Swiftgram/submodules/TelegramCore/Sources/ConvertGroupToSupergroup.swift

import Foundation
import Postbox
import SwiftSignalKit
import TelegramApi
import MtProtoKit

public enum ConvertGroupToSupergroupError {
    case generic
    case tooManyChannels
}

public func convertGroupToSupergroup(account: Account, peerId: PeerId) -> Signal<PeerId, ConvertGroupToSupergroupError> {
    return account.network.request(Api.functions.messages.migrateChat(chatId: peerId.id))
    |> mapError { error -> ConvertGroupToSupergroupError in
        if error.errorDescription == "CHANNELS_TOO_MUCH" {
            return .tooManyChannels
        } else {
            return .generic
        }
    }
    |> timeout(5.0, queue: Queue.concurrentDefaultQueue(), alternate: .fail(.generic))
    |> mapToSignal { updates -> Signal<PeerId, ConvertGroupToSupergroupError> in
        account.stateManager.addUpdates(updates)
        var createdPeerId: PeerId?
        for message in updates.messages {
            if apiMessagePeerId(message) != peerId {
                createdPeerId = apiMessagePeerId(message)
                break
            }
        }
        
        if let createdPeerId = createdPeerId {
            return account.postbox.multiplePeersView([createdPeerId])
            |> filter { view in
                return view.peers[createdPeerId] != nil
            }
            |> take(1)
            |> map { _ in
                return createdPeerId
            }
            |> mapError { _ -> ConvertGroupToSupergroupError in
                return .generic
            }
            |> timeout(5.0, queue: Queue.concurrentDefaultQueue(), alternate: .fail(.generic))
        }
        return .fail(.generic)
    }
}