import {AppState} from 'react-native';
import App from "./app"
import KeysManager from "./lib/keysManager"
var _ = require('lodash');


export default class ApplicationState {

  // When the app first launches
  static Launching = "Launching";

  // When the app enters the background completely
  static Backgrounding = "Backgrounding";

  // When the app resumes from the background
  static Resuming = "Resuming";

  // When the user enters their local passcode and/or fingerprint
  static Locking = "Locking";

  // When the user enters their local passcode and/or fingerprint
  static Unlocking = "Unlocking";

  static instance = null;
  static get() {
    if (this.instance == null) {
      this.instance = new ApplicationState();
    }

    return this.instance;
  }

  constructor() {
    this.observers = [];
    this.locked = true;
    AppState.addEventListener('change', this.handleAppStateChange);
    this.didLaunch();
  }

  // Sent from App.js
  receiveApplicationStartEvent() {
    var authProps = this.getAuthenticationPropsForAppState(ApplicationState.Launching);
    if(!authProps.passcode && !authProps.fingerprint) {
      this.unlockApplication();
    }
  }


  handleAppStateChange = (nextAppState) => {

    this.nextAppState = nextAppState;

    var isResuming = nextAppState === "active";
    var isEnteringBackground = nextAppState == 'background';

    console.log("APP STATE CHANGE FROM", this.mostRecentState,
    "TO STATE", nextAppState,
    "IS ENTERING BACKGROUND", isEnteringBackground,
    "IS RESUMING", isResuming,
    );

    if(isEnteringBackground) {
      this.didEnterBackground();
    }

    if(isResuming) {
      this.didResume();
    }

    this.mostRecentState = nextAppState;
  }





  /* State Changes */

  didLaunch() {
    this.notifyOfState(ApplicationState.Launching);
  }

  didEnterBackground() {
    this.notifyOfState(ApplicationState.Backgrounding);

    if(this.shouldLockApplication) {
      this.lockApplication();
    }
  }

  didResume() {
    this.notifyOfState(ApplicationState.Resuming);
  }

  /* End State */





  getMostRecentState() {
    return this.mostRecentState;
  }

  notifyOfState(state) {
    console.log("ApplicationState notifying of state:", state);
    for(var observer of this.observers) {
      observer.callback(state);
    }
  }

  addStateObserver(callback) {
    var observer = {key: Math.random, callback: callback};
    this.observers.push(observer);
    return observer;
  }

  removeStateObserver(observer) {
    _.pull(this.observers, observer);
  }




  /* Locking / Unlocking */

  isLocked() {
    return this.locked;
  }

  isUnlocked() {
    return !this.locked;
  }

  shouldLockApplication() {
    var showPasscode = KeysManager.get().hasOfflinePasscode() && KeysManager.get().passcodeTiming == "immediately";
    var showFingerprint = KeysManager.get().hasFingerprint() && KeysManager.get().fingerprintTiming == "immediately";
    return showPasscode || showFingerprint;
  }

  lockApplication() {
    this.notifyOfState(ApplicationState.Locking);
    this.locked = true;
  }

  unlockApplication() {
    this.notifyOfState(ApplicationState.Unlocking);
    this.locked = false;
  }

  setAuthenticationInProgress(inProgress) {
    this.authenticationInProgress = inProgress;
  }

  isAuthenticationInProgress() {
    return this.authenticationInProgress;
  }

  getAuthenticationPropsForAppState(state) {
    if(state == ApplicationState.Unlocking) {
      return {};
    }

    var hasPasscode = KeysManager.get().hasOfflinePasscode();
    var hasFingerprint = KeysManager.get().hasFingerprint();

    var showPasscode = hasPasscode, showFingerprint = hasFingerprint;

    if(state == ApplicationState.Resuming) {
     showPasscode = hasPasscode && KeysManager.get().passcodeTiming == "immediately";
     showFingerprint = hasFingerprint && KeysManager.get().fingerprintTiming == "immediately";
    }

    var title = showPasscode && showFingerprint ? "Authentication Required" : (showPasscode ? "Passcode Required" : "Fingerprint Required");

    return {
      title: title,
      passcode: showPasscode || false,
      fingerprint: showFingerprint || false,
      onAuthenticate: this.unlockApplication.bind(this)
    }
  }
}