Coverage Summary for Class: TransactionFiltersState (com.georgeci.moneysurfer.feature.transaction.filters)

 package com.georgeci.moneysurfer.feature.transaction.filters
 
 import com.georgeci.moneysurfer.domain.model.Account
 import com.georgeci.moneysurfer.domain.model.Category
 import com.georgeci.moneysurfer.domain.preferences.UiPreferences
 import com.georgeci.moneysurfer.domain.primitives.AccountId
 import com.georgeci.moneysurfer.domain.primitives.CategoryId
 import com.georgeci.moneysurfer.domain.primitives.ClockUseCase
 import com.georgeci.moneysurfer.domain.usecase.GetAccountsUseCase
 import com.georgeci.moneysurfer.domain.usecase.GetCategoriesUseCase
 import com.georgeci.moneysurfer.domain.usecase.GetTransactionsByAccountUseCase
 import com.georgeci.moneysurfer.feature.transaction.filter.TransactionDatePreset
 import com.georgeci.moneysurfer.feature.transaction.filter.TransactionDateRange
 import com.georgeci.moneysurfer.feature.transaction.filter.TransactionFilterStore
 import com.georgeci.moneysurfer.feature.transaction.filter.TransactionFilters
 import com.georgeci.moneysurfer.feature.transaction.filter.TransactionSort
 import com.georgeci.moneysurfer.feature.transaction.filter.TransactionTypeFilter
 import com.georgeci.moneysurfer.feature.transaction.filter.compile
 import com.georgeci.moneysurfer.feature.transaction.filter.resolveWindow
 import com.georgeci.moneysurfer.feature.transaction.list.collapseSplitLegs
 import com.georgeci.moneysurfer.utils.MviViewModel
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.map
 import kotlinx.datetime.LocalDate
 import kotlinx.datetime.TimeZone
 import kotlinx.datetime.toLocalDateTime
 import org.koin.core.annotation.KoinViewModel
 
 /**
  * How many rows the live result count looks at.
  *
  * The count is a real query, not an estimate — the same windowed query the list itself runs, with
  * the same matcher applied — because an estimate that disagreed with the list the user lands on
  * would be worse than no number at all. It is capped so that "Apply" on an unbounded date range
  * cannot pull an entire history into memory on every keystroke; beyond the cap the screen says
  * "500+" rather than a wrong exact number.
  */
 private const val COUNT_LIMIT = 500
 
 /**
  * The filter screen's draft.
  *
  * Nothing here touches [TransactionFilterStore] until `Apply`: the draft is local, so backing out
  * with `Cancel` — or with the system back gesture — leaves the list exactly as it was.
  */
 @KoinViewModel
 class TransactionFiltersViewModel(
     private val accountId: AccountId?,
     /**
      * The day the list is paged to, or null to fall back to today. Only used while the range still
      * follows the period pager — a preset or custom range resolves its own window regardless.
      */
     private val anchorEpochDay: Long?,
     private val filterStore: TransactionFilterStore,
     private val getTransactionsByAccount: GetTransactionsByAccountUseCase,
     private val getAccounts: GetAccountsUseCase,
     private val getCategories: GetCategoriesUseCase,
     private val uiPreferences: UiPreferences,
     private val clock: ClockUseCase,
 ) : MviViewModel<TransactionFiltersState, TransactionFiltersEvent, TransactionFiltersEffect>(
     initialState = TransactionFiltersState(
         draft = TransactionFilters.Empty,
         // The accounts section is meaningless on a list already scoped to one account: the query
         // is restricted to it, so picking another one could only ever produce an empty list.
         showAccounts = accountId == null,
     ),
 ) {
 
     private val zone = TimeZone.currentSystemDefault()
     private val today: LocalDate get() = clock.now().toLocalDateTime(zone).date
 
     private val draft = MutableStateFlow(filterStore.filters.value)
 
     init {
         observeData()
     }
 
     @Suppress("CyclomaticComplexMethod")
     override fun onEvent(event: TransactionFiltersEvent) {
         when (event) {
             TransactionFiltersEvent.OnCancelClick ->
                 postSideEffect(TransactionFiltersEffect.NavigateBack)
             TransactionFiltersEvent.OnResetClick -> draft.value = draft.value.cleared()
             TransactionFiltersEvent.OnApplyClick -> {
                 filterStore.commit(draft.value)
                 postSideEffect(TransactionFiltersEffect.NavigateBack)
             }
             is TransactionFiltersEvent.OnDatePresetClick -> edit { withPreset(event.preset) }
             TransactionFiltersEvent.OnCustomDateClick -> edit { withCustomRange() }
             is TransactionFiltersEvent.OnCustomFromPicked -> edit { withCustomFrom(event.date) }
             is TransactionFiltersEvent.OnCustomToPicked -> edit { withCustomTo(event.date) }
             is TransactionFiltersEvent.OnTypeSelected -> edit { copy(type = event.type) }
             is TransactionFiltersEvent.OnAccountToggled -> edit {
                 copy(accountIds = accountIds.toggle(event.accountId))
             }
             is TransactionFiltersEvent.OnCategoryToggled -> edit {
                 copy(categoryIds = categoryIds.toggle(event.categoryId))
             }
             TransactionFiltersEvent.OnAllCategoriesClick -> edit { copy(categoryIds = emptySet()) }
             is TransactionFiltersEvent.OnMinAmountChanged -> edit { copy(minAmount = event.text) }
             is TransactionFiltersEvent.OnMaxAmountChanged -> edit { copy(maxAmount = event.text) }
             is TransactionFiltersEvent.OnRecurringOnlyChanged -> edit { copy(recurringOnly = event.enabled) }
             is TransactionFiltersEvent.OnPlannedOnlyChanged -> edit { copy(plannedOnly = event.enabled) }
             is TransactionFiltersEvent.OnSortSelected -> edit { copy(sort = event.sort) }
         }
     }
 
     private fun edit(block: TransactionFilters.() -> TransactionFilters) {
         draft.value = draft.value.block()
     }
 
     /** Tapping a selected preset clears it — otherwise a date range could only ever be swapped. */
     private fun TransactionFilters.withPreset(preset: TransactionDatePreset): TransactionFilters {
         val already = (dateRange as? TransactionDateRange.Preset)?.preset == preset
         return copy(
             dateRange = if (already) {
                 TransactionDateRange.FollowPeriod
             } else {
                 TransactionDateRange.Preset(preset)
             },
         )
     }
 
     private fun TransactionFilters.withCustomRange(): TransactionFilters =
         if (dateRange is TransactionDateRange.Custom) {
             copy(dateRange = TransactionDateRange.FollowPeriod)
         } else {
             copy(dateRange = TransactionDateRange.Custom(from = null, to = null))
         }
 
     private fun TransactionFilters.withCustomFrom(date: LocalDate?): TransactionFilters =
         copy(dateRange = customRange().copy(from = date))
 
     private fun TransactionFilters.withCustomTo(date: LocalDate?): TransactionFilters =
         copy(dateRange = customRange().copy(to = date))
 
     /** Picking a From/To date is itself the switch to a custom range. */
     private fun TransactionFilters.customRange(): TransactionDateRange.Custom =
         dateRange as? TransactionDateRange.Custom ?: TransactionDateRange.Custom(null, null)
 
     private fun <T> Set<T>.toggle(value: T): Set<T> =
         if (value in this) this - value else this + value
 
     @OptIn(ExperimentalCoroutinesApi::class)
     private fun observeData() {
         launch {
             val periodMode = uiPreferences.transactionsPeriodMode.flow.first()
             // The window the list is actually showing when the range still follows the pager: the
             // day it was paged to, not necessarily today.
             val anchor = anchorEpochDay?.let(LocalDate::fromEpochDays) ?: today
             val counted = draft
                 .map { filters -> filters.forCount() }
                 .distinctUntilChanged()
                 .flatMapLatest { filters ->
                     val window = resolveWindow(filters.dateRange, periodMode, anchor, today)
                     val matcher = filters.compile()
                     getTransactionsByAccount.window(accountId, window, COUNT_LIMIT + 1)
                         // Matched *then* collapsed, the same two steps in the same order the list
                         // applies: the button promises how many rows the user is about to see, and
                         // a receipt split across three categories is one of them, not three.
                         .map { rows -> collapseSplitLegs(rows.filter { matcher.matches(it) }).size }
                 }
 
             combine(draft, counted, getAccounts(), getCategories()) { filters, count, accounts, categories ->
                 TransactionFiltersState(
                     draft = filters,
                     showAccounts = accountId == null,
                     accounts = accounts.filterNot { it.archived },
                     categories = categories,
                     resultCount = count.coerceAtMost(COUNT_LIMIT),
                     resultCountCapped = count > COUNT_LIMIT,
                 )
             }.collect { state -> updateState { state } }
         }
     }
 
     /**
      * The draft as the count query sees it: an account-scoped list ignores the account selection,
      * exactly as the list does.
      */
     private fun TransactionFilters.forCount(): TransactionFilters =
         if (accountId != null) copy(accountIds = emptySet()) else this
 }
 
 /**
  * A plain data class rather than the sealed `Loading` / `Content` the repo uses elsewhere: the
  * screen has no async-load phase. The draft is available synchronously from
  * [TransactionFilterStore] at construction, so there is never a "Loading" state to model — the
  * accounts, categories and result count merely refine an already-usable screen as they arrive.
  */
 data class TransactionFiltersState(
     val draft: TransactionFilters,
     val showAccounts: Boolean,
     val accounts: List<Account> = emptyList(),
     val categories: List<Category> = emptyList(),
     val resultCount: Int = 0,
     /** The count hit [COUNT_LIMIT]; the screen shows "500+" rather than an exact number. */
     val resultCountCapped: Boolean = false,
 ) {
     val canReset: Boolean get() = draft.activeCount > 0
 }
 
 sealed interface TransactionFiltersEvent {
     data object OnCancelClick : TransactionFiltersEvent
     data object OnResetClick : TransactionFiltersEvent
     data object OnApplyClick : TransactionFiltersEvent
     data class OnDatePresetClick(val preset: TransactionDatePreset) : TransactionFiltersEvent
     data object OnCustomDateClick : TransactionFiltersEvent
     data class OnCustomFromPicked(val date: LocalDate?) : TransactionFiltersEvent
     data class OnCustomToPicked(val date: LocalDate?) : TransactionFiltersEvent
     data class OnTypeSelected(val type: TransactionTypeFilter) : TransactionFiltersEvent
     data class OnAccountToggled(val accountId: AccountId) : TransactionFiltersEvent
     data class OnCategoryToggled(val categoryId: CategoryId) : TransactionFiltersEvent
     data object OnAllCategoriesClick : TransactionFiltersEvent
     data class OnMinAmountChanged(val text: String) : TransactionFiltersEvent
     data class OnMaxAmountChanged(val text: String) : TransactionFiltersEvent
     data class OnRecurringOnlyChanged(val enabled: Boolean) : TransactionFiltersEvent
     data class OnPlannedOnlyChanged(val enabled: Boolean) : TransactionFiltersEvent
     data class OnSortSelected(val sort: TransactionSort) : TransactionFiltersEvent
 }
 
 sealed interface TransactionFiltersEffect {
     data object NavigateBack : TransactionFiltersEffect
 }