/*
 * Copyright (c) 2019 Hemanth Savarala.
 *
 * Licensed under the GNU General Public License v3
 *
 * This 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 software 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.
 */

package code.name.monkey.retromusic.misc

import com.google.android.material.appbar.AppBarLayout
import kotlin.math.abs

/**
 * @author Hemanth S (h4h13).
 * https://stackoverflow.com/a/33891727
 */

abstract class AppBarStateChangeListener : AppBarLayout.OnOffsetChangedListener {

    private var mCurrentState = State.IDLE

    override fun onOffsetChanged(appBarLayout: AppBarLayout, i: Int) {
        when {
            i == 0 -> {
                if (mCurrentState != State.EXPANDED) {
                    onStateChanged(appBarLayout, State.EXPANDED)
                }
                mCurrentState = State.EXPANDED
            }
            abs(i) >= appBarLayout.totalScrollRange -> {
                if (mCurrentState != State.COLLAPSED) {
                    onStateChanged(appBarLayout, State.COLLAPSED)
                }
                mCurrentState = State.COLLAPSED
            }
            else -> {
                if (mCurrentState != State.IDLE) {
                    onStateChanged(appBarLayout, State.IDLE)
                }
                mCurrentState = State.IDLE
            }
        }
    }

    abstract fun onStateChanged(appBarLayout: AppBarLayout, state: State)

    enum class State {
        EXPANDED,
        COLLAPSED,
        IDLE
    }
}