/*
 * Copyright (C) 2011 Alexander Blom
 *
 * 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 com.github.mobile;

import android.content.Context;
import android.support.v4.content.AsyncTaskLoader;

/**
 * Loader which extends AsyncTaskLoaders and handles caveats as pointed out in
 * http://code.google.com/p/android/issues/detail?id=14944.
 * <p/>
 * Based on CursorLoader.java in the Fragment compatibility package
 *
 * @param <D>
 *            data type
 * @author Alexander Blom (me@alexanderblom.se)
 */
public abstract class AsyncLoader<D> extends AsyncTaskLoader<D> {

    private D data;

    /**
     * Create async loader
     *
     * @param context
     */
    public AsyncLoader(Context context) {
        super(context);
    }

    @Override
    public void deliverResult(D data) {
        if (isReset())
            // An async query came in while the loader is stopped
            return;

        this.data = data;

        super.deliverResult(data);
    }

    @Override
    protected void onStartLoading() {
        if (data != null)
            deliverResult(data);

        if (takeContentChanged() || data == null)
            forceLoad();
    }

    @Override
    protected void onStopLoading() {
        // Attempt to cancel the current load task if possible.
        cancelLoad();
    }

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

        // Ensure the loader is stopped
        onStopLoading();

        data = null;
    }
}