implementation 'com.squareup.retrofit2:retrofit:2.9.0'
implementation 'com.squareup.retrofit2:converter-gson:2.9.0'

implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.8.0"
implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.8.0"

implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.3"

data class Post(
    val userId: Int,
    val id: Int,
    val title: String,
    val body: String
)

import retrofit2.http.GET

interface ApiService {

    @GET("posts")
    suspend fun getPosts(): List<Post>
}

import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory

object RetrofitInstance {

    private const val BASE_URL =
        "https://jsonplaceholder.typicode.com/"

    val api: ApiService by lazy {

        Retrofit.Builder()
            .baseUrl(BASE_URL)
            .addConverterFactory(
                GsonConverterFactory.create()
            )
            .build()
            .create(ApiService::class.java)
    }
}

class PostRepository {

    suspend fun getPosts(): List<Post> {
        return RetrofitInstance.api.getPosts()
    }
}

import androidx.lifecycle.*
import kotlinx.coroutines.launch

class PostViewModel : ViewModel() {

    private val repository = PostRepository()

    private val _posts = MutableLiveData<List<Post>>()
    val posts: LiveData<List<Post>> = _posts

    fun fetchPosts() {

        viewModelScope.launch {

            try {

                val result = repository.getPosts()
                _posts.value = result

            } catch (e: Exception) {

                e.printStackTrace()

            }
        }
    }
}

class MainActivity : AppCompatActivity() {

    private lateinit var viewModel: PostViewModel

    override fun onCreate(savedInstanceState: Bundle?) {

        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        viewModel = ViewModelProvider(this)
            .get(PostViewModel::class.java)

        viewModel.fetchPosts()

        viewModel.posts.observe(this) { posts ->

            println(posts)

        }
    }
}

sealed class Resource<T>(
    val data: T? = null,
    val message: String? = null
) {

    class Loading<T> : Resource<T>()

    class Success<T>(data: T)
        : Resource<T>(data)

    class Error<T>(message: String)
        : Resource<T>(message = message)
}

private val _state =
    MutableLiveData<Resource<List<Post>>>()

val state: LiveData<Resource<List<Post>>> =
    _state

private val _posts =
    MutableStateFlow<List<Post>>(emptyList())

val posts = _posts.asStateFlow()

RetrofitInstance.api.getPosts()