package agzam.vyatsu.ui.groups

import agzam.vyatsu.domain.model.Group
import agzam.vyatsu.domain.repository.GroupRepository
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.asStateFlow
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext

/**
 * @author Agzam
 */
class GroupPickerViewModel(private val repository: GroupRepository) : ViewModel() {

    private val _uiState = MutableStateFlow(GroupPickerUiState())
    val uiState: StateFlow<GroupPickerUiState> = _uiState.asStateFlow()

    init {
        load()
    }

    private fun load() {
        viewModelScope.launch {
            withContext(Dispatchers.IO) {
                val ok = try {
                    repository.refreshIfStale()
                } catch (e: Exception) {
                    _uiState.value = _uiState.value.copy(
                        error = e.message ?: "Не удалось загрузить группы"
                    )
                    false
                }
                if (!ok && _uiState.value.groups.isEmpty()) {
                    _uiState.value = _uiState.value.copy(
                        error = _uiState.value.error ?: "Не удалось обновить список групп"
                    )
                }
            }
            repository.observeGroups().collect { groups ->
                val query = _uiState.value.searchQuery
                _uiState.value = _uiState.value.copy(
                    isLoading = false,
                    groups = groups,
                    filteredGroups = filterGroups(groups, query),
                    error = null
                )
            }
        }
    }

    fun search(query: String) {
        val groups = _uiState.value.groups
        _uiState.value = _uiState.value.copy(
            searchQuery = query,
            filteredGroups = filterGroups(groups, query)
        )
    }

    private fun filterGroups(groups: List<Group>, query: String): List<Group> {
        if (query.isBlank()) return groups
        val lowerQuery = query.lowercase()
        return groups.filter { group ->
            group.name.lowercase().contains(lowerQuery) || group.faculty.lowercase().contains(lowerQuery)
        }
    }

    fun retry() {
        _uiState.value = _uiState.value.copy(isLoading = true, error = null)
        load()
    }

    fun refresh() {
        _uiState.value = _uiState.value.copy(isLoading = true, error = null)
        viewModelScope.launch {
            withContext(Dispatchers.IO) {
                try {
                    repository.forceRefresh()
                } catch (e: Exception) {
                    _uiState.value = _uiState.value.copy(
                        isLoading = false,
                        error = e.message ?: "Не удалось обновить список групп"
                    )
                    return@withContext
                }
            }
        }
    }
}

data class GroupPickerUiState(
    val isLoading: Boolean = true,
    val error: String? = null,
    val groups: List<Group> = emptyList(),
    val searchQuery: String = "",
    val filteredGroups: List<Group> = emptyList()
)