MainPresenter.java

package com.fastaccess.ui.modules.main;

import android.support.annotation.IdRes;
import android.support.annotation.NonNull;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;

import com.fastaccess.App;
import com.fastaccess.R;
import com.fastaccess.data.dao.model.Login;
import com.fastaccess.helper.RxHelper;
import com.fastaccess.provider.rest.RestProvider;
import com.fastaccess.ui.base.mvp.presenter.BasePresenter;
import com.fastaccess.ui.modules.feeds.FeedsFragment;
import com.fastaccess.ui.modules.main.issues.pager.MyIssuesPagerFragment;
import com.fastaccess.ui.modules.main.pullrequests.pager.MyPullsPagerFragment;
import com.fastaccess.ui.modules.user.UserPagerActivity;

import static com.fastaccess.helper.ActivityHelper.getVisibleFragment;
import static com.fastaccess.helper.AppHelper.getFragmentByTag;

/**
 * Created by Kosh on 09 Nov 2016, 7:53 PM
 */

class MainPresenter extends BasePresenter<MainMvp.View> implements MainMvp.Presenter {


    MainPresenter() {
        manageSubscription(RxHelper.getObserver(RestProvider.getUserService().getUser())
                .flatMap(login -> login.update(login))
                .subscribe(login -> {
                    if (login != null) {
                        sendToView(MainMvp.View::onUpdateDrawerMenuHeader);
                    }
                }, Throwable::printStackTrace/*fail silently*/));
    }

    @Override public boolean canBackPress(@NonNull DrawerLayout drawerLayout) {
        return !drawerLayout.isDrawerOpen(GravityCompat.START);
    }

    @SuppressWarnings("ConstantConditions")
    @Override public void onModuleChanged(@NonNull FragmentManager fragmentManager, @MainMvp.NavigationType int type) {
        Fragment currentVisible = getVisibleFragment(fragmentManager);
        FeedsFragment homeView = (FeedsFragment) getFragmentByTag(fragmentManager, FeedsFragment.TAG);
        MyPullsPagerFragment pullRequestView = (MyPullsPagerFragment) getFragmentByTag(fragmentManager, MyPullsPagerFragment.TAG);
        MyIssuesPagerFragment issuesView = (MyIssuesPagerFragment) getFragmentByTag(fragmentManager, MyIssuesPagerFragment.TAG);
        switch (type) {
            case MainMvp.PROFILE:
                UserPagerActivity.startActivity(App.getInstance().getApplicationContext(), Login.getUser().getLogin());
                break;
            case MainMvp.FEEDS:
                if (homeView == null) {
                    onAddAndHide(fragmentManager, FeedsFragment.newInstance(), currentVisible);
                } else {
                    onShowHideFragment(fragmentManager, homeView, currentVisible);
                }
                break;
            case MainMvp.PULL_REQUESTS:
                if (pullRequestView == null) {
                    onAddAndHide(fragmentManager, MyPullsPagerFragment.newInstance(), currentVisible);
                } else {
                    onShowHideFragment(fragmentManager, pullRequestView, currentVisible);
                }
                break;
            case MainMvp.ISSUES:
                if (issuesView == null) {
                    onAddAndHide(fragmentManager, MyIssuesPagerFragment.newInstance(), currentVisible);
                } else {
                    onShowHideFragment(fragmentManager, issuesView, currentVisible);
                }
                break;
        }
    }

    @Override public void onShowHideFragment(@NonNull FragmentManager fragmentManager, @NonNull Fragment toShow, @NonNull Fragment toHide) {
        toHide.onHiddenChanged(true);
        fragmentManager
                .beginTransaction()
                .hide(toHide)
                .show(toShow)
                .commit();
        toShow.onHiddenChanged(false);
    }

    @Override public void onAddAndHide(@NonNull FragmentManager fragmentManager, @NonNull Fragment toAdd, @NonNull Fragment toHide) {
        toHide.onHiddenChanged(true);
        fragmentManager
                .beginTransaction()
                .hide(toHide)
                .add(R.id.container, toAdd, toAdd.getClass().getSimpleName())
                .commit();
        toAdd.onHiddenChanged(false);
    }

    @Override public void onMenuItemSelect(@IdRes int id, int position, boolean fromUser) {
        if (getView() != null) {
            getView().onNavigationChanged(position);
        }
    }

    @Override public void onMenuItemReselect(@IdRes int id, int position, boolean fromUser) {}
}