(R.id.textViewLinkRegister);


}

/**
 * implemetation of listerners of all views
 *
 * @param view
 */
@Override
public void onClick(View view) {
    switch (view.getId()){
       case R.id.appCompatButtonLogin : verifyFromSQLite();
       break;
       case R.id.textViewLinkRegister :Intent intentReg = new Intent(getApplicationContext(),RegisterActivity.class);
       startActivity(intentReg);
       break;
    }
}

/**
 * verify all input textfields and verify credentials
 */
public Boolean verifyFromSQLite() {
    if(!validations.isInputEditTextFilled(textInputEditTextEmail,textInputLayoutEmail,getString(R.string.error_message_email))){
        return false;
    }
        if(!validations.isTextEmailEmpty(textInputEditTextEmail,textInputLayoutEmail,getString(R.string.error_message_email))){
           return false;
        }
            if ((!validations.isInputEditTextFilled(textInputEditTextPassword,textInputLayoutPassword,getString(R.string.error_message_password)))){
               return false;
            }
            Users users = dbHelper.checkUser(textInputEditTextEmail.getText().toString().trim(),textInputEditTextPassword.getText().toString().trim());
   // if (dbHelper.checkUser(textInputEditTextEmail.getText().toString().trim()
                //, textInputEditTextPassword.getText().toString().trim())) {
                if(users ==null){
                    //snack bar to show success message that record is wrong
                    Snackbar.make(relativeLayout,getString(R.string.error_valid_email_password),Snackbar.LENGTH_LONG).show();
    }
                 else{
                    Intent accintent = new Intent(activity,MainMenuActivity.class);
                    accintent.putExtra("EMAIL",textInputEditTextEmail.getText().toString().trim());
                    emptyInputTextFields();
                    startActivity(accintent);
                    finish();
                    return true;


                 }
                 return true;
}


private void emptyInputTextFields() {
   textInputEditTextEmail.setText(null);
    textInputEditTextPassword.setText(null);

}

public class UserProfileActivity extends AppCompatActivity implements View.OnClickListener {
private final AppCompatActivity activity = UserProfileActivity.this;
private RelativeLayout relativeLayout;
private TextInputLayout textInputLayoutNameP;
private TextInputLayout textInputLayoutOldPass;
private TextInputLayout textInputLayoutNewPasswordP;
private TextInputLayout textInputLayoutConfirmPassword;

private TextInputEditText textInputEditTextNameP;
private TextInputEditText textInputEditTextOldPass;
private TextInputEditText textInputEditTextNewPasswordP;
private TextInputEditText textInputEditTextConfirmNewPassword;

private Validation validation;
private DbHelper dbHelper;
private Users users;

private AppCompatButton appCompatButtonUPDATE,appCompatButtonDELETE;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_user_profile);

    initViews();
    initListeners();
    initObjects();
    loadData();

}

private void initViews() {
    relativeLayout = findViewById(R.id.relativeLayout);
    textInputLayoutNameP = findViewById(R.id.textInputLayoutNameP);
    textInputLayoutOldPass = findViewById(R.id.textInputLayoutOldPass);
    textInputLayoutNewPasswordP = findViewById(R.id.textInputLayoutNewPasswordP);
    textInputLayoutConfirmPassword = findViewById(R.id.textInputLayoutConfirmPassword);

    textInputEditTextNameP = findViewById(R.id.textInputEditTextNameP);
    textInputEditTextNewPasswordP = findViewById(R.id.textInputEditTextNewPasswordP);
    textInputEditTextOldPass = findViewById(R.id.textInputEditTextOldPass);
    textInputEditTextConfirmNewPassword = findViewById(R.id.textInputEditTextConfirmPassword);

    appCompatButtonDELETE = findViewById(R.id.appCompatButtonDELETE);
    appCompatButtonUPDATE = findViewById(R.id.appCompatButtonUPDATE);
}

private void initListeners() {
    appCompatButtonDELETE.setOnClickListener(this);
    appCompatButtonUPDATE.setOnClickListener(this);
}

private void initObjects() {
    dbHelper = new DbHelper(activity);
    validation = new Validation(activity);
    users = new Users();
}

@Override
public void onClick(View v) {
    switch (v.getId()){
        case R.id.appCompatButtonUPDATE : updateMethod();
        break;
        case R.id.appCompatButtonDELETE : deleteMethod();
                                            //Intent intent =new Intent(getApplicationContext(),LoginActivity.class);
                                            //startActivity(intent);
                                           // break;
    }


}



private void loadData(){
    Intent intent = getIntent();
    users = (Users) intent.getSerializableExtra("user");
    textInputEditTextNameP.setText(users.getName());

}

private boolean updateMethod(){
    if(!validation.isInputEditTextFilled(textInputEditTextNameP,textInputLayoutNameP,getString(R.string.error_message_email))){
        return false;
    }
    if(!validation.isTextFiledsMatches(textInputEditTextNewPasswordP,textInputEditTextConfirmNewPassword,textInputLayoutConfirmPassword,getString(R.string.error_password_match))){
        return false;
    }
     if(dbHelper.checkWithOldPassword(textInputEditTextOldPass.getText().toString().trim())){

        users.setName(textInputEditTextNameP.getText().toString().trim());
        //users.setEmail(textInputEditTextEmail.getText().toString().trim());
        users.setPassword(textInputEditTextNewPasswordP.getText().toString().trim());
        dbHelper.updateUser(users);
        Snackbar.make(relativeLayout, getString(R.string.profile_update), Snackbar.LENGTH_LONG).show();
        return true;
    }
    else
     {
         Snackbar.make(relativeLayout, getString(R.string.error_oldPassword), Snackbar.LENGTH_LONG).show();
         return false;
     }
}

private void deleteMethod() {
    dbHelper.deleteUser(users);
    Snackbar.make(relativeLayout,"USER DELETED", Snackbar.LENGTH_LONG).show();
}

public class Users implements Serializable {
private static int userId;
private static String name;
private static String password;
private static String email;