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()
        xmpp.reconnectAll()
        NotificationCenter.default.post(name: Notification.Name(kMonalRefresh), object: nil)
    }

    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
        } else {
            NotificationCenter.default.post(name: Notification.Name(kMonalRefresh), object: nil)
        }
    }

    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 {
        // swiftlint:disable:next force_unwrapping
        let account = accounts.first { $0.id == with.ownerId }!
        let chatModel = WrapperChat(account: account, contact: with, db: db, xmpp: xmpp)
        return chatModel
    }

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

        var contact = contacts.first(where: { $0.ownerId == with.accountId && $0.contactJid == with.participantJid })
        if contact == nil {
            let semaphore = DispatchSemaphore(value: 0)
            Task {
                await addContact(contactJid: with.participantJid, forAccountID: with.accountId)
                semaphore.signal()
            }
            semaphore.wait()
            refreshChats()
            refreshContacts()
            contact = contacts.first(where: { $0.ownerId == with.accountId && $0.contactJid == with.participantJid })
        }

        guard let contact else { return nil }
        let chatModel = WrapperChat(account: account, contact: contact, db: db, xmpp: xmpp)
        return chatModel
    }
}

// MARK: - Handle notifications
private extension WrapperXMPP {
    func subscribeToUpdates() {
        // General
        let generalRefresh = NotificationCenter.default.addObserver(forName: Notification.Name(kMonalRefresh), object: nil, queue: .main) { [weak self] _ in
            self?.refreshAccounts()
            self?.refreshContacts()
            self?.refreshChats()
        }
        notificationObservers.append(generalRefresh)

        // For contacts
        let contactRefresh = NotificationCenter.default.addObserver(forName: Notification.Name(kMonalContactRefresh), object: nil, queue: .main) { [weak self] _ in
            self?.refreshContacts()
            self?.refreshChats()
        }
        let contactRemove = NotificationCenter.default.addObserver(forName: Notification.Name(kMonalContactRemoved), object: nil, queue: .main) { [weak self] _ in
            self?.refreshContacts()
            self?.refreshChats()
        }
        notificationObservers.append(contentsOf: [contactRefresh, contactRemove])
    }

    func refreshAccounts() {
        let accounts = db.accountList()
            .compactMap { dict -> Account? in
                guard let dict = dict as? NSDictionary else { return nil }
                return Account(dict)
            }
        self.accounts = accounts
        xmpp.connectIfNecessary()

        // mark accounts availability
        if accounts.isEmpty {
            accountsAvailability = .noAccounts
        } else if accounts.filter({ $0.isEnabled }).isEmpty {
            accountsAvailability = .allDisabled
        } else {
            accountsAvailability = .someEnabled
        }
    }

    func refreshContacts() {
        contacts = db.contactList()
            .filter { $0.isSubscribedTo || $0.hasOutgoingContactRequest || $0.isSubscribedFrom }
            .filter { !$0.isSelfChat } // removed for now
            .compactMap { Contact($0) }
    }

    func refreshChats() {
        activeChats = db.activeContacts(withPinned: false)
            .compactMap {
                guard let contact = $0 as? MLContact else { return nil }
                return Chat(contact)
            }
    }
}