import Foundation
import monalxmpp

enum AccountsAvailability {
    case noAccounts
    case allDisabled
    case someEnabled
}

final class WrapperXMPP: ObservableObject {
    @Published private(set) var accountsAvailability: AccountsAvailability = .noAccounts
    @Published private(set) var accounts: [Account] = []
    @Published private(set) var contacts: [Contact] = []
    @Published private(set) var activeChats: [Chat] = []

    private let xmpp: MLXMPPManager
    private let db: DataLayer

    private var notificationObservers: [AnyObject] = []

    init() {
        // init monalxmpp components
        xmpp = MLXMPPManager.sharedInstance()
        db = DataLayer.sharedInstance()

        // subscribe to monalxmpp notifications and fire notification for update
        subscribeToUpdates()
        processOnStart()
    }

    deinit {
        notificationObservers.forEach { NotificationCenter.default.removeObserver($0) }
    }
}

// MARK: - Public
extension WrapperXMPP {
    func tryLogin(_ login: String, _ password: String) async throws {
        let scenario = ScenarioLogIn()
        let result = await scenario.tryLogin(login, password)
        if !result {
            throw AimErrors.loginError
        }
    }

    func addContact(contactJid: String, forAccountID: Int) async {
        let contact = MLContact.createContact(fromJid: contactJid, andAccountID: NSNumber(value: forAccountID))
        xmpp.add(contact)
    }

    func deleteContact(_ contact: Contact) async throws {
        if let mlContact = db.contactList().first(where: { $0.contactJid == contact.contactJid }) {
            xmpp.remove(mlContact)
        } else {
            throw AimErrors.contactRemoveError
        }
    }

    func chat(with: Contact) -> WrapperChat? {
        guard let account = accounts.first(where: { $0.id == with.ownerId }) else { return nil }
        return WrapperChat(with: with, account: account)
    }

    func chat(with: Chat) -> WrapperChat? {
        guard let account = accounts.first(where: { $0.id == with.accountId }) else { return nil }
        return WrapperChat(with: with, account: account)
    }
}

// MARK: - Handle notifications
private extension WrapperXMPP {
    // Subsribe to monalxmpp events
    func subscribeToUpdates() {
        let notificationNames = [
            kMonalRefresh,
            kMonalContactRefresh,
            kMonalContactRemoved,
            kMLResourceBoundNotice,
            kMonalNewMessageNotice,
            kMonalHistoryMessagesNotice
        ]
        notificationObservers = notificationNames.map { name in
            NotificationCenter.default.addObserver(forName: Notification.Name(name), object: nil, queue: .main) { [weak self] notification in
                self?.processEvent(notification)
            }
        }
    }

    // Process monalxmpp events
    func processEvent(_ notification: Notification) {
        switch notification.name.rawValue {
        case kMonalRefresh:
            print("refresh?")

        case kMonalContactRefresh:
            if let mlContact = notification.userInfo?["contact"] as? MLContact, !mlContact.isSelfChat {
                if let contact = Contact(mlContact) {
                    if let index = contacts.firstIndex(where: { $0.id == mlContact.id }) {
                        contacts[index] = contact
                    } else {
                        contacts.append(contact)
                        contacts.sort { $0.name < $1.name }
                    }
                }
            }

        case kMonalContactRemoved:
            if let mlContact = notification.userInfo?["contact"] as? MLContact {
                contacts = contacts.filter { $0.id != mlContact.id }
            }

        case kMLResourceBoundNotice:
            processOnStart()

        case kMonalNewMessageNotice, kMonalHistoryMessagesNotice:
            if let mlContact = notification.userInfo?["contact"] as? MLContact, !mlContact.isSelfChat {
                let contactJid = mlContact.contactJid
                let accountId = mlContact.account?.accountID.intValue ?? 0
                if activeChats.first(where: { $0.accountId == accountId && $0.participantJid == contactJid }) == nil {
                    if let chat = Chat(mlContact) {
                        activeChats.append(chat)
                        activeChats.sort { $0.participantJid < $1.participantJid }
                    }
                }
            }

        default:
            break
        }
    }

    // Initital monalxmpp db fetch
    func processOnStart() {
        // get all accounts and contacts once
        let accounts = db.accountList()
            .compactMap { dict -> Account? in
                guard let dict = dict as? NSDictionary else { return nil }
                return Account(dict)
            }
        self.accounts = accounts

        // check if active accounts existed
        if accounts.isEmpty {
            accountsAvailability = .noAccounts
        } else if accounts.filter({ $0.isEnabled }).isEmpty {
            accountsAvailability = .allDisabled
        } else {
            accountsAvailability = .someEnabled
        }

        // get all contacts
        if !accounts.isEmpty {
            contacts = db.contactList()
                .filter { $0.isSubscribedTo || $0.hasOutgoingContactRequest || $0.isSubscribedFrom }
                .filter { !$0.isSelfChat } // removed for now
                .compactMap { Contact($0) }

            // get active chats
            if !contacts.isEmpty {
                activeChats = db.activeContacts(withPinned: false)
                    .compactMap {
                        guard let contact = $0 as? MLContact else { return nil }
                        return Chat(contact)
                    }
            }
        }

        // try reconnect active clients
        xmpp.connectIfNecessary()
    }
}