Introduce FollowSetFeedViewModel and FollowSetState.

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/lists/FollowSetFeedViewModel.kt

@@ -0,0 +1,126 @@
+/**
+ * Copyright (c) 2024 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.ui.screen.loggedIn.lists
+
+import android.util.Log
+import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.Stable
+import androidx.compose.runtime.mutableStateOf
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.vitorpamplona.amethyst.model.LocalCache
+import com.vitorpamplona.amethyst.service.checkNotInMainThread
+import com.vitorpamplona.amethyst.ui.dal.FeedFilter
+import com.vitorpamplona.amethyst.ui.feeds.InvalidatableContent
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.notifications.equalImmutableLists
+import com.vitorpamplona.ammolite.relays.BundledUpdate
+import kotlinx.collections.immutable.ImmutableList
+import kotlinx.collections.immutable.toImmutableList
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.update
+import kotlinx.coroutines.launch
+
+@Stable
+open class FollowSetFeedViewModel(
+    val dataSource: FeedFilter<FollowSet>,
+) : ViewModel(),
+    InvalidatableContent {
+    private val _feedContent = MutableStateFlow<FollowSetState>(FollowSetState.Loading)
+    val feedContent = _feedContent.asStateFlow()
+
+    private fun refresh() {
+        viewModelScope.launch(Dispatchers.Default) { refreshSuspended() }
+    }
+
+    override val isRefreshing: MutableState<Boolean> = mutableStateOf(false)
+
+    private fun refreshSuspended() {
+        checkNotInMainThread()
+
+        try {
+            isRefreshing.value = true
+
+            val notes = dataSource.loadTop().toImmutableList()
+
+            val oldNotesState = _feedContent.value
+            if (oldNotesState is FollowSetState.Loaded) {
+                // Using size as a proxy for has changed.
+                if (!equalImmutableLists(notes, oldNotesState.feed.value.toImmutableList())) {
+                    updateFeed(notes)
+                }
+            } else {
+                updateFeed(notes)
+            }
+        } finally {
+            isRefreshing.value = false
+        }
+    }
+
+    private fun updateFeed(notes: ImmutableList<FollowSet>) {
+        viewModelScope.launch(Dispatchers.Main) {
+            val currentState = _feedContent.value
+            if (notes.isEmpty()) {
+                _feedContent.update { FollowSetState.Empty }
+            } else if (currentState is FollowSetState.Loaded) {
+                // updates the current list
+                currentState.feed.value = notes
+            } else {
+                _feedContent.update { FollowSetState.Loaded(mutableStateOf(notes)) }
+            }
+        }
+    }
+
+    private val bundler = BundledUpdate(250, Dispatchers.IO)
+
+    override fun invalidateData(ignoreIfDoing: Boolean) {
+        bundler.invalidate(ignoreIfDoing) {
+            // adds the time to perform the refresh into this delay
+            // holding off new updates in case of heavy refresh routines.
+            refreshSuspended()
+        }
+    }
+
+    var collectorJob: Job? = null
+
+    init {
+        Log.d("Init", "${this.javaClass.simpleName}")
+        collectorJob =
+            viewModelScope.launch(Dispatchers.IO) {
+                checkNotInMainThread()
+
+                LocalCache.live.newEventBundles.collect { newNotes ->
+                    checkNotInMainThread()
+
+                    invalidateData()
+                }
+            }
+    }
+
+    override fun onCleared() {
+        Log.d("Init", "OnCleared: ${this.javaClass.simpleName}")
+        bundler.cancel()
+        collectorJob?.cancel()
+        super.onCleared()
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/lists/FollowSetState.kt

@@ -0,0 +1,38 @@
+/**
+ * Copyright (c) 2024 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.ui.screen.loggedIn.lists
+
+import androidx.compose.runtime.MutableState
+import kotlinx.collections.immutable.ImmutableList
+
+sealed class FollowSetState {
+    data object Loading : FollowSetState()
+
+    class Loaded(
+        val feed: MutableState<ImmutableList<FollowSet>>,
+    ) : FollowSetState()
+
+    object Empty : FollowSetState()
+
+    class FeedError(
+        val errorMessage: String,
+    ) : FollowSetState()
+}