Refactor: Extract boilerplate: safeLaunchLoad, clearToast, ToastEffect (CODE-21/22/23) (#312)

- Extracted `safeLaunchLoad` inline extension function to `ViewModelExt.kt` to encapsulate API call success/failure handling logic and replaced usages across 18 viewmodels.
- Extracted `ToastHost` interface to standardize `clearToast()` behavior across all ViewModels displaying toasts.
- Extracted `ToastEffect` composable to `SharedComponents.kt` and applied it to 16 screens, reducing repetitive side effect code blocks.

Fixes #286

app/src/main/java/com/m57/hermescontrol/ui/channels/ChannelsScreen.kt

@@ -1,6 +1,5 @@
 package com.m57.hermescontrol.ui.channels
 
-import android.widget.Toast
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
@@ -27,7 +26,6 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
@@ -39,6 +37,7 @@ import com.m57.hermescontrol.ui.common.ErrorState
 import com.m57.hermescontrol.ui.common.HermesScaffold
 import com.m57.hermescontrol.ui.common.LoadingState
 import com.m57.hermescontrol.ui.common.SearchBar
+import com.m57.hermescontrol.ui.common.ToastEffect
 import com.m57.hermescontrol.ui.common.listContentPadding
 import com.m57.hermescontrol.ui.common.listItemSpacing
 
@@ -49,7 +48,6 @@ fun ChannelsScreen(
     viewModel: ChannelsViewModel = viewModel { ChannelsViewModel() },
 ) {
     val state by viewModel.uiState.collectAsStateWithLifecycle()
-    val context = LocalContext.current
 
     var query by remember { mutableStateOf("") }
 
@@ -64,12 +62,7 @@ fun ChannelsScreen(
         viewModel.loadPlatforms()
     }
 
-    LaunchedEffect(state.toastMessage) {
-        state.toastMessage?.let { msg ->
-            Toast.makeText(context, msg, Toast.LENGTH_SHORT).show()
-            viewModel.clearToast()
-        }
-    }
+    ToastEffect(toastMessage = state.toastMessage, onClearToast = viewModel::clearToast)
 
     HermesScaffold(
         title = { Text(stringResource(R.string.screen_channels)) },

app/src/main/java/com/m57/hermescontrol/ui/channels/ChannelsViewModel.kt

@@ -1,19 +1,16 @@
 package com.m57.hermescontrol.ui.channels
 
 import androidx.lifecycle.ViewModel
-import androidx.lifecycle.viewModelScope
 import com.m57.hermescontrol.data.model.MessagingPlatform
 import com.m57.hermescontrol.data.model.MessagingPlatformUpdate
 import com.m57.hermescontrol.data.remote.ApiClient
-import com.m57.hermescontrol.data.remote.NetworkResult
 import com.m57.hermescontrol.data.remote.safeApiCall
-import kotlinx.coroutines.Dispatchers
+import com.m57.hermescontrol.ui.common.ToastHost
+import com.m57.hermescontrol.ui.common.safeLaunchLoad
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.update
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.withContext
 
 data class ChannelsUiState(
     val isLoading: Boolean = false,
@@ -22,67 +19,55 @@ data class ChannelsUiState(
     val toastMessage: String? = null,
 )
 
-class ChannelsViewModel : ViewModel() {
+class ChannelsViewModel : ViewModel(), ToastHost {
     private val _uiState = MutableStateFlow(ChannelsUiState())
     val uiState: StateFlow<ChannelsUiState> = _uiState.asStateFlow()
 
     fun loadPlatforms() {
-        _uiState.update { it.copy(isLoading = true, errorMessage = null) }
-        viewModelScope.launch {
-            val result =
-                withContext(Dispatchers.IO) {
-                    safeApiCall { ApiClient.hermesApi.getMessagingPlatforms() }
+        safeLaunchLoad(
+            apiCall = { safeApiCall { ApiClient.hermesApi.getMessagingPlatforms() } },
+            onStart = { _uiState.update { it.copy(isLoading = true, errorMessage = null) } },
+            onSuccess = { data ->
+                _uiState.update { it.copy(isLoading = false, platforms = data?.platforms.orEmpty()) }
+            },
+            onError = { errorMsg ->
+                _uiState.update {
+                    it.copy(
+                        isLoading = false,
+                        errorMessage = "Failed to load platforms: $errorMsg",
+                    )
                 }
-            when (result) {
-                is NetworkResult.Success -> {
-                    _uiState.update { it.copy(isLoading = false, platforms = result.data?.platforms.orEmpty()) }
-                }
-
-                is NetworkResult.Failure -> {
-                    _uiState.update {
-                        it.copy(
-                            isLoading = false,
-                            errorMessage = "Failed to load platforms: ${result.error.message}",
-                        )
-                    }
-                }
-            }
-        }
+            },
+        )
     }
 
     fun configurePlatform(
         platformId: String,
         update: MessagingPlatformUpdate,
     ) {
-        _uiState.update { it.copy(isLoading = true, errorMessage = null) }
-        viewModelScope.launch {
-            val result =
-                withContext(Dispatchers.IO) {
-                    safeApiCall { ApiClient.hermesApi.configurePlatform(platformId, update) }
+        safeLaunchLoad(
+            apiCall = { safeApiCall { ApiClient.hermesApi.configurePlatform(platformId, update) } },
+            onStart = { _uiState.update { it.copy(isLoading = true, errorMessage = null) } },
+            onSuccess = { data ->
+                val message = "$platformId configured successfully — restart the gateway for changes to take effect"
+                _uiState.update {
+                    it.copy(
+                        isLoading = false,
+                        toastMessage = message,
+                    )
                 }
-            when (result) {
-                is NetworkResult.Success -> {
-                    val message = "$platformId configured successfully — restart the gateway for changes to take effect"
-                    _uiState.update {
-                        it.copy(
-                            isLoading = false,
-                            toastMessage = message,
-                        )
-                    }
-                    loadPlatforms()
+                loadPlatforms()
+            },
+            onError = { errorMsg ->
+                _uiState.update {
+                    it.copy(
+                        isLoading = false,
+                        errorMessage = "Failed to configure platform: $errorMsg",
+                        toastMessage = "Failed to configure platform: $errorMsg",
+                    )
                 }
-
-                is NetworkResult.Failure -> {
-                    _uiState.update {
-                        it.copy(
-                            isLoading = false,
-                            errorMessage = "Failed to configure platform: ${result.error.message}",
-                            toastMessage = "Failed to configure platform: ${result.error.message}",
-                        )
-                    }
-                }
-            }
-        }
+            },
+        )
     }
 
     fun configurePlatform(
@@ -92,7 +77,7 @@ class ChannelsViewModel : ViewModel() {
         configurePlatform(platformId, MessagingPlatformUpdate(env = config))
     }
 
-    fun clearToast() {
+    override fun clearToast() {
         _uiState.update { it.copy(toastMessage = null) }
     }
 }