class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        WindowCompat.setDecorFitsSystemWindows(window, false)

        setContent {
            PictureInPicturePOCTheme {
                val navController = rememberNavController()
                val navigationActions = remember(navController) {
                    PictureInPicturePOCNavigationActions(navController)
                }
                // A surface container using the 'background' color from the theme
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colorScheme.background
                ) {
                    PictureInPicturePOCNavGraph(
                        modifier = Modifier.fillMaxSize(),
                        navController = navController,
                        navigateToDetails = navigationActions.navigateToDetails,
                        navigateToPlayer = navigationActions.navigateToPlayer
                    )
                }
            }
        }
    }
}

object PictureInPicturePOCDestinations {
    const val HOME_ROUTE = "home"
    const val DETAILS_ROUTE = "details"
    const val PLAYER_ROUTE = "player"
}

class PictureInPicturePOCNavigationActions(navController: NavHostController) {
    val navigateToHome: () -> Unit = {
        navController.navigate(PictureInPicturePOCDestinations.HOME_ROUTE) {
            // Pop up to the start destination of the graph to
            // avoid building up a large stack of destinations
            // on the back stack as users select items
            popUpTo(navController.graph.findStartDestination().id) {
                saveState = true
            }
            // Avoid multiple copies of the same destination when
            // reselecting the same item
            launchSingleTop = true
            // Restore state when reselecting a previously selected item
            restoreState = true
        }
    }

    val navigateToDetails: () -> Unit = {
        navController.navigate(PictureInPicturePOCDestinations.DETAILS_ROUTE) {
            launchSingleTop = true
            restoreState = true
        }
    }

    val navigateToPlayer: () -> Unit = {
        navController.navigate(PictureInPicturePOCDestinations.PLAYER_ROUTE) {
            launchSingleTop = true
            restoreState = true
        }
    }
}

@Composable
fun PictureInPicturePOCNavGraph(
    modifier: Modifier = Modifier,
    navController: NavHostController = rememberNavController(),
    startDestination: String = PictureInPicturePOCDestinations.HOME_ROUTE,
    navigateToDetails: () -> Unit,
    navigateToPlayer: () -> Unit
) {
    NavHost(
        navController = navController,
        startDestination = startDestination,
        modifier = modifier
    ) {
        composable(PictureInPicturePOCDestinations.HOME_ROUTE) {
            HomeRoute(
                navigateToDetails = navigateToDetails,
                navigateToPlayer = navigateToPlayer
            )
        }
        composable(PictureInPicturePOCDestinations.DETAILS_ROUTE) {
            DetailsRoute(
                navigateToDetails = navigateToDetails,
                navigateToPlayer = navigateToPlayer
            )
        }
        activity(PictureInPicturePOCDestinations.PLAYER_ROUTE) {
            activityClass = PlayerActivity::class
        }
    }
}

@Composable
fun HomeRoute(
    navigateToDetails: () -> Unit,
    navigateToPlayer: () -> Unit
) {
    Column(
        Modifier
            .fillMaxSize()
            .background(Color.White)
            .padding(100.dp)
    ) {
        Button(modifier = Modifier.wrapContentSize(), onClick = { navigateToDetails.invoke() }) {
            Text(text = "navigate to details")
        }
        Button(modifier = Modifier.wrapContentSize(), onClick = { navigateToPlayer.invoke() }) {
            Text(text = "navigate to player")
        }
    }
}

@Composable
fun DetailsRoute(
    navigateToDetails: () -> Unit,
    navigateToPlayer: () -> Unit
) {
    Column(
        Modifier
            .fillMaxSize()
            .background(Color.Yellow)
            .padding(100.dp)
    ) {
        Button(modifier = Modifier.wrapContentSize(), onClick = { navigateToDetails.invoke() }) {
            Text(text = "navigate to details")
        }
        Button(modifier = Modifier.wrapContentSize(), onClick = { navigateToPlayer.invoke() }) {
            Text(text = "navigate to player")
        }
    }
}

class PlayerActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        WindowCompat.setDecorFitsSystemWindows(window, false)

        setContent {
            PictureInPicturePOCTheme {
                val navController = rememberNavController()
                val navigationActions = remember(navController) {
                    PictureInPicturePOCNavigationActions(navController)
                }
                // A surface container using the 'background' color from the theme
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colorScheme.background
                ) {
                    PlayerRoute(
                        navigateToDetails = navigationActions.navigateToDetails,
                        enterPip = { enterPictureInPictureMode() }
                    )
                }
            }
        }
    }
}

@Composable
fun PlayerRoute(
    navigateToDetails: () -> Unit,
    enterPip: () -> Unit
) {
    Column {
        Box(
            Modifier
                .aspectRatio(1.7777778F)
                .background(Color.Black)
        ) {
            Button(modifier = Modifier
                .wrapContentSize()
                .align(Alignment.Center),
                onClick = { enterPip.invoke() }
            ) {
                Text(text = "enter pip")
            }
        }
        Box(
            Modifier
                .fillMaxSize()
                .background(Color.White)
        ) {
            Button(
                modifier = Modifier
                    .wrapContentSize()
                    .align(Alignment.Center),
                onClick = {
                    enterPip.invoke()
                    navigateToDetails.invoke()
                }
            ) {
                Text(text = "navigate to details")
            }
        }
    }
}