refactor: Remove duplicate strings from Filter contexts (#478)

A filter's context (previously referred to as its `kind`) controls where
the filter is applied.

This was implemented as an enum with a specific property to control how
it would serialise when @FormUrlEncoded, and with a @Json annotation for
Moshi.

In addition, the model objects kept the filter context in its string
form throughout Pachli, requiring periodic conversion to/from the enum
type, making the code more complicated.

Fix this, by:

1. Converting the incoming JSON value to the enum type immediately, so
the rest of the code uses the enum constants exclusively.

2. Implement a Retrofit converter that serialises the enum value when
@FormUrlEncoded to the same string used in JSON serialisation

app/src/main/java/app/pachli/StatusListActivity.kt

@@ -33,6 +33,7 @@ import app.pachli.core.navigation.StatusListActivityIntent
 import app.pachli.core.network.ServerOperation.ORG_JOINMASTODON_FILTERS_CLIENT
 import app.pachli.core.network.ServerOperation.ORG_JOINMASTODON_FILTERS_SERVER
 import app.pachli.core.network.model.Filter
+import app.pachli.core.network.model.FilterContext
 import app.pachli.core.network.model.FilterV1
 import app.pachli.core.network.model.TimelineKind
 import app.pachli.databinding.ActivityStatuslistBinding
@@ -243,7 +244,7 @@ class StatusListActivity : BottomSheetActivity(), AppBarLayoutHost, ActionButton
             mastodonApi.getFilters().fold(
                 { filters ->
                     mutedFilter = filters.firstOrNull { filter ->
-                        filter.context.contains(Filter.Kind.HOME.kind) && filter.keywords.any {
+                        filter.contexts.contains(FilterContext.HOME) && filter.keywords.any {
                             it.keyword == tagWithHash
                         }
                     }
@@ -254,7 +255,7 @@ class StatusListActivity : BottomSheetActivity(), AppBarLayoutHost, ActionButton
                         mastodonApi.getFiltersV1().fold(
                             { filters ->
                                 mutedFilterV1 = filters.firstOrNull { filter ->
-                                    tagWithHash == filter.phrase && filter.context.contains(FilterV1.HOME)
+                                    tagWithHash == filter.phrase && filter.contexts.contains(FilterContext.HOME)
                                 }
                                 updateTagMuteState(mutedFilterV1 != null)
                             },
@@ -288,7 +289,7 @@ class StatusListActivity : BottomSheetActivity(), AppBarLayoutHost, ActionButton
         lifecycleScope.launch {
             mastodonApi.createFilter(
                 title = tagWithHash,
-                context = listOf(FilterV1.HOME),
+                context = listOf(FilterContext.HOME),
                 filterAction = Filter.Action.WARN.action,
                 expiresInSeconds = null,
             ).fold(
@@ -296,7 +297,7 @@ class StatusListActivity : BottomSheetActivity(), AppBarLayoutHost, ActionButton
                     if (mastodonApi.addFilterKeyword(filterId = filter.id, keyword = tagWithHash, wholeWord = true).isSuccess) {
                         mutedFilter = filter
                         updateTagMuteState(true)
-                        eventHub.dispatch(FilterChangedEvent(Filter.Kind.from(filter.context[0])))
+                        eventHub.dispatch(FilterChangedEvent(filter.contexts[0]))
                         Snackbar.make(binding.root, getString(R.string.confirmation_hashtag_muted, hashtag), Snackbar.LENGTH_SHORT).show()
                     } else {
                         Snackbar.make(binding.root, getString(R.string.error_muting_hashtag_format, hashtag), Snackbar.LENGTH_SHORT).show()
@@ -307,7 +308,7 @@ class StatusListActivity : BottomSheetActivity(), AppBarLayoutHost, ActionButton
                     if (throwable is HttpException && throwable.code() == 404) {
                         mastodonApi.createFilterV1(
                             tagWithHash,
-                            listOf(FilterV1.HOME),
+                            listOf(FilterContext.HOME),
                             irreversible = false,
                             wholeWord = true,
                             expiresInSeconds = null,
@@ -315,7 +316,7 @@ class StatusListActivity : BottomSheetActivity(), AppBarLayoutHost, ActionButton
                             { filter ->
                                 mutedFilterV1 = filter
                                 updateTagMuteState(true)
-                                eventHub.dispatch(FilterChangedEvent(Filter.Kind.from(filter.context[0])))
+                                eventHub.dispatch(FilterChangedEvent(filter.contexts[0]))
                                 Snackbar.make(binding.root, getString(R.string.confirmation_hashtag_muted, hashtag), Snackbar.LENGTH_SHORT).show()
                             },
                             { throwable ->
@@ -340,23 +341,23 @@ class StatusListActivity : BottomSheetActivity(), AppBarLayoutHost, ActionButton
 
             val result = if (mutedFilter != null) {
                 val filter = mutedFilter!!
-                if (filter.context.size > 1) {
+                if (filter.contexts.size > 1) {
                     // This filter exists in multiple contexts, just remove the home context
                     mastodonApi.updateFilter(
                         id = filter.id,
-                        context = filter.context.filter { it != Filter.Kind.HOME.kind },
+                        context = filter.contexts.filter { it != FilterContext.HOME },
                     )
                 } else {
                     mastodonApi.deleteFilter(filter.id)
                 }
             } else if (mutedFilterV1 != null) {
                 mutedFilterV1?.let { filter ->
-                    if (filter.context.size > 1) {
+                    if (filter.contexts.size > 1) {
                         // This filter exists in multiple contexts, just remove the home context
                         mastodonApi.updateFilterV1(
                             id = filter.id,
                             phrase = filter.phrase,
-                            context = filter.context.filter { it != FilterV1.HOME },
+                            context = filter.contexts.filter { it != FilterContext.HOME },
                             irreversible = null,
                             wholeWord = null,
                             expiresInSeconds = null,
@@ -373,7 +374,7 @@ class StatusListActivity : BottomSheetActivity(), AppBarLayoutHost, ActionButton
                 {
                     updateTagMuteState(false)
                     Snackbar.make(binding.root, getString(R.string.confirmation_hashtag_unmuted, hashtag), Snackbar.LENGTH_SHORT).show()
-                    eventHub.dispatch(FilterChangedEvent(Filter.Kind.HOME))
+                    eventHub.dispatch(FilterChangedEvent(FilterContext.HOME))
                     mutedFilterV1 = null
                     mutedFilter = null
                 },

app/src/main/java/app/pachli/appstore/Events.kt

@@ -2,7 +2,7 @@ package app.pachli.appstore
 
 import app.pachli.core.database.model.TabData
 import app.pachli.core.network.model.Account
-import app.pachli.core.network.model.Filter
+import app.pachli.core.network.model.FilterContext
 import app.pachli.core.network.model.Poll
 import app.pachli.core.network.model.Status
 
@@ -21,7 +21,7 @@ data class StatusComposedEvent(val status: Status) : Event
 data object StatusScheduledEvent : Event
 data class StatusEditedEvent(val originalId: String, val status: Status) : Event
 data class ProfileEditedEvent(val newProfileData: Account) : Event
-data class FilterChangedEvent(val filterKind: Filter.Kind) : Event
+data class FilterChangedEvent(val filterContext: FilterContext) : Event
 data class MainTabsChangedEvent(val newTabs: List<TabData>) : Event
 data class PollVoteEvent(val statusId: String, val poll: Poll) : Event
 data class DomainMuteEvent(val instance: String) : Event

app/src/main/java/app/pachli/components/filters/EditFilterActivity.kt

@@ -18,6 +18,7 @@ import app.pachli.core.common.extensions.viewBinding
 import app.pachli.core.common.extensions.visible
 import app.pachli.core.navigation.EditFilterActivityIntent
 import app.pachli.core.network.model.Filter
+import app.pachli.core.network.model.FilterContext
 import app.pachli.core.network.model.FilterKeyword
 import app.pachli.core.network.retrofit.MastodonApi
 import app.pachli.databinding.ActivityEditFilterBinding
@@ -48,20 +49,20 @@ class EditFilterActivity : BaseActivity() {
 
     private lateinit var filter: Filter
     private var originalFilter: Filter? = null
-    private lateinit var contextSwitches: Map<SwitchMaterial, Filter.Kind>
+    private lateinit var filterContextSwitches: Map<SwitchMaterial, FilterContext>
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
         originalFilter = EditFilterActivityIntent.getFilter(intent)
-        filter = originalFilter ?: Filter("", "", listOf(), null, Filter.Action.WARN.action, listOf())
+        filter = originalFilter ?: Filter("", "", listOf(), null, Filter.Action.WARN, listOf())
         binding.apply {
-            contextSwitches = mapOf(
+            filterContextSwitches = mapOf(
-                filterContextHome to Filter.Kind.HOME,
+                filterContextHome to FilterContext.HOME,
-                filterContextNotifications to Filter.Kind.NOTIFICATIONS,
+                filterContextNotifications to FilterContext.NOTIFICATIONS,
-                filterContextPublic to Filter.Kind.PUBLIC,
+                filterContextPublic to FilterContext.PUBLIC,
-                filterContextThread to Filter.Kind.THREAD,
+                filterContextThread to FilterContext.THREAD,
-                filterContextAccount to Filter.Kind.ACCOUNT,
+                filterContextAccount to FilterContext.ACCOUNT,
             )
         }
 
@@ -90,9 +91,9 @@ class EditFilterActivity : BaseActivity() {
         }
         binding.filterDeleteButton.visible(originalFilter != null)
 
-        for (switch in contextSwitches.keys) {
+        for (switch in filterContextSwitches.keys) {
             switch.setOnCheckedChangeListener { _, isChecked ->
-                val context = contextSwitches[switch]!!
+                val context = filterContextSwitches[switch]!!
                 if (isChecked) {
                     viewModel.addContext(context)
                 } else {
@@ -156,7 +157,7 @@ class EditFilterActivity : BaseActivity() {
         }
         lifecycleScope.launch {
             viewModel.contexts.collect { contexts ->
-                for ((key, value) in contextSwitches) {
+                for ((key, value) in filterContextSwitches) {
                     key.isChecked = contexts.contains(value)
                 }
             }

app/src/main/java/app/pachli/components/filters/EditFilterViewModel.kt

@@ -6,6 +6,7 @@ import androidx.lifecycle.viewModelScope
 import app.pachli.appstore.EventHub
 import app.pachli.appstore.FilterChangedEvent
 import app.pachli.core.network.model.Filter
+import app.pachli.core.network.model.FilterContext
 import app.pachli.core.network.model.FilterKeyword
 import app.pachli.core.network.retrofit.MastodonApi
 import at.connyduck.calladapter.networkresult.fold
@@ -22,7 +23,7 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
     val keywords = MutableStateFlow(listOf<FilterKeyword>())
     val action = MutableStateFlow(Filter.Action.WARN)
     val duration = MutableStateFlow(0)
-    val contexts = MutableStateFlow(listOf<Filter.Kind>())
+    val contexts = MutableStateFlow(listOf<FilterContext>())
 
     fun load(filter: Filter) {
         originalFilter = filter
@@ -34,7 +35,7 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
         } else {
             -1
         }
-        contexts.value = filter.kinds
+        contexts.value = filter.contexts
     }
 
     fun addKeyword(keyword: FilterKeyword) {
@@ -66,14 +67,14 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
         this.action.value = action
     }
 
-    fun addContext(context: Filter.Kind) {
+    fun addContext(filterContext: FilterContext) {
-        if (!contexts.value.contains(context)) {
+        if (!contexts.value.contains(filterContext)) {
-            contexts.value += context
+            contexts.value += filterContext
         }
     }
 
-    fun removeContext(context: Filter.Kind) {
+    fun removeContext(filterContext: FilterContext) {
-        contexts.value = contexts.value.filter { it != context }
+        contexts.value = contexts.value.filter { it != filterContext }
     }
 
     fun validate(): Boolean {
@@ -83,7 +84,7 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
     }
 
     suspend fun saveChanges(context: Context): Boolean {
-        val contexts = contexts.value.map { it.kind }
+        val contexts = contexts.value
         val title = title.value
         val durationIndex = duration.value
         val action = action.value.action
@@ -97,9 +98,9 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
             // e.g., removing a filter from "home" still notifies anything showing
             // the home timeline, so the timeline can be refreshed.
             if (success) {
-                val originalKinds = originalFilter?.context?.map { Filter.Kind.from(it) } ?: emptyList()
+                val originalContexts = originalFilter?.contexts ?: emptyList()
-                val newKinds = contexts.map { Filter.Kind.from(it) }
+                val newFilterContexts = contexts
-                (originalKinds + newKinds).distinct().forEach {
+                (originalContexts + newFilterContexts).distinct().forEach {
                     eventHub.dispatch(FilterChangedEvent(it))
                 }
             }
@@ -107,7 +108,7 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
         }
     }
 
-    private suspend fun createFilter(title: String, contexts: List<String>, action: String, durationIndex: Int, context: Context): Boolean {
+    private suspend fun createFilter(title: String, contexts: List<FilterContext>, action: String, durationIndex: Int, context: Context): Boolean {
         val expiresInSeconds = EditFilterActivity.getSecondsForDurationIndex(durationIndex, context)
         api.createFilter(
             title = title,
@@ -131,7 +132,7 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
         )
     }
 
-    private suspend fun updateFilter(originalFilter: Filter, title: String, contexts: List<String>, action: String, durationIndex: Int, context: Context): Boolean {
+    private suspend fun updateFilter(originalFilter: Filter, title: String, contexts: List<FilterContext>, action: String, durationIndex: Int, context: Context): Boolean {
         val expiresInSeconds = EditFilterActivity.getSecondsForDurationIndex(durationIndex, context)
         api.updateFilter(
             id = originalFilter.id,
@@ -167,18 +168,18 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
         )
     }
 
-    private suspend fun createFilterV1(context: List<String>, expiresInSeconds: Int?): Boolean {
+    private suspend fun createFilterV1(contexts: List<FilterContext>, expiresInSeconds: Int?): Boolean {
         return keywords.value.map { keyword ->
-            api.createFilterV1(keyword.keyword, context, false, keyword.wholeWord, expiresInSeconds)
+            api.createFilterV1(keyword.keyword, contexts, false, keyword.wholeWord, expiresInSeconds)
         }.none { it.isFailure }
     }
 
-    private suspend fun updateFilterV1(context: List<String>, expiresInSeconds: Int?): Boolean {
+    private suspend fun updateFilterV1(contexts: List<FilterContext>, expiresInSeconds: Int?): Boolean {
         val results = keywords.value.map { keyword ->
             if (originalFilter == null) {
                 api.createFilterV1(
                     phrase = keyword.keyword,
-                    context = context,
+                    context = contexts,
                     irreversible = false,
                     wholeWord = keyword.wholeWord,
                     expiresInSeconds = expiresInSeconds,
@@ -187,7 +188,7 @@ class EditFilterViewModel @Inject constructor(val api: MastodonApi, val eventHub
                 api.updateFilterV1(
                     id = originalFilter!!.id,
                     phrase = keyword.keyword,
-                    context = context,
+                    context = contexts,
                     irreversible = false,
                     wholeWord = keyword.wholeWord,
                     expiresInSeconds = expiresInSeconds,

app/src/main/java/app/pachli/components/filters/FiltersAdapter.kt

@@ -22,7 +22,7 @@ class FiltersAdapter(val listener: FiltersListener, val filters: List<Filter>) :
         val binding = holder.binding
         val resources = binding.root.resources
         val actions = resources.getStringArray(R.array.filter_actions)
-        val contexts = resources.getStringArray(R.array.filter_contexts)
+        val filterContextNames = resources.getStringArray(R.array.filter_contexts)
 
         val filter = filters[position]
         val context = binding.root.context
@@ -37,7 +37,7 @@ class FiltersAdapter(val listener: FiltersListener, val filters: List<Filter>) :
         binding.textSecondary.text = context.getString(
             R.string.filter_description_format,
             actions.getOrNull(filter.action.ordinal - 1),
-            filter.context.map { contexts.getOrNull(Filter.Kind.from(it).ordinal) }.joinToString("/"),
+            filter.contexts.map { filterContextNames.getOrNull(it.ordinal) }.joinToString("/"),
         )
 
         binding.delete.setOnClickListener {

app/src/main/java/app/pachli/components/filters/FiltersViewModel.kt

@@ -70,8 +70,8 @@ class FiltersViewModel @Inject constructor(
             api.deleteFilter(filter.id).fold(
                 {
                     this@FiltersViewModel._state.value = State(this@FiltersViewModel._state.value.filters.filter { it.id != filter.id }, LoadingState.LOADED)
-                    for (context in filter.context) {
+                    for (context in filter.contexts) {
-                        eventHub.dispatch(FilterChangedEvent(Filter.Kind.from(context)))
+                        eventHub.dispatch(FilterChangedEvent(context))
                     }
                 },
                 { throwable ->
@@ -79,8 +79,8 @@ class FiltersViewModel @Inject constructor(
                         api.deleteFilterV1(filter.id).fold(
                             {
                                 this@FiltersViewModel._state.value = State(this@FiltersViewModel._state.value.filters.filter { it.id != filter.id }, LoadingState.LOADED)
-                                filter.context.forEach {
+                                filter.contexts.forEach {
-                                    eventHub.dispatch(FilterChangedEvent(Filter.Kind.from(it)))
+                                    eventHub.dispatch(FilterChangedEvent(it))
                                 }
                             },
                             {

app/src/main/java/app/pachli/components/notifications/NotificationsViewModel.kt

@@ -35,6 +35,7 @@ import app.pachli.components.timeline.FiltersRepository
 import app.pachli.components.timeline.util.ifExpected
 import app.pachli.core.accounts.AccountManager
 import app.pachli.core.network.model.Filter
+import app.pachli.core.network.model.FilterContext
 import app.pachli.core.network.model.Notification
 import app.pachli.core.network.model.Poll
 import app.pachli.core.preferences.PrefKeys
@@ -472,7 +473,7 @@ class NotificationsViewModel @Inject constructor(
         viewModelScope.launch {
             eventHub.events
                 .filterIsInstance<FilterChangedEvent>()
-                .filter { it.filterKind == Filter.Kind.NOTIFICATIONS }
+                .filter { it.filterContext == FilterContext.NOTIFICATIONS }
                 .map {
                     getFilters()
                     repository.invalidate()
@@ -538,8 +539,8 @@ class NotificationsViewModel @Inject constructor(
     private fun getFilters() = viewModelScope.launch {
         try {
             filterModel = when (val filters = filtersRepository.getFilters()) {
-                is FilterKind.V1 -> FilterModel(Filter.Kind.NOTIFICATIONS, filters.filters)
+                is FilterKind.V1 -> FilterModel(FilterContext.NOTIFICATIONS, filters.filters)
-                is FilterKind.V2 -> FilterModel(Filter.Kind.NOTIFICATIONS)
+                is FilterKind.V2 -> FilterModel(FilterContext.NOTIFICATIONS)
             }
         } catch (throwable: Throwable) {
             _uiErrorChannel.send(UiError.GetFilters(throwable))

app/src/main/java/app/pachli/components/timeline/viewmodel/TimelineViewModel.kt

@@ -46,6 +46,7 @@ import app.pachli.components.timeline.FiltersRepository
 import app.pachli.components.timeline.util.ifExpected
 import app.pachli.core.accounts.AccountManager
 import app.pachli.core.network.model.Filter
+import app.pachli.core.network.model.FilterContext
 import app.pachli.core.network.model.Poll
 import app.pachli.core.network.model.Status
 import app.pachli.core.network.model.TimelineKind
@@ -521,7 +522,7 @@ abstract class TimelineViewModel(
     /** Updates the current set of filters if filter-related preferences change */
     private fun updateFiltersFromPreferences() = eventHub.events
         .filterIsInstance<FilterChangedEvent>()
-        .filter { filterContextMatchesKind(timelineKind, listOf(it.filterKind)) }
+        .filter { filterContextMatchesKind(timelineKind, listOf(it.filterContext)) }
         .map {
             getFilters()
             Timber.d("Reload because FilterChangedEvent")
@@ -534,10 +535,10 @@ abstract class TimelineViewModel(
         viewModelScope.launch {
             Timber.d("getFilters()")
             try {
-                val filterKind = Filter.Kind.from(timelineKind)
+                val filterContext = FilterContext.from(timelineKind)
                 filterModel = when (val filters = filtersRepository.getFilters()) {
-                    is FilterKind.V1 -> FilterModel(filterKind, filters.filters)
+                    is FilterKind.V1 -> FilterModel(filterContext, filters.filters)
-                    is FilterKind.V2 -> FilterModel(filterKind)
+                    is FilterKind.V2 -> FilterModel(filterContext)
                 }
             } catch (throwable: Throwable) {
                 Timber.d(throwable, "updateFilter(): Error fetching filters")
@@ -635,9 +636,9 @@ abstract class TimelineViewModel(
 
         fun filterContextMatchesKind(
             timelineKind: TimelineKind,
-            filterContext: List<Filter.Kind>,
+            filterContext: List<FilterContext>,
         ): Boolean {
-            return filterContext.contains(Filter.Kind.from(timelineKind))
+            return filterContext.contains(FilterContext.from(timelineKind))
         }
     }
 }

app/src/main/java/app/pachli/components/trending/viewmodel/TrendingTagsViewModel.kt

@@ -20,7 +20,7 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import app.pachli.appstore.EventHub
 import app.pachli.appstore.FilterChangedEvent
-import app.pachli.core.network.model.Filter
+import app.pachli.core.network.model.FilterContext
 import app.pachli.core.network.model.TrendingTag
 import app.pachli.core.network.model.end
 import app.pachli.core.network.model.start
@@ -96,7 +96,7 @@ class TrendingTagsViewModel @Inject constructor(
                     TrendingTagsUiState(emptyList(), LoadingState.LOADED)
                 } else {
                     val homeFilters = deferredFilters.await().getOrNull()?.filter { filter ->
-                        filter.context.contains(Filter.Kind.HOME.kind)
+                        filter.contexts.contains(FilterContext.HOME)
                     }
                     val tags = tagResponse
                         .filter { tag ->

app/src/main/java/app/pachli/components/viewthread/ViewThreadViewModel.kt

@@ -38,6 +38,7 @@ import app.pachli.core.database.model.AccountEntity
 import app.pachli.core.database.model.TranslatedStatusEntity
 import app.pachli.core.database.model.TranslationState
 import app.pachli.core.network.model.Filter
+import app.pachli.core.network.model.FilterContext
 import app.pachli.core.network.model.Poll
 import app.pachli.core.network.model.Status
 import app.pachli.core.network.retrofit.MastodonApi
@@ -112,7 +113,7 @@ class ViewThreadViewModel @Inject constructor(
                         is StatusDeletedEvent -> handleStatusDeletedEvent(event)
                         is StatusEditedEvent -> handleStatusEditedEvent(event)
                         is FilterChangedEvent -> {
-                            if (event.filterKind == Filter.Kind.THREAD) {
+                            if (event.filterContext == FilterContext.THREAD) {
                                 loadFilters()
                             }
                         }
@@ -527,8 +528,8 @@ class ViewThreadViewModel @Inject constructor(
         viewModelScope.launch {
             try {
                 filterModel = when (val filters = filtersRepository.getFilters()) {
-                    is FilterKind.V1 -> FilterModel(Filter.Kind.THREAD, filters.filters)
+                    is FilterKind.V1 -> FilterModel(FilterContext.THREAD, filters.filters)
-                    is FilterKind.V2 -> FilterModel(Filter.Kind.THREAD)
+                    is FilterKind.V2 -> FilterModel(FilterContext.THREAD)
                 }
                 updateStatuses()
             } catch (_: Exception) {

app/src/main/java/app/pachli/network/FilterModel.kt

@@ -1,6 +1,7 @@
 package app.pachli.network
 
 import app.pachli.core.network.model.Filter
+import app.pachli.core.network.model.FilterContext
 import app.pachli.core.network.model.FilterV1
 import app.pachli.core.network.model.Status
 import app.pachli.core.network.parseAsMastodonHtml
@@ -10,16 +11,16 @@ import java.util.regex.Pattern
 /**
  * Filter statuses using V1 or V2 filters.
  *
- * Construct with [filterKind] that corresponds to the kind of timeline, and optionally the set
+ * Construct with [filterContext] that corresponds to the kind of timeline, and optionally the set
  * of v1 filters that should be applied.
  */
-class FilterModel constructor(private val filterKind: Filter.Kind, v1filters: List<FilterV1>? = null) {
+class FilterModel(private val filterContext: FilterContext, v1filters: List<FilterV1>? = null) {
     /** Pattern to use when matching v1 filters against a status. Null if these are v2 filters */
     private var pattern: Pattern? = null
 
     init {
         pattern = v1filters?.let { list ->
-            makeFilter(list.filter { it.context.contains(filterKind.kind) })
+            makeFilter(list.filter { it.contexts.contains(filterContext) })
         }
     }
 
@@ -48,7 +49,7 @@ class FilterModel constructor(private val filterKind: Filter.Kind, v1filters: Li
         }
 
         val matchingKind = status.filtered?.filter { result ->
-            result.filter.kinds.contains(filterKind)
+            result.filter.contexts.contains(filterContext)
         }
 
         return if (matchingKind.isNullOrEmpty()) {

app/src/test/java/app/pachli/FilterV1Test.kt

@@ -21,6 +21,7 @@ import androidx.test.ext.junit.runners.AndroidJUnit4
 import app.pachli.components.filters.EditFilterActivity
 import app.pachli.core.network.model.Attachment
 import app.pachli.core.network.model.Filter
+import app.pachli.core.network.model.FilterContext
 import app.pachli.core.network.model.FilterV1
 import app.pachli.core.network.model.Poll
 import app.pachli.core.network.model.PollOption
@@ -45,7 +46,7 @@ class FilterV1Test {
             FilterV1(
                 id = "123",
                 phrase = "badWord",
-                context = listOf(FilterV1.HOME),
+                contexts = listOf(FilterContext.HOME),
                 expiresAt = null,
                 irreversible = false,
                 wholeWord = false,
@@ -53,7 +54,7 @@ class FilterV1Test {
             FilterV1(
                 id = "123",
                 phrase = "badWholeWord",
-                context = listOf(FilterV1.HOME, FilterV1.PUBLIC),
+                contexts = listOf(FilterContext.HOME, FilterContext.PUBLIC),
                 expiresAt = null,
                 irreversible = false,
                 wholeWord = true,
@@ -61,7 +62,7 @@ class FilterV1Test {
             FilterV1(
                 id = "123",
                 phrase = "@twitter.com",
-                context = listOf(FilterV1.HOME),
+                contexts = listOf(FilterContext.HOME),
                 expiresAt = null,
                 irreversible = false,
                 wholeWord = true,
@@ -69,7 +70,7 @@ class FilterV1Test {
             FilterV1(
                 id = "123",
                 phrase = "#hashtag",
-                context = listOf(FilterV1.HOME),
+                contexts = listOf(FilterContext.HOME),
                 expiresAt = null,
                 irreversible = false,
                 wholeWord = true,
@@ -77,7 +78,7 @@ class FilterV1Test {
             FilterV1(
                 id = "123",
                 phrase = "expired",
-                context = listOf(FilterV1.HOME),
+                contexts = listOf(FilterContext.HOME),
                 expiresAt = Date.from(Instant.now().minusSeconds(10)),
                 irreversible = false,
                 wholeWord = true,
@@ -85,7 +86,7 @@ class FilterV1Test {
             FilterV1(
                 id = "123",
                 phrase = "unexpired",
-                context = listOf(FilterV1.HOME),
+                contexts = listOf(FilterContext.HOME),
                 expiresAt = Date.from(Instant.now().plusSeconds(3600)),
                 irreversible = false,
                 wholeWord = true,
@@ -93,14 +94,14 @@ class FilterV1Test {
             FilterV1(
                 id = "123",
                 phrase = "href",
-                context = listOf(FilterV1.HOME),
+                contexts = listOf(FilterContext.HOME),
                 expiresAt = null,
                 irreversible = false,
                 wholeWord = false,
             ),
         )
 
-        filterModel = FilterModel(Filter.Kind.HOME, filters)
+        filterModel = FilterModel(FilterContext.HOME, filters)
     }
 
     @Test

core/network/src/main/kotlin/app/pachli/core/network/di/NetworkModule.kt

@@ -24,6 +24,7 @@ import app.pachli.core.mastodon.model.MediaUploadApi
 import app.pachli.core.network.BuildConfig
 import app.pachli.core.network.json.BooleanIfNull
 import app.pachli.core.network.json.DefaultIfNull
+import app.pachli.core.network.json.EnumConstantConverterFactory
 import app.pachli.core.network.json.Guarded
 import app.pachli.core.network.json.HasDefault
 import app.pachli.core.network.retrofit.InstanceSwitchAuthInterceptor
@@ -127,6 +128,7 @@ object NetworkModule {
     ): Retrofit {
         return Retrofit.Builder().baseUrl("https://" + MastodonApi.PLACEHOLDER_DOMAIN)
             .client(httpClient)
+            .addConverterFactory(EnumConstantConverterFactory)
             .addConverterFactory(MoshiConverterFactory.create(moshi))
             .addCallAdapterFactory(NetworkResultCallAdapterFactory.create())
             .build()

core/network/src/main/kotlin/app/pachli/core/network/json/EnumConstantConverterFactory.kt

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2024 Pachli Association
+ *
+ * This file is a part of Pachli.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Pachli is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Pachli; if not,
+ * see <http://www.gnu.org/licenses>.
+ */
+
+package app.pachli.core.network.json
+
+import com.squareup.moshi.Json
+import java.lang.reflect.Type
+import retrofit2.Converter
+import retrofit2.Retrofit
+
+/**
+ * Retrofit [Converter.Factory] that converts enum constants to strings using the
+ * value of any `@Json(name = ...)` annotation on the constant, falling back to
+ * the enum's name if the annotation is not present.
+ *
+ * This ensures that the same string is used for an enum constant's value whether
+ * it is sent/received as JSON or sent as a [retrofit2.http.FormUrlEncoded] value.
+ *
+ * To install in Retrofit call `.addConverterFactory(EnumConstantConverterFactory)`
+ * on the Retrofit builder.
+ */
+object EnumConstantConverterFactory : Converter.Factory() {
+    object EnumConstantConverter : Converter<Enum<*>, String> {
+        override fun convert(enum: Enum<*>): String {
+            return try {
+                enum.javaClass.getField(enum.name).getAnnotation(Json::class.java)?.name
+            } catch (_: Exception) {
+                null
+            } ?: enum.toString()
+        }
+    }
+
+    override fun stringConverter(
+        type: Type,
+        annotations: Array<out Annotation>,
+        retrofit: Retrofit,
+    ): Converter<Enum<*>, String>? {
+        return if (type is Class<*> && type.isEnum) EnumConstantConverter else null
+    }
+}

core/network/src/main/kotlin/app/pachli/core/network/model/Filter.kt

@@ -13,9 +13,9 @@ import kotlinx.parcelize.Parcelize
 data class Filter(
     val id: String,
     val title: String,
-    val context: List<String>,
+    @Json(name = "context") val contexts: List<FilterContext>,
     @Json(name = "expires_at") val expiresAt: Date?,
-    @Json(name = "filter_action") val filterAction: String,
+    @Json(name = "filter_action") val action: Action,
     // This should not normally be empty. However, Mastodon does not include
     // this in a status' `filtered.filter` property (it's not null or empty,
     // it's missing) which breaks deserialisation. Patch this by ensuring it's
@@ -26,48 +26,14 @@ data class Filter(
 ) : Parcelable {
     @HasDefault
     enum class Action(val action: String) {
+        @Json(name = "none")
         NONE("none"),
 
+        @Json(name = "warn")
         @Default
         WARN("warn"),
+
+        @Json(name = "hide")
         HIDE("hide"),
-        ;
-
-        companion object {
-            fun from(action: String): Action = entries.firstOrNull { it.action == action } ?: WARN
-        }
     }
-
-    @HasDefault
-    enum class Kind(val kind: String) {
-        HOME("home"),
-        NOTIFICATIONS("notifications"),
-
-        @Default
-        PUBLIC("public"),
-        THREAD("thread"),
-        ACCOUNT("account"),
-        ;
-
-        companion object {
-            fun from(kind: String): Kind = entries.firstOrNull { it.kind == kind } ?: PUBLIC
-
-            fun from(kind: TimelineKind): Kind = when (kind) {
-                is TimelineKind.Home, is TimelineKind.UserList -> HOME
-                is TimelineKind.PublicFederated,
-                is TimelineKind.PublicLocal,
-                is TimelineKind.Tag,
-                is TimelineKind.Favourites,
-                -> PUBLIC
-                is TimelineKind.User -> ACCOUNT
-                else -> PUBLIC
-            }
-        }
-    }
-
-    val action: Action
-        get() = Action.from(filterAction)
-
-    val kinds: List<Kind>
-        get() = context.map { Kind.from(it) }
 }

core/network/src/main/kotlin/app/pachli/core/network/model/FilterContext.kt

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2024 Pachli Association
+ *
+ * This file is a part of Pachli.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Pachli is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Pachli; if not,
+ * see <http://www.gnu.org/licenses>.
+ */
+
+package app.pachli.core.network.model
+
+import app.pachli.core.network.json.Default
+import app.pachli.core.network.json.HasDefault
+import com.squareup.moshi.Json
+import com.squareup.moshi.JsonClass
+
+/**
+ * The contexts in which a filter should be applied, for both a
+ * [v2](https://docs.joinmastodon.org/entities/Filter/#context) and
+ * [v1](https://docs.joinmastodon.org/entities/V1_Filter/#context) Mastodon
+ * filter. The API versions have identical contexts.
+ */
+@JsonClass(generateAdapter = false)
+@HasDefault
+enum class FilterContext {
+    /** Filter applies to home timeline and lists */
+    @Json(name = "home")
+    HOME,
+
+    /** Filter applies to notifications */
+    @Json(name = "notifications")
+    NOTIFICATIONS,
+
+    /** Filter applies to public timelines */
+    @Default
+    @Json(name = "public")
+    PUBLIC,
+
+    /** Filter applies to expanded thread */
+    @Json(name = "thread")
+    THREAD,
+
+    /** Filter applies when viewing a profile */
+    @Json(name = "account")
+    ACCOUNT,
+    ;
+
+    companion object {
+        fun from(kind: TimelineKind): FilterContext = when (kind) {
+            is TimelineKind.Home, is TimelineKind.UserList -> HOME
+            is TimelineKind.PublicFederated,
+            is TimelineKind.PublicLocal,
+            is TimelineKind.Tag,
+            is TimelineKind.Favourites,
+            -> PUBLIC
+            is TimelineKind.User -> ACCOUNT
+            else -> PUBLIC
+        }
+    }
+}

core/network/src/main/kotlin/app/pachli/core/network/model/FilterV1.kt

@@ -24,19 +24,11 @@ import java.util.Date
 data class FilterV1(
     val id: String,
     val phrase: String,
-    val context: List<String>,
+    @Json(name = "context") val contexts: List<FilterContext>,
     @Json(name = "expires_at") val expiresAt: Date?,
     val irreversible: Boolean,
     @Json(name = "whole_word") val wholeWord: Boolean,
 ) {
-    companion object {
-        const val HOME = "home"
-        const val NOTIFICATIONS = "notifications"
-        const val PUBLIC = "public"
-        const val THREAD = "thread"
-        const val ACCOUNT = "account"
-    }
-
     override fun hashCode(): Int {
         return id.hashCode()
     }
@@ -53,9 +45,9 @@ data class FilterV1(
         return Filter(
             id = id,
             title = phrase,
-            context = context,
+            contexts = contexts,
             expiresAt = expiresAt,
-            filterAction = Filter.Action.WARN.action,
+            action = Filter.Action.WARN,
             keywords = listOf(
                 FilterKeyword(
                     id = id,

core/network/src/main/kotlin/app/pachli/core/network/retrofit/MastodonApi.kt

@@ -25,6 +25,7 @@ import app.pachli.core.network.model.Conversation
 import app.pachli.core.network.model.DeletedStatus
 import app.pachli.core.network.model.Emoji
 import app.pachli.core.network.model.Filter
+import app.pachli.core.network.model.FilterContext
 import app.pachli.core.network.model.FilterKeyword
 import app.pachli.core.network.model.FilterV1
 import app.pachli.core.network.model.HashTag
@@ -614,7 +615,7 @@ interface MastodonApi {
     @POST("api/v1/filters")
     suspend fun createFilterV1(
         @Field("phrase") phrase: String,
-        @Field("context[]") context: List<String>,
+        @Field("context[]") context: List<FilterContext>,
         @Field("irreversible") irreversible: Boolean?,
         @Field("whole_word") wholeWord: Boolean?,
         @Field("expires_in") expiresInSeconds: Int?,
@@ -625,7 +626,7 @@ interface MastodonApi {
     suspend fun updateFilterV1(
         @Path("id") id: String,
         @Field("phrase") phrase: String,
-        @Field("context[]") context: List<String>,
+        @Field("context[]") context: List<FilterContext>,
         @Field("irreversible") irreversible: Boolean?,
         @Field("whole_word") wholeWord: Boolean?,
         @Field("expires_in") expiresInSeconds: Int?,
@@ -640,7 +641,7 @@ interface MastodonApi {
     @POST("api/v2/filters")
     suspend fun createFilter(
         @Field("title") title: String,
-        @Field("context[]") context: List<String>,
+        @Field("context[]") context: List<FilterContext>,
         @Field("filter_action") filterAction: String,
         @Field("expires_in") expiresInSeconds: Int?,
     ): NetworkResult<Filter>
@@ -650,7 +651,7 @@ interface MastodonApi {
     suspend fun updateFilter(
         @Path("id") id: String,
         @Field("title") title: String? = null,
-        @Field("context[]") context: List<String>? = null,
+        @Field("context[]") context: List<FilterContext>? = null,
         @Field("filter_action") filterAction: String? = null,
         @Field("expires_in") expiresInSeconds: Int? = null,
     ): NetworkResult<Filter>

core/network/src/test/kotlin/app/pachli/core/network/json/EnumConstantConverterFactoryTest.kt

@@ -0,0 +1,26 @@
+package app.pachli.core.network.json
+
+import com.google.common.truth.Truth.assertThat
+import com.squareup.moshi.Json
+import org.junit.Test
+
+class EnumConstantConverterFactoryTest {
+    enum class Enum {
+        @Json(name = "one")
+        ONE,
+
+        TWO,
+    }
+
+    private val converter = EnumConstantConverterFactory.EnumConstantConverter
+
+    @Test
+    fun `Annotated enum constant uses annotation`() {
+        assertThat(converter.convert(Enum.ONE)).isEqualTo("one")
+    }
+
+    @Test
+    fun `Unannotated enum constant uses constant name`() {
+        assertThat(converter.convert(Enum.TWO)).isEqualTo("TWO")
+    }
+}