import Foundation
import Capacitor
import FirebaseCore
import FirebaseAuth

public typealias AuthStateChangedObserver = () -> Void

@objc public class FirebaseAuthentication: NSObject {
    public let errorDeviceUnsupported = "Device is not supported. At least iOS 13 is required."
    public let errorCustomTokenSkipNativeAuth = "signInWithCustomToken cannot be used in combination with skipNativeAuth."
    public var authStateObserver: AuthStateChangedObserver?
    private let plugin: FirebaseAuthenticationPlugin
    private let config: FirebaseAuthenticationConfig
    private var appleAuthProviderHandler: AppleAuthProviderHandler?
    private var facebookAuthProviderHandler: FacebookAuthProviderHandler?
    private var googleAuthProviderHandler: GoogleAuthProviderHandler?
    private var oAuthProviderHandler: OAuthProviderHandler?
    private var phoneAuthProviderHandler: PhoneAuthProviderHandler?
    private var savedCall: CAPPluginCall?

    init(plugin: FirebaseAuthenticationPlugin, config: FirebaseAuthenticationConfig) {
        self.plugin = plugin
        self.config = config
        super.init()
        if FirebaseApp.app() == nil {
            FirebaseApp.configure()
        }
        self.initAuthProviderHandlers(config: config)
        Auth.auth().addStateDidChangeListener {_, _ in
            self.authStateObserver?()
        }
    }

    @objc func getCurrentUser() -> User? {
        return Auth.auth().currentUser
    }

    @objc func getIdToken(_ forceRefresh: Bool, completion: @escaping (String?, Error?) -> Void) {
        let user = self.getCurrentUser()
        user?.getIDTokenResult(forcingRefresh: forceRefresh, completion: { result, error in
            if let error = error {
                completion(nil, error)
                return
            }
            completion(result?.token, nil)
        })
    }

    @objc func setLanguageCode(_ languageCode: String) {
        Auth.auth().languageCode = languageCode
    }

    @objc func signInWithApple(_ call: CAPPluginCall) {
        self.savedCall = call
        self.appleAuthProviderHandler?.signIn(call: call)
    }

    @objc func signInWithFacebook(_ call: CAPPluginCall) {
        self.savedCall = call
        self.facebookAuthProviderHandler?.signIn(call: call)
    }

    @objc func signInWithGithub(_ call: CAPPluginCall) {
        self.savedCall = call
        self.oAuthProviderHandler?.signIn(call: call, providerId: "github.com")
    }

    @objc func signInWithGoogle(_ call: CAPPluginCall) {
        self.savedCall = call
        self.googleAuthProviderHandler?.signIn(call: call)
    }

    @objc func signInWithMicrosoft(_ call: CAPPluginCall) {
        self.savedCall = call
        self.oAuthProviderHandler?.signIn(call: call, providerId: "microsoft.com")
    }

    @objc func signInWithPhoneNumber(_ call: CAPPluginCall) {
        self.savedCall = call
        self.phoneAuthProviderHandler?.signIn(call: call)
    }

    @objc func signInWithTwitter(_ call: CAPPluginCall) {
        self.savedCall = call
        self.oAuthProviderHandler?.signIn(call: call, providerId: "twitter.com")
    }

    @objc func signInWithYahoo(_ call: CAPPluginCall) {
        self.savedCall = call
        self.oAuthProviderHandler?.signIn(call: call, providerId: "yahoo.com")
    }

    @objc func signInWithCustomToken(_ call: CAPPluginCall) {
        if config.skipNativeAuth == true {
            call.reject(self.errorCustomTokenSkipNativeAuth)
            return
        }

        let token = call.getString("token", "")

        self.savedCall = call
        Auth.auth().signIn(withCustomToken: token) { _, error in
            if let error = error {
                self.handleFailedSignIn(message: nil, error: error)
                return
            }
            guard let savedCall = self.savedCall else {
                return
            }
            let user = self.getCurrentUser()
            let result = FirebaseAuthenticationHelper.createSignInResult(credential: nil, user: user, idToken: nil, nonce: nil)
            savedCall.resolve(result)
        }
    }

    @objc func signOut(_ call: CAPPluginCall) {
        do {
            try Auth.auth().signOut()
            googleAuthProviderHandler?.signOut()
            facebookAuthProviderHandler?.signOut()
            call.resolve()
        } catch let signOutError as NSError {
            call.reject("Error signing out: \(signOutError)")
        }
    }

    @objc func useAppLanguage() {
        Auth.auth().useAppLanguage()
    }

    func handleSuccessfulSignIn(credential: AuthCredential, idToken: String?, nonce: String?) {
        if config.skipNativeAuth == true {
            guard let savedCall = self.savedCall else {
                return
            }
            let result = FirebaseAuthenticationHelper.createSignInResult(credential: credential, user: nil, idToken: idToken, nonce: nonce)
            savedCall.resolve(result)
            return
        }
        Auth.auth().signIn(with: credential) { (_, error) in
            if let error = error {
                self.handleFailedSignIn(message: nil, error: error)
                return
            }
            guard let savedCall = self.savedCall else {
                return
            }
            let user = self.getCurrentUser()
            let result = FirebaseAuthenticationHelper.createSignInResult(credential: credential, user: user, idToken: idToken, nonce: nonce)
            savedCall.resolve(result)
        }
    }

    func handleFailedSignIn(message: String?, error: Error?) {
        guard let savedCall = self.savedCall else {
            return
        }
        let errorMessage = message ?? error?.localizedDescription ?? ""
        savedCall.reject(errorMessage, nil, error)
    }

    func getPlugin() -> FirebaseAuthenticationPlugin {
        return self.plugin
    }

    private func initAuthProviderHandlers(config: FirebaseAuthenticationConfig) {
        if config.providers.contains("apple.com") {
            self.appleAuthProviderHandler = AppleAuthProviderHandler(self)
        }
        if config.providers.contains("facebook.com") {
            self.facebookAuthProviderHandler = FacebookAuthProviderHandler(self)
        }
        if config.providers.contains("google.com") {
            self.googleAuthProviderHandler = GoogleAuthProviderHandler(self)
        }
        if config.providers.contains("phone") {
            self.phoneAuthProviderHandler = PhoneAuthProviderHandler(self)
        }
        self.oAuthProviderHandler = OAuthProviderHandler(self)
    }
}