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())

        // file transfer modules
        client.modulesManager.register(HttpFileUploadModule())

        // 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 }
    }

    func sendMessage(message: Message, completion: @escaping (Bool) -> Void) {
        guard let client = getClient(for: message.from), let to = message.to else {
            completion(false)
            return
        }
        guard let chat = client.module(MessageModule.self).chatManager.chat(for: client.context, with: BareJID(to)) else {
            completion(false)
            return
        }

        let msg = chat.createMessage(text: message.body ?? "??", id: message.id)
        chat.send(message: msg) { res in
            switch res {
            case .success:
                completion(true)

            case .failure:
                completion(false)
            }
        }
    }

    func uploadAttachment(message: Message, completion: @escaping (Error?, String) -> Void) {
        guard let client = getClient(for: message.from), let to = message.to else {
            completion(XMPPError.bad_request("No such client"), "")
            return
        }
        guard let fileName = message.attachmentLocalName else {
            completion(XMPPError.bad_request("No such file"), "")
            return
        }
        let url = FileProcessing.fileFolder.appendingPathComponent(fileName)
        guard let data = try? Data(contentsOf: url) else {
            completion(XMPPError.bad_request("No such file"), "")
            return
        }
        guard let chat = client.module(MessageModule.self).chatManager.chat(for: client.context, with: BareJID(to)) else {
            completion(XMPPError.bad_request("No such chat"), "")
            return
        }

        let httpModule = client.module(HttpFileUploadModule.self)
        httpModule.findHttpUploadComponent { res in
            switch res {
            case .success(let components):
                guard let component = components.first(where: { $0.maxSize > data.count }) else {
                    completion(XMPPError.bad_request("File too big"), "")
                    return
                }
                httpModule.requestUploadSlot(componentJid: component.jid, filename: fileName, size: data.count, contentType: url.mimeType) { res in
                    switch res {
                    case .success(let slot):
                        var request = URLRequest(url: slot.putUri)
                        for (k, v) in slot.putHeaders {
                            request.addValue(v, forHTTPHeaderField: k)
                        }
                        request.httpMethod = "PUT"
                        request.httpBody = data
                        request.addValue(String(data.count), forHTTPHeaderField: "Content-Length")
                        request.addValue(url.mimeType, forHTTPHeaderField: "Content-Type")
                        let session = URLSession(configuration: URLSessionConfiguration.default)
                        session.dataTask(with: request) { _, response, error in
                            let code = (response as? HTTPURLResponse)?.statusCode ?? 500
                            guard error == nil, code == 200 || code == 201 else {
                                completion(XMPPError.bad_request("Upload failed"), "")
                                return
                            }
                            if code == 200 {
                                completion(XMPPError.bad_request("Invalid response code"), "")
                            } else {
                                let mesg = chat.createMessage(text: slot.getUri.absoluteString, id: message.id)
                                mesg.oob = slot.getUri.absoluteString
                                chat.send(message: mesg) { res in
                                    switch res {
                                    case .success:
                                        completion(nil, slot.getUri.absoluteString)

                                    case .failure:
                                        completion(XMPPError.bad_request("File uploaded, but message sent failed"), slot.getUri.absoluteString)
                                    }
                                }
                            }
                        }.resume()

                    case .failure(let error):
                        completion(error, "")
                    }
                }

            case .failure(let error):
                completion(error, "")
            }
        }
    }
}