mihon/app/src/main/java/eu/kanade/tachiyomi/widget/FABAnimationBase.kt

package eu.kanade.tachiyomi.widget

import android.support.design.widget.CoordinatorLayout
import android.support.design.widget.FloatingActionButton
import android.support.v4.view.ViewCompat
import android.view.View

abstract class FABAnimationBase() : FloatingActionButton.Behavior() {

    var isAnimatingOut = false

    override fun onStartNestedScroll(coordinatorLayout: CoordinatorLayout, child: FloatingActionButton,
                                     directTargetChild: View, target: View, nestedScrollAxes: Int): Boolean {
        // Ensure we react to vertical scrolling
        return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL ||
                super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, nestedScrollAxes)
    }

    override fun onNestedScroll(coordinatorLayout: CoordinatorLayout, child: FloatingActionButton, target: View,
                                dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int) {
        super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed)
        if (dyConsumed > 0 && !isAnimatingOut && child.visibility == View.VISIBLE) {
            // User scrolled down and the FAB is currently visible -> hide the FAB
            animateOut(child)
        } else if (dyConsumed < 0 && child.visibility != View.VISIBLE) {
            // User scrolled up and the FAB is currently not visible -> show the FAB
            animateIn(child)
        }
    }

    abstract fun animateOut(button: FloatingActionButton)
    abstract fun animateIn(button: FloatingActionButton)
}