ui: Fix issue where relays with trailing slashes cannot be removed (#1531)

Summary
-------

This fixes the issue at Github #1531 where relays with trailing slashes cannot be removed.

The root cause (Identified by @fishcakeday) was that for a relay to be removed, a certain dictionary entry containing the relay url needed to be removed prior to sending the updated relay list. However those dictionary keys used `String` objects, which cannot tell that two URLs are the same with or without a trailing slash.

To fix the issue, I have used a dictionary with the type `[RelayURL: RelayInfo]`, and made the necessary protocol conformance implementations for RelayURL. This way, URLs are handled with higher accuracy (e.g. Trailing slashes do not matter, URLs that resolve to the same location will match no matter what).

This allows us to leverage the existing parsing and handling logic that comes with the `URL` type, instead of manually handling URL strings.

Generally speaking it is preferrable to work with higher level `URL` or `RelayURL` objects than handle URLs via `String`. There is an opportunity to refactor more code, but I intentionally kept the changes to `RelayURL` limited to the functionality in this issue, because otherwise the changeset becomes very big and risky.

Issue reproduction
------------------

**Device:** iPhone 14 Pro simulator
**iOS:** 17.0
**Damus:** Local build from `476f52562` with the following local change:
``` diff

Signed-off-by: William Casarin <jb55@jb55.com>

damus.xcodeproj/project.pbxproj

@@ -430,6 +430,7 @@
 		D7870BC12AC4750B0080BA88 /* MentionView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D7870BC02AC4750B0080BA88 /* MentionView.swift */; };
 		D7870BC32AC47EBC0080BA88 /* EventLoaderView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D7870BC22AC47EBC0080BA88 /* EventLoaderView.swift */; };
 		D7DEEF2F2A8C021E00E0C99F /* NostrEventTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = D7DEEF2E2A8C021E00E0C99F /* NostrEventTests.swift */; };
+		D7FF94002AC7AC5300FD969D /* RelayURL.swift in Sources */ = {isa = PBXBuildFile; fileRef = D7FF93FF2AC7AC5200FD969D /* RelayURL.swift */; };
 		E4FA1C032A24BB7F00482697 /* SearchSettingsView.swift in Sources */ = {isa = PBXBuildFile; fileRef = E4FA1C022A24BB7F00482697 /* SearchSettingsView.swift */; };
 		E990020F2955F837003BBC5A /* EditMetadataView.swift in Sources */ = {isa = PBXBuildFile; fileRef = E990020E2955F837003BBC5A /* EditMetadataView.swift */; };
 		E9E4ED0B295867B900DD7078 /* ThreadView.swift in Sources */ = {isa = PBXBuildFile; fileRef = E9E4ED0A295867B900DD7078 /* ThreadView.swift */; };
@@ -1115,6 +1116,7 @@
 		D7870BC02AC4750B0080BA88 /* MentionView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MentionView.swift; sourceTree = "<group>"; };
 		D7870BC22AC47EBC0080BA88 /* EventLoaderView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = EventLoaderView.swift; sourceTree = "<group>"; };
 		D7DEEF2E2A8C021E00E0C99F /* NostrEventTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NostrEventTests.swift; sourceTree = "<group>"; };
+		D7FF93FF2AC7AC5200FD969D /* RelayURL.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RelayURL.swift; sourceTree = "<group>"; };
 		E4FA1C022A24BB7F00482697 /* SearchSettingsView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SearchSettingsView.swift; sourceTree = "<group>"; };
 		E990020E2955F837003BBC5A /* EditMetadataView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = EditMetadataView.swift; sourceTree = "<group>"; };
 		E9E4ED0A295867B900DD7078 /* ThreadView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ThreadView.swift; sourceTree = "<group>"; };
@@ -1717,6 +1719,7 @@
 				50088DA029E8271A008A1FDF /* WebSocket.swift */,
 				4C28A4112A6D03D200C1A7A5 /* ReferencedId.swift */,
 				4C2B7BF12A71B6540049DEE7 /* Id.swift */,
+				D7FF93FF2AC7AC5200FD969D /* RelayURL.swift */,
 			);
 			path = Nostr;
 			sourceTree = "<group>";
@@ -2732,6 +2735,7 @@
 				3A23838E2A297DD200E5AA2E /* ZapButtonModel.swift in Sources */,
 				F71694F82A6983AF001F4053 /* GrayGradient.swift in Sources */,
 				4C1D4FB12A7958E60024F453 /* VersionInfo.swift in Sources */,
+				D7FF94002AC7AC5300FD969D /* RelayURL.swift in Sources */,
 				4C64305C2A945AFF00B0C0E9 /* MusicController.swift in Sources */,
 				5053ACA72A56DF3B00851AE3 /* DeveloperSettingsView.swift in Sources */,
 				F79C7FAD29D5E9620000F946 /* EditPictureControl.swift in Sources */,

damus/Models/Contacts.swift

@@ -184,8 +184,13 @@ func decode_json_relays(_ content: String) -> [String: RelayInfo]? {
     return decode_json(content)
 }
 
-func remove_relay(ev: NostrEvent, current_relays: [RelayDescriptor], keypair: FullKeypair, relay: String) -> NostrEvent?{
+func decode_json_relays(_ content: String) -> [RelayURL: RelayInfo]? {
+    return decode_json(content)
+}
+
+func remove_relay(ev: NostrEvent, current_relays: [RelayDescriptor], keypair: FullKeypair, relay: RelayURL) -> NostrEvent?{
     var relays = ensure_relay_info(relays: current_relays, content: ev.content)
+    
     relays.removeValue(forKey: relay)
     
     guard let content = encode_json(relays) else {
@@ -195,9 +200,10 @@ func remove_relay(ev: NostrEvent, current_relays: [RelayDescriptor], keypair: Fu
     return NostrEvent(content: content, keypair: keypair.to_keypair(), kind: 3, tags: ev.tags.strings())
 }
 
-func add_relay(ev: NostrEvent, keypair: FullKeypair, current_relays: [RelayDescriptor], relay: String, info: RelayInfo) -> NostrEvent? {
+func add_relay(ev: NostrEvent, keypair: FullKeypair, current_relays: [RelayDescriptor], relay: RelayURL, info: RelayInfo) -> NostrEvent? {
     var relays = ensure_relay_info(relays: current_relays, content: ev.content)
     
+    
     guard relays.index(forKey: relay) == nil else {
         return nil
     }
@@ -211,11 +217,8 @@ func add_relay(ev: NostrEvent, keypair: FullKeypair, current_relays: [RelayDescr
     return NostrEvent(content: content, keypair: keypair.to_keypair(), kind: 3, tags: ev.tags.strings())
 }
 
-func ensure_relay_info(relays: [RelayDescriptor], content: String) -> [String: RelayInfo] {
+func ensure_relay_info(relays: [RelayDescriptor], content: String) -> [RelayURL: RelayInfo] {
-    guard let relay_info = decode_json_relays(content) else {
+    return decode_json_relays(content) ?? make_contact_relays(relays)
-        return make_contact_relays(relays)
-    }
-    return relay_info
 }
 
 func is_already_following(contacts: NostrEvent, follow: FollowRef) -> Bool {
@@ -245,8 +248,8 @@ func follow_with_existing_contacts(keypair: FullKeypair, our_contacts: NostrEven
     return NostrEvent(content: our_contacts.content, keypair: keypair.to_keypair(), kind: kind, tags: tags)
 }
 
-func make_contact_relays(_ relays: [RelayDescriptor]) -> [String: RelayInfo] {
+func make_contact_relays(_ relays: [RelayDescriptor]) -> [RelayURL: RelayInfo] {
     return relays.reduce(into: [:]) { acc, relay in
-        acc[relay.url.url.absoluteString] = relay.info
+        acc[relay.url] = relay.info
     }
 }

damus/Models/HomeModel.swift

@@ -849,7 +849,7 @@ func load_our_relays(state: DamusState, m_old_ev: NostrEvent?, ev: NostrEvent) {
         d[r] = .rw
     }
     
-    guard let decoded = decode_json_relays(ev.content) else {
+    guard let decoded: [String: RelayInfo] = decode_json_relays(ev.content) else {
         return
     }
     

damus/Nostr/RelayConnection.swift

@@ -13,37 +13,6 @@ enum NostrConnectionEvent {
     case nostr_event(NostrResponse)
 }
 
-public struct RelayURL: Hashable {
-    private(set) var url: URL
-    
-    var id: String {
-        return url.absoluteString
-    }
-    
-    init?(_ str: String) {
-        guard let last = str.last else { return nil }
-
-        var urlstr = str
-        if last == "/" {
-            urlstr = String(str.dropLast(1))
-        }
-
-        guard let url = URL(string: urlstr) else {
-            return nil
-        }
-        
-        guard let scheme = url.scheme else {
-            return nil
-        }
-        
-        guard scheme == "ws" || scheme == "wss" else {
-            return nil
-        }
-        
-        self.url = url
-    }
-}
-
 final class RelayConnection: ObservableObject {
     @Published private(set) var isConnected = false
     @Published private(set) var isConnecting = false

damus/Nostr/RelayURL.swift

@@ -0,0 +1,87 @@
+//
+//  RelayURL.swift
+//  damus
+//
+//  Created by Daniel D’Aquino on 2023-09-29.
+//
+
+import Foundation
+
+public struct RelayURL: Hashable, Equatable, Codable, CodingKeyRepresentable {
+    private(set) var url: URL
+    
+    var id: String {
+        return url.absoluteString
+    }
+    
+    init?(_ str: String) {
+        guard let last = str.last else { return nil }
+
+        var urlstr = str
+        if last == "/" {
+            urlstr = String(str.dropLast(1))
+        }
+
+        guard let url = URL(string: urlstr) else {
+            return nil
+        }
+        
+        guard let scheme = url.scheme else {
+            return nil
+        }
+        
+        guard scheme == "ws" || scheme == "wss" else {
+            return nil
+        }
+        
+        self.url = url
+    }
+    
+    // MARK: - Codable
+    public init(from decoder: Decoder) throws {
+        let container = try decoder.singleValueContainer()
+        let urlString = try container.decode(String.self)
+        guard let instance = RelayURL(urlString) else {
+            throw DecodingError.dataCorruptedError(in: container, debugDescription: "Invalid URL string.")
+        }
+        self = instance
+    }
+
+    public func encode(to encoder: Encoder) throws {
+        var container = encoder.singleValueContainer()
+        try container.encode(url.absoluteString)
+    }
+    
+    // MARK: - CodingKeyRepresentable
+    // CodingKeyRepresentable conformance is necessary to ensure that
+    // a dictionary with type "[RelayURL: T] where T: Codable" can be encoded into a keyed container
+    // e.g. `{<URL>: <VALUE>, <URL>: <VALUE>}` instead of `[<URL>, <VALUE>, <URL>, <VALUE>]`, which is Swift's default for non-string-keyed dictionaries
+    
+    public var codingKey: CodingKey {
+        return StringKey(stringValue: self.url.absoluteString)
+    }
+    
+    public init?<T>(codingKey: T) where T : CodingKey {
+        self.init(codingKey.stringValue)
+    }
+    
+    // MARK: - Equatable
+    public static func == (lhs: RelayURL, rhs: RelayURL) -> Bool {
+        return lhs.url == rhs.url
+    }
+    
+    // MARK: - Hashable
+    public func hash(into hasher: inout Hasher) {
+        hasher.combine(self.url)
+    }
+    
+}
+
+private struct StringKey: CodingKey {
+    var stringValue: String
+    init(stringValue: String) {
+        self.stringValue = stringValue
+    }
+    var intValue: Int? { return nil }
+    init?(intValue: Int) { return nil }
+}

damus/Views/AddRelayView.swift

@@ -82,9 +82,11 @@ struct AddRelayView: View {
                     new_relay = "wss://" + new_relay
                 }
 
+                /*
                 if new_relay.hasSuffix("/") {
                     new_relay.removeLast();
                 }
+                */
 
                 guard let url = RelayURL(new_relay),
                       let ev = state.contacts.event,
@@ -109,7 +111,7 @@ struct AddRelayView: View {
 
                 state.pool.connect(to: [new_relay])
 
-                guard let new_ev = add_relay(ev: ev, keypair: keypair, current_relays: state.pool.our_descriptors, relay: new_relay, info: info) else {
+                guard let new_ev = add_relay(ev: ev, keypair: keypair, current_relays: state.pool.our_descriptors, relay: url, info: info) else {
                     return
                 }
 

damus/Views/Relays/RecommendedRelayView.swift

@@ -118,7 +118,8 @@ struct RecommendedRelayView: View {
         guard let ev_before_add = damus.contacts.event else {
             return
         }
-        guard let ev_after_add = add_relay(ev: ev_before_add, keypair: keypair, current_relays: damus.pool.our_descriptors, relay: relay, info: .rw) else {
+        guard let relay_url = RelayURL(relay),
+            let ev_after_add = add_relay(ev: ev_before_add, keypair: keypair, current_relays: damus.pool.our_descriptors, relay: relay_url, info: .rw) else {
             return
         }
         process_contact_event(state: damus, ev: ev_after_add)

damus/Views/Relays/RelayDetailView.swift

@@ -48,7 +48,8 @@ struct RelayDetailView: View {
             }
 
             let descriptors = state.pool.our_descriptors
-            guard let new_ev = remove_relay( ev: ev, current_relays: descriptors, keypair: keypair, relay: relay) else {
+            guard let relay_url = RelayURL(relay),
+                let new_ev = remove_relay( ev: ev, current_relays: descriptors, keypair: keypair, relay: relay_url) else {
                 return
             }
 
@@ -71,7 +72,8 @@ struct RelayDetailView: View {
                             guard let ev_before_add = state.contacts.event else {
                                 return
                             }
-                            guard let ev_after_add = add_relay(ev: ev_before_add, keypair: keypair, current_relays: state.pool.our_descriptors, relay: relay, info: .rw) else {
+                            guard let relay_url = RelayURL(relay),
+                                let ev_after_add = add_relay(ev: ev_before_add, keypair: keypair, current_relays: state.pool.our_descriptors, relay: relay_url, info: .rw) else {
                                 return
                             }
                             process_contact_event(state: state, ev: ev_after_add)

damus/Views/Relays/RelayView.swift

@@ -95,7 +95,8 @@ struct RelayView: View {
             
             let descriptors = state.pool.our_descriptors
             guard let keypair = state.keypair.to_full(),
-                  let new_ev = remove_relay(ev: ev, current_relays: descriptors, keypair: keypair, relay: relay) else {
+                  let relay_url = RelayURL(relay),
+                  let new_ev = remove_relay(ev: ev, current_relays: descriptors, keypair: keypair, relay: relay_url) else {
                 return
             }