move some stuff around, reply desc

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

damus/Models/EventRef.swift

@@ -0,0 +1,153 @@
+//
+//  EventRef.swift
+//  damus
+//
+//  Created by William Casarin on 2022-05-08.
+//
+
+import Foundation
+
+enum EventRef {
+    case mention(Mention)
+    case thread_id(ReferencedId)
+    case reply(ReferencedId)
+    case reply_to_root(ReferencedId)
+    
+    var is_mention: Mention? {
+        if case .mention(let m) = self {
+            return m
+        }
+        return nil
+    }
+    
+    var is_direct_reply: ReferencedId? {
+        switch self {
+        case .mention:
+            return nil
+        case .thread_id:
+            return nil
+        case .reply(let refid):
+            return refid
+        case .reply_to_root(let refid):
+            return refid
+        }
+    }
+    
+    var is_thread_id: ReferencedId? {
+        switch self {
+        case .mention(let mention):
+            return nil
+        case .thread_id(let referencedId):
+            return referencedId
+        case .reply(let referencedId):
+            return nil
+        case .reply_to_root(let referencedId):
+            return referencedId
+        }
+    }
+    
+    var is_reply: ReferencedId? {
+        switch self {
+        case .mention:
+            return nil
+        case .thread_id:
+            return nil
+        case .reply(let refid):
+            return refid
+        case .reply_to_root(let refid):
+            return refid
+        }
+    }
+}
+
+func has_any_e_refs(_ tags: [[String]]) -> Bool {
+    for tag in tags {
+        if tag.count >= 2 && tag[0] == "e" {
+            return true
+        }
+    }
+    return false
+}
+
+func build_mention_indices(_ blocks: [Block], type: MentionType) -> Set<Int> {
+    return blocks.reduce(into: []) { acc, block in
+        switch block {
+        case .mention(let m):
+            if m.type == type {
+                acc.insert(m.index)
+            }
+        case .text:
+            return
+        }
+    }
+}
+
+func interp_event_refs_without_mentions(_ refs: [ReferencedId]) -> [EventRef] {
+    if refs.count == 0 {
+        return []
+    }
+
+    if refs.count == 1 {
+        return [.reply_to_root(refs[0])]
+    }
+    
+    var evrefs: [EventRef] = []
+    var first: Bool = true
+    for ref in refs {
+        if first {
+            evrefs.append(.thread_id(ref))
+            first = false
+        } else {
+            evrefs.append(.reply(ref))
+        }
+    }
+    return evrefs
+}
+
+func interp_event_refs_with_mentions(tags: [[String]], mention_indices: Set<Int>) -> [EventRef] {
+    var mentions: [EventRef] = []
+    var ev_refs: [ReferencedId] = []
+    var i: Int = 0
+    
+    for tag in tags {
+        if tag.count >= 2 && tag[0] == "e" {
+            let ref = tag_to_refid(tag)!
+            if mention_indices.contains(i) {
+                let mention = Mention(index: i, type: .event, ref: ref)
+                mentions.append(.mention(mention))
+            } else {
+                ev_refs.append(ref)
+            }
+        }
+        i += 1
+    }
+    
+    var replies = interp_event_refs_without_mentions(ev_refs)
+    replies.append(contentsOf: mentions)
+    return replies
+}
+
+func interpret_event_refs(blocks: [Block], tags: [[String]]) -> [EventRef] {
+    if tags.count == 0 {
+        return []
+    }
+    
+    /// build a set of indices for each event mention
+    let mention_indices = build_mention_indices(blocks, type: .event)
+    
+    /// simpler case with no mentions
+    if mention_indices.count == 0 {
+        let ev_refs = get_referenced_ids(tags: tags, key: "e")
+        return interp_event_refs_without_mentions(ev_refs)
+    }
+    
+    return interp_event_refs_with_mentions(tags: tags, mention_indices: mention_indices)
+}
+
+
+func event_is_reply(_ ev: NostrEvent) -> Bool {
+    return ev.event_refs.contains { evref in
+        return evref.is_reply != nil
+    }
+}
+