import android.view.View
import android.view.ViewGroup
import android.view.animation.Animation
import android.view.animation.Transformation

/**
 * Created by andrii.kovalchuk on 3/27/17.
 */

class DropDownAnimation(
        private val view: View,
        var down: Boolean,
        private val durationAnimation: Long
) : Animation() {

    init {
        this.duration = durationAnimation
    }

    override fun applyTransformation(interpolatedTime: Float, transformation: Transformation?) {
        when {
            down -> expand(interpolatedTime, transformation)
            else -> collapse(interpolatedTime, transformation)
        }
    }

    override fun willChangeBounds(): Boolean {
        return true
    }

    private fun expand(interpolatedTime: Float, transformation: Transformation?) {
        view.measure(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT)
        val targetHeight = view.measuredHeight
        // Older versions of android (pre API 21) cancel animations for views with a height of 0.
        view.layoutParams.height = 1
        view.visibility = View.VISIBLE

        view.layoutParams.height = if (interpolatedTime == 1f)
            ViewGroup.LayoutParams.WRAP_CONTENT
        else
            (targetHeight * interpolatedTime).toInt()
        view.requestLayout()
    }

    private fun collapse(interpolatedTime: Float, transformation: Transformation?) {
        val initialHeight = view.measuredHeight

        if (interpolatedTime == 1f) {
            view.visibility = View.GONE
        } else {
            view.layoutParams.height = initialHeight - (initialHeight * interpolatedTime).toInt()
            view.requestLayout()
        }
    }
}