Fix link char count (IOS-285) (#1336)

This PR fixes the link char count which should be static (by default 23 chars per link) rather than the length of the link itself.
mastodon · Jul 31, 2024 · 8543142 · 8543142
2 parents 42b47af + f15311f
commit 8543142
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Showing 2 changed files with 31 additions and 1 deletion.
diff --git a/MastodonSDK/Sources/MastodonCore/MastodonAuthentication.swift b/MastodonSDK/Sources/MastodonCore/MastodonAuthentication.swift
@@ -5,6 +5,8 @@ import CoreDataStack
 import MastodonSDK
 
 public struct MastodonAuthentication: Codable, Hashable, UserIdentifier {
+    public static let fallbackCharactersReservedPerURL = 23
+
     public enum InstanceConfiguration: Codable, Hashable {
         case v1(Mastodon.Entity.Instance)
         case v2(Mastodon.Entity.V2.Instance, TranslationLanguages)
@@ -38,6 +40,15 @@ public struct MastodonAuthentication: Codable, Hashable, UserIdentifier {
             }
             return version?.majorServerVersion(greaterThanOrEquals: 4) ?? false // following Tags is support beginning with Mastodon v4.0.0
         }
+
+        public var charactersReservedPerURL: Int {
+            switch self {
+            case let .v1(instance):
+                return instance.configuration?.statuses?.charactersReservedPerURL ?? fallbackCharactersReservedPerURL
+            case let .v2(instance, _):
+                return instance.configuration?.statuses?.charactersReservedPerURL ?? fallbackCharactersReservedPerURL
+            }
+        }
     }
 
     public typealias ID = UUID

diff --git a/MastodonSDK/Sources/MastodonUI/Scene/ComposeContent/ComposeContentViewModel.swift b/MastodonSDK/Sources/MastodonUI/Scene/ComposeContent/ComposeContentViewModel.swift
@@ -324,7 +324,26 @@ extension ComposeContentViewModel {
 
         // bind text
         $content
-            .map { $0.count }
+            .receive(on: DispatchQueue.global(qos: .background))
+            .map { [weak self] input in
+                guard let self, let detector = try? NSDataDetector(types: NSTextCheckingResult.CheckingType.link.rawValue) else {
+                    return input.count
+                }
+                let matches = detector.matches(in: input, options: [], range: NSRange(location: 0, length: input.count))
+                let lengthWithoutLinks = input.count - matches.map({ match in
+                    guard let range = Range(match.range, in: input) else {
+                        return 0
+                    }
+                    let url = input[range]
+                    return url.count
+                }).reduce(0, +)
+                let charactersReservedPerURL = authContext.mastodonAuthenticationBox
+                    .authentication
+                    .instanceConfiguration?
+                    .charactersReservedPerURL ?? MastodonAuthentication.fallbackCharactersReservedPerURL
+                return lengthWithoutLinks + (matches.count * charactersReservedPerURL)
+            }
+            .receive(on: DispatchQueue.main)
             .assign(to: &$contentWeightedLength)
 
         Publishers.CombineLatest(