import Combine
import Foundation
import GRDB
import Martin

protocol MartinsManager: Martin.RosterManager & Martin.ChatManager {}

final class XMPPService: ObservableObject {
    private let manager: MartinsManager
    private let clientStatePublisher = PassthroughSubject<(XMPPClient, XMPPClient.State), Never>()
    private let clientMessagesPublisher = PassthroughSubject<(XMPPClient, Martin.Message), Never>()
    private var clientStateCancellables: Set<AnyCancellable> = []
    private var clientMessagesCancellables: Set<AnyCancellable> = []

    @Published private(set) var clients: [XMPPClient] = []
    var clientState: AnyPublisher<(XMPPClient, XMPPClient.State), Never> {
        clientStatePublisher.eraseToAnyPublisher()
    }

    var clientMessages: AnyPublisher<(XMPPClient, Martin.Message), Never> {
        clientMessagesPublisher.eraseToAnyPublisher()
    }

    init(manager: MartinsManager) {
        self.manager = manager
    }

    func updateClients(for accounts: [Account]) {
        // get simple diff
        let forAdd = accounts
            .filter { !self.clients.map { $0.connectionConfiguration.userJid.stringValue }.contains($0.bareJid) }
        let forRemove = clients
            .map { $0.connectionConfiguration.userJid.stringValue }
            .filter { !accounts.map { $0.bareJid }.contains($0) }

        // init and add clients
        for account in forAdd {
            // add client
            let client = makeClient(for: account, with: manager)
            clients.append(client)

            // subscribe to client state
            client.$state
                .sink { [weak self] state in
                    self?.clientStatePublisher.send((client, state))
                }
                .store(in: &clientStateCancellables)

            // subscribe to client messages
            client.module(MessageModule.self).messagesPublisher
                .sink { [weak self] message in
                    self?.clientMessagesPublisher.send((client, message.message))
                }
                .store(in: &clientMessagesCancellables)

            client.login()
        }

        // remove clients
        for jid in forRemove {
            deinitClient(jid: jid)
        }
    }

    private func makeClient(for account: Account, with manager: MartinsManager) -> XMPPClient {
        let client = XMPPClient()

        // register modules
        // core modules RFC 6120
        client.modulesManager.register(StreamFeaturesModule())
        client.modulesManager.register(SaslModule())
        client.modulesManager.register(AuthModule())
        client.modulesManager.register(SessionEstablishmentModule())
        client.modulesManager.register(ResourceBinderModule())
        client.modulesManager.register(DiscoveryModule(identity: .init(category: "client", type: "iOS", name: Const.appName)))

        // messaging modules RFC 6121
        client.modulesManager.register(RosterModule(rosterManager: manager))
        client.modulesManager.register(PresenceModule())

        client.modulesManager.register(PubSubModule())
        client.modulesManager.register(MessageModule(chatManager: manager))
        client.modulesManager.register(MessageCarbonsModule())
        client.modulesManager.register(MessageArchiveManagementModule())

        // extensions
        client.modulesManager.register(SoftwareVersionModule())
        client.modulesManager.register(PingModule())
        client.connectionConfiguration.userJid = .init(account.bareJid)
        client.connectionConfiguration.credentials = .password(password: account.pass)

        // add client to clients
        return client
    }

    func deinitClient(jid: String) {
        if let index = clients.firstIndex(where: { $0.connectionConfiguration.userJid.stringValue == jid }) {
            let client = clients.remove(at: index)
            _ = client.disconnect()
        }
    }

    func getClient(for jid: String) -> XMPPClient? {
        clients.first { $0.connectionConfiguration.userJid.stringValue == jid }
    }
}