another.im-ios/ConversationsClassic/AppData/Store/ConversationStore.swift

import Collections
import Combine
import Foundation
import GRDB

@MainActor
final class ConversationStore: ObservableObject {
    @Published private(set) var messages: [Message] = []
    @Published var replyText = ""
    private(set) var roster: Roster

    private let client: Client
    private let blockSize = Const.messagesPageSize
    private let messagesMax = Const.messagesMaxSize

    private var messagesCancellable: AnyCancellable?

    init(roster: Roster, client: Client) {
        self.client = client
        self.roster = roster
        subscribe()
    }
}

extension ConversationStore {
    func sendMessage(_ message: String) async {
        // prepare message
        let message = Message(
            id: UUID().uuidString,
            type: .chat,
            date: Date(),
            contentType: .text,
            status: .pending,
            from: roster.bareJid,
            to: roster.contactBareJid,
            body: message,
            subject: nil,
            thread: nil,
            oobUrl: nil
        )

        // store as pending on db, and send
        do {
            try await message.save()
            try await client.sendMessage(message)
            try await message.setStatus(.sent)
        } catch {
            try? await message.setStatus(.error)
        }
    }
}

private extension ConversationStore {
    func subscribe() {
        messagesCancellable = ValueObservation.tracking(Message
            .filter(
                (Column("to") == roster.bareJid && Column("from") == roster.contactBareJid) ||
                    (Column("from") == roster.bareJid && Column("to") == roster.contactBareJid)
            )
            .order(Column("date").desc)
            .fetchAll
        )
        .publisher(in: Database.shared.dbQueue, scheduling: .immediate)
        .receive(on: DispatchQueue.main)
        .sink { _ in
        } receiveValue: { [weak self] messages in
            self?.messages = messages
        }
    }
}