MicrOBU/app/src/main/java/com/hawhamburg/micr0bu/viewmodel/MqttViewModel.kt

package com.hawhamburg.micr0bu.viewmodel

import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import com.hawhamburg.micr0bu.data.cam.CamUseCaseRepository
import com.hawhamburg.micr0bu.data.mqtt.MqttConnectionState
import com.hawhamburg.micr0bu.data.mqtt.MqttMessage
import com.hawhamburg.micr0bu.data.mqtt.MqttPreferences
import com.hawhamburg.micr0bu.data.mqtt.MqttPrefs
import com.hawhamburg.micr0bu.data.mqtt.MqttRepository
import com.hawhamburg.micr0bu.data.transport.TransportType
import com.hawhamburg.micr0bu.data.transport.UsbNetworkDetector
import com.hawhamburg.micr0bu.domain.denm.DenmUseCase
import com.hawhamburg.micr0bu.domain.usecase.UseCaseAlert
import com.hawhamburg.micr0bu.domain.usecase.UseCaseType
import dagger.hilt.android.lifecycle.HiltViewModel
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.SharingStarted
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.asStateFlow
import kotlinx.coroutines.flow.map
import kotlinx.coroutines.flow.stateIn
import kotlinx.coroutines.launch
import org.json.JSONObject
import javax.inject.Inject

@HiltViewModel
class MqttViewModel @Inject constructor(
    private val repo: MqttRepository,
    private val prefs: MqttPreferences,
    private val usbDetector: UsbNetworkDetector,
    private val camUseCaseRepository: CamUseCaseRepository,
) : ViewModel() {

    // ── MQTT connection & messages ────────────────────────────────────────────

    val connectionState: StateFlow<MqttConnectionState> = repo.connectionState

    val topicMessages: StateFlow<Map<String, List<MqttMessage>>> = repo.topicMessages

    private val _selectedTopic = MutableStateFlow<String?>(null)
    val selectedTopic: StateFlow<String?> = _selectedTopic.asStateFlow()

    private val _autoScroll = MutableStateFlow(true)
    val autoScroll: StateFlow<Boolean> = _autoScroll.asStateFlow()

    // ── Transport & USB ───────────────────────────────────────────────────────

    val activeTransport: StateFlow<TransportType> = repo.activeTransport

    /** True when a 192.168.42.x USB-C tethering network is detected. */
    val usbConnected: StateFlow<Boolean> = usbDetector.usbNetwork
        .map { it != null }
        .stateIn(viewModelScope, SharingStarted.Eagerly, false)

    /** Auto-detected OBU gateway IP on the USB interface. */
    val detectedObuIp: StateFlow<String?> = usbDetector.detectedGatewayIp

    // ── Prefs ─────────────────────────────────────────────────────────────────

    val mqttPrefs: StateFlow<MqttPrefs> = prefs.prefsFlow.stateIn(
        viewModelScope,
        SharingStarted.Eagerly,
        MqttPrefs(),
    )

    // ── OBU identity (parsed from v2x/rx/obu_gnss own_info) ──────────────────

    /**
     * stationType from the OBU's own_info (v2x/rx/obu_gnss). Should be 2 (cyclist/VRU) per
     * ETSI EN 302 637-2 Table 1. Null until the first obu_gnss message arrives.
     */
    private val _obuStationType = MutableStateFlow<Int?>(null)

    /**
     * The raw stationType value last reported by the OBU. Null until the first
     * obu_gnss message arrives. Exposed so the UI can show the actual value.
     */
    val obuStationType: StateFlow<Int?> = _obuStationType.asStateFlow()

    /**
     * True when the OBU has reported a stationType other than 2 (cyclist).
     * Triggers a persistent warning banner — an incorrect stationType means this OBU will
     * not be detected as a VRU at equipped intersections.
     */
    val obuStationTypeWarning: StateFlow<Boolean> = _obuStationType
        .map { it != null && it != 2 }
        .stateIn(viewModelScope, SharingStarted.Eagerly, false)

    // ── DENM transmission ─────────────────────────────────────────────────────

    /** True while a DENM use case is actively broadcasting on the OBU. */
    val denmActive: StateFlow<Boolean> = repo.denmActive

    /** JSON string of the most recently transmitted DENM control message. */
    val lastDenmPayload: StateFlow<String?> = repo.lastDenmPayload

    /** The use case id currently active on the OBU, if any (e.g. for showing in the UI). */
    val activeDenmUseCase: StateFlow<String?> = repo.activeDenmUseCase

    // ── CAM-based Use Case Detection (Section 10.2 / 10.4) ────────────────────
    // Entirely separate from the DENM transmission above: this consumes CAM only, raises
    // local HMI alerts, and never triggers an outbound V2X message.

    /** The ego OBU's own station ID, learned from v2x/rx/obu_gnss's own_info. */
    val ownStationId: StateFlow<Long?> = camUseCaseRepository.ownStationId

    /** Active CAM-based use case alerts, filtered to the use cases enabled in Settings. */
    val useCaseAlerts: StateFlow<List<UseCaseAlert>> = camUseCaseRepository.enabledAlerts

    /** Per-use-case enable/disable state (Settings > Use Case Alerts). */
    val useCaseEnabledMap: StateFlow<Map<UseCaseType, Boolean>> = camUseCaseRepository.enabledMap

    /** True if [stationId] is the ego OBU's own — used for OWN/REMOTE badges in the raw message list. */
    fun isOwnStationId(stationId: Long): Boolean = camUseCaseRepository.isOwnStationId(stationId)

    fun setUseCaseEnabled(type: UseCaseType, enabled: Boolean) {
        camUseCaseRepository.setUseCaseEnabled(type, enabled)
    }

    // ── Init ──────────────────────────────────────────────────────────────────

    init {
        viewModelScope.launch {
            // Per-topic message lists now live in MqttRepository (survives screen close);
            // here we just watch for own_info to track the OBU's reported stationType.
            repo.messages.collect { msg ->
                if (msg.topic == "v2x/rx/obu_gnss") {
                    runCatching {
                        val stType = JSONObject(msg.payload)
                            .optJSONObject("own_info")
                            ?.optInt("stationType", -1) ?: -1
                        if (stType >= 0) _obuStationType.value = stType
                    }
                }
            }
        }
    }

    // ── Actions ───────────────────────────────────────────────────────────────

    fun connect()    = repo.connect()
    fun disconnect() = repo.disconnect()

    fun selectTopic(topic: String?) { _selectedTopic.value = topic }
    fun setAutoScroll(enabled: Boolean) { _autoScroll.value = enabled }

    fun updatePrefs(newPrefs: MqttPrefs) {
        viewModelScope.launch { prefs.update(newPrefs) }
    }

    // ── DENM actions ──────────────────────────────────────────────────────────

    /**
     * Publish a uca-denmctrl activate message with the retain flag so the OBU's Use Case app
     * receives it on any (re)connect. Only one use case may be active at a time
     * (no-op if another use case, manual or automatic, is already active).
     */
    fun sendDenm(useCase: String = DenmUseCase.STATIONARY.id) {
        repo.activateDenm(useCase)
    }

    /**
     * Publish a uca-denmctrl deactivate message (retained) for whichever use case is
     * currently active.
     */
    fun stopDenm() {
        repo.deactivateDenm()
    }

    // ── Lifecycle ─────────────────────────────────────────────────────────────

    override fun onCleared() {
        super.onCleared()
        repo.disconnect()
    }
}