<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context=".LoginFragment"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceLarge"
            android:text="Login."
            android:id="@+id/login_title_text"
            android:layout_alignParentTop="true"
            android:textSize="40sp"
            android:layout_marginTop="100dp"
            android:fontFamily="sans-serif-light"
            android:textColor="@color/colorAlt"
            android:layout_centerHorizontal="true" />

        <!-- E-mail section -->
        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:inputType="textEmailAddress"
            android:hint="E-mail address"
            android:layout_marginLeft="50dp"
            android:layout_marginTop="10dp"
            android:layout_marginRight="20dp"
            android:ems="10"
            android:id="@+id/login_emailField"
            android:layout_above="@+id/login_passwordField" />
        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/register_email_icon"
            android:layout_alignBottom="@id/login_emailField"
            android:layout_marginLeft="15dp"
            android:layout_marginBottom="10dp"/>


        <!-- Password section -->
        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/register_password_icon"
            android:layout_alignBottom="@id/login_passwordField"
            android:layout_marginLeft="15dp"
            android:layout_marginBottom="10dp"/>

        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:inputType="textPassword"
            android:layout_marginTop="10dp"
            android:hint="Password"
            android:id="@+id/login_passwordField"
            android:layout_centerVertical="true"
            android:layout_marginLeft="50dp"
            android:layout_marginRight="20dp"
            android:layout_marginBottom="25dp" />

        <android.support.v7.widget.CardView
            xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:card_view="http://schemas.android.com/apk/res-auto"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/login_login_button"
            android:layout_gravity="center_vertical"
            android:layout_below="@+id/login_passwordField"
            android:layout_marginBottom="29dp"
            android:layout_marginLeft="20dp"
            android:layout_marginRight="20dp"
            card_view:cardBackgroundColor="#E91E63"
            card_view:cardCornerRadius="2dp"
            card_view:cardElevation="6dp">

            <TextView
                android:id="@+id/material_text"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:paddingTop="13dp"
                android:paddingBottom="13dp"
                android:layout_gravity="center_horizontal"
                android:textColor="#FFF"
                android:textSize="19sp"
                android:fontFamily="sans-serif-medium"
                android:text="Login" />
        </android.support.v7.widget.CardView>



        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="Forgotten your username or password?"
            android:layout_below="@id/login_login_button"
            android:gravity="center"
            android:layout_centerHorizontal="true"
            android:id="@+id/login_footer_text"
            android:layout_marginTop="40dp"/>
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="Tap here"
            android:textColor="#000000"
            android:layout_below="@id/login_footer_text"
            android:gravity="center"
            android:layout_centerHorizontal="true"
            android:id="@+id/loginForgottenTapText"
            android:layout_marginTop="20dp"/>
    </RelativeLayout>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<ScrollView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context=".LoginFragment"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceLarge"
            android:text="Login."
            android:id="@+id/login_title_text"
            android:layout_alignParentTop="true"
            android:textSize="40sp"
            android:layout_marginTop="100dp"
            android:fontFamily="sans-serif-light"
            android:textColor="@color/colorAlt"
            android:layout_centerHorizontal="true" />

        <!-- E-mail section -->
        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:inputType="textEmailAddress"
            android:hint="E-mail address"
            android:layout_marginLeft="50dp"
            android:layout_marginTop="10dp"
            android:layout_marginRight="20dp"
            android:ems="10"
            android:id="@+id/login_emailField"
            android:layout_below="@+id/login_title_text" />
        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/register_email_icon"
            android:layout_alignBottom="@id/login_emailField"
            android:layout_marginLeft="15dp"
            android:layout_marginBottom="10dp"/>


        <!-- Password section -->

        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:inputType="textPassword"
            android:layout_marginTop="10dp"
            android:hint="Password"
            android:layout_below="@id/login_emailField"
            android:id="@+id/login_passwordField"
            android:layout_marginLeft="50dp"
            android:layout_marginRight="20dp"
            android:layout_marginBottom="25dp" />

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/register_password_icon"
            android:layout_alignBottom="@id/login_passwordField"
            android:layout_marginLeft="15dp"
            android:layout_marginBottom="10dp"/>

        <android.support.v7.widget.CardView
            xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:card_view="http://schemas.android.com/apk/res-auto"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/login_login_button"
            android:layout_gravity="center_vertical"
            android:layout_below="@+id/login_passwordField"
            android:layout_marginBottom="29dp"
            android:layout_marginLeft="20dp"
            android:layout_marginRight="20dp"
            card_view:cardBackgroundColor="#E91E63"
            card_view:cardCornerRadius="2dp"
            card_view:cardElevation="6dp">

            <TextView
                android:id="@+id/material_text"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:paddingTop="13dp"
                android:paddingBottom="13dp"
                android:layout_gravity="center_horizontal"
                android:textColor="#FFF"
                android:textSize="19sp"
                android:fontFamily="sans-serif-medium"
                android:text="Login" />
        </android.support.v7.widget.CardView>



        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="Forgotten your username or password?"
            android:layout_below="@id/login_login_button"
            android:gravity="center"
            android:layout_centerHorizontal="true"
            android:id="@+id/login_footer_text"
            android:layout_marginTop="20dp"/>
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="Tap here"
            android:textColor="#000000"
            android:layout_below="@id/login_footer_text"
            android:gravity="center"
            android:layout_centerHorizontal="true"
            android:id="@+id/loginForgottenTapText"
            android:layout_marginTop="10dp"/>
    </RelativeLayout>

</ScrollView>

public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener, LoginFragment.OnLoginCallback {

    MenuItem register;
    MenuItem login;
    MenuItem logout;
    MenuItem completeListing;
    MenuItem expiredListing;
    MenuItem activeListing;

    NavigationView navigationView;
    UserCredentialHandler userStatus;

    protected static final String KEY_USER_STATUS = "USER_STATUS";
    protected static final String USER_PREFS = "userNamePrefs";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        userStatus = new UserCredentialHandler();

        final HomeFragment homeFragment = new HomeFragment();

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();


        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent i = new Intent(getApplicationContext(), CreateListingActivity.class);
                startActivity(i);
            }
        });

        navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        getMenuItems(navigationView);

        if(userStatus.checkIfUserIsLoggedIn(getApplicationContext())){
            userStatus.setNavHeaderOnLogin(getApplicationContext(), navigationView);
            updateNavDrawer("login", register, login, logout, expiredListing, completeListing, activeListing);
        } else {
            userStatus.setNavHeaderOnLogout(navigationView);
            updateNavDrawer("logout", register, login, logout, expiredListing, completeListing, activeListing);
        }

        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager
                .beginTransaction();
        fragmentTransaction.replace(R.id.main_container,homeFragment);
        fragmentTransaction.commit();
    }

    @Override
    public void onLoginSuccess() {
        HomeFragment homeFragment = new HomeFragment();
        userStatus.setNavHeaderOnLogin(getApplicationContext(), navigationView);

        updateNavDrawer("login",register,login,logout, expiredListing, completeListing, activeListing);

        register.setVisible(false);
        login.setVisible(false);
        logout.setVisible(true);

        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager
                .beginTransaction();
        fragmentTransaction.replace(R.id.main_container,homeFragment);
        fragmentTransaction.commit();
    }


    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            getSupportFragmentManager().popBackStack();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main_activity_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        } else if (id == R.id.search_mag_icon){
            SearchFragment searchFragment = new SearchFragment();
            getSupportFragmentManager()
                    .beginTransaction()
                    .replace(R.id.main_container, searchFragment)
                    .addToBackStack(null)
                    .commit();
        }
        return super.onOptionsItemSelected(item);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();

        if (id == R.id.nav_register) {
            final RegisterFragment registerFragment = new RegisterFragment();

            getSupportFragmentManager()
                    .beginTransaction()
                    .replace(R.id.main_container, registerFragment)
                    .addToBackStack(null)
                    .commit();

        } else if (id == R.id.nav_login) {
            final LoginFragment loginFragment = new LoginFragment();
            getSupportFragmentManager()
                    .beginTransaction()
                    .replace(R.id.main_container, loginFragment)
                    .addToBackStack(null)
                    .commit();

        } else if(id == R.id.nav_logout) {
            userStatus.logoutUser(getApplicationContext());
            userStatus.setNavHeaderOnLogout(navigationView);
            updateNavDrawer("logout",register,login,logout, expiredListing, completeListing, activeListing);

        } else if (id == R.id.nav_my_listings) {
            // navigate to my listings
        } else if (id == R.id.nav_how) {
            // navigate to how it works page
        } else if (id == R.id.nav_help) {
            // navigate to help page
        } else if (id == R.id.nav_contact_us) {
            // navigate to contact page,
        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }

    private void updateNavDrawer(String action, MenuItem register, MenuItem login, MenuItem logout, MenuItem expiredListing, MenuItem completeListing, MenuItem activeListing){
        if(action=="login"){
            register.setVisible(false);
            login.setVisible(false);
            logout.setVisible(true);
            completeListing.setVisible(true);
            activeListing.setVisible(true);
            expiredListing.setVisible(true);
        } else {
            register.setVisible(true);
            login.setVisible(true);
            logout.setVisible(false);
            completeListing.setVisible(false);
            activeListing.setVisible(false);
            expiredListing.setVisible(false);
        }
    }

    private void getMenuItems(NavigationView nv){
        register = nv.getMenu().getItem(0);
        login = nv.getMenu().getItem(1);
        logout = nv.getMenu().getItem(2);
        activeListing = nv.getMenu().getItem(3);
        completeListing = nv.getMenu().getItem(4);
        expiredListing = nv.getMenu().getItem(5);
    }

}