//
//  Copyright (c) 2016 Google Inc.
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.
//

import UIKit

// [START usermanagement_view_import]
import Firebase
// [END usermanagement_view_import]
import GoogleSignIn
import FBSDKCoreKit
import FBSDKLoginKit
import TwitterKit

@objc(MainViewController)
class MainViewController: UITableViewController, GIDSignInDelegate, GIDSignInUIDelegate {

  let kSectionToken = 3
  let kSectionProviders = 2
  let kSectionUser = 1
  let kSectionSignIn = 0

  enum AuthProvider {
    case AuthEmail
    case AuthAnonymous
    case AuthFacebook
    case AuthGoogle
    case AuthTwitter
    case AuthCustom
  }

  /*! @var kOKButtonText
  @brief The text of the "OK" button for the Sign In result dialogs.
  */
  let kOKButtonText = "OK"

  /*! @var kTokenRefreshedAlertTitle
  @brief The title of the "Token Refreshed" alert.
  */
  let kTokenRefreshedAlertTitle = "Token"

  /*! @var kTokenRefreshErrorAlertTitle
  @brief The title of the "Token Refresh error" alert.
  */
  let kTokenRefreshErrorAlertTitle = "Get Token Error"

  /** @var kSetDisplayNameTitle
  @brief The title of the "Set Display Name" error dialog.
  */
  let kSetDisplayNameTitle = "Set Display Name"

  /** @var kUnlinkTitle
   @brief The text of the "Unlink from Provider" error Dialog.
   */
  let kUnlinkTitle = "Unlink from Provider"

  /** @var kChangeEmailText
  @brief The title of the "Change Email" button.
  */
  let kChangeEmailText = "Change Email"

  /** @var kChangePasswordText
  @brief The title of the "Change Password" button.
  */
  let kChangePasswordText = "Change Password"

  /** @var handle
   @brief The handler for the auth state listener, to allow cancelling later.
   */
  var handle: FIRAuthStateDidChangeListenerHandle?

  func showAuthPicker(providers: [AuthProvider]) {
    let picker = UIAlertController(title: "Select Provider",
                                   message: nil,
                                   preferredStyle: .ActionSheet)
    for provider in providers {
      var action : UIAlertAction
      switch(provider) {
      case .AuthEmail:
        action = UIAlertAction(title: "Email", style: .Default, handler: { (UIAlertAction) in
          self.performSegueWithIdentifier("email", sender:nil)
        })
      case .AuthCustom:
        action = UIAlertAction(title: "Custom", style: .Default, handler: { (UIAlertAction) in
          self.performSegueWithIdentifier("customToken", sender: nil)
        })
      case .AuthAnonymous:
        action = UIAlertAction(title: "Guest", style: .Default, handler: { (UIAlertAction) in
          self.showSpinner({
            // [START firebase_auth_anonymous]
            FIRAuth.auth()?.signInAnonymouslyWithCompletion() { (user, error) in
              // [START_EXCLUDE]
              self.hideSpinner({
                if let error = error {
                  self.showMessagePrompt(error.localizedDescription)
                  return
                }
              })
              // [END_EXCLUDE]
            }
            // [END firebase_auth_anonymous]
          })

        })
      case .AuthFacebook:
        action = UIAlertAction(title: "Facebook", style: .Default, handler: { (UIAlertAction) in
          let loginManager = FBSDKLoginManager()
          loginManager.logInWithReadPermissions(["email"], fromViewController: self, handler: { (result, error) in
            if let error = error {
              self.showMessagePrompt(error.localizedDescription)
            } else if(result.isCancelled) {
              print("FBLogin cancelled")
            } else {
              // [START headless_facebook_auth]
              let credential = FIRFacebookAuthProvider.credentialWithAccessToken(FBSDKAccessToken.currentAccessToken().tokenString)
              // [END headless_facebook_auth]
              self.firebaseLogin(credential)
            }
          })
        })
      case .AuthGoogle:
        action = UIAlertAction(title: "Google", style: .Default, handler: { (UIAlertAction) in
          GIDSignIn.sharedInstance().clientID = FIRApp.defaultApp()?.options.clientID
          GIDSignIn.sharedInstance().uiDelegate = self
          GIDSignIn.sharedInstance().delegate = self
          GIDSignIn.sharedInstance().signIn()

        })
      case .AuthTwitter:
        action = UIAlertAction(title: "Twitter", style: .Default, handler: { (UIAlertAction) in
          Twitter.sharedInstance().logInWithCompletion() { (session, error) in
            if let session = session {
              // [START headless_twitter_auth]
              let credential = FIRTwitterAuthProvider.credentialWithToken(session.authToken, secret: session.authTokenSecret)
              // [END headless_twitter_auth]
              self.firebaseLogin(credential)
            } else {
              self.showMessagePrompt((error?.localizedDescription)!)
            }
          }
        })
      }
      picker.addAction(action)
    }

    picker.addAction(UIAlertAction(title: "Cancel", style: .Cancel, handler: nil))
    presentViewController(picker, animated: true, completion: nil)

  }


  @IBAction func didTapSignIn(sender: AnyObject) {
    showAuthPicker([
      AuthProvider.AuthEmail,
      AuthProvider.AuthAnonymous,
      AuthProvider.AuthGoogle,
      AuthProvider.AuthFacebook,
      AuthProvider.AuthTwitter,
      AuthProvider.AuthCustom
    ])
  }

  @IBAction func didTapLink(sender: AnyObject) {
    var providers = Set([
      AuthProvider.AuthEmail,
      AuthProvider.AuthGoogle,
      AuthProvider.AuthFacebook,
      AuthProvider.AuthTwitter
    ])
    // Remove any existing providers. Note that this is not a complete list of
    // providers, so always check the documentation for a complete reference:
    // https://firebase.google.com/docs/auth
    let user = FIRAuth.auth()?.currentUser
    for info in (user?.providerData)! {
      if (info.providerID == FIREmailPasswordAuthProviderID) {
        providers.remove(AuthProvider.AuthEmail)
      } else if (info.providerID == FIRTwitterAuthProviderID) {
        providers.remove(AuthProvider.AuthTwitter)
      } else if (info.providerID == FIRFacebookAuthProviderID) {
        providers.remove(AuthProvider.AuthFacebook)
      } else if (info.providerID == FIRGoogleAuthProviderID) {
        providers.remove(AuthProvider.AuthGoogle)
      }
    }
    showAuthPicker(Array(providers))
  }

  func setTitleDisplay(user: FIRUser?) {
    if let name = user?.displayName {
      self.navigationItem.title = "Welcome \(name)"
    } else {
      self.navigationItem.title = "Authentication Example"
    }
  }

  func firebaseLogin(credential: FIRAuthCredential) {
    showSpinner({
      if let user = FIRAuth.auth()?.currentUser {
        // [START link_credential]
        user.linkWithCredential(credential) { (user, error) in
          // [START_EXCLUDE]
          self.hideSpinner({
            if let error = error {
              self.showMessagePrompt(error.localizedDescription)
              return
            }
          })
          // [END_EXCLUDE]
        }
        // [END link_credential]
      } else {
        // [START signin_credential]
        FIRAuth.auth()?.signInWithCredential(credential) { (user, error) in
          // [START_EXCLUDE]
          self.hideSpinner({
            if let error = error {
              self.showMessagePrompt(error.localizedDescription)
              return
            }
          })
          // [END_EXCLUDE]
        }
        // [END signin_credential]
      }
    })
  }

  // [START headless_google_auth]
  func signIn(signIn: GIDSignIn!, didSignInForUser user: GIDGoogleUser!, withError error: NSError?) {
    if let error = error {
      self.showMessagePrompt(error.localizedDescription)
      return
    }

    let authentication = user.authentication
    let credential = FIRGoogleAuthProvider.credentialWithIDToken(authentication.idToken,
        accessToken: authentication.accessToken)
    // [START_EXCLUDE]
    firebaseLogin(credential)
    // [END_EXCLUDE]
  }
  // [END headless_google_auth]

  @IBAction func didTapSignOut(sender: AnyObject) {
    // [START signout]
    let firebaseAuth = FIRAuth.auth()
    do {
      try firebaseAuth?.signOut()
    } catch let signOutError as NSError {
      print ("Error signing out: %@", signOutError)
    }
    // [END signout]
  }

  override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)
    handle = FIRAuth.auth()?.addAuthStateDidChangeListener() { (auth, user) in
      self.setTitleDisplay(user)
      self.tableView.reloadData()
    }
  }

  override func viewWillDisappear(animated: Bool) {
    super.viewWillDisappear(animated)
    FIRAuth.auth()?.removeAuthStateDidChangeListener(handle!)
  }

  override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    switch section {
    case kSectionSignIn:
      return 1
    case kSectionUser, kSectionToken:
      if FIRAuth.auth()?.currentUser != nil {
        return 1
      } else {
        return 0
      }
    case kSectionProviders:
      if let user = FIRAuth.auth()?.currentUser {
        return user.providerData.count
      }
      return 0
    default:
      return 0
    }
  }

  override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell: UITableViewCell?
    switch indexPath.section {
    case kSectionSignIn:
      if FIRAuth.auth()?.currentUser != nil {
        cell = tableView.dequeueReusableCellWithIdentifier("SignOut")
      } else {
        cell = tableView.dequeueReusableCellWithIdentifier("SignIn")
      }
    case kSectionUser:
      cell = tableView.dequeueReusableCellWithIdentifier("Profile")
      let user = FIRAuth.auth()?.currentUser
      let emailLabel = cell?.viewWithTag(1) as! UILabel
      let userIDLabel = cell?.viewWithTag(2) as! UILabel
      let profileImageView = cell?.viewWithTag(3) as! UIImageView
      emailLabel.text = user?.email
      userIDLabel.text = user?.uid

      let photoURL = user?.photoURL
      struct last {
        static var photoURL: NSURL? = nil
      }
      last.photoURL = photoURL;  // to prevent earlier image overwrites later one.
      if let photoURL = photoURL {
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), {
          let data = NSData.init(contentsOfURL: photoURL)
          if let data = data {
            let image = UIImage.init(data: data)
            dispatch_async(dispatch_get_main_queue(), {
              if (photoURL == last.photoURL) {
                profileImageView.image = image
              }
            })
          }
        })
      } else {
        profileImageView.image = UIImage.init(named: "ic_account_circle")
      }
    case kSectionProviders:
      cell = tableView.dequeueReusableCellWithIdentifier("Provider")
      let userInfo = FIRAuth.auth()?.currentUser?.providerData[indexPath.row]
      cell?.textLabel?.text = userInfo?.providerID
      cell?.detailTextLabel?.text = userInfo?.uid
    case kSectionToken:
      cell = tableView.dequeueReusableCellWithIdentifier("Token")
    default:
      cell = nil
    }
    return cell!
  }

  override func tableView(tableView: UITableView, titleForDeleteConfirmationButtonForRowAtIndexPath indexPath: NSIndexPath) -> String? {
    return "Unlink"
  }

  // Swipe to delete
  override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
    if editingStyle == .Delete {
      let providerID = FIRAuth.auth()?.currentUser?.providerData[indexPath.row].providerID
      showSpinner({
        // [START unlink_provider]
        FIRAuth.auth()?.currentUser?.unlinkFromProvider(providerID!) { (user, error) in
          // [START_EXCLUDE]
          self.hideSpinner({
            if let error = error {
              self.showMessagePrompt(error.localizedDescription)
              return
            }
            tableView.reloadData()
          })
          // [END_EXCLUDE]
        }
        // [END unlink_provider]
      })
    }
  }

  override func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
    if indexPath.section == kSectionUser {
      return 200
    }
    return 44
  }

  override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    return 4
  }

  @IBAction func didTokenRefresh(sender: AnyObject) {
    let action: FIRAuthTokenCallback = {(token, error) in
      let okAction = UIAlertAction.init(title: self.kOKButtonText, style: .Default)
        {action in print(self.kOKButtonText)}
      if let error = error {
        let alertController  = UIAlertController.init(title: self.kTokenRefreshErrorAlertTitle,
          message: error.localizedDescription, preferredStyle: .Alert)
        alertController.addAction(okAction)
        self.presentViewController(alertController, animated: true, completion: nil)
        return
      }

      // Log token refresh event to Scion.
      FIRAnalytics.logEventWithName("tokenrefresh", parameters: nil)

      let alertController = UIAlertController.init(title: self.kTokenRefreshedAlertTitle,
          message: token, preferredStyle: .Alert)
        alertController.addAction(okAction)
        self.presentViewController(alertController, animated: true, completion: nil)
    }
    // [START token_refresh]
    FIRAuth.auth()?.currentUser?.getTokenForcingRefresh(true, completion: action)
    // [END token_refresh]
  }

  /** @fn setDisplayName
  @brief Changes the display name of the current user.
  */
  @IBAction func didSetDisplayName(sender: AnyObject) {
    showTextInputPromptWithMessage("Display Name:") { (userPressedOK, userInput) in
      if let userInput = userInput {
        self.showSpinner({
          // [START profile_change]
          let changeRequest = FIRAuth.auth()?.currentUser?.profileChangeRequest()
          changeRequest?.displayName = userInput
          changeRequest?.commitChangesWithCompletion() { (error) in
            // [END profile_change]
            self.hideSpinner({
              self.showTypicalUIForUserUpdateResultsWithTitle(self.kSetDisplayNameTitle, error: error)
              self.setTitleDisplay(FIRAuth.auth()?.currentUser)
            })
          }
        })
      } else {
        self.showMessagePrompt("displayname can't be empty")
      }
    }
  }

  /** @fn requestVerifyEmail
  @brief Requests a "verify email" email be sent.
  */
  @IBAction func didRequestVerifyEmail(sender: AnyObject) {
    showSpinner({
      // [START send_verification_email]
      FIRAuth.auth()?.currentUser?.sendEmailVerificationWithCompletion({ (error) in
        // [START_EXCLUDE]
        self.hideSpinner({
          if let error = error {
            self.showMessagePrompt(error.localizedDescription)
            return
          }
          self.showMessagePrompt("Sent")
        })
        // [END_EXCLUDE]
      })
      // [END send_verification_email]
    })
  }

  /** @fn changeEmail
  @brief Changes the email address of the current user.
  */
  @IBAction func didChangeEmail(sender: AnyObject) {
    showTextInputPromptWithMessage("Email Address:") { (userPressedOK, userInput) in
      if let userInput = userInput {
        self.showSpinner({
          // [START change_email]
          FIRAuth.auth()?.currentUser?.updateEmail(userInput) { (error) in
            // [START_EXCLUDE]
            self.hideSpinner({
              self.showTypicalUIForUserUpdateResultsWithTitle(self.kChangeEmailText, error:error)
            })
            // [END_EXCLUDE]
          }
          // [END change_email]
        })
      } else {
        self.showMessagePrompt("email can't be empty")
      }
    }
  }

  /** @fn changePassword
  @brief Changes the password of the current user.
  */
  @IBAction func didChangePassword(sender: AnyObject) {
    showTextInputPromptWithMessage("New Password:") { (userPressedOK, userInput) in
      if let userInput = userInput {
        self.showSpinner({
          // [START change_password]
          FIRAuth.auth()?.currentUser?.updatePassword(userInput) { (error) in
            // [START_EXCLUDE]
            self.hideSpinner({
              self.showTypicalUIForUserUpdateResultsWithTitle(self.kChangePasswordText, error:error)
            })
            // [END_EXCLUDE]
          }
          // [END change_password]
        })
      } else {
        self.showMessagePrompt("password can't be empty")
      }
    }
  }

  // MARK: - Helpers

  /** @fn showTypicalUIForUserUpdateResultsWithTitle:error:
  @brief Shows a @c UIAlertView if error is non-nil with the localized description of the error.
  @param resultsTitle The title of the @c UIAlertView
  @param error The error details to display if non-nil.
  */
  func showTypicalUIForUserUpdateResultsWithTitle(resultsTitle: String, error: NSError?) {
    if let error = error {
      let message = "\(error.domain) (\(error.code))\n\(error.localizedDescription)"
      let okAction = UIAlertAction.init(title: self.kOKButtonText, style: .Default)
        {action in print(self.kOKButtonText)}
      let alertController  = UIAlertController.init(title: resultsTitle,
        message: message, preferredStyle: .Alert)
      alertController.addAction(okAction)
      self.presentViewController(alertController, animated: true, completion: nil)
      return
    }
    tableView.reloadData()
  }

}