ykonsole2/ykonsole-iconsole/src/main/kotlin/net/aiterp/git/ykonsole2/infrastructure/IConsole.kt

package net.aiterp.git.ykonsole2.infrastructure

import com.welie.blessed.*
import com.welie.blessed.BluetoothGattCharacteristic.WriteType.WITHOUT_RESPONSE
import kotlinx.coroutines.*
import net.aiterp.git.ykonsole2.domain.models.Device
import net.aiterp.git.ykonsole2.domain.runtime.*
import net.aiterp.git.ykonsole2.infrastructure.drivers.abstracts.ActiveDriver
import net.aiterp.git.ykonsole2.infrastructure.iconsole.*
import net.aiterp.git.ykonsole2.application.logging.log
import java.time.Instant
import java.util.*
import kotlin.time.Duration
import kotlin.time.Duration.Companion.milliseconds

class IConsole : ActiveDriver() {
  private val logger = log

  private var lastTime = 0
  private var lastLevel = 0
  private var running = false
  private var connected = false
  private var wantsConnection = false
  private var health = 0

  private var tryingSince: Instant? = null

  private var maxLevel = 20
  private var lastCals = 0
  private var lastMeters = 0

  private var bonusLevel = 0
  private var bonusTime = 0
  private var bonusCals = 0
  private var bonusMeters = 0

  private val queue = Collections.synchronizedSet<Request?>(LinkedHashSet())

  private var central: BluetoothCentralManager? = null
  private var current: BluetoothPeripheral? = null

  private var btCommandInput: BluetoothGattCharacteristic? = null

  private fun onConnect(device: Device, output: FlowBus<Event>) {
    if (!device.connectionString.startsWith("iconsole:")) {
      logger.info("Ignoring non-iConsole $device")
      return
    }
    val connectionString = device.connectionString.substring("iconsole:".length)

    health = 7
    bonusTime = 0
    bonusCals = 0
    bonusMeters = 0
    wantsConnection = true

    connect(connectionString, output)
  }

  private fun connect(connectionString: String, output: FlowBus<Event>) {
    health--
    if (health == 0) {
      runBlocking {
        output.emit(ErrorOccurred("Disconnected seven times during exercise"))
        output.emit(Disconnected)
      }
      return
    }

    central?.stopScan()
    current?.cancelConnection()
    tryingSince = Instant.now()

    if (central == null) {
      val cbScan = object : BluetoothCentralManagerCallback() {
        override fun onScanStarted() {
          logger.info("Scanning for $connectionString...")
        }

        override fun onScanStopped() {
          logger.info("Scan stopped")

          tryingSince?.let { ts ->
            if (ts.isBefore(Instant.now().minusSeconds(20))) {
              central?.stopScan()
              tryingSince = null
              runBlocking {
                output.emit(ErrorOccurred("Connection timeout after 20 seconds"))
                output.emit(Disconnected)
              }
            }
          }
        }

        override fun onDiscoveredPeripheral(peripheral: BluetoothPeripheral, scanResult: ScanResult) {
          logger.info("Connecting to ${peripheral.name} (${peripheral.address})...")

          if (tryingSince != null) {
            val cbPeripheral = object : BluetoothPeripheralCallback() {
              override fun onServicesDiscovered(peripheral: BluetoothPeripheral, services: MutableList<BluetoothGattService>) {
                logger.info("Checking device...")

                val service1 = services.firstOrNull { it.uuid == S1_SERVICE }
                val service2 = services.firstOrNull { it.uuid == S2_SERVICE }

                if (service1 != null && service2 != null) {
                  btCommandInput = service1.getCharacteristic(S1_CHAR_COMMAND_INPUT)
                  val s1out = service1.getCharacteristic(S1_CHAR_DATA_OUTPUT)
                  val s1mys = service1.getCharacteristic(S1_CHAR_MYSTERY_OUTPUT)
                  val s2mys = service2.getCharacteristic(S2_CHAR_MYSTERY_OUTPUT)
                  if (btCommandInput == null || s1out == null || s1mys == null || s2mys == null) {
                    logger.warn("Something is off about this i-CONSOLE device")
                    output.emitBlocking(ErrorOccurred("(Maybe) a malfunctioning i-CONSOLE device"))
                    peripheral.cancelConnection()
                    return
                  }

                  peripheral.setNotify(btCommandInput!!, true)
                  peripheral.setNotify(s1out, true)
                  peripheral.setNotify(s1mys, true)
                  peripheral.setNotify(s2mys, true)

                  logger.info("Device setup successfully; sending first request...")

                  runBlocking {
                    peripheral.writeCharacteristic(
                      btCommandInput!!,
                      AckRequest.toBytes(),
                      WITHOUT_RESPONSE,
                    )
                  }

                  current = peripheral
                } else {
                  logger.warn("This is maybe not an i-CONSOLE device, since it lacks the required services")
                  output.emitBlocking(ErrorOccurred("(Maybe) not an i-CONSOLE device"))
                  peripheral.cancelConnection()
                }
              }

              override fun onCharacteristicUpdate(
                peripheral: BluetoothPeripheral,
                value: ByteArray?,
                characteristic: BluetoothGattCharacteristic,
                status: BluetoothCommandStatus,
              ) {
                val res = value?.let { Response.fromBytes(it) }

                if (!connected && res is AckResponse) {
                  logger.info("Device is now ready")

                  connected = true
                  output.emitBlocking(Connected)
                }

                if (res is MaxLevelResponse) {
                  maxLevel = res.level
                }

                if (res is ControlStateResponse) {
                  if (res.value == 1) {
                    running = true
                    output.emitBlocking(Started)
                  } else {
                    running = false
                    output.emitBlocking(Stopped)
                  }
                }

                if (res is WorkoutStatusResponse) {
                  val currentTime = (res.minutes * 60) + res.seconds

                  if (currentTime > lastTime) {
                    lastTime = currentTime
                    lastCals = maxOf(res.calories, lastCals)
                    lastMeters = maxOf((res.distance * 1000).toInt(), lastMeters)

                    output.emitBlocking(
                      ValuesReceived(
                        listOfNotNull(
                          Time(lastTime + bonusTime),
                          Calories(lastCals + bonusCals),
                          Distance(lastMeters + bonusMeters),
                          Level(res.level),
                          RpmSpeed(res.rpm),
                          res.pulse.takeIf { it >= 70 }?.let { Pulse(it) },
                        )
                      )
                    )
                  }
                }
              }
            }

            tryingSince = null
            central?.connectPeripheral(peripheral, cbPeripheral)
            central?.stopScan()
          }
        }

        override fun onDisconnectedPeripheral(peripheral: BluetoothPeripheral, status: BluetoothCommandStatus) {
          if (peripheral.address == current?.address) {
            if (wantsConnection) {
              logger.warn("Will try restarting in 10 seconds (disconnection)")
              prepareReconnect(connectionString, output)
            } else {
              current = null
              output.emitBlocking(Disconnected)
            }
          }
        }

        override fun onConnectionFailed(peripheral: BluetoothPeripheral, status: BluetoothCommandStatus) {
          central?.stopScan()

          runBlocking {
            if (health > 1) {
              logger.warn("Will try restarting in 10 seconds (connection error)")
              prepareReconnect(connectionString, output)
            } else {
              output.emit(ErrorOccurred("Failure: $status"))
              output.emit(Disconnected)
            }
          }
        }
      }

      central = BluetoothCentralManager(cbScan)
    }

    central?.scanForPeripheralsWithAddresses(arrayOf(connectionString))
  }

  private fun onDisconnect() {
    lastTime = 0
    lastCals = 0
    lastMeters = 0
    running = false
    connected = false
    wantsConnection = false

    current?.cancelConnection()
  }

  private fun onSetValue(value: Value) {
    if (current == null || btCommandInput === null || !running) return

    if (value is Level) {
      lastLevel = value.toInt()
      queue += SetResistanceLevelRequest(minOf(lastLevel, maxLevel))
    }
  }

  private fun onStart() {
    if (current == null || btCommandInput === null || running) return

    if (lastTime == 0) {
      logger.info("STARTED")
      queue += AckRequest
      queue += SetWorkoutModeRequest(0)
      queue += SetWorkoutParamsRequest()
      queue += SetWorkoutControlStateRequest(1)

      if (bonusLevel > 0) {
        onSetValue(Level(bonusLevel))
        bonusLevel = 0
      }
    } else {
      logger.info("RESUMED")
      queue += SetWorkoutControlStateRequest(1)
    }
  }

  private fun onStop() {
    if (current == null || btCommandInput === null || !running) return

    queue += SetWorkoutControlStateRequest(2)
  }

  override suspend fun onCommand(command: Command, output: FlowBus<Event>) {
    when (command) {
      is ConnectCommand -> onConnect(command.device, output)
      DisconnectCommand -> onDisconnect()
      is SetValueCommand -> onSetValue(command.value)
      StartCommand -> onStart()
      StopCommand -> onStop()
      SkipCommand -> {}
    }
  }

  override suspend fun onTick(output: FlowBus<Event>) {
    current?.apply {
      if (connected && btCommandInput != null) {
        val s1input = btCommandInput!!

        // Fetch one queued event when running, otherwise take up to five at a time
        val max = if (running) 1 else 5
        for (i in 0 until max) {
          if (queue.isEmpty()) {
            break
          }

          val first = queue.first()
          writeCharacteristic(s1input, first.toBytes(), WITHOUT_RESPONSE)
          queue -= first
          delay(pollDuration)
        }

        if (running) {
          // Fetch current state
          writeCharacteristic(
            s1input,
            GetWorkoutStateRequest.toBytes(),
            WITHOUT_RESPONSE,
          )
        } else {
          // This is just to keep the connection alive, as far as I know…
          runBlocking {
            writeCharacteristic(
              s1input,
              GetMaxLevelRequest.toBytes(),
              WITHOUT_RESPONSE,
            )
            delay(pollDuration)
          }
        }
      }
    }

    delay(pollDuration)
  }

  private fun prepareReconnect(connectionString: String, output: FlowBus<Event>) {
    running = false
    connected = false

    bonusLevel = lastLevel
    bonusTime += lastTime
    bonusCals += lastCals
    bonusMeters += bonusMeters

    lastTime = 0
    lastCals = 0
    lastMeters = 0

    runBlocking {
      output.emit(Stopped)
      delay(timeMillis = 10_000)
      connect(connectionString, output)
    }
  }

  companion object {
    private val S1_SERVICE = UUID.fromString("49535343-fe7d-4ae5-8fa9-9fafd205e455")
    private val S1_CHAR_COMMAND_INPUT = UUID.fromString("49535343-8841-43f4-a8d4-ecbe34729bb3")
    private val S1_CHAR_DATA_OUTPUT = UUID.fromString("49535343-1e4d-4bd9-ba61-23c647249616")
    private val S1_CHAR_MYSTERY_OUTPUT = UUID.fromString("49535343-4c8a-39b3-2f49-511cff073b7e")

    private val S2_SERVICE = UUID.fromString("49535343-5d82-6099-9348-7aac4d5fbc51")
    private val S2_CHAR_MYSTERY_OUTPUT = UUID.fromString("49535343-026e-3a9b-954c-97daef17e26e")

    private val pollDuration: Duration = 500.milliseconds
  }
}