packages/SystemUI/src/com/android/systemui/media/SeekBarObserver.kt

/*
 * Copyright (C) 2020 The Android Open Source Project
 *
 * 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 com.android.systemui.media

import android.animation.Animator
import android.animation.ObjectAnimator
import android.text.format.DateUtils
import androidx.annotation.UiThread
import androidx.lifecycle.Observer
import com.android.internal.annotations.VisibleForTesting
import com.android.systemui.R
import com.android.systemui.animation.Interpolators

/**
 * Observer for changes from SeekBarViewModel.
 *
 * <p>Updates the seek bar views in response to changes to the model.
 */
open class SeekBarObserver(
    private val holder: MediaViewHolder
) : Observer<SeekBarViewModel.Progress> {

    companion object {
        @JvmStatic val RESET_ANIMATION_DURATION_MS: Int = 750
        @JvmStatic val RESET_ANIMATION_THRESHOLD_MS: Int = 250
    }

    val seekBarEnabledMaxHeight = holder.seekBar.context.resources
        .getDimensionPixelSize(R.dimen.qs_media_enabled_seekbar_height)
    val seekBarDisabledHeight = holder.seekBar.context.resources
        .getDimensionPixelSize(R.dimen.qs_media_disabled_seekbar_height)
    val seekBarEnabledVerticalPadding = holder.seekBar.context.resources
                .getDimensionPixelSize(R.dimen.qs_media_session_enabled_seekbar_vertical_padding)
    val seekBarDisabledVerticalPadding = holder.seekBar.context.resources
                .getDimensionPixelSize(R.dimen.qs_media_session_disabled_seekbar_vertical_padding)
    var seekBarResetAnimator: Animator? = null

    init {
        val seekBarProgressWavelength = holder.seekBar.context.resources
                .getDimensionPixelSize(R.dimen.qs_media_seekbar_progress_wavelength).toFloat()
        val seekBarProgressAmplitude = holder.seekBar.context.resources
                .getDimensionPixelSize(R.dimen.qs_media_seekbar_progress_amplitude).toFloat()
        val seekBarProgressPhase = holder.seekBar.context.resources
                .getDimensionPixelSize(R.dimen.qs_media_seekbar_progress_phase).toFloat()
        val seekBarProgressStrokeWidth = holder.seekBar.context.resources
                .getDimensionPixelSize(R.dimen.qs_media_seekbar_progress_stroke_width).toFloat()
        val progressDrawable = holder.seekBar.progressDrawable as? SquigglyProgress
        progressDrawable?.let {
            it.waveLength = seekBarProgressWavelength
            it.lineAmplitude = seekBarProgressAmplitude
            it.phaseSpeed = seekBarProgressPhase
            it.strokeWidth = seekBarProgressStrokeWidth
        }
    }

    /** Updates seek bar views when the data model changes. */
    @UiThread
    override fun onChanged(data: SeekBarViewModel.Progress) {
        val progressDrawable = holder.seekBar.progressDrawable as? SquigglyProgress
        if (!data.enabled) {
            if (holder.seekBar.maxHeight != seekBarDisabledHeight) {
                holder.seekBar.maxHeight = seekBarDisabledHeight
                setVerticalPadding(seekBarDisabledVerticalPadding)
            }
            holder.seekBar.isEnabled = false
            progressDrawable?.animate = false
            holder.seekBar.thumb.alpha = 0
            holder.seekBar.progress = 0
            holder.seekBar.contentDescription = ""
            holder.scrubbingElapsedTimeView.text = ""
            holder.scrubbingTotalTimeView.text = ""
            return
        }

        holder.seekBar.thumb.alpha = if (data.seekAvailable) 255 else 0
        holder.seekBar.isEnabled = data.seekAvailable
        progressDrawable?.animate = data.playing && !data.scrubbing
        progressDrawable?.transitionEnabled = !data.seekAvailable

        if (holder.seekBar.maxHeight != seekBarEnabledMaxHeight) {
            holder.seekBar.maxHeight = seekBarEnabledMaxHeight
            setVerticalPadding(seekBarEnabledVerticalPadding)
        }

        holder.seekBar.setMax(data.duration)
        val totalTimeString = DateUtils.formatElapsedTime(
            data.duration / DateUtils.SECOND_IN_MILLIS)
        if (data.scrubbing) {
            holder.scrubbingTotalTimeView.text = totalTimeString
        }

        data.elapsedTime?.let {
            if (!data.scrubbing && !(seekBarResetAnimator?.isRunning ?: false)) {
                if (it <= RESET_ANIMATION_THRESHOLD_MS &&
                        holder.seekBar.progress > RESET_ANIMATION_THRESHOLD_MS) {
                    // This animation resets for every additional update to zero.
                    val animator = buildResetAnimator(it)
                    animator.start()
                    seekBarResetAnimator = animator
                } else {
                    holder.seekBar.progress = it
                }
            }

            val elapsedTimeString = DateUtils.formatElapsedTime(
                it / DateUtils.SECOND_IN_MILLIS)
            if (data.scrubbing) {
                holder.scrubbingElapsedTimeView.text = elapsedTimeString
            }

            holder.seekBar.contentDescription = holder.seekBar.context.getString(
                R.string.controls_media_seekbar_description,
                elapsedTimeString,
                totalTimeString
            )
        }
    }

    @VisibleForTesting
    open fun buildResetAnimator(targetTime: Int): Animator {
        val animator = ObjectAnimator.ofInt(holder.seekBar, "progress",
                holder.seekBar.progress, targetTime + RESET_ANIMATION_DURATION_MS)
        animator.setAutoCancel(true)
        animator.duration = RESET_ANIMATION_DURATION_MS.toLong()
        animator.interpolator = Interpolators.EMPHASIZED
        return animator
    }

    @UiThread
    fun setVerticalPadding(padding: Int) {
        val leftPadding = holder.seekBar.paddingLeft
        val rightPadding = holder.seekBar.paddingRight
        val bottomPadding = holder.seekBar.paddingBottom
        holder.seekBar.setPadding(leftPadding, padding, rightPadding, bottomPadding)
    }
}