Coverage Summary for Class: CategoryChooserViewModel (com.georgeci.moneysurfer.feature.category.picker)

 package com.georgeci.moneysurfer.feature.category.picker
 
 import arrow.optics.optics
 import com.georgeci.moneysurfer.domain.model.Category
 import com.georgeci.moneysurfer.domain.primitives.CategoryId
 import com.georgeci.moneysurfer.domain.primitives.CategoryType
 import com.georgeci.moneysurfer.domain.usecase.GetCategoriesUseCase
 import com.georgeci.moneysurfer.utils.MviViewModel
 import org.koin.core.annotation.KoinViewModel
 
 @KoinViewModel
 class CategoryChooserViewModel(
     initialSelectedId: CategoryId?,
     private val filterType: CategoryType?,
     private val initialVariant: CategoryPickerVariant,
     private val getCategories: GetCategoriesUseCase,
 ) : MviViewModel<CategoryChooserState, CategoryChooserEvent, CategoryChooserEffect>(
     initialState = CategoryChooserState.Loading(selectedId = initialSelectedId),
 ) {
 
     /**
      * Every category of every type, unfiltered. The tab row switches type without another read,
      * and the state only ever carries what the current tab renders.
      */
     private var allCategories: List<Category> = emptyList()
 
     init {
         observeCategories()
     }
 
     override fun onEvent(event: CategoryChooserEvent) {
         when (event) {
             is CategoryChooserEvent.OnCategorySelected ->
                 postSideEffect(CategoryChooserEffect.PublishResult(event.id))
             CategoryChooserEvent.OnCreateNewCategoryClick ->
                 postSideEffect(CategoryChooserEffect.NavigateToCategoryCreation)
             CategoryChooserEvent.OnDismiss -> postSideEffect(CategoryChooserEffect.Dismiss)
             is CategoryChooserEvent.OnTypeSelected -> updateContent {
                 // Expansion is per-parent and the parents differ per type, so a stale set would
                 // only ever open the wrong rows.
                 copy(type = event.type, expandedIds = expandedFor(event.type))
             }
             is CategoryChooserEvent.OnQueryChange -> updateContent { copy(query = event.query) }
             CategoryChooserEvent.OnVariantToggle -> updateContent { copy(variant = variant.other()) }
             is CategoryChooserEvent.OnParentExpandToggle -> updateContent {
                 copy(
                     expandedIds = if (event.id in expandedIds) {
                         expandedIds - event.id
                     } else {
                         expandedIds + event.id
                     },
                 )
             }
         }
     }
 
     private fun observeCategories() {
         launch {
             getCategories().collect { categories ->
                 allCategories = categories
                 updateState {
                     when (this) {
                         // Type, query and expansion are the user's; a re-emission from sync
                         // rebuilds the rows underneath them without resetting any of it.
                         is CategoryChooserState.Content -> this
                         is CategoryChooserState.Loading -> newContent()
                     }.rebuild()
                 }
             }
         }
     }
 
     private fun CategoryChooserState.Loading.newContent(): CategoryChooserState.Content {
         val type = CategoryPickerRows.initialType(allCategories, selectedId, filterType)
         return CategoryChooserState.Content(
             selectedId = selectedId,
             selectedName = null,
             type = type,
             typeLocked = filterType != null,
             query = "",
             expandedIds = expandedFor(type),
             variant = initialVariant,
         )
     }
 
     private fun CategoryPickerVariant.other(): CategoryPickerVariant = when (this) {
         CategoryPickerVariant.GRID -> CategoryPickerVariant.TREE
         CategoryPickerVariant.TREE -> CategoryPickerVariant.GRID
     }
 
     private fun expandedFor(type: CategoryType): Set<CategoryId> {
         val selected = currentState.selectedId?.takeIf { id ->
             allCategories.firstOrNull { it.id == id }?.type == type
         }
         return CategoryPickerRows.expandedForSelection(allCategories, selected)
     }
 
     /** Applies [reducer] once the sheet has content; events that land while loading are dropped. */
     private fun updateContent(reducer: CategoryChooserState.Content.() -> CategoryChooserState.Content) =
         updateState {
             when (this) {
                 is CategoryChooserState.Content -> reducer().rebuild()
                 is CategoryChooserState.Loading -> this
             }
         }
 
     /** Re-derives everything the sheet draws from the inputs the events just changed. */
     private fun CategoryChooserState.Content.rebuild() = copy(
         selectedName = allCategories.firstOrNull { it.id == selectedId }?.name,
         gridItems = CategoryPickerRows.grid(allCategories, type, query, selectedId),
         treeItems = CategoryPickerRows.tree(allCategories, type, query, selectedId, expandedIds),
     )
 }
 
 @optics
 sealed interface CategoryChooserState {
     val selectedId: CategoryId?
 
     @optics
     data class Loading(override val selectedId: CategoryId?) : CategoryChooserState {
         companion object
     }
 
     @optics
     data class Content(
         override val selectedId: CategoryId?,
         /** Name behind [selectedId], for the `Currently: …` subline. Null until it resolves. */
         val selectedName: String?,
         val type: CategoryType,
         /** True when the caller pinned the type — the tab row is then not offered at all. */
         val typeLocked: Boolean,
         val query: String,
         val expandedIds: Set<CategoryId>,
         val variant: CategoryPickerVariant,
         val gridItems: List<CategoryPickerItem> = emptyList(),
         val treeItems: List<CategoryTreeGroup> = emptyList(),
     ) : CategoryChooserState {
         companion object
     }
 
     companion object
 }
 
 sealed interface CategoryChooserEvent {
     data class OnCategorySelected(val id: CategoryId) : CategoryChooserEvent
     data class OnTypeSelected(val type: CategoryType) : CategoryChooserEvent
     data class OnQueryChange(val query: String) : CategoryChooserEvent
     data class OnParentExpandToggle(val id: CategoryId) : CategoryChooserEvent
     data object OnVariantToggle : CategoryChooserEvent
     data object OnCreateNewCategoryClick : CategoryChooserEvent
     data object OnDismiss : CategoryChooserEvent
 }
 
 sealed interface CategoryChooserEffect {
     data object NavigateToCategoryCreation : CategoryChooserEffect
     data object Dismiss : CategoryChooserEffect
     data class PublishResult(val id: CategoryId) : CategoryChooserEffect
 }