ContractionAverageFragment.java

package com.ianhanniballake.contractiontimer.ui;

import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.database.Cursor;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.support.v4.app.Fragment;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.CursorLoader;
import android.support.v4.content.Loader;
import android.text.format.DateUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import com.ianhanniballake.contractiontimer.R;
import com.ianhanniballake.contractiontimer.provider.ContractionContract;

/**
 * Fragment which displays the average duration and frequency
 */
public class ContractionAverageFragment extends Fragment implements LoaderManager.LoaderCallbacks<Cursor> {
    @Override
    public void onActivityCreated(final Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        getLoaderManager().initLoader(0, null, this);
    }

    @Override
    public Loader<Cursor> onCreateLoader(final int id, final Bundle args) {
        final String[] projection = {ContractionContract.Contractions.COLUMN_NAME_START_TIME,
                ContractionContract.Contractions.COLUMN_NAME_END_TIME};
        final String selection = ContractionContract.Contractions.COLUMN_NAME_START_TIME + ">?";
        final SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(getActivity());
        final long averagesTimeFrame = Long.parseLong(preferences.getString(
                Preferences.AVERAGE_TIME_FRAME_PREFERENCE_KEY,
                getString(R.string.pref_average_time_frame_default)));
        final long timeCutoff = System.currentTimeMillis() - averagesTimeFrame;
        final String[] selectionArgs = {Long.toString(timeCutoff)};
        return new CursorLoader(getActivity(), getActivity().getIntent().getData(), projection, selection,
                selectionArgs, null);
    }

    @Override
    public View onCreateView(final LayoutInflater inflater, final ViewGroup container, final Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_contraction_average, container, false);
    }

    @Override
    public void onLoaderReset(final Loader<Cursor> loader) {
        final View view = getView();
        if (view == null)
            return;
        final View averageLayout = view.findViewById(R.id.average_layout);
        final TextView averageDurationView = (TextView) view.findViewById(R.id.average_duration);
        final TextView averageFrequencyView = (TextView) view.findViewById(R.id.average_frequency);
        averageLayout.setVisibility(View.GONE);
        averageDurationView.setText("");
        averageFrequencyView.setText("");
    }

    @Override
    public void onLoadFinished(final Loader<Cursor> loader, final Cursor data) {
        final View view = getView();
        if (view == null)
            return;
        final View averageLayout = view.findViewById(R.id.average_layout);
        final TextView averageDurationView = (TextView) view.findViewById(R.id.average_duration);
        final TextView averageFrequencyView = (TextView) view.findViewById(R.id.average_frequency);
        if (data == null || !data.moveToFirst()) {
            averageLayout.setVisibility(View.GONE);
            averageDurationView.setText("");
            averageFrequencyView.setText("");
            return;
        }
        double averageDuration = 0;
        double averageFrequency = 0;
        int numDurations = 0;
        int numFrequencies = 0;
        while (!data.isAfterLast()) {
            final int startTimeColumnIndex = data
                    .getColumnIndex(ContractionContract.Contractions.COLUMN_NAME_START_TIME);
            final long startTime = data.getLong(startTimeColumnIndex);
            final int endTimeColumnIndex = data.getColumnIndex(ContractionContract.Contractions.COLUMN_NAME_END_TIME);
            if (!data.isNull(endTimeColumnIndex)) {
                final long endTime = data.getLong(endTimeColumnIndex);
                final long curDuration = endTime - startTime;
                averageDuration = (curDuration + numDurations * averageDuration) / (numDurations + 1);
                numDurations++;
            }
            if (data.moveToNext()) {
                final int prevContractionStartTimeColumnIndex = data
                        .getColumnIndex(ContractionContract.Contractions.COLUMN_NAME_START_TIME);
                final long prevContractionStartTime = data.getLong(prevContractionStartTimeColumnIndex);
                final long curFrequency = startTime - prevContractionStartTime;
                averageFrequency = (curFrequency + numFrequencies * averageFrequency) / (numFrequencies + 1);
                numFrequencies++;
            }
        }
        averageLayout.setVisibility(View.VISIBLE);
        final long averageDurationInSeconds = (long) (averageDuration / 1000);
        averageDurationView.setText(DateUtils.formatElapsedTime(averageDurationInSeconds));
        final long averageFrequencyInSeconds = (long) (averageFrequency / 1000);
        averageFrequencyView.setText(DateUtils.formatElapsedTime(averageFrequencyInSeconds));
    }

    @Override
    public void onResume() {
        super.onResume();
        final SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(getActivity());
        final boolean averageTimeFrameChanged = preferences.getBoolean(
                Preferences.AVERAGE_TIME_FRAME_CHANGED_FRAGMENT_PREFERENCE_KEY, false);
        if (averageTimeFrameChanged) {
            final Editor editor = preferences.edit();
            editor.remove(Preferences.AVERAGE_TIME_FRAME_CHANGED_FRAGMENT_PREFERENCE_KEY);
            editor.commit();
            getLoaderManager().restartLoader(0, null, this);
        }
    }
}