ItemListFragment.java

/*
    Copyright (C) 2013 Prasanna Thirumalai
    
    This file is part of StackX.

    StackX is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    StackX is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with StackX.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.prasanna.android.stacknetwork.fragment;

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

import android.app.Activity;
import android.app.ListFragment;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ProgressBar;
import android.widget.TextView;

import com.prasanna.android.http.HttpException;
import com.prasanna.android.stacknetwork.R;
import com.prasanna.android.stacknetwork.adapter.ItemListAdapter;
import com.prasanna.android.stacknetwork.model.IdentifiableItem;
import com.prasanna.android.stacknetwork.model.StackXPage;
import com.prasanna.android.stacknetwork.receiver.RestQueryResultReceiver;
import com.prasanna.android.stacknetwork.receiver.RestQueryResultReceiver.StackXRestQueryResultReceiver;
import com.prasanna.android.stacknetwork.service.AbstractIntentService;
import com.prasanna.android.stacknetwork.utils.AppUtils;
import com.prasanna.android.stacknetwork.utils.StackUri;
import com.prasanna.android.stacknetwork.utils.StringConstants;
import com.prasanna.android.utils.LogWrapper;

public abstract class ItemListFragment<T extends IdentifiableItem> extends ListFragment implements OnScrollListener,
    StackXRestQueryResultReceiver {
  private static final String TAG = ItemListFragment.class.getSimpleName();

  private boolean activityCreated = false;
  private ProgressBar progressBar;
  private StackXPage<T> currentPageObject;

  protected boolean serviceRunning = false;
  protected RestQueryResultReceiver resultReceiver;
  protected List<StackXPage<T>> pages;
  protected ViewGroup itemsContainer;
  protected ArrayList<T> items;
  protected ItemListAdapter<T> itemListAdapter;
  private TextView emptyItemsTextView;

  private Context applicationContext;

  protected abstract String getReceiverExtraName();

  protected abstract void startIntentService();

  protected abstract String getLogTag();

  @Override
  public void onAttach(Activity activity) {
    super.onAttach(activity);

    applicationContext = activity.getApplicationContext();
  }

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    if (resultReceiver == null) resultReceiver = new RestQueryResultReceiver(new Handler());

    resultReceiver.setReceiver(this);

    if (pages == null) pages = new ArrayList<StackXPage<T>>();
  }

  @SuppressWarnings("unchecked")
  @Override
  public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    if (!activityCreated) {
      getListView().addFooterView(getProgressBar());
      setListAdapter(itemListAdapter);
      getListView().setOnScrollListener(this);
      activityCreated = true;
    }

    if (savedInstanceState != null) {
      items = (ArrayList<T>) savedInstanceState.getSerializable(StringConstants.ITEMS);
      if (items != null) itemListAdapter.addAll(items);
    }
  }

  @Override
  public void onResume() {
    super.onResume();

    if (itemListAdapter != null) {
      if (itemListAdapter.getCount() > 0) itemListAdapter.notifyDataSetChanged();
      else {
        if (items != null && !items.isEmpty()) itemListAdapter.addAll(items);
      }
    }
  }

  protected boolean isServiceRunning() {
    return serviceRunning;
  }

  protected void showProgressBar() {
    getProgressBar().setVisibility(View.VISIBLE);
  }

  protected void dismissProgressBar() {
    getProgressBar().setVisibility(View.GONE);
  }

  protected Intent getIntentForService(Class<?> clazz, String action) {
    if (!serviceRunning) {
      Intent intentForService = new Intent(applicationContext, clazz);
      if (action != null) intentForService.setAction(action);
      return intentForService;
    }

    return null;
  }

  protected void startService(Intent intent) {
    if (!isServiceRunning() && intent != null) {
      getActivity().startService(intent);
      serviceRunning = true;
    } else dismissProgressBar();
  }

  protected void stopService(Intent intent) {
    if (intent != null) {
      getActivity().stopService(intent);
      serviceRunning = false;
    }
  }

  protected ViewGroup getParentLayout() {
    return itemsContainer;
  }

  public void refresh() {
    removeErrorViewIfShown();

    startIntentService();
  }

  protected void removeErrorViewIfShown() {
    if (getListView().getVisibility() == View.GONE) getListView().setVisibility(View.VISIBLE);

    View errorView = getParentLayout().findViewById(R.id.errorLayout);
    if (errorView != null) getParentLayout().removeView(errorView);
  }

  @SuppressWarnings("unchecked")
  @Override
  public void onReceiveResult(int resultCode, Bundle resultData) {
    serviceRunning = false;

    dismissProgressBar();

    if (resultCode == AbstractIntentService.ERROR) onHttpError((HttpException) resultData
        .getSerializable(StringConstants.EXCEPTION));
    else {
      currentPageObject = (StackXPage<T>) resultData.getSerializable(getReceiverExtraName());
      if (currentPageObject != null) {
        pages.add(currentPageObject);
        displayItems(currentPageObject.items);
      }
    }
  }

  private void displayItems(ArrayList<T> newItems) {
    if (itemListAdapter != null && newItems != null) {
      if (items == null) items = new ArrayList<T>();

      items.addAll(newItems);
      if (items.isEmpty()) {
        if (emptyItemsTextView == null) emptyItemsTextView = (TextView) itemsContainer.findViewById(R.id.emptyItems);

        emptyItemsTextView.setVisibility(View.VISIBLE);
      } else {
        itemListAdapter.addAll(newItems);
        if (emptyItemsTextView != null && View.VISIBLE == emptyItemsTextView.getVisibility())
          emptyItemsTextView.setVisibility(View.GONE);
      }
    }
  }

  private void onHttpError(HttpException e) {
    LogWrapper.d(TAG, "Http error " + e.getStatusCode() + " " + e.getErrorResponse());

    if (activityCreated) getListView().setVisibility(View.GONE);

    View errorLayout = getParentLayout().findViewById(R.id.errorLayout);
    if (errorLayout == null) getParentLayout().addView(AppUtils.getErrorView(applicationContext, e));
    else {
      TextView textView = (TextView) errorLayout.findViewById(R.id.errorMsg);
      textView.setText(AppUtils.getStackXErrorMsg(e));
    }
  }

  @Override
  public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
    if (!isServiceRunning() && totalItemCount >= StackUri.QueryParamDefaultValues.PAGE_SIZE
        && (totalItemCount - visibleItemCount) <= (firstVisibleItem + 1)) {
      if (currentPageObject != null && currentPageObject.hasMore) loadNextPage();
    }
  }

  @Override
  public void onScrollStateChanged(AbsListView view, int scrollState) {
  }

  protected ProgressBar getProgressBar() {
    if (progressBar == null)
      progressBar = (ProgressBar) LayoutInflater.from(applicationContext).inflate(R.layout.progress_bar, null);
    return progressBar;
  }

  protected void loadNextPage() {
    startIntentService();
  }
}