/*
 * Copyright 2010, 2011, 2012, 2013 mapsforge.org
 *
 * This program is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later version.
 *
 * This program 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along with
 * this program. If not, see <http://www.gnu.org/licenses/>.
 */
package org.mapsforge.samples.android;

import android.annotation.TargetApi;
import android.app.Activity;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.view.View;
import android.widget.AbsListView;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import org.mapsforge.samples.android.dummy.DummyContent;

/**
 * A list fragment representing a list of Items. This fragment also supports
 * tablet devices by allowing list items to be given an 'activated' state upon
 * selection. This helps indicate which item is currently being viewed in a
 * {@link ItemDetailFragment}.
 * <p/>
 * Activities containing this fragment MUST implement the {@link Callbacks}
 * interface.
 */
public class ItemListFragment extends ListFragment {
    /**
     * A callback interface that all activities containing this fragment must
     * implement. This mechanism allows activities to be notified of item
     * selections.
     */
    public interface Callbacks {
        /**
         * Callback for when an item has been selected.
         */
        void onItemSelected(String id);
    }

    /**
     * A dummy implementation of the {@link Callbacks} interface that does
     * nothing. Used only when this fragment is not attached to an activity.
     */
    private static Callbacks sDummyCallbacks = new Callbacks() {
        @Override
        public void onItemSelected(String id) {
            // no op
        }
    };

    /**
     * The serialization (saved instance state) Bundle key representing the
     * activated item position. Only used on tablets.
     */
    private static final String STATE_ACTIVATED_POSITION = "activated_position";

    /**
     * The current activated item position. Only used on tablets.
     */
    private int mActivatedPosition = AdapterView.INVALID_POSITION;

    /**
     * The fragment's current callback object, which is notified of list item
     * clicks.
     */
    private Callbacks mCallbacks = sDummyCallbacks;

    /**
     * Mandatory empty constructor for the fragment manager to instantiate the
     * fragment (e.g. upon screen orientation changes).
     */
    public ItemListFragment() {
        super();
    }

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

        // Activities containing this fragment must implement its callbacks.
        if (!(activity instanceof Callbacks)) {
            throw new IllegalStateException(
                    "Activity must implement fragment's callbacks.");
        }

        this.mCallbacks = (Callbacks) activity;
    }

    @Override
    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        int layout = android.R.layout.simple_list_item_1;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            layout = android.R.layout.simple_list_item_activated_1;
        }
        setListAdapter(new ArrayAdapter<DummyContent.DummyItem>(getActivity(),
                layout, android.R.id.text1, DummyContent.ITEMS));
    }

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

        // Reset the active callbacks interface to the dummy implementation.
        this.mCallbacks = sDummyCallbacks;
    }

    @Override
    public void onListItemClick(ListView listView, View view, int position,
                                long id) {
        super.onListItemClick(listView, view, position, id);

        // Notify the active callbacks interface (the activity, if the
        // fragment is attached to one) that an item has been selected.
        this.mCallbacks.onItemSelected(DummyContent.ITEMS.get(position).id);
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        if (this.mActivatedPosition != AdapterView.INVALID_POSITION) {
            // Serialize and persist the activated item position.
            outState.putInt(STATE_ACTIVATED_POSITION, this.mActivatedPosition);
        }
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        // Restore the previously serialized activated item position.
        if (savedInstanceState != null
                && savedInstanceState.containsKey(STATE_ACTIVATED_POSITION)) {
            setActivatedPosition(savedInstanceState
                    .getInt(STATE_ACTIVATED_POSITION));
        }
    }

    /**
     * Turns on activate-on-click mode. When this mode is on, list items will be
     * given the 'activated' state when touched.
     */
    public void setActivateOnItemClick(boolean activateOnItemClick) {
        // When setting CHOICE_MODE_SINGLE, ListView will automatically
        // give items the 'activated' state when touched.
        getListView().setChoiceMode(
                activateOnItemClick ? AbsListView.CHOICE_MODE_SINGLE
                        : AbsListView.CHOICE_MODE_NONE);
    }

    private void setActivatedPosition(int position) {
        if (position == AdapterView.INVALID_POSITION) {
            getListView().setItemChecked(this.mActivatedPosition, false);
        } else {
            getListView().setItemChecked(position, true);
        }

        this.mActivatedPosition = position;
    }
}
