Add improvements to login screen

app/src/main/java/com/paulohenriquesg/fahrenheit/LoginActivity.kt

@@ -14,15 +14,29 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.text.KeyboardActions
+import androidx.compose.foundation.text.KeyboardOptions
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Language
+import androidx.compose.material.icons.filled.Lock
+import androidx.compose.material.icons.filled.Person
 import androidx.compose.material3.Button
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.OutlinedTextField
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.MutableState
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.focus.FocusDirection
+import androidx.compose.ui.platform.LocalFocusManager
+import androidx.compose.ui.text.input.ImeAction
 import androidx.compose.ui.text.input.PasswordVisualTransformation
 import androidx.compose.ui.unit.dp
 import androidx.tv.material3.ExperimentalTvMaterial3Api
@@ -34,6 +48,7 @@ import retrofit2.Call
 import retrofit2.Callback
 import retrofit2.Response
 
+
 class LoginActivity : ComponentActivity() {
     @OptIn(ExperimentalTvMaterial3Api::class)
     override fun onCreate(savedInstanceState: Bundle?) {
@@ -63,49 +78,101 @@ class LoginActivity : ComponentActivity() {
         var host by remember { mutableStateOf(sharedPreferences.getString("host", "") ?: "") }
         var username by remember { mutableStateOf(sharedPreferences.getString("username", "") ?: "") }
         var password by remember { mutableStateOf("") }
+        var isLoading = remember { mutableStateOf(false) }
+        val focusManager = LocalFocusManager.current
 
         Column(
             modifier = Modifier
                 .fillMaxSize()
                 .padding(16.dp),
-            verticalArrangement = Arrangement.Center
+            verticalArrangement = Arrangement.Center,
+            horizontalAlignment = Alignment.CenterHorizontally
         ) {
+            Text(
+                text = getString(R.string.app_name),
+                style = MaterialTheme.typography.headlineMedium,
+                modifier = Modifier
+                    .padding(bottom = 16.dp)
+            )
             OutlinedTextField(
                 value = host,
                 onValueChange = { host = it },
                 label = { Text("Host") },
-                modifier = Modifier.fillMaxWidth()
+                leadingIcon = { Icon(Icons.Filled.Language, contentDescription = "Host Icon") },
+                modifier = Modifier.fillMaxWidth(),
+                keyboardOptions = KeyboardOptions.Default.copy(
+                    imeAction = ImeAction.Next
+                ),
+                keyboardActions = KeyboardActions(
+                    onNext = { focusManager.moveFocus(FocusDirection.Down) }
+                )
             )
             Spacer(modifier = Modifier.height(8.dp))
             OutlinedTextField(
                 value = username,
                 onValueChange = { username = it },
                 label = { Text("Username") },
-                modifier = Modifier.fillMaxWidth()
+                leadingIcon = { Icon(Icons.Filled.Person, contentDescription = "Username Icon") },
+                modifier = Modifier.fillMaxWidth(),
+                keyboardOptions = KeyboardOptions.Default.copy(
+                    imeAction = ImeAction.Next
+                ),
+                keyboardActions = KeyboardActions(
+                    onNext = { focusManager.moveFocus(FocusDirection.Down) }
+                )
             )
             Spacer(modifier = Modifier.height(8.dp))
             OutlinedTextField(
                 value = password,
                 onValueChange = { password = it },
                 label = { Text("Password") },
+                leadingIcon = { Icon(Icons.Filled.Lock, contentDescription = "Password Icon") },
                 visualTransformation = PasswordVisualTransformation(),
-                modifier = Modifier.fillMaxWidth()
+                modifier = Modifier.fillMaxWidth(),
+                keyboardOptions = KeyboardOptions.Default.copy(
+                    imeAction = ImeAction.Next
+                ),
+                keyboardActions = KeyboardActions(
+                    onNext = { focusManager.moveFocus(FocusDirection.Down) }
+                )
             )
             Spacer(modifier = Modifier.height(16.dp))
-            Button(
-                onClick = { handleLogin(host, username, password) },
-                modifier = Modifier.fillMaxWidth()
-            ) {
-                Text("Login")
+            if (isLoading.value) {
+                CircularProgressIndicator()
+            } else {
+                Button(
+                    onClick = { handleLogin(host, username, password, isLoading) },
+                    modifier = Modifier.fillMaxWidth()
+                ) {
+                    Text("Login")
+                }
             }
         }
     }
 
-    private fun handleLogin(host: String, username: String, password: String) {
+    private fun handleLogin(
+        host: String,
+        username: String,
+        password: String,
+        isLoading: MutableState<Boolean>
+    ) {
+        if (host.isBlank() || username.isBlank() || password.isBlank()) {
+            Toast.makeText(this, "All fields are required", Toast.LENGTH_SHORT).show()
+            return
+        }
+
+        if (!host.startsWith("http://") && !host.startsWith("https://")) {
+            Toast.makeText(this, "Host must start with http:// or https://", Toast.LENGTH_SHORT)
+                .show()
+            return
+        }
+
+        isLoading.value = true
         val loginRequest = LoginRequest(username, password, host)
         val apiService = ApiClient.getApiServiceForLogin(host)
         apiService.login(loginRequest).enqueue(object : Callback<LoginResponse> {
             override fun onResponse(call: Call<LoginResponse>, response: Response<LoginResponse>) {
+                isLoading.value = false
                 if (response.isSuccessful) {
                     val loginResponse = response.body()
                     // Handle successful login
@@ -122,14 +189,23 @@ class LoginActivity : ComponentActivity() {
                     }
                 } else {
                     // Handle login failure
-                    Toast.makeText(this@LoginActivity, "Login failed", Toast.LENGTH_SHORT).show()
+                    Toast.makeText(
+                        this@LoginActivity,
+                        "Login failed: ${response.message()}",
+                        Toast.LENGTH_SHORT
+                    ).show()
                 }
             }
 
             override fun onFailure(call: Call<LoginResponse>, t: Throwable) {
+                isLoading.value = false
                 // Log the error message
                 Log.e("LoginActivity", "Network error", t)
-                Toast.makeText(this@LoginActivity, "Network error: ${t.message}", Toast.LENGTH_SHORT).show()
+                Toast.makeText(
+                    this@LoginActivity,
+                    "Network error: ${t.message}",
+                    Toast.LENGTH_SHORT
+                ).show()
             }
         })
     }