refactor: hoist state out of comments page

common/src/main/kotlin/dev/msfjarvis/claw/common/comments/CommentsPage.kt

@@ -10,13 +10,12 @@ import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.PaddingValues
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.produceState
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import com.github.michaelbull.result.coroutines.runSuspendCatching
-import com.github.michaelbull.result.fold
-import dev.msfjarvis.claw.common.NetworkState
+import com.deliveryhero.whetstone.compose.injectedViewModel
 import dev.msfjarvis.claw.common.NetworkState.Error
 import dev.msfjarvis.claw.common.NetworkState.Loading
 import dev.msfjarvis.claw.common.NetworkState.Success
@@ -35,23 +34,17 @@ fun CommentsPage(
   getSeenComments: suspend (String) -> PostComments?,
   markSeenComments: (String, List<Comment>) -> Unit,
   contentPadding: PaddingValues,
-  modifier: Modifier = Modifier,
   openUserProfile: (String) -> Unit,
+  modifier: Modifier = Modifier,
+  viewModel: CommentsViewModel = injectedViewModel(),
 ) {
-  val postDetails by
-    produceState<NetworkState>(Loading, key1 = postId) {
-      runSuspendCatching { postActions.getComments(postId) }
-        .fold(
-          success = { details -> value = Success(details) },
-          failure = { value = Error(error = it, description = "Failed to load comments") },
-        )
-    }
+  LaunchedEffect(postId) { viewModel.loadPostDetails(postId) }
   val commentState by
     produceState<PostComments?>(initialValue = null, key1 = postId) {
       value = getSeenComments(postId)
     }
 
-  when (postDetails) {
+  when (val postDetails = viewModel.postDetails) {
     is Success<*> -> {
       CommentsPageInternal(
         details = (postDetails as Success<UIPost>).data,
@@ -64,7 +57,7 @@ fun CommentsPage(
       )
     }
     is Error -> {
-      val error = postDetails as Error
+      val error = postDetails
       Box(modifier = Modifier.fillMaxSize()) {
         NetworkError(
           label = error.description,

common/src/main/kotlin/dev/msfjarvis/claw/common/comments/CommentsViewModel.kt

@@ -0,0 +1,61 @@
+/*
+ * Copyright © Harsh Shandilya.
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
+ */
+package dev.msfjarvis.claw.common.comments
+
+import android.app.Application
+import android.content.Context
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.lifecycle.AndroidViewModel
+import com.deliveryhero.whetstone.app.ApplicationScope
+import com.deliveryhero.whetstone.viewmodel.ContributesViewModel
+import com.github.michaelbull.result.coroutines.runSuspendCatching
+import com.github.michaelbull.result.fold
+import com.slack.eithernet.ApiResult.Failure
+import com.slack.eithernet.ApiResult.Success
+import com.squareup.anvil.annotations.optional.ForScope
+import dev.msfjarvis.claw.api.LobstersApi
+import dev.msfjarvis.claw.api.toError
+import dev.msfjarvis.claw.common.NetworkState
+import dev.msfjarvis.claw.core.injection.IODispatcher
+import dev.msfjarvis.claw.model.UIPost
+import dev.msfjarvis.claw.model.toUIPost
+import java.io.IOException
+import javax.inject.Inject
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.withContext
+
+@ContributesViewModel
+class CommentsViewModel
+@Inject
+constructor(
+  private val api: LobstersApi,
+  @IODispatcher private val ioDispatcher: CoroutineDispatcher,
+  @ForScope(ApplicationScope::class) context: Context,
+) : AndroidViewModel(context as Application) {
+  var postDetails by mutableStateOf<NetworkState>(NetworkState.Loading)
+
+  suspend fun loadPostDetails(postId: String) {
+    postDetails =
+      runSuspendCatching<UIPost> {
+          withContext(ioDispatcher) {
+            when (val result = api.getPostDetails(postId)) {
+              is Success -> result.value.toUIPost()
+              is Failure.NetworkFailure -> throw result.error
+              is Failure.UnknownFailure -> throw result.error
+              is Failure.HttpFailure -> throw result.toError()
+              is Failure.ApiFailure -> throw IOException("API returned an invalid response")
+            }
+          }
+        }
+        .fold(
+          success = { details -> NetworkState.Success(details) },
+          failure = { NetworkState.Error(error = it, description = "Failed to load comments") },
+        )
+  }
+}