import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AbsListView;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

public class ads extends AppCompatActivity {


private boolean goNext = false;


private String url_ads;
private int current_page = 0;

private List<HashMap<String , Object>> all_ads = new ArrayList<>();

private ListView lv;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_ads);

    getWindow().getDecorView().setLayoutDirection(View.LAYOUT_DIRECTION_RTL);

    /*------------------------------------------*/

    clearCache();

    lv = (ListView) findViewById(R.id.ads_list);

    Bundle address = getIntent().getExtras();

    url_ads = address.getString("url");


    make_ads_list();

    lv.setOnScrollListener(new AbsListView.OnScrollListener() {
        @Override
        public void onScrollStateChanged(AbsListView view, int i) {

            if (i == 1) {

                if (view.getId() == lv.getId()) {
                    int currentFirstVisibleItem = lv.getFirstVisiblePosition();
                    int mLastFirstVisibleItem = lv.getLastVisiblePosition();

                    if (currentFirstVisibleItem > mLastFirstVisibleItem) {
                        //go up
                    } else if (currentFirstVisibleItem < mLastFirstVisibleItem) {
                        // go down
                        if (goNext == true) {
                            goNext = false;
                            make_ads_list();

                        }
                    }

                    mLastFirstVisibleItem = currentFirstVisibleItem;
                }

            }
        }

        @Override
        public void onScroll(AbsListView absListView, int i, int i1, int i2) {

        }
    });

    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {

            Intent intent = new Intent(getApplicationContext(), show_full_ads.class);

            intent.putExtra("ads", all_ads.get(position));

            startActivity(intent);

        }
    });

}

@Override
protected void onDestroy() {
    super.onDestroy();

    clearCache();
}

public void make_ads_list()
{
    try {


        goNext = true;

        DownloadTask dl = new DownloadTask();

        dl.execute(url_ads + current_page);

        current_page ++;

        goNext = true;

    }
    catch (Exception e)
    {
        Log.i("NaqibMessage" , "error in ads Class in method make_ads_list -> " + e.toString());
    }
}

private class DownloadTask extends AsyncTask <String , Void , String>
{
    @Override
    protected String doInBackground(String... params) {

        String temp = "";

    try {
            JSONDownloader jd = new JSONDownloader();

            temp = jd.downloadURL( params[0]);
        }
        catch (Exception e)
        {
            Log.i("NaqibMessage" , "error in ads Class in DownloadTask -> " + e.toString());
        }


        return (temp);
    }

    @Override
    protected void onPostExecute(String s)
    {
        ListViewLoaderTask loader = new ListViewLoaderTask();

        loader.execute(s);
    }
}


private class ListViewLoaderTask extends AsyncTask <String , Void , SimpleAdapter>
{
    @Override
    protected SimpleAdapter doInBackground(String... params)
    {

        try
        {
           AdsParser parser = new AdsParser();
           all_ads.addAll(parser.parse( params[0]) );
        }
        catch (Exception e)
        {
            Log.i("NaqibMessage" , "error in ads Class in ListViewLoaderTask-> " + e.toString());
        }

        String[] from ={ "image" ,"title" , "intro" ,  "date" , "cat" };

        int[] to = { R.id.ads_img ,R.id.ads_title , R.id.ads_intro , R.id.ads_date , R.id.ads_cat};

        SimpleAdapter adb = new SimpleAdapter(getBaseContext() , all_ads , R.layout.ads_list_row, from ,to);

        return adb;
    }

    @Override
    protected void onPostExecute(SimpleAdapter adapter)
    {
        lv.setAdapter(adapter);

        for (int i = 0; i < adapter.getCount(); i++)
        {
            HashMap<String , Object> hm = (HashMap<String , Object>) adapter.getItem(i);

            String imgURL = (String) hm.get("image_path");

            HashMap<String , Object> forDownload = new HashMap<>();

            forDownload.put("image_path" , imgURL);
            forDownload.put("position" , i);

            ImageDownloaderTask imageDownloader = new ImageDownloaderTask();

            imageDownloader.execute(forDownload);
        }

        goNext = true;
    }
}


private class ImageDownloaderTask extends AsyncTask<HashMap<String , Object>,Void,HashMap<String , Object>>
{
    @Override
    protected HashMap<String, Object> doInBackground(HashMap<String, Object>... params)
    {
        InputStream myStream;

        String imgURL = (String) params[0].get("image_path");
        int position = (Integer) params[0].get("position");

        try
        {
            URL url = new URL(imgURL);

            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

            connection.setDoInput(true);

            connection.connect();

            myStream  = connection.getInputStream();

            File cacheDirectory = getBaseContext().getCacheDir();

            File temp = new File(cacheDirectory.getPath() + "/image_" + position + "_" + current_page + ".png");

            FileOutputStream outStream = new FileOutputStream(temp);

            Bitmap b = BitmapFactory.decodeStream(myStream);

            b.compress(Bitmap.CompressFormat.PNG, 100, outStream);

            outStream.flush();

            outStream.close();

            HashMap<String , Object> bitmap = new HashMap<>();

            bitmap.put("image" ,temp.getPath() );
            bitmap.put("position" ,position );

            return (bitmap);

        }
        catch (Exception e)
        {
            Log.i("NaqibMessage" , "error in ads Class in ImageDownloaderTask -> " + e.toString());

        }
        return null;
    }

    @Override
    protected void onPostExecute(HashMap<String, Object> result)
    {
        String image = (String) result.get( "image" );

        int position = (Integer) result.get( "position" );

        SimpleAdapter adb = (SimpleAdapter) lv.getAdapter();

        HashMap<String , Object> hm = (HashMap<String , Object>) adb.getItem( position );

        hm.put( "image" , image );

        adb.notifyDataSetChanged();
    }
}
public void clearCache ()
{
    try
    {
        File[] f = getBaseContext().getCacheDir().listFiles();

        for (File file : f)
        {
            file.delete();
        }
    }
    catch (Exception e)
    {
        Log.i("NaqibMessage" , "error in ads Class in ClearCache -> " + e.toString());

    }


}

public void ononBtnBackToHomeClick()
{
    finish();
}


}

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object java.util.HashMap.get(java.lang.Object)' on a null object reference
        at naqibshayea.afghanbazaar.ads$ImageDownloaderTask.onPostExecute(ads.java:275)
        at naqibshayea.afghanbazaar.ads$ImageDownloaderTask.onPostExecute(ads.java:220)
        at android.os.AsyncTask.finish(AsyncTask.java:651)
        at android.os.AsyncTask.access$500(AsyncTask.java:180)
        at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:668)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:158)
        at android.app.ActivityThread.main(ActivityThread.java:7225)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)