package com.hawhamburg.micr0bu.service

import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.asStateFlow

/**
 * Process-level singleton that bridges [TripRecordingService] (writes) and
 * [TripRecordingViewModel] (reads) without requiring a bound service.
 *
 * The service updates [state] on every relevant change; the ViewModel collects
 * it as a cold StateFlow.
 */
object TripServiceBus {

    data class State(
        val isRecording: Boolean = false,
        val currentTripId: Long = -1L,
        val elapsedSeconds: Long = 0L,
        val currentSpeedMs: Float = 0f,
    )

    private val _state = MutableStateFlow(State())
    val state: StateFlow<State> = _state.asStateFlow()

    /** Called exclusively from [TripRecordingService]. */
    internal fun update(transform: State.() -> State) {
        _state.value = _state.value.transform()
    }

    /** Resets to idle — called when recording stops. */
    internal fun reset() {
        _state.value = State()
    }
}