import kotlinx.io.core.BytePacketBuilder
import kotlinx.io.core.ByteReadPacket
import kotlinx.io.core.buildPacket
import kotlinx.io.nio.readPacketExact
import kotlinx.io.nio.writePacket
import java.net.InetSocketAddress
import java.nio.channels.ServerSocketChannel
import java.nio.channels.SocketChannel
import java.util.*
import java.util.concurrent.Executors

class MainActivity : AppCompatActivity() {
    companion object {
        const val PORT = 12345
    }

    private val controls = Arrays.asList(
            Control("Forward", 0), Control("Backward", 1),
            Control("Right", 2), Control("Left", 3)
    )
    private val executor = Executors.newCachedThreadPool()
    private val server = ServerSocketChannel.open().bind(InetSocketAddress(PORT))
    private val channels = ArrayList<SocketChannel>()
    private val responses = HashMap<Byte, ByteReadPacket.() -> Unit>()

    init {
        executor.submit {
            while (server.isOpen) {
                val channel = server.accept()
                synchronized(channels) {
                    channels.add(channel)
                }
                executor.submit {
                    while (channel.isOpen) {
                        val packet = channel.readPacketExact(5)
                        val response = responses[(packet.readByte())]
                        response?.invoke(channel.readPacketExact(packet.readInt().toLong()))
                    }
                    synchronized(channels) {
                        channels.remove(channel)
                    }
                }
            }
        }
    }

    override fun onCreate(bundleIn: Bundle) {
        val binding: MainActivityBinding = inflate(from(this), R.layout.main_activity, null, false)

        controls.forEach { control ->
            val button = Button(this)
            button.setText(control.name);
            button.onClick {
                synchronized(channels) {
                    channels.forEach { channel ->
                        channel.writePacket {
                            writeByte(control.opcode)
                            val message = buildPacket {
                                control.message(this)
                            }
                            writeInt(message.remaining)
                            writePacket(message)
                        }
                    }
                }
            }
            binding.controls.addView(button)
        }

        setContentView(binding.getRoot())
        super.onCreate(bundleIn)
    }

    class Control(
            val name: String,
            val opcode: Byte,
            val message: BytePacketBuilder.() -> Unit = {}
    )
}