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

package com.android.systemui.media

import android.content.Context
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.HorizontalScrollView
import android.widget.LinearLayout
import com.android.settingslib.bluetooth.LocalBluetoothManager
import com.android.settingslib.media.InfoMediaManager
import com.android.settingslib.media.LocalMediaManager
import com.android.systemui.R
import com.android.systemui.dagger.qualifiers.Background
import com.android.systemui.dagger.qualifiers.Main
import com.android.systemui.plugins.ActivityStarter
import com.android.systemui.statusbar.notification.VisualStabilityManager
import com.android.systemui.util.animation.MeasurementOutput
import com.android.systemui.util.animation.UniqueObjectHostView
import com.android.systemui.util.concurrency.DelayableExecutor
import java.util.concurrent.Executor
import javax.inject.Inject
import javax.inject.Singleton

/**
 * Class that is responsible for keeping the view carousel up to date.
 * This also handles changes in state and applies them to the media carousel like the expansion.
 */
@Singleton
class MediaViewManager @Inject constructor(
    private val context: Context,
    @Main private val foregroundExecutor: Executor,
    @Background private val backgroundExecutor: DelayableExecutor,
    private val localBluetoothManager: LocalBluetoothManager?,
    private val visualStabilityManager: VisualStabilityManager,
    private val activityStarter: ActivityStarter,
    mediaManager: MediaDataManager
) {
    private var playerWidth: Int = 0
    private var playerWidthPlusPadding: Int = 0
    private var desiredState: MediaHost.MediaHostState? = null
    private var currentState: MediaState? = null
    val mediaCarousel: HorizontalScrollView
    private val mediaContent: ViewGroup
    private val mediaPlayers: MutableMap<String, MediaControlPanel> = mutableMapOf()
    private val visualStabilityCallback = ::reorderAllPlayers
    private var activeMediaIndex: Int = 0
    private var scrollIntoCurrentMedia: Int = 0

    private var currentlyExpanded = true
        set(value) {
            if (field != value) {
                field = value
                for (player in mediaPlayers.values) {
                    player.setListening(field)
                }
            }
        }
    private val scrollChangedListener = object : View.OnScrollChangeListener {
        override fun onScrollChange(v: View?, scrollX: Int, scrollY: Int, oldScrollX: Int,
                                    oldScrollY: Int) {
            if (playerWidthPlusPadding == 0) {
                return
            }
            onMediaScrollingChanged(scrollX / playerWidthPlusPadding,
                    scrollX % playerWidthPlusPadding)
        }
    }

    init {
        mediaCarousel = inflateMediaCarousel()
        mediaCarousel.setOnScrollChangeListener(scrollChangedListener)
        mediaContent = mediaCarousel.requireViewById(R.id.media_carousel)
        mediaManager.addListener(object : MediaDataManager.Listener {
            override fun onMediaDataLoaded(key: String, data: MediaData) {
                updateView(key, data)
                updatePlayerVisibilities()
            }

            override fun onMediaDataRemoved(key: String) {
                val removed = mediaPlayers.remove(key)
                removed?.apply {
                    val beforeActive = mediaContent.indexOfChild(removed.view) <= activeMediaIndex
                    mediaContent.removeView(removed.view)
                    removed.onDestroy()
                    updateMediaPaddings()
                    if (beforeActive) {
                        // also update the index here since the scroll below might not always lead
                        // to a scrolling changed
                        activeMediaIndex = Math.max(0, activeMediaIndex - 1)
                        mediaCarousel.scrollX = Math.max(mediaCarousel.scrollX
                                - playerWidthPlusPadding, 0)
                    }
                    updatePlayerVisibilities()
                }
            }
        })
    }

    private fun inflateMediaCarousel(): HorizontalScrollView {
        return LayoutInflater.from(context).inflate(R.layout.media_carousel,
                UniqueObjectHostView(context), false) as HorizontalScrollView
    }

    private fun reorderAllPlayers() {
        for (mediaPlayer in mediaPlayers.values) {
            val view = mediaPlayer.view
            if (mediaPlayer.isPlaying && mediaContent.indexOfChild(view) != 0) {
                mediaContent.removeView(view)
                mediaContent.addView(view, 0)
            }
        }
        updateMediaPaddings()
        updatePlayerVisibilities()
    }

    private fun onMediaScrollingChanged(newIndex: Int, scrollInAmount: Int) {
        val wasScrolledIn = scrollIntoCurrentMedia != 0
        scrollIntoCurrentMedia = scrollInAmount
        val nowScrolledIn = scrollIntoCurrentMedia != 0
        if (newIndex != activeMediaIndex || wasScrolledIn != nowScrolledIn) {
            activeMediaIndex = newIndex
            updatePlayerVisibilities()
        }
    }

    private fun updatePlayerVisibilities() {
        val scrolledIn = scrollIntoCurrentMedia != 0
        for (i in 0 until mediaContent.childCount) {
            val view = mediaContent.getChildAt(i)
            val visible = (i == activeMediaIndex) || ((i == (activeMediaIndex + 1)) && scrolledIn)
            view.visibility = if (visible) View.VISIBLE else View.INVISIBLE
        }
    }

    private fun updateView(key: String, data: MediaData) {
        var existingPlayer = mediaPlayers[key]
        if (existingPlayer == null) {
            // Set up listener for device changes
            // TODO: integrate with MediaTransferManager?
            val imm = InfoMediaManager(context, data.packageName,
                    null /* notification */, localBluetoothManager)
            val routeManager = LocalMediaManager(context, localBluetoothManager,
                    imm, data.packageName)

            existingPlayer = MediaControlPanel(context, mediaContent, routeManager,
                    foregroundExecutor, backgroundExecutor, activityStarter)
            mediaPlayers[key] = existingPlayer
            val lp = LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT)
            existingPlayer.view.setLayoutParams(lp)
            existingPlayer.setListening(currentlyExpanded)
            if (existingPlayer.isPlaying) {
                mediaContent.addView(existingPlayer.view, 0)
            } else {
                mediaContent.addView(existingPlayer.view)
            }
            updatePlayerToCurrentState(existingPlayer)
        } else if (existingPlayer.isPlaying &&
                    mediaContent.indexOfChild(existingPlayer.view) != 0) {
            if (visualStabilityManager.isReorderingAllowed) {
                mediaContent.removeView(existingPlayer.view)
                mediaContent.addView(existingPlayer.view, 0)
            } else {
                visualStabilityManager.addReorderingAllowedCallback(visualStabilityCallback)
            }
        }
        existingPlayer.bind(data)
        // Resetting the progress to make sure it's taken into account for the latest
        // motion model
        existingPlayer.view.progress = currentState?.expansion ?: 0.0f
        updateMediaPaddings()
    }

    private fun updatePlayerToCurrentState(existingPlayer: MediaControlPanel) {
        if (desiredState != null && desiredState!!.measurementInput != null) {
            // make sure the player width is set to the current state
            existingPlayer.setPlayerWidth(playerWidth)
        }
    }

    private fun updateMediaPaddings() {
        val padding = context.resources.getDimensionPixelSize(R.dimen.qs_media_padding)
        val childCount = mediaContent.childCount
        for (i in 0 until childCount) {
            val mediaView = mediaContent.getChildAt(i)
            val desiredPaddingEnd = if (i == childCount - 1) 0 else padding
            val layoutParams = mediaView.layoutParams as ViewGroup.MarginLayoutParams
            if (layoutParams.marginEnd != desiredPaddingEnd) {
                layoutParams.marginEnd = desiredPaddingEnd
                mediaView.layoutParams = layoutParams
            }
        }

    }

    /**
     * Set the current state of a view. This is updated often during animations and we shouldn't
     * do anything expensive.
     */
    fun setCurrentState(state: MediaState) {
        currentState = state
        currentlyExpanded = state.expansion > 0
        for (mediaPlayer in mediaPlayers.values) {
            val view = mediaPlayer.view
            view.progress = state.expansion
        }
    }

    /**
     * The desired location of this view has changed. We should remeasure the view to match
     * the new bounds and kick off bounds animations if necessary.
     * If an animation is happening, an animation is kicked of externally, which sets a new
     * current state until we reach the targetState.
     *
     * @param desiredState the target state we're transitioning to
     * @param animate should this be animated
     */
    fun onDesiredLocationChanged(desiredState: MediaState?, animate: Boolean, duration: Long,
                                 startDelay: Long) {
        if (desiredState is MediaHost.MediaHostState) {
            // This is a hosting view, let's remeasure our players
            this.desiredState = desiredState
            val width = desiredState.boundsOnScreen.width()
            if (playerWidth != width) {
                setPlayerWidth(width)
                for (mediaPlayer in mediaPlayers.values) {
                    if (animate && mediaPlayer.view.visibility == View.VISIBLE) {
                        mediaPlayer.animatePendingSizeChange(duration, startDelay)
                    }
                }
                val widthSpec = desiredState.measurementInput?.widthMeasureSpec ?: 0
                val heightSpec = desiredState.measurementInput?.heightMeasureSpec ?: 0
                var left = 0
                for (i in 0 until mediaContent.childCount) {
                    val view = mediaContent.getChildAt(i)
                    view.measure(widthSpec, heightSpec)
                    view.layout(left, 0, left + width, view.measuredHeight)
                    left = left + playerWidthPlusPadding
                }
            }
        }
    }

    fun setPlayerWidth(width: Int) {
        if (width != playerWidth) {
            playerWidth = width
            playerWidthPlusPadding = playerWidth + context.resources.getDimensionPixelSize(
                    R.dimen.qs_media_padding)
            for (mediaPlayer in mediaPlayers.values) {
                mediaPlayer.setPlayerWidth(width)
            }
            // The player width has changed, let's update the scroll position to make sure
            // it's still at the same place
            var newScroll = activeMediaIndex * playerWidthPlusPadding
            if (scrollIntoCurrentMedia > playerWidthPlusPadding) {
                newScroll += playerWidthPlusPadding
                - (scrollIntoCurrentMedia - playerWidthPlusPadding)
            } else {
                newScroll += scrollIntoCurrentMedia
            }
            mediaCarousel.scrollX = newScroll
        }
    }

    /**
     * Get a measurement for the given input state. This measures the first player and returns
     * its bounds as if it were measured with the given measurement dimensions
     */
    fun obtainMeasurement(input: MediaMeasurementInput) : MeasurementOutput? {
        val firstPlayer = mediaPlayers.values.firstOrNull() ?: return null
        // Let's measure the size of the first player and return its height
        val previousProgress = firstPlayer.view.progress
        val previousRight = firstPlayer.view.right
        val previousBottom = firstPlayer.view.bottom
        firstPlayer.view.progress = input.expansion
        firstPlayer.measure(input)
        // Relayouting is necessary in motionlayout to obtain its size properly ....
        firstPlayer.view.layout(0, 0, firstPlayer.view.measuredWidth,
                firstPlayer.view.measuredHeight)
        val result = MeasurementOutput(firstPlayer.view.measuredWidth,
                firstPlayer.view.measuredHeight)
        firstPlayer.view.progress = previousProgress
        if (desiredState != null) {
            // remeasure it to the old size again!
            firstPlayer.measure(desiredState!!.measurementInput)
            firstPlayer.view.layout(0, 0, previousRight, previousBottom)
        }
        return result
    }

    fun onViewReattached() {
        if (desiredState is MediaHost.MediaHostState) {
            // HACK: MotionLayout doesn't always properly reevalate the state, let's kick of
            // a measure to force it.
            val widthSpec = desiredState!!.measurementInput?.widthMeasureSpec ?: 0
            val heightSpec = desiredState!!.measurementInput?.heightMeasureSpec ?: 0
            for (mediaPlayer in mediaPlayers.values) {
                mediaPlayer.view.measure(widthSpec, heightSpec)
            }
        }
    }
}