package com.syncflow.ui.files

import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import com.syncflow.data.db.SyncFileStateDao
import com.syncflow.data.db.SyncPairDao
import com.syncflow.data.db.entities.SyncFileStateEntity
import com.syncflow.data.db.entities.SyncPairEntity
import dagger.hilt.android.lifecycle.HiltViewModel
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.flow.*
import javax.inject.Inject

@OptIn(ExperimentalCoroutinesApi::class)
@HiltViewModel
class FilesViewModel @Inject constructor(
    syncPairDao: SyncPairDao,
    private val fileStateDao: SyncFileStateDao,
) : ViewModel() {

    val pairs: StateFlow<List<SyncPairEntity>> = syncPairDao.observeAll()
        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), emptyList())

    private val _selectedPairId = MutableStateFlow<Long?>(null)

    val selectedPair: StateFlow<SyncPairEntity?> = combine(_selectedPairId, pairs) { id, list ->
        list.firstOrNull { it.id == id } ?: list.firstOrNull()
    }.stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), null)

    val files: StateFlow<List<SyncFileStateEntity>> = _selectedPairId
        .flatMapLatest { id ->
            if (id == null) pairs.map { it.firstOrNull()?.id }.filterNotNull()
                .flatMapLatest { fileStateDao.observeForPair(it) }
            else fileStateDao.observeForPair(id)
        }
        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5_000), emptyList())

    fun selectPair(id: Long) { _selectedPairId.value = id }
}