following and unfollowing

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

damus/Models/Contacts.swift

@@ -0,0 +1,122 @@
+//
+//  Contacts.swift
+//  damus
+//
+//  Created by William Casarin on 2022-05-14.
+//
+
+import Foundation
+
+
+class Contacts {
+    var friends: Set<String> = Set()
+    var event: NostrEvent?
+    
+    func is_friend(_ pubkey: String) -> Bool {
+        return friends.contains(pubkey)
+    }
+    
+    func follow_state(_ pubkey: String) -> FollowState {
+        return is_friend(pubkey) ? .follows : .unfollows
+    }
+}
+
+
+func create_contacts(relays: [RelayDescriptor], our_pubkey: String, follow: ReferencedId) -> NostrEvent {
+    let kind = NostrKind.contacts.rawValue
+    let content = create_contacts_content(relays) ?? "{}"
+    let tags = [refid_to_tag(follow)]
+    return NostrEvent(content: content, pubkey: our_pubkey, kind: kind, tags: tags)
+}
+
+func create_contacts_content(_ relays: [RelayDescriptor]) -> String? {
+    // TODO: just create a new one of this is corrupted?
+    let crelays = make_contact_relays(relays)
+    guard let encoded = encode_json(crelays) else {
+        return nil
+    }
+    return encoded
+}
+
+
+func follow_user(pool: RelayPool, our_contacts: NostrEvent?, pubkey: String, privkey: String, follow: ReferencedId) -> Bool {
+    guard let ev = follow_user_event(our_contacts: our_contacts, our_pubkey: pubkey, follow: follow) else {
+        return false
+    }
+    
+    ev.calculate_id()
+    ev.sign(privkey: privkey)
+    
+    pool.send(.event(ev))
+    
+    return true
+}
+
+func unfollow_user(pool: RelayPool, our_contacts: NostrEvent?, pubkey: String, privkey: String, unfollow: String) -> Bool {
+    guard let cs = our_contacts else {
+        return false
+    }
+    
+    let ev = unfollow_user_event(our_contacts: cs, our_pubkey: pubkey, unfollow: unfollow)
+    ev.calculate_id()
+    ev.sign(privkey: privkey)
+    
+    pool.send(.event(ev))
+    
+    return true
+}
+
+func unfollow_user_event(our_contacts: NostrEvent, our_pubkey: String, unfollow: String) -> NostrEvent {
+    let tags = our_contacts.tags.filter { tag in
+        if tag.count >= 2 && tag[0] == "p" && tag[1] == unfollow {
+            return false
+        }
+        return true
+    }
+    
+    let kind = NostrKind.contacts.rawValue
+    return NostrEvent(content: our_contacts.content, pubkey: our_pubkey, kind: kind, tags: tags)
+}
+
+func follow_user_event(our_contacts: NostrEvent?, our_pubkey: String, follow: ReferencedId) -> NostrEvent? {
+    guard let cs = our_contacts else {
+        // don't create contacts for now so we don't nuke our contact list due to connectivity issues
+        // we should only create contacts during profile creation
+        //return create_contacts(relays: relays, our_pubkey: our_pubkey, follow: follow)
+        return nil
+    }
+
+    guard let ev = follow_with_existing_contacts(our_pubkey: our_pubkey, our_contacts: cs, follow: follow) else {
+        return nil
+    }
+    
+    return ev
+}
+
+/*
+func ensure_relay_info(relays: [RelayDescriptor], content: String) -> [String: RelayInfo] {
+    guard let relay_info = decode_json_relays(content) else {
+        return make_contact_relays(relays)
+    }
+    return relay_info
+}
+ */
+
+func follow_with_existing_contacts(our_pubkey: String, our_contacts: NostrEvent, follow: ReferencedId) -> NostrEvent? {
+    // don't update if we're already following
+    if our_contacts.references(id: follow.ref_id, key: "p") {
+        return nil
+    }
+    
+    let kind = NostrKind.contacts.rawValue
+    var tags = our_contacts.tags
+    tags.append(refid_to_tag(follow))
+    return NostrEvent(content: our_contacts.content, pubkey: our_pubkey, kind: kind, tags: tags)
+}
+
+func make_contact_relays(_ relays: [RelayDescriptor]) -> [String: RelayInfo] {
+    return relays.reduce(into: [:]) { acc, relay in
+        acc[relay.url.absoluteString] = relay.info
+    }
+}
+