From d84ca7bc75309d0c8ea26c8ec7a605bb06443726 Mon Sep 17 00:00:00 2001
From: Marcus Kida <marcus.kida@bearologics.com>
Date: Wed, 31 Jul 2024 11:29:47 +0200
Subject: [PATCH] Fix link char count (IOS-285)

---
 .../MastodonCore/MastodonAuthentication.swift | 11 +++++++++++
 .../ComposeContentViewModel.swift             | 19 ++++++++++++++++++-
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/MastodonSDK/Sources/MastodonCore/MastodonAuthentication.swift b/MastodonSDK/Sources/MastodonCore/MastodonAuthentication.swift
index 6e304d5800..d29995f540 100644
--- 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
index aec028a391..0d27d844a5 100644
--- a/MastodonSDK/Sources/MastodonUI/Scene/ComposeContent/ComposeContentViewModel.swift
+++ b/MastodonSDK/Sources/MastodonUI/Scene/ComposeContent/ComposeContentViewModel.swift
@@ -324,7 +324,24 @@ extension ComposeContentViewModel {
         
         // bind text
         $content
-            .map { $0.count }
+            .map { [weak self] input in
+                guard let self, let detector = try? NSDataDetector(types: NSTextCheckingResult.CheckingType.link.rawValue) else {
+                    return input.count
+                }
+                let matches = detector.matches(in: input, options: [], range: NSRange(location: 0, length: input.count))
+                let lengthWithoutLinks = input.count - matches.map({ match in
+                    guard let range = Range(match.range, in: input) else {
+                        return 0
+                    }
+                    let url = input[range]
+                    return url.count
+                }).reduce(0, +)
+                let charactersReservedPerURL = authContext.mastodonAuthenticationBox
+                    .authentication
+                    .instanceConfiguration?
+                    .charactersReservedPerURL ?? MastodonAuthentication.fallbackCharactersReservedPerURL
+                return lengthWithoutLinks + (matches.count * charactersReservedPerURL)
+            }
             .assign(to: &$contentWeightedLength)
         
         Publishers.CombineLatest(