Try to compress videos to fit within instance limits

Closes #425

Packages/ComposeUI/Sources/ComposeUI/CoreData/DraftAttachment.swift

@@ -216,7 +216,7 @@ extension DraftAttachment {
                 options.isNetworkAccessAllowed = true
                 PHImageManager.default().requestExportSession(forVideo: asset, options: options, exportPreset: AVAssetExportPresetHighestQuality) { exportSession, info in
                     if let exportSession {
-                        Self.exportVideoData(session: exportSession, completion: completion)
+                        Self.exportVideoData(session: exportSession, features: features, completion: completion)
                     } else if let error = info?[PHImageErrorKey] as? Error {
                         completion(.failure(.videoExport(error)))
                     } else {
@@ -242,7 +242,7 @@ extension DraftAttachment {
                     completion(.failure(.noVideoExportSession))
                     return
                 }
-                Self.exportVideoData(session: session, completion: completion)
+                Self.exportVideoData(session: session, features: features, completion: completion)
             } else {
                 let fileData: Data
                 do {
@@ -300,9 +300,12 @@ extension DraftAttachment {
         return (data, type)
     }
     
-    private static func exportVideoData(session: AVAssetExportSession, completion: @escaping (Result<(Data, UTType), ExportError>) -> Void) {
+    private static func exportVideoData(session: AVAssetExportSession, features: InstanceFeatures, completion: @escaping (Result<(Data, UTType), ExportError>) -> Void) {
         session.outputFileType = .mp4
         session.outputURL = FileManager.default.temporaryDirectory.appendingPathComponent("exported_video_\(UUID())").appendingPathExtension("mp4")
+        if let configuration = features.mediaAttachmentsConfiguration {
+            session.fileLengthLimit = Int64(configuration.videoSizeLimit)
+        }
         session.exportAsynchronously {
             guard session.status == .completed else {
                 completion(.failure(.videoExport(session.error!)))

Packages/InstanceFeatures/Sources/InstanceFeatures/InstanceFeatures.swift

@@ -21,6 +21,7 @@ public class InstanceFeatures: ObservableObject {
     @Published public private(set) var charsReservedPerURL = 23
     @Published public private(set) var maxPollOptionChars: Int?
     @Published public private(set) var maxPollOptionsCount: Int?
+    @Published public private(set) var mediaAttachmentsConfiguration: Instance.MediaAttachmentsConfiguration?
     
     public var localOnlyPosts: Bool {
         switch instanceType {
@@ -211,6 +212,7 @@ public class InstanceFeatures: ObservableObject {
             maxPollOptionChars = pollsConfig.maxCharactersPerOption
             maxPollOptionsCount = pollsConfig.maxOptions
         }
+        mediaAttachmentsConfiguration = instance.configuration?.mediaAttachments
         
         _featuresUpdated.send()
     }