/*
 * Copyright 2020 Google LLC
 *
 * 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
 *
 *     https://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 me.zhanghai.android.fastscroll;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;

import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;

import androidx.annotation.AttrRes;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.recyclerview.widget.RecyclerView;

public class FixOnItemTouchListenerRecyclerView extends RecyclerView {

    @NonNull
    private final OnItemTouchDispatcher mOnItemTouchDispatcher = new OnItemTouchDispatcher();

    public FixOnItemTouchListenerRecyclerView(@NonNull Context context) {
        super(context);

        init();
    }

    public FixOnItemTouchListenerRecyclerView(@NonNull Context context,
                                              @Nullable AttributeSet attrs) {
        super(context, attrs);

        init();
    }

    public FixOnItemTouchListenerRecyclerView(@NonNull Context context,
                                              @Nullable AttributeSet attrs,
                                              @AttrRes int defStyleAttr) {
        super(context, attrs, defStyleAttr);

        init();
    }

    private void init() {
        super.addOnItemTouchListener(mOnItemTouchDispatcher);
    }

    @Override
    public void addOnItemTouchListener(@NonNull OnItemTouchListener listener) {
        mOnItemTouchDispatcher.addListener(listener);
    }

    @Override
    public void removeOnItemTouchListener(@NonNull OnItemTouchListener listener) {
        mOnItemTouchDispatcher.removeListener(listener);
    }

    private static class OnItemTouchDispatcher implements OnItemTouchListener {

        @NonNull
        private final List<OnItemTouchListener> mListeners = new ArrayList<>();

        @NonNull
        private final Set<OnItemTouchListener> mTrackingListeners = new LinkedHashSet<>();

        @Nullable
        private OnItemTouchListener mInterceptingListener;

        public void addListener(@NonNull OnItemTouchListener listener) {
            mListeners.add(listener);
        }

        public void removeListener(@NonNull OnItemTouchListener listener) {
            mListeners.remove(listener);
            mTrackingListeners.remove(listener);
            if (mInterceptingListener == listener) {
                mInterceptingListener = null;
            }
        }

        // @see RecyclerView#findInterceptingOnItemTouchListener
        @Override
        public boolean onInterceptTouchEvent(@NonNull RecyclerView recyclerView,
                                             @NonNull MotionEvent event) {
            int action = event.getAction();
            for (OnItemTouchListener listener : mListeners) {
                boolean intercepted = listener.onInterceptTouchEvent(recyclerView, event);
                if (action == MotionEvent.ACTION_CANCEL) {
                    mTrackingListeners.remove(listener);
                    continue;
                }
                if (intercepted) {
                    mTrackingListeners.remove(listener);
                    event.setAction(MotionEvent.ACTION_CANCEL);
                    for (OnItemTouchListener trackingListener : mTrackingListeners) {
                        trackingListener.onInterceptTouchEvent(recyclerView, event);
                    }
                    event.setAction(action);
                    mTrackingListeners.clear();
                    mInterceptingListener = listener;
                    return true;
                } else {
                    mTrackingListeners.add(listener);
                }
            }
            return false;
        }

        @Override
        public void onTouchEvent(@NonNull RecyclerView recyclerView, @NonNull MotionEvent event) {
            if (mInterceptingListener == null) {
                return;
            }
            mInterceptingListener.onTouchEvent(recyclerView, event);
            int action = event.getAction();
            if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) {
                mInterceptingListener = null;
            }
        }

        @Override
        public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {
            for (OnItemTouchListener listener : mListeners) {
                listener.onRequestDisallowInterceptTouchEvent(disallowIntercept);
            }
        }
    }
}