import Foundation
import Postbox
import SwiftSignalKit
import TelegramApi
import MtProtoKit

public enum CreateGroupError {
    case generic
    case privacy
    case restricted
    case tooMuchJoined
    case tooMuchLocationBasedGroups
    case serverProvided(String)
}

public struct CreateGroupResult {
    public var peerId: EnginePeer.Id
    public var failedToInvitePeerIds: [EnginePeer.Id]
    
    public init(
        peerId: EnginePeer.Id,
        failedToInvitePeerIds: [EnginePeer.Id]
    ) {
        self.peerId = peerId
        self.failedToInvitePeerIds = failedToInvitePeerIds
    }
}

func _internal_createGroup(account: Account, title: String, peerIds: [PeerId], ttlPeriod: Int32?) -> Signal<CreateGroupResult?, CreateGroupError> {
    return account.postbox.transaction { transaction -> Signal<CreateGroupResult?, CreateGroupError> in
        var inputUsers: [Api.InputUser] = []
        for peerId in peerIds {
            if let peer = transaction.getPeer(peerId), let inputUser = apiInputUser(peer) {
                inputUsers.append(inputUser)
            } else {
                return .single(nil)
            }
        }
        
        var flags: Int32 = 0
        if let _ = ttlPeriod {
            flags |= 1 << 0
        }
        
        return account.network.request(Api.functions.messages.createChat(flags: flags, users: inputUsers, title: title, ttlPeriod: ttlPeriod))
        |> mapError { error -> CreateGroupError in
            if error.errorDescription == "USERS_TOO_FEW" {
                return .privacy
            }
            return .generic
        }
        |> mapToSignal { updates -> Signal<CreateGroupResult?, CreateGroupError> in
            var failedToInvitePeerIds: [EnginePeer.Id] = []
            failedToInvitePeerIds = []
            switch updates {
            case let .updates(updates, _, _, _, _):
                for update in updates {
                    if case let .updateGroupInvitePrivacyForbidden(userId) = update {
                        failedToInvitePeerIds.append(EnginePeer.Id(namespace: Namespaces.Peer.CloudUser, id: EnginePeer.Id.Id._internalFromInt64Value(userId)))
                    }
                }
            default:
                break
            }
            
            account.stateManager.addUpdates(updates)
            if let message = updates.messages.first, let peerId = apiMessagePeerId(message) {
                return account.postbox.multiplePeersView([peerId])
                |> filter { view in
                    return view.peers[peerId] != nil
                }
                |> take(1)
                |> castError(CreateGroupError.self)
                |> map { _ -> CreateGroupResult in
                    return CreateGroupResult(
                        peerId: peerId,
                        failedToInvitePeerIds: failedToInvitePeerIds
                    )
                }
            } else {
                return .single(nil)
            }
        }
    }
    |> castError(CreateGroupError.self)
    |> switchToLatest
}