PageController.java

package net.miz_hi.smileessence.system;

import android.app.Activity;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import net.miz_hi.smileessence.view.fragment.ISingleton;
import net.miz_hi.smileessence.view.fragment.NamedFragment;
import net.miz_hi.smileessence.view.fragment.NamedFragmentPagerAdapter;
import net.miz_hi.smileessence.view.fragment.impl.HistoryFragment;
import net.miz_hi.smileessence.view.fragment.impl.HomeFragment;
import net.miz_hi.smileessence.view.fragment.impl.MentionsFragment;
import net.miz_hi.smileessence.view.fragment.impl.PostFragment;

import java.util.ArrayList;
import java.util.List;


public class PageController
{

    private static PageController instance;
    public static final int PAGE_POST = 0;
    private NamedFragmentPagerAdapter adapter;
    private ViewPager pager;
    private FragmentActivity activity;

    public static PageController getInstance()
    {
        return instance;
    }

    public static void init(FragmentActivity activity, ViewPager pager)
    {
        instance = new PageController(activity, pager);
    }

    private PageController(FragmentActivity activity, ViewPager pager)
    {
        adapter = new NamedFragmentPagerAdapter(activity.getSupportFragmentManager());
        this.activity = activity;
        this.pager = pager;
        initPages(activity);
    }

    private void initPages(Activity activity)
    {
        adapter.add((NamedFragment) Fragment.instantiate(activity, PostFragment.class.getName()));
        adapter.add((NamedFragment) Fragment.instantiate(activity, HomeFragment.class.getName()));
        adapter.add((NamedFragment) Fragment.instantiate(activity, MentionsFragment.class.getName()));
        adapter.add((NamedFragment) Fragment.instantiate(activity, HistoryFragment.class.getName()));
    }

    public void move(int index)
    {
        move(index, true);
    }

    public void move(int index, boolean smooth)
    {
        pager.setCurrentItem(index, smooth);
        ((NamedFragment) adapter.getItem(index)).onSelected();
    }

    public void moveToLast()
    {
        move(adapter.getCount() - 1, false);
    }

    public int getCurrentPage()
    {
        return pager.getCurrentItem();
    }

    public void addPage(NamedFragment fragment)
    {
        if(fragment instanceof ISingleton)
        {
            for(int i = 0; i < getCount(); i++)
            {
                if(getPage(i).getClass().isInstance(fragment))
                {
                    removePage(i);
                }
            }
        }
        adapter.add(fragment);
        pager.setOffscreenPageLimit(pager.getChildCount());
    }

    public void removePage()
    {
        int current = pager.getCurrentItem();
        removePage(current);
        pager.setCurrentItem(current, false);
    }

    public void removePage(int index)
    {
        removePage(((NamedFragment) adapter.getItem(index)).getTitle());
    }

    public void removePage(String name)
    {
        adapter.remove(name);
        List<NamedFragment> list = new ArrayList<NamedFragment>();
        list.addAll(adapter.getList());
        adapter = new NamedFragmentPagerAdapter(activity.getSupportFragmentManager(), list); //Refresh page caches
        pager.setAdapter(instance.adapter);
        pager.setOffscreenPageLimit(pager.getChildCount());
    }

    public NamedFragment getPage(int index)
    {
        return (NamedFragment) adapter.getItem(index);
    }

    public NamedFragment getPage(String name)
    {
        return adapter.getByName(name);
    }

    public int getPageIndex(Fragment fragment)
    {
        return adapter.getItemPosition(fragment);
    }

    public int getCount()
    {
        return adapter.getCount();
    }

    public NamedFragmentPagerAdapter getAdapter()
    {
        return adapter;
    }
}