Filtering

Databases/ContentDatabase.swift

@@ -143,10 +143,15 @@ extension ContentDatabase {
             .eraseToAnyPublisher()
     }
 
-    func activeFiltersObservation(date: Date) -> AnyPublisher<[Filter], Error> {
+    func activeFiltersObservation(date: Date, context: Filter.Context? = nil) -> AnyPublisher<[Filter], Error> {
         ValueObservation.tracking(Filter.filter(Column("expiresAt") == nil || Column("expiresAt") > date).fetchAll)
             .removeDuplicates()
             .publisher(in: databaseQueue)
+            .map {
+                guard let context = context else { return $0 }
+
+                return $0.filter { $0.context.contains(context) }
+            }
             .eraseToAnyPublisher()
     }
 

Model/Filter.swift

@@ -32,6 +32,30 @@ extension Filter {
                           wholeWord: true)
 }
 
+extension Array where Element == Filter {
+    // Adapted from https://github.com/tootsuite/mastodon/blob/bf477cee9f31036ebf3d164ddec1cebef5375513/app/javascript/mastodon/selectors/index.js#L43
+    func regularExpression() -> String? {
+        guard !isEmpty else { return nil }
+
+        return map {
+            var expression = NSRegularExpression.escapedPattern(for: $0.phrase)
+
+            if $0.wholeWord {
+                if expression.range(of: #"^[\w]"#, options: .regularExpression) != nil {
+                    expression = #"\b"# + expression
+                }
+
+                if expression.range(of: #"[\w]$"#, options: .regularExpression) != nil {
+                    expression += #"\b"#
+                }
+            }
+
+            return expression
+        }
+        .joined(separator: "|")
+    }
+}
+
 extension Filter.Context: Identifiable {
     var id: Self { self }
 }

Model/Status.swift

@@ -110,6 +110,14 @@ extension Status {
     var displayStatus: Status {
         reblog ?? self
     }
+
+    var filterableContent: String {
+        [content.attributed.string,
+         spoilerText,
+         (poll?.options.map(\.title) ?? []).joined(separator: " "),
+         reblog?.filterableContent ?? ""]
+            .joined(separator: " ")
+    }
 }
 
 extension Status: Hashable {

Services/Status List Services/ContextService.swift

@@ -33,6 +33,10 @@ struct ContextService {
 }
 
 extension ContextService: StatusListService {
+    var filters: AnyPublisher<[Filter], Error> {
+        contentDatabase.activeFiltersObservation(date: Date(), context: .thread)
+    }
+
     var contextParentID: String? { status.id }
 
     func isReplyInContext(status: Status) -> Bool {

Services/Status List Services/StatusListService.swift

@@ -5,6 +5,7 @@ import Combine
 
 protocol StatusListService {
     var statusSections: AnyPublisher<[[Status]], Error> { get }
+    var filters: AnyPublisher<[Filter], Error> { get }
     var paginates: Bool { get }
     var contextParentID: String? { get }
     func isPinned(status: Status) -> Bool

Services/Status List Services/TimelineService.swift

@@ -21,6 +21,10 @@ struct TimelineService {
 }
 
 extension TimelineService: StatusListService {
+    var filters: AnyPublisher<[Filter], Error> {
+        contentDatabase.activeFiltersObservation(date: Date(), context: filterContext)
+    }
+
     func request(maxID: String?, minID: String?) -> AnyPublisher<Never, Error> {
         networkClient.request(Paged(timeline.endpoint, maxID: maxID, minID: minID))
             .map { ($0, timeline) }
@@ -36,3 +40,14 @@ extension TimelineService: StatusListService {
         ContextService(status: status.displayStatus, networkClient: networkClient, contentDatabase: contentDatabase)
     }
 }
+
+private extension TimelineService {
+    var filterContext: Filter.Context {
+        switch timeline {
+        case .home, .list:
+            return .home
+        case .local, .federated:
+            return .public
+        }
+    }
+}

View Models/StatusListViewModel.swift

@@ -8,6 +8,8 @@ class StatusListViewModel: ObservableObject {
     @Published var alertItem: AlertItem?
     @Published private(set) var loading = false
     private(set) var maintainScrollPositionOfStatusID: String?
+
+    @Published private var filterRegularExpression: String?
     private var statuses = [String: Status]()
     private let statusListService: StatusListService
     private var statusViewModelCache = [Status: (StatusViewModel, AnyCancellable)]()
@@ -16,7 +18,22 @@ class StatusListViewModel: ObservableObject {
     init(statusListService: StatusListService) {
         self.statusListService = statusListService
 
+        statusListService.filters
+            .assignErrorsToAlertItem(to: \.alertItem, on: self)
+            .map { $0.regularExpression() }
+            .assign(to: &$filterRegularExpression)
+
         statusListService.statusSections
+            .map {
+                $0.map {
+                    $0.filter { [weak self] in
+                        guard let filterRegularExpression = self?.filterRegularExpression else { return true }
+
+                        return $0.filterableContent.range(of: filterRegularExpression,
+                                                          options: [.regularExpression, .caseInsensitive]) == nil
+                    }
+                }
+            }
             .handleEvents(receiveOutput: { [weak self] in
                 self?.determineIfScrollPositionShouldBeMaintained(newStatusSections: $0)
                 self?.cleanViewModelCache(newStatusSections: $0)