/*
 * Copyright 2017 Martijn Brekhof. All rights reserved.
 *
 * 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.xbmc.kore.ui.behaviors;

import android.content.Context;

import androidx.annotation.NonNull;
import androidx.coordinatorlayout.widget.CoordinatorLayout;
import androidx.core.view.ViewCompat;
import android.util.AttributeSet;
import android.view.View;

public class FadeOutOnVerticalScrollBehavior extends CoordinatorLayout.Behavior {

    private int maxScroll = 0;
    private int currentScroll;

    public FadeOutOnVerticalScrollBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean onStartNestedScroll(@NonNull CoordinatorLayout coordinatorLayout, @NonNull View child, @NonNull View directTargetChild, @NonNull View target, int axes, int type) {
        if ( axes == ViewCompat.SCROLL_AXIS_VERTICAL ) {
            if (maxScroll == 0)
                maxScroll = child.getHeight();

            return true;
        }
        return false;
    }

    @Override
    public void onNestedScroll(@NonNull CoordinatorLayout coordinatorLayout, @NonNull View child, @NonNull View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int type) {
        currentScroll += dyConsumed;
        child.setAlpha((float) ((maxScroll - currentScroll) / (double) maxScroll));
    }
}