/*
 * Firetweet - Twitter client for Android
 *
 *  Copyright (C) 2012-2015 Mariotaku Lee <mariotaku.lee@gmail.com>
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.getlantern.firetweet.util;

import android.support.annotation.NonNull;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.RecyclerView.OnScrollListener;

import org.getlantern.firetweet.adapter.iface.IContentCardAdapter;

/**
 * Created by mariotaku on 15/3/15.
 */
public class ContentListScrollListener extends OnScrollListener {

    private int mScrollState;
    private int mScrollSum;
    private int mTouchSlop;

    private ContentListSupport mContentListSupport;
    private OnScrollListener mOnScrollListener;

    public ContentListScrollListener(@NonNull ContentListSupport contentListSupport) {
        mContentListSupport = contentListSupport;
    }

    public void setOnScrollListener(OnScrollListener listener) {
        mOnScrollListener = listener;
    }


    @Override
    public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
        if (mOnScrollListener != null) {
            mOnScrollListener.onScrollStateChanged(recyclerView, newState);
        }
        final IContentCardAdapter adapter = mContentListSupport.getAdapter();
        final LinearLayoutManager layoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
        if (!mContentListSupport.isRefreshing() && adapter.isLoadMoreSupported()
                && !adapter.isLoadMoreIndicatorVisible() && mScrollState != RecyclerView.SCROLL_STATE_IDLE
                && layoutManager.findLastVisibleItemPosition() == adapter.getItemCount() - 1) {
            mContentListSupport.onLoadMoreContents();
        }
        mScrollState = newState;
    }

    @Override
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        if (mOnScrollListener != null) {
            mOnScrollListener.onScrolled(recyclerView, dx, dy);
        }
        //Reset mScrollSum when scrolling in reverse direction
        if (dy * mScrollSum < 0) {
            mScrollSum = 0;
        }
        mScrollSum += dy;
        if (Math.abs(mScrollSum) > mTouchSlop) {
            mContentListSupport.setControlVisible(dy < 0);
            mScrollSum = 0;
        }
    }


    public void setTouchSlop(int touchSlop) {
        mTouchSlop = touchSlop;
    }

    public static interface ContentListSupport {

        boolean isRefreshing();

        IContentCardAdapter getAdapter();

        void setControlVisible(boolean visible);

        void onLoadMoreContents();

    }
}