Cleanup logic in UpdatesPresenter (#8035)

app/src/main/java/eu/kanade/presentation/updates/UpdatesState.kt

@@ -5,24 +5,47 @@ import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.setValue
+import eu.kanade.core.util.insertSeparators
+import eu.kanade.tachiyomi.ui.recent.updates.UpdatesItem
 import eu.kanade.tachiyomi.ui.recent.updates.UpdatesPresenter
+import eu.kanade.tachiyomi.util.lang.toDateKey
+import java.util.Date
 
 @Stable
 interface UpdatesState {
     val isLoading: Boolean
-    val uiModels: List<UpdatesUiModel>
-    val selected: List<UpdatesUiModel.Item>
+    val items: List<UpdatesItem>
+    val selected: List<UpdatesItem>
     val selectionMode: Boolean
+    val uiModels: List<UpdatesUiModel>
     var dialog: UpdatesPresenter.Dialog?
 }
 fun UpdatesState(): UpdatesState = UpdatesStateImpl()
 class UpdatesStateImpl : UpdatesState {
     override var isLoading: Boolean by mutableStateOf(true)
-    override var uiModels: List<UpdatesUiModel> by mutableStateOf(emptyList())
-    override val selected: List<UpdatesUiModel.Item> by derivedStateOf {
-        uiModels.filterIsInstance<UpdatesUiModel.Item>()
-            .filter { it.item.selected }
+    override var items: List<UpdatesItem> by mutableStateOf(emptyList())
+    override val selected: List<UpdatesItem> by derivedStateOf {
+        items.filter { it.selected }
     }
     override val selectionMode: Boolean by derivedStateOf { selected.isNotEmpty() }
+    override val uiModels: List<UpdatesUiModel> by derivedStateOf {
+        items.toUpdateUiModel()
+    }
     override var dialog: UpdatesPresenter.Dialog? by mutableStateOf(null)
 }
+
+fun List<UpdatesItem>.toUpdateUiModel(): List<UpdatesUiModel> {
+    return this.map {
+        UpdatesUiModel.Item(it)
+    }
+        .insertSeparators { before, after ->
+            val beforeDate = before?.item?.update?.dateFetch?.toDateKey() ?: Date(0)
+            val afterDate = after?.item?.update?.dateFetch?.toDateKey() ?: Date(0)
+            when {
+                beforeDate.time != afterDate.time && afterDate.time != 0L ->
+                    UpdatesUiModel.Header(afterDate)
+                // Return null to avoid adding a separator between two items.
+                else -> null
+            }
+        }
+}