Note Sharing, distributing updates

Peered/ContentView.swift

@@ -12,14 +12,16 @@ extension EnvironmentValues {
 }
 
 struct ContentView: View {
-  @AppStorage("peered_username") private var username: String = ""
+  @AppStorage("peered_username") private var username: String = "fallback_user"
   @State private var notes = [Note]()
 	@State private var notesClient: NoteEditingSessionClient?
 	@State private var ownPeer: OwnPeer?
 	
   var body: some View {
 		NavigationStack {
-			List(notes) { note in
+			List {
+				Section("Your notes") {
+					ForEach(notes) { note in
 						NavigationLink(note.name) {
 							let peer = ownPeer ?? .init(peer: .init(displayName: username))
 							if ownPeer == nil {
@@ -28,6 +30,18 @@ struct ContentView: View {
 							return NoteEditorScreen(note: note, peer: peer)
 						}
 					}
+				}
+				
+				if let notesClient {
+					Section("External notes") {
+						ForEach(notesClient.invitations) { invitation in
+							NavigationLink(invitation.noteName) {
+								SharedNoteEditor(invitation: invitation, noteClient: notesClient)
+							}
+						}
+					}
+				}
+			}
 			.environment(\.ownPeer, ownPeer ?? .fallback)
 			.navigationTitle("Peered")
 			.toolbar {
@@ -44,7 +58,7 @@ struct ContentView: View {
 			}
 			notesClient?.startBrowsingForNotes()
 		}
-    .sheet(isPresented: .constant(username.isEmpty)) {
+		.sheet(isPresented: .constant(username == "fallback_user" || username.isEmpty)) {
       SetUserNameBottomSheetView(username: $username)
     }
   }

Peered/NoteEditor/ManageMembersView.swift

@@ -8,6 +8,8 @@ import SwiftUI
 
 struct ManageMembersView: View {
 	@Bindable var noteAdvertiser: NoteEditingSessionServer
+	let noteTitle: String
+	@Binding var noteContent: String
 	
 	var body: some View {
 		List(noteAdvertiser.visiblePeers) { peer in
@@ -17,7 +19,7 @@ struct ManageMembersView: View {
 				Spacer()
 				
 					PeerStateButton(peerState: peer.state) {
-						noteAdvertiser.invite(peer: peer)
+						noteAdvertiser.invite(peer: peer, to: .init(title: noteTitle, noteSnapshot: noteContent))
 					}
 			}
 		}

Peered/NoteEditor/NoteEditingSessionServer.swift

@@ -1,5 +1,6 @@
 import MultipeerConnectivity
 import Foundation
+import Combine
 
 struct OwnPeer {
 	let peer: MCPeerID
@@ -29,6 +30,7 @@ final class NoteEditingSessionServer: NSObject {
 	private let ownPeer: OwnPeer
 	
 	var visiblePeers: [Peer] = []
+	let noteChangesEmitter = PassthroughSubject<String, Never>()
 	
 	init(peer: OwnPeer) {
 		ownPeer = peer
@@ -36,6 +38,7 @@ final class NoteEditingSessionServer: NSObject {
 		session = .init(peer: peer.peer)
 		super.init()
 		browser.delegate = self
+		session.delegate = self
 	}
 	
 	func startServer() {
@@ -46,14 +49,17 @@ final class NoteEditingSessionServer: NSObject {
 		browser.stopBrowsingForPeers()
 	}
 	
-	func invite(peer: Peer) {
+	func invite(peer: Peer, to note: NoteInvitation.NoteContent) {
 		guard peer.state == .available else { return }
 		browser.invitePeer(
 			peer.mcPeer,
 			to: session,
-			withContext: nil, // FIXME: put note here?
+			withContext: try! JSONEncoder().encode(note),
 			timeout: 5
 		)
+		
+		let idxToUpdate = visiblePeers.firstIndex(where: { $0.mcPeer == peer.mcPeer })!
+		visiblePeers[idxToUpdate].state = .invitationPending
 	}
 }
 
@@ -73,3 +79,46 @@ extension NoteEditingSessionServer: MCNearbyServiceBrowserDelegate {
 		visiblePeers.remove(at: peerIdx)
 	}
 }
+
+extension NoteEditingSessionServer: MCSessionDelegate {
+	func session(
+		_ session: MCSession,
+		peer peerID: MCPeerID,
+		didChange state: MCSessionState
+	) {
+		
+	}
+	
+	func session(
+		_ session: MCSession,
+		didReceive stream: InputStream,
+		withName streamName: String,
+		fromPeer peerID: MCPeerID
+	) {
+		
+	}
+	
+	func session(
+		_ session: MCSession,
+		didStartReceivingResourceWithName resourceName: String,
+		fromPeer peerID: MCPeerID,
+		with progress: Progress
+	) {
+		
+	}
+	
+	func session(
+		_ session: MCSession,
+		didFinishReceivingResourceWithName resourceName: String,
+		fromPeer peerID: MCPeerID,
+		at localURL: URL?,
+		withError error: (any Error)?
+	) {
+		
+	}
+	
+	func session(_ session: MCSession, didReceive data: Data, fromPeer peerID: MCPeerID) {
+		guard let note = String(data: data, encoding: .utf8) else { fatalError() }
+		noteChangesEmitter.send(note)
+	}
+}

Peered/NoteEditor/NoteEditorScreen.swift

@@ -32,9 +32,16 @@ struct NoteEditorScreen: View {
 			}
 			.sheet(isPresented: $showManageMembers) {
 				NavigationStack {
-					ManageMembersView(noteAdvertiser: noteAdvertiser)
+					ManageMembersView(
+						noteAdvertiser: noteAdvertiser,
+						noteTitle: note.name,
+						noteContent: $noteContent
+					)
 				}
 			}
+			.onReceive(noteAdvertiser.noteChangesEmitter) { updatedNote in
+				self.noteContent = updatedNote
+			}
 			.onAppear {
 				noteContent = try! String(contentsOf: note.path, encoding: .utf8)
 				noteAdvertiser.startServer()

Peered/NoteEditor/SharedNoteEditor.swift

@@ -0,0 +1,48 @@
+//
+//  SharedNoteEditor.swift
+//  Peered
+//
+//  Created by Oskar Chybowski on 07/10/2025.
+//
+import SwiftUI
+
+struct SharedNoteEditor: View {
+	@State var note: String?
+	@State var sendTask: Task<Void, Never>?
+	@State var invitation: NoteInvitation
+	@Bindable var noteClient: NoteEditingSessionClient
+	
+	init(
+		invitation: NoteInvitation,
+		noteClient: NoteEditingSessionClient
+	) {
+		self._invitation = .init(initialValue: invitation)
+		self._noteClient = .init(noteClient)
+	}
+	
+	var body: some View {
+		ZStack {
+		if let note = Binding($note) {
+			TextEditor(text: note)
+		} else {
+			ProgressView {
+				Text("Fetching note...")
+			}
+		}
+		}
+		.onChange(of: note) { _, newValue in
+			sendTask?.cancel()
+			sendTask = Task {
+				try? await Task.sleep(nanoseconds: 500000000)
+				guard let note else { return }
+				DispatchQueue.main.async {
+					noteClient.send(note: note, to: invitation.invitatorID)
+				}
+			}
+		}
+		.onAppear {
+			invitation.accept()
+			note = invitation.note.noteSnapshot
+		}
+	}
+}

Peered/NotesList/NoteEditingSessionClient.swift

@@ -1,20 +1,53 @@
-//
-//  NoteEditingSessionClient.swift
-//  Peered
-//
-//  Created by Oskar Chybowski on 05/10/2025.
-//
-
-
 import MultipeerConnectivity
 import Foundation
 
+struct NoteInvitation: Identifiable {
+	struct NoteContent: Codable {
+		let title: String
+		let noteSnapshot: String
+	}
+	
+	var id: MCPeerID { invitatorID }
+	let noteName: String
+	let invitatorID: MCPeerID
+	let note: NoteContent
+	private var invitationHandler: ((Bool) -> Void)?
+	
+	init(
+		noteName: String,
+		invitatorID: MCPeerID,
+		note: NoteContent,
+		invitationHandler: ((Bool) -> Void)? = nil
+	) {
+		self.noteName = noteName
+		self.invitatorID = invitatorID
+		self.note = note
+		self.invitationHandler = invitationHandler
+	}
+	
+	mutating func accept() {
+		invitationHandler?(true)
+		invitationHandler = nil
+	}
+	
+	mutating func decline() {
+		invitationHandler?(false)
+		invitationHandler = nil
+	}
+}
+
 @Observable
 final class NoteEditingSessionClient: NSObject {
 	private let session: MCSession
 	private let advertiser: MCNearbyServiceAdvertiser
 	private let ownPeer: MCPeerID
 	
+	var invitations: [NoteInvitation] = [] {
+		didSet {
+			print(invitations)
+		}
+	}
+
 	init(peer: MCPeerID) {
 		ownPeer = peer
 		session = MCSession(
@@ -38,6 +71,14 @@ final class NoteEditingSessionClient: NSObject {
 	 func stopBrowsingForNotes() {
 			 advertiser.stopAdvertisingPeer()
 	 }
+	
+	func send(note: String, to peer: MCPeerID) {
+		try! session.send(
+			note.data(using: .utf8)!,
+			toPeers: [peer],
+			with: .reliable
+		)
+	}
 }
 
 extension NoteEditingSessionClient: MCNearbyServiceAdvertiserDelegate {
@@ -47,8 +88,26 @@ extension NoteEditingSessionClient: MCNearbyServiceAdvertiserDelegate {
 		withContext context: Data?,
 		invitationHandler: @escaping (Bool, MCSession?) -> Void
 	) {
+		guard
+			let context,
+			let noteContent = try? JSONDecoder().decode(NoteInvitation.NoteContent.self, from: context)
+		else { fatalError() }
+		
+		invitations.append(
+			.init(
+				noteName: noteContent.title,
+				invitatorID: peerID,
+				note: noteContent,
+				invitationHandler: { [weak self, invitationHandler] accepted in
+					guard let self else { return }
+					invitationHandler(accepted, self.session)
+					
 					DispatchQueue.main.async {
-				invitationHandler(true, self.session)
+						guard let idx = self.invitations.firstIndex(where: { $0.id == peerID }) else { return }
+						self.invitations.remove(at: idx)
 					}
 				}
+			)
+		)
+	}
 }

Peered/NotesList/NoteInvitationView.swift

@@ -0,0 +1,14 @@
+import SwiftUI
+
+struct NoteInvitationView: View {
+	@Binding var invitation: NoteInvitation
+	let joinTapped: () -> Void
+	
+	var body: some View {
+		HStack {
+			Text(invitation.noteName)
+			Spacer()
+			Button("Join", action: joinTapped)
+		}
+	}
+}