Repo and code for Android Facebook auth

build.gradle

compile 'com.facebook.android:facebook-android-sdk:4.1.0'

layout.xml

<ScrollView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:facebook="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
  <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
  
      <com.facebook.login.widget.LoginButton
              android:id="@+id/login_button"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_gravity="center_horizontal"
              android:layout_marginTop="30dp"
              android:layout_marginBottom="30dp" />

    </LinearLayout>
</ScrollView>

LoginFragment.kt

public fun facebookAuth(fragment: Fragment) {

        val permissions = Arrays.asList("email", "public_profile", "user_events")

        val loginButton = rootView!!.findViewById(R.id.login_button) as LoginButton
        loginButton.setReadPermissions(permissions)
        // If using in a fragment
        loginButton.setFragment(this)
        // Other app specific specialization

        loginButton.setOnClickListener(object : View.OnClickListener {

            override fun onClick(v: View) {
                object : AccessTokenTracker() {
                    override fun onCurrentAccessTokenChanged(oldAccessToken: AccessToken?, currentAccessToken: AccessToken?) {
                        if (currentAccessToken == null) {
                            // Here you put when do Logout
                        }
                    }
                }
            }
        })



        // Callback registration
        loginButton.registerCallback(callbackManager, object : FacebookCallback<LoginResult> {
            override fun onSuccess(loginResult: LoginResult) {
                // App code
                val accessToken = loginResult.getAccessToken().getToken()
                GraphRequest.newMeRequest(loginResult.getAccessToken(), object : GraphRequest.GraphJSONObjectCallback {

                    override fun onCompleted(user: JSONObject?, response: GraphResponse) {

                        if (user != null) {
                            /**
                            * How to get user login info
                            * user.optString("id")
                            * user.optString("name")
                            * user.optString("email")
                            */
                        }

                    }
                }).executeAsync()
            }

            override fun onCancel() {
            }

            override fun onError(exception: FacebookException) {
            }
        })


    }