implement: simple LoginPage, LoginViewModel, LoginUseCase

android/app/src/main/java/com/goliath/emojihub/usecases/LoginUseCase.kt

@@ -0,0 +1,16 @@
+package com.goliath.emojihub.usecases
+
+import com.goliath.emojihub.models.User
+import com.goliath.emojihub.models.UserDto
+import com.goliath.emojihub.viewmodels.Resource
+
+class LoginUseCase {
+    fun login(username: String, password: String): Resource<User>? {
+        val dummyUser = User(UserDto(
+            userId = "1",
+            likedEmojiList = arrayOf(),
+            createdEmojiList = arrayOf()
+        ))
+        return Resource.Success(dummyUser);
+    }
+}

android/app/src/main/java/com/goliath/emojihub/viewmodels/LoginViewModel.kt

@@ -0,0 +1,30 @@
+package com.goliath.emojihub.viewmodels
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.goliath.emojihub.models.User
+import com.goliath.emojihub.usecases.LoginUseCase
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.launch
+import javax.inject.Inject
+
+@HiltViewModel
+class LoginViewModel @Inject constructor(
+    private val loginUseCase: LoginUseCase
+) {
+
+    private val _loginState = MutableLiveData<Resource<User>>()
+    val loginState: LiveData<Resource<User>> = _loginState
+
+    fun onLoginClicked(username: String, password: String) {
+            _loginState.value = loginUseCase.login(username, password)  // Hand
+    }
+}
+
+sealed class Resource<out T> {
+    object Loading : Resource<Nothing>()
+    open class Success<out T>(val data: T) : Resource<T>()
+    open class Error(val exception: Throwable) : Resource<Nothing>()
+}

android/app/src/main/java/com/goliath/emojihub/views/LoginPage.kt

@@ -0,0 +1,67 @@
+package com.goliath.emojihub.views
+
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material.Button
+import androidx.compose.material.Text
+import androidx.compose.material.TextField
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+
+@Preview(showBackground = true)
+@Composable
+fun PreviewLoginView() {
+    LoginPage(onLoginClicked = { _, _ -> },
+                onCreateAccountClicked = {})
+}
+
+@Composable
+fun LoginPage(
+    onLoginClicked: (String, String) -> Unit,
+    onCreateAccountClicked: () -> Unit
+) {
+    var username by remember { mutableStateOf("") }
+    var password by remember { mutableStateOf("") }
+
+    // Your UI components here
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .padding(all = 16.dp)
+    ) {
+        Text("EmojiHub")
+        Spacer(modifier = Modifier.height(16.dp))
+        TextField(
+            value = username,
+            onValueChange = { username = it },
+            label = { Text("Username") }
+        )
+        Spacer(modifier = Modifier.height(16.dp))
+        TextField(
+            value = password,
+            onValueChange = { password = it },
+            label = { Text("Password") }
+        )
+        Spacer(modifier = Modifier.height(16.dp))
+        Button(
+            onClick = { onLoginClicked(username, password) }
+        ) {
+            Text("로그인")
+        }
+        Spacer(modifier = Modifier.height(16.dp))
+        Button(
+            onClick = { onCreateAccountClicked() }
+        ) {
+            Text("계정 생성")
+        }
+    }
+}