[WIP] Topic APIs

submodules/Postbox/Sources/MessageHistoryThreadIndexView.swift

@@ -0,0 +1,131 @@
+import Foundation
+
+final class MutableMessageHistoryThreadIndexView: MutablePostboxView {
+    final class Item {
+        let id: Int64
+        let index: MessageIndex
+        var info: CodableEntry
+        var topMessage: Message?
+        
+        init(
+            id: Int64,
+            index: MessageIndex,
+            info: CodableEntry,
+            topMessage: Message?
+        ) {
+            self.id = id
+            self.index = index
+            self.info = info
+            self.topMessage = topMessage
+        }
+    }
+    
+    fileprivate let peerId: PeerId
+    fileprivate var peer: Peer?
+    fileprivate var items: [Item] = []
+    
+    init(postbox: PostboxImpl, peerId: PeerId) {
+        self.peerId = peerId
+        
+        self.reload(postbox: postbox)
+    }
+    
+    private func reload(postbox: PostboxImpl) {
+        self.items.removeAll()
+        
+        self.peer = postbox.peerTable.get(self.peerId)
+        
+        for item in postbox.messageHistoryThreadIndexTable.getAll(peerId: self.peerId) {
+            self.items.append(Item(
+                id: item.threadId,
+                index: item.index,
+                info: item.info,
+                topMessage: postbox.getMessage(item.index.id)
+            ))
+        }
+    }
+    
+    func replay(postbox: PostboxImpl, transaction: PostboxTransaction) -> Bool {
+        var updated = false
+        
+        if transaction.updatedMessageThreadPeerIds.contains(self.peerId) {
+            self.reload(postbox: postbox)
+            updated = true
+        }
+        
+        return updated
+    }
+
+    func refreshDueToExternalTransaction(postbox: PostboxImpl) -> Bool {
+        return false
+    }
+    
+    func immutableView() -> PostboxView {
+        return MessageHistoryThreadIndexView(self)
+    }
+}
+
+public final class EngineMessageHistoryThread {
+    public final class Item: Equatable {
+        public let id: Int64
+        public let index: MessageIndex
+        public let info: CodableEntry
+        public let topMessage: Message?
+        
+        public init(
+            id: Int64,
+            index: MessageIndex,
+            info: CodableEntry,
+            topMessage: Message?
+        ) {
+            self.id = id
+            self.index = index
+            self.info = info
+            self.topMessage = topMessage
+        }
+        
+        public static func ==(lhs: Item, rhs: Item) -> Bool {
+            if lhs.id != rhs.id {
+                return false
+            }
+            if lhs.index != rhs.index {
+                return false
+            }
+            if lhs.info != rhs.info {
+                return false
+            }
+            if let lhsMessage = lhs.topMessage, let rhsMessage = rhs.topMessage {
+                if lhsMessage.index != rhsMessage.index {
+                    return false
+                }
+                if lhsMessage.stableVersion != rhsMessage.stableVersion {
+                    return false
+                }
+            } else if (lhs.topMessage == nil) != (rhs.topMessage == nil) {
+                return false
+            }
+            
+            return true
+        }
+    }
+}
+
+public final class MessageHistoryThreadIndexView: PostboxView {
+    public let peer: Peer?
+    public let items: [EngineMessageHistoryThread.Item]
+    
+    init(_ view: MutableMessageHistoryThreadIndexView) {
+        self.peer = view.peer
+        
+        var items: [EngineMessageHistoryThread.Item] = []
+        for item in view.items {
+            items.append(EngineMessageHistoryThread.Item(
+                id: item.id,
+                index: item.index,
+                info: item.info,
+                topMessage: item.topMessage
+            ))
+        }
+        self.items = items
+    }
+}