/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * 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 org.getlantern.dynamicgridview;

import android.content.Context;

import org.getlantern.firetweet.adapter.ArrayAdapter;

import java.util.Collection;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;

public class DraggableArrayAdapter<T> extends ArrayAdapter<T> implements DraggableAdapter {

    final int INVALID_ID = -1;

    private final HashMap<T, Integer> mIdMap = new HashMap<T, Integer>();

    public DraggableArrayAdapter(final Context context, final int layoutRes) {
        this(context, layoutRes, null);
    }

    public DraggableArrayAdapter(final Context context, final int layoutRes, final Collection<? extends T> collection) {
        super(context, layoutRes, collection);
        rebuildIdMap();
    }

    @Override
    public void add(final T item) {
        super.add(item);
        rebuildIdMap();
    }

    @Override
    public void addAll(final Collection<? extends T> collection) {
        super.addAll(collection);
        rebuildIdMap();
    }

    @Override
    public void clear() {
        super.clear();
        rebuildIdMap();
    }

    @Override
    public long getItemId(final int position) {
        if (position < 0 || position >= mIdMap.size()) return INVALID_ID;
        final T item = getItem(position);
        return mIdMap.get(item);
    }

    @Override
    public boolean hasStableIds() {
        return true;
    }

    public void removeAt(final int position) {
        super.removeAt(position);
        rebuildIdMap();
    }

    @Override
    public void removeAll(final Collection<? extends T> collection) {
        super.removeAll(collection);
        rebuildIdMap();
    }

    @Override
    public void reorderElements(final int position, final int newPosition) {
        final List<T> objects = getObjects();

        T previous = objects.get(position);
        final int iterator = newPosition < position ? 1 : -1;
        final int afterPosition = position + iterator;
        for (int cellPosition = newPosition; cellPosition != afterPosition; cellPosition += iterator) {
            final T tmp = objects.get(cellPosition);
            objects.set(cellPosition, previous);
            previous = tmp;
        }
        notifyDataSetChanged();
    }

    @Override
    public void sort(final Comparator<? super T> comparator) {
        super.sort(comparator);
        rebuildIdMap();
    }

    @Override
    public void swapElements(final int position, final int newPosition) {
        final List<T> objects = getObjects();
        final T temp = objects.get(position);
        objects.set(position, objects.get(newPosition));
        objects.set(newPosition, temp);
        notifyDataSetChanged();
    }

    private void rebuildIdMap() {
        mIdMap.clear();
        final List<T> objects = getObjects();
        for (int i = 0, j = objects.size(); i < j; ++i) {
            mIdMap.put(objects.get(i), i);
        }
    }
}