/**
 * 用于缓存View使用
 *
 * @author legendmohe
 */
public final class ViewCache {

    private static final String TAG = "ViewCache";

    private final ExecutorService service;
    private final SparseArray<List<View>> mStack;

    private ViewCache() {
        service = Executors.newSingleThreadExecutor();
        mStack = new SparseArray<>(2);
    }

    private static class LazyHolder {
        private static final ViewCache INSTANCE = new ViewCache();
    }

    public static ViewCache getInstance() {
        return LazyHolder.INSTANCE;
    }

    /**
     * 获取缓存View
     *
     * @return View
     */
    @Nullable
    public synchronized View popAndAquire(Configuration configuration) {
        List<View> views = mStack.get(configuration.orientation);
        push(configuration);

        if (views != null && views.size() > 0) {
            return views.remove(views.size() - 1);
        }
        return null;
    }

    /**
     * 在其他线程进行View初始化
     *
     * @param configuration Configuration
     */
    private void push(final Configuration configuration) {
        service.execute(new Runnable() {
            @Override
            public void run() {
                if (Looper.myLooper() == null) {
                    Looper.prepare();
                }

                long startTime = SystemClock.uptimeMillis();
                View view = View.inflate(activity, R.layout.your_layout_id, null);
                long endTime = SystemClock.uptimeMillis() - startTime;


                List<View> views = mStack.get(configuration.orientation);
                if (views == null) {
                    views = new ArrayList<>();
                    mStack.put(configuration.orientation, views);
                }

                views.add(view);
                Log.i(TAG, "push finished, inflate time=" + endTime + " size=" + views.size());
            }
        });
    }

    public void push(Configuration configuration, boolean onlyNotExist) {
        if (onlyNotExist && isInstanceExisted(configuration)) {
            return;
        }
        push(configuration);
    }

    public synchronized void push(Configuration configuration, int maxStackSize) {
        if (maxStackSize <= 0) {
            return;
        }

        List<View> views = mStack.get(configuration.orientation);
        if (views != null && views.size() >= maxStackSize) {
            return;
        }

        push(configuration);
    }

    public synchronized boolean isInstanceExisted(Configuration configuration) {
        if (configuration == null) {
            return false;
        }
        List<View> views = mStack.get(configuration.orientation);
        return views != null && views.size() != 0;
    }
}