LoginActivity.kt

package com.kweracodes.nyumba

import android.content.Intent
import android.net.Uri
import android.os.Bundle
import android.view.View
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import com.kweracodes.nyumba.network.LoginResponse
import com.kweracodes.nyumba.services.AuthApiClient
import com.kweracodes.nyumba.storage.SharedPrefManager
import kotlinx.android.synthetic.main.activity_login.*
import retrofit2.Call
import retrofit2.Callback
import retrofit2.Response


class LoginActivity : AppCompatActivity() {

    private lateinit var apiClient: AuthApiClient

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_login)


        val sharedPrefManager = SharedPrefManager(this)
        buttonLogin.setOnClickListener {

            val email = emailaddress.text.toString().trim()
            val password = clientpassword.text.toString().trim()

            if (email.isEmpty()) {
                emailaddress.error = "Email required"
                emailaddress.requestFocus()
                return@setOnClickListener
            }

            if (password.isEmpty()) {
                clientpassword.error = "Password required"
                clientpassword.requestFocus()
                return@setOnClickListener
            }

            progressbarlogin.visibility = View.VISIBLE
            buttonLogin.visibility = View.GONE

            apiClient = AuthApiClient

            apiClient.instance.userLogin(email, password)
                    .enqueue(object : Callback<LoginResponse> {
                        override fun onFailure(call: Call<LoginResponse>, t: Throwable) {
                            Toast.makeText(applicationContext, "Error connecting to the server", Toast.LENGTH_LONG).show()

                            progressbarlogin.visibility = View.GONE
                            buttonLogin.visibility = View.VISIBLE
                        }

                        override fun onResponse(call: Call<LoginResponse>, response: Response<LoginResponse>) {

                            if (response.isSuccessful) {

                                //Store user session
                                sharedPrefManager.saveUser(response.body()?.user!!)
                                //Save token if login is successful
                                sharedPrefManager.saveAuthToken(response.body()?.token!!)

                                Toast.makeText(this@LoginActivity, "Done saving", Toast.LENGTH_LONG).show()
                                progressbarlogin.visibility = View.GONE

                                Toast.makeText(applicationContext, response.body()?.message, Toast.LENGTH_SHORT).show()
                                val intent = Intent(applicationContext, NyumbaHome::class.java)
                                intent.flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
                                startActivity(intent)

                            } else {

                                Toast.makeText(applicationContext, "Sorry, login Unsuccessful. Please check credentials and try again", Toast.LENGTH_LONG).show()
                                progressbarlogin.visibility = View.GONE

                                buttonLogin.visibility = View.VISIBLE

                            }

                        }


                    })
        }

        //start forgot Password 
        forgotpassword.setOnClickListener {
            val url = "https://www.usenyumba.com/password/reset"
            val reset = Intent(Intent.ACTION_VIEW)
            reset.data = Uri.parse(url)
            startActivity(reset)
        }

        signup.setOnClickListener {
            val intent = Intent(this, RegisterActivity::class.java)
            startActivity(intent)
        }
    }

    override fun onStart() {
        super.onStart()
        val sharedPrefManager = SharedPrefManager.getInstance(this)
        if (sharedPrefManager.isLoggedIn) {
            val intent = Intent(applicationContext, NyumbaHome::class.java)
            intent.flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK

            startActivity(intent)
        }
    }

}

SharedPrefManager.kt

package com.kweracodes.nyumba.storage

import android.content.Context
import com.kweracodes.nyumba.models.User

class SharedPrefManager constructor(private val mCtx: Context) {

    val isLoggedIn: Boolean
        get() {
            val sharedPreferences = mCtx.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE)
            return sharedPreferences.getInt("id", -1) != -1
        }

    val user: User
        get() {
            val sharedPreferences = mCtx.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE)
            return User(
                    sharedPreferences.getString("about", null),
                    sharedPreferences.getString("address", null),
                    sharedPreferences.getString("city", null),
                    sharedPreferences.getString("company", null),
                    sharedPreferences.getString("createdAt", null),
                    sharedPreferences.getString("email", null),
                    sharedPreferences.getString("emailVerifiedAt", ""),
                    sharedPreferences.getString("fname", ""),
                    sharedPreferences.getInt("id", -1),
                    sharedPreferences.getString("lname", null),
                    sharedPreferences.getString("locality", null),
                    sharedPreferences.getString("phone", null),
                    sharedPreferences.getString("preferredComm", null),
                    sharedPreferences.getString("profilePic", null),
                    sharedPreferences.getString("updatedAt", null)
            )
        }
    
    fun saveUser(user: User) {

        val sharedPreferences = mCtx.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE)
        val editor = sharedPreferences.edit()

        editor.putInt("id", user.id)
        editor.putString("email", user.email)
        editor.putString("lname", user.lname)
        editor.putString("lname", user.fname)
        editor.putString("lname", user.about)
        editor.putString("lname", user.address)
        editor.putString("lname", user.emailVerifiedAt.toString())
        editor.putString("lname", user.city)
        editor.putString("lname", user.locality)
        editor.putString("lname", user.company)
        editor.putString("lname", user.createdAt)
        editor.putString("lname", user.phone)
        editor.putString("lname", user.preferredComm)
        editor.putString("school", user.updatedAt)

        editor.apply()

    }

    fun saveAuthToken(token: String?) {
        val sharedPreferences = mCtx.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE)
        val editor = sharedPreferences.edit()
        editor.putString(AUTH_TOKEN, token)
        editor.apply()

    }

    fun fetchAuthToken(): String? {
        val sharedPreferences = mCtx.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE)
        return sharedPreferences.getString(SharedPrefManager.AUTH_TOKEN, null)
    }

    fun clear() {
        val sharedPreferences = mCtx.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE)
        val editor = sharedPreferences.edit()
        editor.clear()
        editor.apply()
    }

    companion object {
        private val SHARED_PREF_NAME = "my_shared_preff"
        private var mInstance: SharedPrefManager? = null
        private val AUTH_TOKEN = ""

        @Synchronized
        fun getInstance(mCtx: Context): SharedPrefManager {
            if (mInstance == null) {
                mInstance = SharedPrefManager(mCtx)
            }
            return mInstance as SharedPrefManager
        }
    }

}