package world.respect.shared.viewmodel.assignment.list

import androidx.lifecycle.SavedStateHandle
import androidx.lifecycle.viewModelScope
import io.ktor.http.Url
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.asStateFlow
import kotlinx.coroutines.flow.emptyFlow
import kotlinx.coroutines.flow.update
import kotlinx.coroutines.launch
import org.koin.core.component.KoinScopeComponent
import org.koin.core.component.inject
import org.koin.core.scope.Scope
import world.respect.datalayer.DataLoadParams
import world.respect.datalayer.DataLoadState
import world.respect.datalayer.RespectAppDataSource
import world.respect.datalayer.SchoolDataSource
import world.respect.datalayer.school.AssignmentDataSource
import world.respect.datalayer.school.model.Assignment
import world.respect.datalayer.shared.paging.EmptyPagingSourceFactory
import world.respect.datalayer.shared.paging.IPagingSourceFactory
import world.respect.datalayer.shared.paging.PagingSourceFactoryHolder
import world.respect.lib.opds.model.OpdsPublication
import world.respect.shared.domain.account.RespectAccountManager
import world.respect.shared.generated.resources.Res
import world.respect.shared.generated.resources.assignment
import world.respect.shared.generated.resources.assignments
import world.respect.shared.navigation.AssignmentDetail
import world.respect.shared.navigation.AssignmentEdit
import world.respect.shared.navigation.NavCommand
import world.respect.shared.util.ext.asUiText
import world.respect.shared.util.ext.isAdminOrTeacher
import world.respect.shared.viewmodel.RespectViewModel
import world.respect.shared.viewmodel.app.appstate.FabUiState

data class AssignmentListUiState(
    val assignments: IPagingSourceFactory<Int, Assignment> = EmptyPagingSourceFactory(),
    val learningUnitInfoFlow: (Url) -> Flow<DataLoadState<OpdsPublication>> = { emptyFlow() },
)

class AssignmentListViewModel(
    savedStateHandle: SavedStateHandle,
    accountManager: RespectAccountManager,
    private val respectAppDataSource: RespectAppDataSource,
) : RespectViewModel(savedStateHandle), KoinScopeComponent {

    override val scope: Scope = accountManager.requireSelectedAccountScope()

    private val schoolDataSource: SchoolDataSource by inject()

    private val _uiState = MutableStateFlow(AssignmentListUiState())

    val uiState: StateFlow<AssignmentListUiState> = _uiState.asStateFlow()


    private val pagingSourceHolder = PagingSourceFactoryHolder {
        schoolDataSource.assignmentDataSource.listAsPagingSource(
            loadParams = DataLoadParams(),
            params = AssignmentDataSource.GetListParams()
        )
    }

    init {
        _appUiState.update {
            it.copy(
                title = Res.string.assignments.asUiText(),
                fabState = FabUiState(
                    text = Res.string.assignment.asUiText(),
                    icon = FabUiState.FabIcon.ADD,
                    onClick = ::onClickAdd
                ),
                showBackButton = false,
            )
        }

        _uiState.update {
            it.copy(
                assignments = pagingSourceHolder,
                learningUnitInfoFlow = ::learningUnitInfoFlowFor,
            )
        }

        viewModelScope.launch {
            accountManager.selectedAccountAndPersonFlow.collect { selectedAcct ->
                _appUiState.update { prev ->
                    prev.copy(
                        fabState = prev.fabState.copy(
                            visible = selectedAcct?.person?.isAdminOrTeacher() == true
                        )
                    )
                }
            }
        }

    }

    fun onClickAssignment(assignment: Assignment) {
        _navCommandFlow.tryEmit(
            NavCommand.Navigate(
                AssignmentDetail(assignment.uid)
            )
        )
    }

    fun onClickAdd() {
        _navCommandFlow.tryEmit(
            NavCommand.Navigate(
                AssignmentEdit.create(uid = null)
            )
        )
    }

    fun learningUnitInfoFlowFor(url: Url): Flow<DataLoadState<OpdsPublication>> {
        return respectAppDataSource.opdsDataSource.loadOpdsPublication(
            url = url, params = DataLoadParams(), null, null
        )
    }

}