/* 
 * Copyright 2012 Tallinn University Centre for Educational Technology
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package ee.htk.dippler.app;

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

import android.app.ListActivity;
import android.content.Context;
import android.database.DataSetObserver;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ListView;
import ee.htk.dippler.app.ArrayAdapters.EventArrayAdapter;
import ee.htk.dippler.app.entities.Course;
import ee.htk.dippler.app.entities.Event;
import ee.htk.dippler.app.service.ListingManager;
import ee.htk.dippler.app.service.SessionObject;

public class ActivitesActivity extends ListActivity {
	
	private ListingManager listingManager;
	private Course course;
	private List<Event> events = new ArrayList<Event>();
	private EventArrayAdapter mAdapter;
	private View footerView;
	private ListView listView;
	private View progress;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		Bundle extras = getIntent().getExtras();
        course = extras.getParcelable("dippler-course");
        SessionObject session = extras.getParcelable("dippler-session");
        
		listingManager = new ListingManager(getApplicationContext(), session.getId());
		setContentView(R.layout.course_listing);
		progress = findViewById(R.id.progress_wrapper);
		
		listView = getListView();
		listView.setOnScrollListener(new EndlessScrollListener());
		
		footerView = ((LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(R.layout.listfooter, null, false);
		listView.addFooterView(footerView);
		mAdapter = new EventArrayAdapter(this, R.layout.list_news, events);
		setListAdapter(mAdapter);
		
		mAdapter.registerDataSetObserver(new DataSetObserver() {
		    @Override
		    public void onChanged() {
		        super.onChanged();
		        listView.removeFooterView(footerView);
		        if ( progress.isShown() ) {
		        	progress.setVisibility(View.GONE);
		        }
		    }
		});
		//Init first set of activites - page 1
		new fetchEvents(course.getId()).execute(1);
	}

	private class fetchEvents extends AsyncTask<Integer, Integer, List<Event>> {
		private int course_id = 0;
		private int base_limit = 10;
		
		public fetchEvents(int course_id) {
			this.course_id = course_id;
		}
		
		@Override
		protected List<Event> doInBackground(Integer... pages) {
			int offset = ( (base_limit * pages[0]) - 10 );
			int limit = (base_limit * pages[0]);
			Log.i("dippler-app", "Offset "+ offset+ " limit " +limit);
			return listingManager.getEvents(course_id, offset, limit );
		}

		@Override
		protected void onPostExecute(List<Event> events_in) {
			super.onPostExecute(events_in);
			for (Event event : events_in) {
				if ( !events.contains(event) ) {
					events.add(event);
				}
			}
			mAdapter.notifyDataSetChanged();
		}
		
	}
	
	class EndlessScrollListener implements OnScrollListener {

        private int visibleThreshold = 5;
        private int currentPage = 1;
        private int previousTotal = 0;
        private boolean loading = true;

        public EndlessScrollListener() {
        }
        public EndlessScrollListener(int visibleThreshold) {
            this.visibleThreshold = visibleThreshold;
        }

        @Override
        public void onScroll(AbsListView view, int firstVisibleItem,
                int visibleItemCount, int totalItemCount) {
            if (loading) {
                if (totalItemCount > previousTotal) {
                    loading = false;
                    previousTotal = totalItemCount;
                    currentPage++;
                }
            }
            if (!loading && (totalItemCount - visibleItemCount) <= (firstVisibleItem + visibleThreshold)) {
            	//If no footerViews present, add one
            	if ( listView.getFooterViewsCount() == 0) {
            		listView.addFooterView(footerView);
            	}
            	new fetchEvents(course.getId()).execute(currentPage + 1);
                loading = true;
            }
        }

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