Leanback To Compose Tv Migration

val focusRequester = remember { FocusRequester() }
val focusManager = LocalFocusManager.current

LaunchedEffect(Unit) {
    focusRequester.requestFocus()
}

Row(
    modifier = Modifier
        .fillMaxWidth()
        .padding(horizontal = 48.dp, vertical = 16.dp),
    horizontalArrangement = Arrangement.End
) {
    Button(
        onClick = { /* Search */ },
        modifier = Modifier.focusRequester(topBarFocusRequester)
    ) { Text("Search") }
}

LazyRow(
    modifier = Modifier.focusRestorer(),
    contentPadding = PaddingValues(horizontal = 48.dp),
    horizontalArrangement = Arrangement.spacedBy(16.dp)
) {
    itemsIndexed(videos) { vidIndex, video ->
        CompactCard(
            onClick = { onVideoClick(video) },
            image = {
                AsyncImage(
                    model = video.cardImageUrl,
                    contentDescription = video.title,
                    contentScale = ContentScale.Crop,
                    modifier = Modifier.fillMaxSize()
                )
            },
            title = { Text(video.title) },
            modifier = Modifier
                .then(
                    if (catIndex == 0 && vidIndex == 0) {
                        Modifier.focusRequester(firstCardFocusRequester)
                    } else {
                        Modifier
                    }
                )
                .onFocusChanged { focusState ->
                    if (focusState.isFocused) {
                        focusedVideo = video
                        focusedCategoryIndex = catIndex
                    }
                }
        )
    }
}

Surface(
    onClick = { focusRequester.requestFocus() },
    border = ClickableSurfaceDefaults.border(focusedBorder = Border(border = BorderStroke(2.dp, Color.White))),
    modifier = Modifier
        .fillMaxWidth()
        .focusRequester(focusRequester)
) {
    OutlinedTextField(
        value = username,
        onValueChange = { username = it },
        label = { Text("Username") },
        singleLine = true,
        keyboardOptions = KeyboardOptions(imeAction = ImeAction.Next),
        keyboardActions = KeyboardActions(onNext = { focusManager.moveFocus(FocusDirection.Down) }),
        modifier = Modifier
            .fillMaxWidth()
            .onPreviewKeyEvent { event ->
                if (event.type == KeyEventType.KeyDown && (event.key == Key.Enter || event.key == Key.NumPadEnter)) {
                    focusManager.moveFocus(FocusDirection.Down)
                    true
                } else false
            }
    )
}

Surface(
    onClick = {},
    border = ClickableSurfaceDefaults.border(focusedBorder = Border(border = BorderStroke(2.dp, Color.White))),
    modifier = Modifier.fillMaxWidth()
) {
    OutlinedTextField(
        value = password,
        onValueChange = { password = it },
        label = { Text("Password") },
        singleLine = true,
        visualTransformation = PasswordVisualTransformation(),
        keyboardOptions = KeyboardOptions(imeAction = ImeAction.Done),
        keyboardActions = KeyboardActions(onDone = { onLoginSuccess() }),
        modifier = Modifier
            .fillMaxWidth()
            .onPreviewKeyEvent { event ->
                if (event.type == KeyEventType.KeyDown && (event.key == Key.Enter || event.key == Key.NumPadEnter)) {
                    onLoginSuccess()
                    true
                } else false
            }
    )
}

@Composable
fun CatalogBrowser(
    featuredContentList: List<Movie>,
    sectionList: List<Section>,
    modifier: Modifier = Modifier,
    onItemSelected: (Movie) -> Unit = {},
) {
    LazyColumn(
        modifier = modifier.fillMaxSize(),
        verticalArrangement = Arrangement.spacedBy(16.dp)
    ) {
        items(sectionList.size) { index ->
            val section = sectionList[index]
            SectionRow(section, onItemSelected = onItemSelected)
        }
    }
}

@Composable
fun TvSettingsScreen(
    modifier: Modifier = Modifier
) {
    var autoPlayNext by remember { mutableStateOf(true) }
    var highQualityAudio by remember { mutableStateOf(false) }

    Column(
        modifier = modifier
            .fillMaxSize()
            .padding(48.dp)
    ) {
        Text(
            text = "Settings",
            style = MaterialTheme.typography.headlineMedium,
            modifier = Modifier.padding(bottom = 24.dp)
        )

        LazyColumn(
            verticalArrangement = Arrangement.spacedBy(12.dp),
            contentPadding = PaddingValues(vertical = 8.dp)
        ) {
            item {
                ListItem(
                    selected = false,
                    onClick = { autoPlayNext = !autoPlayNext },
                    headlineContent = { Text("Autoplay Next Video") },
                    supportingContent = { Text("Automatically start playing next item in queue") },
                    trailingContent = {
                        Switch(
                            checked = autoPlayNext,
                            onCheckedChange = null
                        )
                    }
                )
            }

            item {
                ListItem(
                    selected = false,
                    onClick = { highQualityAudio = !highQualityAudio },
                    headlineContent = { Text("High Quality Audio") },
                    supportingContent = { Text("Use spatial audio and multi-channel output when available") },
                    trailingContent = {
                        Switch(
                            checked = highQualityAudio,
                            onCheckedChange = null
                        )
                    }
                )
            }
        }
    }
}

@Composable
fun ImmersiveBrowseScreen(
    categories: Map<String, List<Video>>,
    onVideoClick: (Video) -> Unit
) {
    var focusedVideo by remember { mutableStateOf<Video?>(null) }
    var focusedCategoryIndex by remember { mutableStateOf(0) }
    val listState = rememberLazyListState()
    val topBarFocusRequester = remember { FocusRequester() }
    val firstCardFocusRequester = remember { FocusRequester() }

    Box(modifier = Modifier.fillMaxSize()) {
        AsyncImage(
            model = focusedVideo?.bgImageUrl,
            contentDescription = null,
            contentScale = ContentScale.Crop,
            modifier = Modifier.fillMaxSize()
        )

        PositionFocusedItemInLazyLayout(parentFraction = 0.35f, childFraction = 0.5f) {
            LazyColumn(
                state = listState,
                contentPadding = PaddingValues(top = 36.dp, bottom = 64.dp),
                verticalArrangement = Arrangement.spacedBy(28.dp),
                modifier = Modifier.fillMaxSize()
            ) {
                item {
                    Row(
                        modifier = Modifier
                            .fillMaxWidth()
                            .padding(horizontal = 48.dp, vertical = 16.dp),
                        horizontalArrangement = Arrangement.End
                    ) {
                        Button(
                            onClick = { /* Search */ },
                            modifier = Modifier.focusRequester(topBarFocusRequester)
                        ) { Text("Search") }
                    }
                }

                itemsIndexed(categories.entries.toList()) { catIndex, (categoryName, videos) ->
                    Column {
                        if (catIndex == 0 && focusedCategoryIndex == 0) {
                            Column(
                                modifier = Modifier
                                    .heightIn(min = 200.dp)
                                    .padding(horizontal = 48.dp)
                            ) {
                                Text(
                                    text = focusedVideo?.title ?: "",
                                    style = MaterialTheme.typography.displayMedium
                                )
                                Text(
                                    text = focusedVideo?.description ?: "",
                                    style = MaterialTheme.typography.bodyLarge
                                )
                            }
                        } else {
                            Text(
                                text = categoryName,
                                style = MaterialTheme.typography.titleMedium,
                                modifier = Modifier.padding(horizontal = 48.dp, vertical = 8.dp)
                            )
                        }

                        LazyRow(
                            modifier = Modifier.focusRestorer(),
                            contentPadding = PaddingValues(horizontal = 48.dp),
                            horizontalArrangement = Arrangement.spacedBy(16.dp)
                        ) {
                            itemsIndexed(videos) { vidIndex, video ->
                                CompactCard(
                                    onClick = { onVideoClick(video) },
                                    image = {
                                        AsyncImage(
                                            model = video.cardImageUrl,
                                            contentDescription = video.title,
                                            contentScale = ContentScale.Crop,
                                            modifier = Modifier.fillMaxSize()
                                        )
                                    },
                                    title = { Text(video.title) },
                                    modifier = Modifier
                                        .then(
                                            if (catIndex == 0 && vidIndex == 0) {
                                                Modifier.focusRequester(firstCardFocusRequester)
                                            } else {
                                                Modifier
                                            }
                                        )
                                        .onFocusChanged { focusState ->
                                            if (focusState.isFocused) {
                                                focusedVideo = video
                                                focusedCategoryIndex = catIndex
                                            }
                                        }
                                )
                            }
                        }
                    }
                }
            }
        }
    }
}

@OptIn(ExperimentalFoundationApi::class)
@Composable
private fun PositionFocusedItemInLazyLayout(
    parentFraction: Float = 0.35f,
    childFraction: Float = 0.5f,
    content: @Composable () -> Unit,
) {
    val bringIntoViewSpec = remember(parentFraction, childFraction) {
        object : BringIntoViewSpec {
            override fun calculateScrollDistance(
                offset: Float,
                size: Float,
                containerSize: Float
            ): Float {
                if (offset >= 0f && offset <= containerSize * 0.45f) {
                    return 0f
                }
                val initialTargetForLeadingEdge = parentFraction * containerSize - (childFraction * size)
                val targetForLeadingEdge = if (size <= containerSize && (containerSize - initialTargetForLeadingEdge) < size) {
                    containerSize - size
                } else {
                    initialTargetForLeadingEdge
                }
                return offset - targetForLeadingEdge
            }
        }
    }
    CompositionLocalProvider(LocalBringIntoViewSpec provides bringIntoViewSpec, content = content)
}

@OptIn(UnstableApi::class)
@Composable
fun Media3PlaybackScreen(
    video: Video,
    onFinish: () -> Unit,
    modifier: Modifier = Modifier
) {
    val context = LocalContext.current
    val exoPlayer = remember(context) { ExoPlayer.Builder(context).build() }
    var showControls by remember { mutableStateOf(true) }
    val focusRequester = remember { FocusRequester() }
    val coroutineScope = rememberCoroutineScope()
    var autoHideJob by remember { mutableStateOf<Job?>(null) }

    fun scheduleAutoHide() {
        autoHideJob?.cancel()
        autoHideJob = coroutineScope.launch {
            delay(5000)
            showControls = false
        }
    }

    DisposableEffect(exoPlayer) {
        val listener = object : Player.Listener {
            override fun onPlaybackStateChanged(playbackState: Int) {
                if (playbackState == Player.STATE_ENDED) {
                    onFinish()
                }
            }
        }
        exoPlayer.addListener(listener)
        onDispose {
            autoHideJob?.cancel()
            exoPlayer.removeListener(listener)
            exoPlayer.release()
        }
    }

    LaunchedEffect(video) {
        focusRequester.requestFocus()
        scheduleAutoHide()

        val mediaItem = MediaItem.fromUri(video.videoUrl)
        exoPlayer.setMediaItem(mediaItem)
        exoPlayer.prepare()
        exoPlayer.playWhenReady = true
    }

    Box(
        modifier = modifier
            .fillMaxSize()
            .background(Color.Black)
            .focusRequester(focusRequester)
            .focusable()
            .onPreviewKeyEvent { event ->
                if (event.type == KeyEventType.KeyDown) {
                    when (event.key) {
                        Key.DirectionCenter, Key.Enter, Key.NumPadEnter, Key.MediaPlayPause, Key.Spacebar -> {
                            if (exoPlayer.isPlaying) exoPlayer.pause() else exoPlayer.play()
                            showControls = true
                            scheduleAutoHide()
                            true
                        }
                        Key.DirectionLeft, Key.MediaRewind -> {
                            val newPos = (exoPlayer.currentPosition - 10_000L).coerceAtLeast(0L)
                            exoPlayer.seekTo(newPos)
                            showControls = true
                            scheduleAutoHide()
                            true
                        }
                        Key.DirectionRight, Key.MediaFastForward -> {
                            val duration = exoPlayer.duration.coerceAtLeast(0L)
                            val newPos = (exoPlayer.currentPosition + 10_000L).coerceAtMost(duration)
                            exoPlayer.seekTo(newPos)
                            showControls = true
                            scheduleAutoHide()
                            true
                        }
                        Key.DirectionUp, Key.DirectionDown -> {
                            showControls = !showControls
                            if (showControls) scheduleAutoHide() else autoHideJob?.cancel()
                            true
                        }
                        else -> false
                    }
                } else false
            },
        contentAlignment = Alignment.Center
    ) {
        PlayerSurface(
            player = exoPlayer,
            modifier = Modifier.fillMaxSize()
        )

        if (showControls) {
            Box(
                modifier = Modifier
                    .fillMaxSize()
                    .background(Color(0x80000000))
                    .padding(48.dp),
                contentAlignment = Alignment.BottomCenter
            ) {
                Row(
                    horizontalArrangement = Arrangement.spacedBy(24.dp),
                    verticalAlignment = Alignment.CenterVertically
                ) {
                    SeekBackButton(player = exoPlayer)
                    PlayPauseButton(player = exoPlayer)
                    SeekForwardButton(player = exoPlayer)
                }
            }
        }
    }
}

object VideoFlowRepository {
    fun getVideosFlow(context: Context, contentUri: Uri): Flow<List<Video>> = callbackFlow {
        val contentObserver = object : ContentObserver(Handler(Looper.getMainLooper())) {
            override fun onChange(selfChange: Boolean) {
                trySend(queryVideos(context, contentUri))
            }
        }

        context.contentResolver.registerContentObserver(
            contentUri,
            true,
            contentObserver
        )

        val initialVideos = queryVideos(context, contentUri)
        trySend(initialVideos)

        awaitClose {
            context.contentResolver.unregisterContentObserver(contentObserver)
        }
    }.flowOn(Dispatchers.IO)

    private fun queryVideos(context: Context, uri: Uri): List<Video> {
        // Query database or ContentProvider
        return emptyList()
    }
}