/*
 * CollectionAdapter.kt
 * Implements the CollectionAdapter class
 * A CollectionAdapter is a custom adapter providing station card views for a RecyclerView
 *
 * This file is part of
 * TRANSISTOR - Radio App for Android
 *
 * Copyright (c) 2015-22 - Y20K.org
 * Licensed under the MIT-License
 * http://opensource.org/licenses/MIT
 */


package com.michatec.radio.collection

import android.annotation.SuppressLint
import android.content.Context
import android.content.SharedPreferences
import android.text.Editable
import android.text.TextWatcher
import android.view.KeyEvent
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.view.inputmethod.EditorInfo
import android.widget.ImageView
import android.widget.ProgressBar
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import androidx.cardview.widget.CardView
import androidx.constraintlayout.widget.Group
import androidx.core.net.toUri
import androidx.core.view.isGone
import androidx.core.view.isVisible
import androidx.lifecycle.LifecycleOwner
import androidx.lifecycle.ViewModelProvider
import androidx.navigation.findNavController
import androidx.recyclerview.widget.DiffUtil
import androidx.recyclerview.widget.RecyclerView
import com.google.android.material.button.MaterialButton
import com.google.android.material.floatingactionbutton.ExtendedFloatingActionButton
import com.google.android.material.textfield.TextInputEditText
import com.michatec.radio.Keys
import com.michatec.radio.R
import com.michatec.radio.core.Collection
import com.michatec.radio.core.Station
import com.michatec.radio.helpers.*
import kotlinx.coroutines.*
import kotlinx.coroutines.Dispatchers.IO
import kotlinx.coroutines.Dispatchers.Main
import java.util.*


/*
 * CollectionAdapter class
 */
class CollectionAdapter(
    private val context: Context,
    private val collectionAdapterListener: CollectionAdapterListener
) : RecyclerView.Adapter<RecyclerView.ViewHolder>(), UpdateHelper.UpdateHelperListener {

    /* Main class variables */
    private lateinit var collectionViewModel: CollectionViewModel
    private var collection: Collection = Collection()
    private var editStationsEnabled: Boolean = PreferencesHelper.loadEditStationsEnabled(context)
    private var editStationStreamsEnabled: Boolean = PreferencesHelper.loadEditStreamUrisEnabled(context)
    private var expandedStationUuid: String = PreferencesHelper.loadStationListStreamUuid()
    private var expandedStationPosition: Int = -1
    var isExpandedForEdit: Boolean = false


    /* Listener Interface */
    interface CollectionAdapterListener {
        fun onPlayButtonTapped(stationUuid: String)
        fun onAddNewButtonTapped()
        fun onChangeImageButtonTapped(stationUuid: String)
    }


    /* Overrides onAttachedToRecyclerView */
    override fun onAttachedToRecyclerView(recyclerView: RecyclerView) {
        super.onAttachedToRecyclerView(recyclerView)
        // create view model and observe changes in collection view model
        collectionViewModel =
            ViewModelProvider(context as AppCompatActivity)[CollectionViewModel::class.java]
        observeCollectionViewModel(context as LifecycleOwner)
        // start listening for changes in shared preferences
        PreferencesHelper.registerPreferenceChangeListener(sharedPreferenceChangeListener)
    }


    /* Overrides onDetachedFromRecyclerView */
    override fun onDetachedFromRecyclerView(recyclerView: RecyclerView) {
        super.onDetachedFromRecyclerView(recyclerView)
        // stop listening for changes in shared preferences
        PreferencesHelper.unregisterPreferenceChangeListener(sharedPreferenceChangeListener)
    }


    /* Overrides onCreateViewHolder */
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {

        return when (viewType) {
            Keys.VIEW_TYPE_ADD_NEW -> {
                // get view, put view into holder and return
                val v = LayoutInflater.from(parent.context)
                    .inflate(R.layout.card_add_new_station, parent, false)
                AddNewViewHolder(v)
            }
            else -> {
                // get view, put view into holder and return
                val v = LayoutInflater.from(parent.context)
                    .inflate(R.layout.card_station, parent, false)
                StationViewHolder(v)
            }
        }
    }


    /* Implement the method to handle item move */
    fun onItemMove(fromPosition: Int, toPosition: Int) {
        // Do nothing if in "edit" mode
        if (isExpandedForEdit) {
            return
        }

        val stationList = collection.stations
        val stationCount = stationList.size

        if (fromPosition !in 0 until stationCount || toPosition !in 0 until stationCount) {
            return
        }

        val fromStation = stationList[fromPosition]
        val toStation = stationList[toPosition]

        if (fromStation.starred != toStation.starred) {
            // Prevent moving a starred item into non-starred area or vice versa
            return
        }

        // Move within the same group (either starred or non-starred)
        Collections.swap(stationList, fromPosition, toPosition)

        // Update the value of expandedStationPosition if necessary
        expandedStationPosition = if (fromPosition == expandedStationPosition) toPosition else expandedStationPosition

        // Notify the adapter about the item move
        notifyItemMoved(fromPosition, toPosition)
    }


    /* Implement the method to handle item dismissal */
    fun onItemDismiss(position: Int) {
        // Remove the item at the given position from your data collection
        collection.stations.removeAt(position)
        notifyItemRemoved(position)
    }


    /* Method for saving the collection after the drag-and-drop operation */
    fun saveCollectionAfterDragDrop() {
        // Save the collection after the dragging is completed
        CollectionHelper.saveCollection(context, collection)
    }


    /* Overrides onBindViewHolder */
    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
        when (holder) {
            // CASE ADD NEW CARD
            is AddNewViewHolder -> {
                // get reference to StationViewHolder
                val addNewViewHolder: AddNewViewHolder = holder
                addNewViewHolder.addNewStationView.setOnClickListener {
                    // show the add station dialog
                    collectionAdapterListener.onAddNewButtonTapped()
                }
                addNewViewHolder.settingsButtonView.setOnClickListener {
                    it.findNavController().navigate(R.id.settings_destination)
                }
            }
            // CASE STATION CARD
            is StationViewHolder -> {
                // get station from position
                val station: Station = collection.stations[position]

                // get reference to StationViewHolder
                val stationViewHolder: StationViewHolder = holder

                // set up station views
                setStarredIcon(stationViewHolder, station)
                setStationName(stationViewHolder, station)
                setStationImage(stationViewHolder, station)
                setStationButtons(stationViewHolder, station)
                setEditViews(stationViewHolder, station)
                setPlaybackProgress(stationViewHolder, station)
                setDownloadProgress(stationViewHolder, station)

                // show / hide edit views
                when (expandedStationPosition) {
                    // show edit views
                    position -> {
                        stationViewHolder.stationNameView.isVisible = false
                        stationViewHolder.playButtonView.isGone = true
                        stationViewHolder.stationStarredView.isGone = true
                        stationViewHolder.editViews.isVisible = true
                        if (editStationStreamsEnabled) {
                            stationViewHolder.stationUriEditView.isVisible = true
                            stationViewHolder.stationUriEditView.imeOptions =
                                EditorInfo.IME_ACTION_DONE
                        } else {
                            stationViewHolder.stationUriEditView.isGone = true
                            stationViewHolder.stationNameEditView.imeOptions =
                                EditorInfo.IME_ACTION_DONE
                        }
                        // Allow internal focus
                        stationViewHolder.stationCardView.descendantFocusability = ViewGroup.FOCUS_AFTER_DESCENDANTS
                    }
                    // hide edit views
                    else -> {
                        stationViewHolder.stationNameView.isVisible = true
                        //stationViewHolder.playButtonView.isVisible = true
                        stationViewHolder.stationStarredView.isVisible = station.starred
                        stationViewHolder.editViews.isGone = true
                        stationViewHolder.stationUriEditView.isGone = true
                        // Block internal focus
                        stationViewHolder.stationCardView.descendantFocusability = ViewGroup.FOCUS_BLOCK_DESCENDANTS
                    }
                }
            }
        }
    }


    /* Overrides onStationUpdated from UpdateHelperListener */
    override fun onStationUpdated(
        collection: Collection,
        positionPriorUpdate: Int,
        positionAfterUpdate: Int
    ) {
        // check if position has changed after update and move stations around if necessary
        if (positionPriorUpdate != positionAfterUpdate && positionPriorUpdate != -1 && positionAfterUpdate != -1) {
            notifyItemMoved(positionPriorUpdate, positionAfterUpdate)
            notifyItemChanged(positionPriorUpdate)
        }
        // update station (e.g. name)
        notifyItemChanged(positionAfterUpdate)
    }


    /* Sets the station name view */
    private fun setStationName(stationViewHolder: StationViewHolder, station: Station) {
        stationViewHolder.stationNameView.text = station.name
    }


    /* Sets the playback progress view */
    private fun setPlaybackProgress(stationViewHolder: StationViewHolder, station: Station) {
        if (station.bufferingProgress > 0) {
            stationViewHolder.bufferingProgress.progress = station.bufferingProgress
            stationViewHolder.bufferingProgress.isVisible = true
        } else {
            stationViewHolder.bufferingProgress.isGone = true
        }
    }


    /* Sets the download progress view */
    private fun setDownloadProgress(stationViewHolder: StationViewHolder, station: Station) {
        if (station.downloadProgress > 0) {
            stationViewHolder.downloadProgress.progress = station.downloadProgress
            stationViewHolder.downloadProgress.isVisible = true
        } else {
            stationViewHolder.downloadProgress.isGone = true
        }
    }


    /* Sets the edit views */
    private fun setEditViews(stationViewHolder: StationViewHolder, station: Station) {
        stationViewHolder.stationNameEditView.setText(station.name, TextView.BufferType.EDITABLE)
        stationViewHolder.stationUriEditView.setText(
            station.getStreamUri(),
            TextView.BufferType.EDITABLE
        )
        stationViewHolder.stationUriEditView.addTextChangedListener(object : TextWatcher {
            override fun afterTextChanged(s: Editable?) {
                handleStationUriInput(stationViewHolder, s, station.getStreamUri())
            }

            override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {}
            override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {}
        })
        stationViewHolder.cancelButton.setOnClickListener {
            val position: Int = stationViewHolder.bindingAdapterPosition
            toggleEditViews(position, station.uuid)
            UiHelper.hideSoftKeyboard(context, stationViewHolder.stationNameEditView)
        }
        stationViewHolder.saveButton.setOnClickListener {
            val position: Int = stationViewHolder.bindingAdapterPosition
            toggleEditViews(position, station.uuid)
            saveStation(
                station,
                position,
                stationViewHolder.stationNameEditView.text.toString(),
                stationViewHolder.stationUriEditView.text.toString()
            )
            UiHelper.hideSoftKeyboard(context, stationViewHolder.stationNameEditView)
        }
        stationViewHolder.placeOnHomeScreenButton.setOnClickListener {
            val position: Int = stationViewHolder.bindingAdapterPosition
            ShortcutHelper.placeShortcut(context, station)
            toggleEditViews(position, station.uuid)
            UiHelper.hideSoftKeyboard(context, stationViewHolder.stationNameEditView)
        }
        stationViewHolder.stationImageChangeView.setOnClickListener {
            val position: Int = stationViewHolder.bindingAdapterPosition
            collectionAdapterListener.onChangeImageButtonTapped(station.uuid)
            stationViewHolder.bindingAdapterPosition
            toggleEditViews(position, station.uuid)
            UiHelper.hideSoftKeyboard(context, stationViewHolder.stationNameEditView)
        }
    }


    /* Shows / hides the edit view for a station */
    @SuppressLint("NotifyDataSetChanged")
    private fun toggleEditViews(position: Int, stationUuid: String) {
        when (stationUuid) {
            // CASE: this station's edit view is already expanded
            expandedStationUuid -> {
                isExpandedForEdit = false
                // reset currently expanded info (both uuid and position)
                saveStationListExpandedState()
                // update station view
                notifyItemChanged(position)
            }
            // CASE: this station's edit view is not yet expanded
            else -> {
                isExpandedForEdit = true
                // remember previously expanded position
                val previousExpandedStationPosition: Int = expandedStationPosition
                // if station was expanded - collapse it
                if (previousExpandedStationPosition > -1 && previousExpandedStationPosition < collection.stations.size)
                    notifyItemChanged(previousExpandedStationPosition)
                // store current station as the expanded one
                saveStationListExpandedState(position, stationUuid)
                // update station view
                notifyDataSetChanged()
            }
        }
    }


    /* Toggles the starred icon */
    private fun setStarredIcon(stationViewHolder: StationViewHolder, station: Station) {
        when (station.starred) {
            true -> {
                if (station.imageColor != -1) {
                    // stationViewHolder.stationCardView.setCardBackgroundColor(station.imageColor)
                    stationViewHolder.stationStarredView.setColorFilter(station.imageColor)
                }
                stationViewHolder.stationStarredView.isVisible = true
            }
            false -> stationViewHolder.stationStarredView.isGone = true
        }
    }


    /* Sets the station image view */
    private fun setStationImage(stationViewHolder: StationViewHolder, station: Station) {
        if (station.imageColor != -1) {
            stationViewHolder.stationImageView.setBackgroundColor(station.imageColor)
        }
        stationViewHolder.stationImageView.setImageBitmap(
            ImageHelper.getStationImage(
                context,
                station.smallImage
            )
        )
        stationViewHolder.stationImageView.contentDescription =
            "${context.getString(R.string.descr_player_station_image)}: ${station.name}"
    }


    /* Sets up a station's play and edit buttons */
    private fun setStationButtons(stationViewHolder: StationViewHolder, station: Station) {
        when (station.isPlaying) {
            true -> stationViewHolder.playButtonView.visibility = View.VISIBLE
            false -> stationViewHolder.playButtonView.visibility = View.INVISIBLE
        }
        stationViewHolder.stationCardView.setOnClickListener {
            if (expandedStationPosition == stationViewHolder.bindingAdapterPosition) return@setOnClickListener
            collectionAdapterListener.onPlayButtonTapped(station.uuid)
        }
        stationViewHolder.playButtonView.setOnClickListener {
            collectionAdapterListener.onPlayButtonTapped(station.uuid)
        }
        stationViewHolder.stationNameView.setOnClickListener {
            collectionAdapterListener.onPlayButtonTapped(station.uuid)
        }
        stationViewHolder.stationStarredView.setOnClickListener {
            collectionAdapterListener.onPlayButtonTapped(station.uuid)
        }
        stationViewHolder.stationImageView.setOnClickListener {
            collectionAdapterListener.onPlayButtonTapped(station.uuid)
        }

        // TV improvement: Allow opening edit view with DPAD_LEFT
        stationViewHolder.stationCardView.setOnKeyListener { _, keyCode, event ->
            if (event.action == KeyEvent.ACTION_DOWN) {
                when (keyCode) {
                    KeyEvent.KEYCODE_DPAD_LEFT -> {
                        if (editStationsEnabled && expandedStationPosition != stationViewHolder.bindingAdapterPosition) {
                            val position: Int = stationViewHolder.bindingAdapterPosition
                            toggleEditViews(position, station.uuid)
                            return@setOnKeyListener true
                        }
                    }
                    KeyEvent.KEYCODE_NUMPAD_2, KeyEvent.KEYCODE_2, KeyEvent.KEYCODE_BACK -> {
                        if (expandedStationPosition == stationViewHolder.bindingAdapterPosition) {
                            val position: Int = stationViewHolder.bindingAdapterPosition
                            toggleEditViews(position, station.uuid)
                            return@setOnKeyListener true
                        }
                    }
                    KeyEvent.KEYCODE_NUMPAD_0, KeyEvent.KEYCODE_0, KeyEvent.KEYCODE_DEL -> {
                        removeStation(context, stationViewHolder.bindingAdapterPosition)
                        return@setOnKeyListener true
                    }
                    KeyEvent.KEYCODE_NUMPAD_1, KeyEvent.KEYCODE_1, KeyEvent.KEYCODE_SPACE -> {
                        toggleStarredStation(context, stationViewHolder.bindingAdapterPosition)
                        return@setOnKeyListener true
                    }
                }
            }
            false
        }

        stationViewHolder.playButtonView.setOnLongClickListener {
            if (editStationsEnabled) {
                val position: Int = stationViewHolder.bindingAdapterPosition
                toggleEditViews(position, station.uuid)
                return@setOnLongClickListener true
            } else {
                return@setOnLongClickListener false
            }
        }
        stationViewHolder.stationNameView.setOnLongClickListener {
            if (editStationsEnabled) {
                val position: Int = stationViewHolder.bindingAdapterPosition
                toggleEditViews(position, station.uuid)
                return@setOnLongClickListener true
            } else {
                return@setOnLongClickListener false
            }
        }
        stationViewHolder.stationStarredView.setOnLongClickListener {
            if (editStationsEnabled) {
                val position: Int = stationViewHolder.bindingAdapterPosition
                toggleEditViews(position, station.uuid)
                return@setOnLongClickListener true
            } else {
                return@setOnLongClickListener false
            }
        }
        stationViewHolder.stationImageView.setOnLongClickListener {
            if (editStationsEnabled) {
                val position: Int = stationViewHolder.bindingAdapterPosition
                toggleEditViews(position, station.uuid)
                return@setOnLongClickListener true
            } else {
                return@setOnLongClickListener false
            }
        }
    }


    /* Checks if stream uri input is valid */
    private fun handleStationUriInput(
        stationViewHolder: StationViewHolder,
        s: Editable?,
        streamUri: String
    ) {
        if (editStationStreamsEnabled) {
            val input: String = s.toString()
            if (input == streamUri) {
                // enable save button
                stationViewHolder.saveButton.isEnabled = true
            } else {
                // 1. disable save button
                stationViewHolder.saveButton.isEnabled = false
                // 2. check for valid station uri - and re-enable button
                if (input.startsWith("http")) {
                    // detect content type on background thread
                    CoroutineScope(IO).launch {
                        val deferred: Deferred<NetworkHelper.ContentType> =
                            async(Dispatchers.Default) {
                                NetworkHelper.detectContentTypeSuspended(input)
                            }
                        // wait for result
                        val contentType: String =
                            deferred.await().type.lowercase(Locale.getDefault())
                        // CASE: stream address detected
                        if (Keys.MIME_TYPES_MPEG.contains(contentType) or
                            Keys.MIME_TYPES_OGG.contains(contentType) or
                            Keys.MIME_TYPES_AAC.contains(contentType) or
                            Keys.MIME_TYPES_HLS.contains(contentType)
                        ) {
                            // re-enable save button
                            withContext(Main) {
                                stationViewHolder.saveButton.isEnabled = true
                            }
                        }
                    }
                }
            }
        }
    }


    /* Overrides onBindViewHolder */
    override fun onBindViewHolder(
        holder: RecyclerView.ViewHolder,
        position: Int,
        payloads: List<Any>
    ) {

        if (payloads.isEmpty()) {
            // call regular onBindViewHolder method
            onBindViewHolder(holder, position)

        } else if (holder is StationViewHolder) {
            // get station from position
            val station: Station = collection.stations[holder.bindingAdapterPosition]

            for (data in payloads) {
                when (data as Int) {
                    Keys.HOLDER_UPDATE_COVER -> {
                        setStationImage(holder, station)
                        setStarredIcon(holder, station)
                    }
                    Keys.HOLDER_UPDATE_NAME -> {
                        setStationName(holder, station)
                    }
                    Keys.HOLDER_UPDATE_PLAYBACK_STATE -> {
                        setStationButtons(holder, station)
                    }
                    Keys.HOLDER_UPDATE_PLAYBACK_PROGRESS -> {
                        setPlaybackProgress(holder, station)
                    }
                    Keys.HOLDER_UPDATE_DOWNLOAD_STATE -> {
                        setDownloadProgress(holder, station)
                    }
                }
            }
        }
    }


    /* Overrides getItemViewType */
    override fun getItemViewType(position: Int): Int {
        return when (isPositionFooter(position)) {
            true -> Keys.VIEW_TYPE_ADD_NEW
            false -> Keys.VIEW_TYPE_STATION
        }
    }


    /* Overrides getItemCount */
    override fun getItemCount(): Int {
        // +1 ==> the add station card
        return collection.stations.size + 1
    }


    /* Removes a station from collection */
    fun removeStation(context: Context, position: Int) {
        val newCollection = collection.deepCopy()
        // delete images assets
        CollectionHelper.deleteStationImages(context, newCollection.stations[position])
        // remove station from collection
        newCollection.stations.removeAt(position)
        collection = newCollection
        // update list
        notifyItemRemoved(position)
        // save collection and broadcast changes
        CollectionHelper.saveCollection(context, newCollection)
    }


    /* Toggles starred status of a station */
    fun toggleStarredStation(context: Context, position: Int) {
        // update view (reset "swipe" state of station card)
        notifyItemChanged(position)
        // mark starred
        val stationUuid: String = collection.stations[position].uuid
        collection.stations[position].apply { starred = !starred }
        // sort collection
        collection = CollectionHelper.sortCollection(collection)
        // update list
        notifyItemMoved(position, CollectionHelper.getStationPosition(collection, stationUuid))
        // save collection and broadcast changes
        CollectionHelper.saveCollection(context, collection)
    }


    /* Saves edited station */
    private fun saveStation(
        station: Station,
        position: Int,
        stationName: String,
        streamUri: String
    ) {
        // update station name and stream uri
        collection.stations.forEach {
            if (it.uuid == station.uuid) {
                if (stationName.isNotEmpty()) {
                    it.name = stationName
                    it.nameManuallySet = true
                }
                if (streamUri.isNotEmpty()) {
                    it.streamUris[0] = streamUri
                }
            }
        }
        // sort and save collection
        collection = CollectionHelper.sortCollection(collection)
        // update list
        val newPosition: Int = CollectionHelper.getStationPosition(collection, station.uuid)
        if (position != newPosition && newPosition != -1) {
            notifyItemMoved(position, newPosition)
            notifyItemChanged(position)
        }
        // save collection and broadcast changes
        CollectionHelper.saveCollection(context, collection)
    }


    /* Determines if position is last */
    private fun isPositionFooter(position: Int): Boolean {
        return position == collection.stations.size
    }


    /* Updates the station list - redraws the views with changed content */
    @SuppressLint("NotifyDataSetChanged")
    private fun updateRecyclerView(oldCollection: Collection, newCollection: Collection) {
        collection = newCollection
        if (oldCollection.stations.isEmpty() && newCollection.stations.isNotEmpty()) {
            // data set has been initialized - redraw the whole list
            notifyDataSetChanged()
        } else {
            // calculate differences between current collection and new collection - and inform this adapter about the changes
            val diffResult =
                DiffUtil.calculateDiff(CollectionDiffCallback(oldCollection, newCollection), true)
            diffResult.dispatchUpdatesTo(this@CollectionAdapter)
        }
    }


    /* Updates and saves state of expanded station edit view in list */
    private fun saveStationListExpandedState(
        position: Int = -1,
        stationStreamUri: String = String()
    ) {
        expandedStationUuid = stationStreamUri
        expandedStationPosition = position
        PreferencesHelper.saveStationListStreamUuid(expandedStationUuid)
    }


    /* Observe view model of station collection*/
    private fun observeCollectionViewModel(owner: LifecycleOwner) {
        collectionViewModel.collectionLiveData.observe(owner) { newCollection ->
            updateRecyclerView(collection, newCollection)
        }
    }


    /*
     * Defines the listener for changes in shared preferences
     */
    private val sharedPreferenceChangeListener =
        SharedPreferences.OnSharedPreferenceChangeListener { _, key ->
            when (key) {
                Keys.PREF_EDIT_STATIONS -> editStationsEnabled =
                    PreferencesHelper.loadEditStationsEnabled(context)
                Keys.PREF_EDIT_STREAMS_URIS -> editStationStreamsEnabled =
                    PreferencesHelper.loadEditStreamUrisEnabled(context)
            }
        }
    /*
     * End of declaration
     */


    /*
     * Inner class: ViewHolder for the Add New Station action
     */
    private class AddNewViewHolder(listItemAddNewLayout: View) :
        RecyclerView.ViewHolder(listItemAddNewLayout) {
        val addNewStationView: ExtendedFloatingActionButton =
            listItemAddNewLayout.findViewById(R.id.card_add_new_station)
        val settingsButtonView: ExtendedFloatingActionButton =
            listItemAddNewLayout.findViewById(R.id.card_settings)
    }
    /*
     * End of inner class
     */


    /*
     * Inner class: ViewHolder for a station
     */
    private class StationViewHolder(stationCardLayout: View) :
        RecyclerView.ViewHolder(stationCardLayout) {
        val stationCardView: CardView = stationCardLayout.findViewById(R.id.station_card)
        val stationImageView: ImageView = stationCardLayout.findViewById(R.id.station_icon)
        val stationNameView: TextView = stationCardLayout.findViewById(R.id.station_name)
        val stationStarredView: ImageView = stationCardLayout.findViewById(R.id.starred_icon)
        val bufferingProgress: ProgressBar = stationCardLayout.findViewById(R.id.buffering_progress)
        val downloadProgress: ProgressBar = stationCardLayout.findViewById(R.id.download_progress)

        //        val menuButtonView: ImageView = stationCardLayout.findViewById(R.id.menu_button)
        val playButtonView: ImageView = stationCardLayout.findViewById(R.id.playback_button)
        val editViews: Group = stationCardLayout.findViewById(R.id.default_edit_views)
        val stationImageChangeView: ImageView =
            stationCardLayout.findViewById(R.id.change_image_view)
        val stationNameEditView: TextInputEditText =
            stationCardLayout.findViewById(R.id.edit_station_name)
        val stationUriEditView: TextInputEditText =
            stationCardLayout.findViewById(R.id.edit_stream_uri)
        val placeOnHomeScreenButton: MaterialButton =
            stationCardLayout.findViewById(R.id.place_on_home_screen_button)
        val cancelButton: MaterialButton = stationCardLayout.findViewById(R.id.cancel_button)
        val saveButton: MaterialButton = stationCardLayout.findViewById(R.id.save_button)
    }
    /*
     * End of inner class
     */


    /*
     * Inner class: DiffUtil.Callback that determines changes in data - improves list performance
     */
    private inner class CollectionDiffCallback(
        val oldCollection: Collection,
        val newCollection: Collection
    ) : DiffUtil.Callback() {

        override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
            val oldStation: Station = oldCollection.stations[oldItemPosition]
            val newStation: Station = newCollection.stations[newItemPosition]
            return oldStation.uuid == newStation.uuid
        }

        override fun getOldListSize(): Int {
            return oldCollection.stations.size
        }

        override fun getNewListSize(): Int {
            return newCollection.stations.size
        }

        override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
            val oldStation: Station = oldCollection.stations[oldItemPosition]
            val newStation: Station = newCollection.stations[newItemPosition]

            // compare relevant contents of a station
            if (oldStation.isPlaying != newStation.isPlaying) return false
            if (oldStation.uuid != newStation.uuid) return false
            if (oldStation.starred != newStation.starred) return false
            if (oldStation.name != newStation.name) return false
            if (oldStation.stream != newStation.stream) return false
            if (oldStation.remoteImageLocation != newStation.remoteImageLocation) return false
            if (oldStation.remoteStationLocation != newStation.remoteStationLocation) return false
            if (!oldStation.streamUris.containsAll(newStation.streamUris)) return false
            if (oldStation.imageColor != newStation.imageColor) return false
            if (FileHelper.getFileSize(context, oldStation.image.toUri()) != FileHelper.getFileSize(
                    context,
                    newStation.image.toUri()
                )
            ) return false
            if (FileHelper.getFileSize(
                    context,
                    oldStation.smallImage.toUri()
                ) != FileHelper.getFileSize(context, newStation.smallImage.toUri())
            ) return false

            // none of the above -> contents are the same
            return true
        }
    }
    /*
     * End of inner class
     */
}