Add saved lists feature

Signed-off-by: Aditya Wasan <adityawasan55@gmail.com>

app/src/main/java/dev/msfjarvis/lobsters/MainActivity.kt

@@ -3,18 +3,34 @@ package dev.msfjarvis.lobsters
 import android.os.Bundle
 import androidx.activity.viewModels
 import androidx.appcompat.app.AppCompatActivity
+import androidx.compose.animation.animate
+import androidx.compose.foundation.Icon
 import androidx.compose.foundation.Text
 import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.offset
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyColumnForIndexed
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.material.FloatingActionButton
+import androidx.compose.material.IconToggleButton
+import androidx.compose.material.MaterialTheme
 import androidx.compose.material.Scaffold
+import androidx.compose.material.TopAppBar
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Favorite
+import androidx.compose.material.icons.filled.FavoriteBorder
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.MutableState
 import androidx.compose.runtime.Providers
+import androidx.compose.runtime.State
 import androidx.compose.runtime.ambientOf
 import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.setContent
@@ -23,8 +39,10 @@ import androidx.compose.ui.unit.dp
 import dagger.hilt.android.AndroidEntryPoint
 import dev.msfjarvis.lobsters.compose.utils.IconResource
 import dev.msfjarvis.lobsters.data.LobstersViewModel
+import dev.msfjarvis.lobsters.model.LobstersPost
 import dev.msfjarvis.lobsters.ui.LobstersItem
 import dev.msfjarvis.lobsters.ui.LobstersTheme
+import dev.msfjarvis.lobsters.ui.savedTitleColor
 import dev.msfjarvis.lobsters.urllauncher.UrlLauncher
 import javax.inject.Inject
 
@@ -52,40 +70,111 @@ fun LobstersApp(
   viewModel: LobstersViewModel
 ) {
   val urlLauncher = UrlLauncherAmbient.current
-  val state = viewModel.posts.collectAsState()
-  val lastIndex = state.value.lastIndex
+  val hottestPostsState = viewModel.posts.collectAsState()
+  val savedPostsState = viewModel.savedPosts.collectAsState()
+  val lastIndex = hottestPostsState.value.lastIndex
+  val showSaved = remember { mutableStateOf(false) }
 
   Scaffold(
+    topBar = { LobsterTopAppbar(showSaved) },
     bodyContent = {
-      if (state.value.isEmpty()) {
-        Column(
-          modifier = Modifier.fillMaxSize(),
-          verticalArrangement = Arrangement.Center,
-          horizontalAlignment = Alignment.CenterHorizontally,
-        ) {
-          IconResource(R.drawable.ic_sync_problem_24px)
-          Text(stringResource(R.string.loading))
-        }
+      if ((!showSaved.value && hottestPostsState.value.isEmpty()) || (showSaved.value && savedPostsState.value.isEmpty())) {
+        LobsterEmptyList(showSaved)
       } else {
+        LobsterList(
+          showSaved,
+          savedPostsState,
+          hottestPostsState,
+          lastIndex,
+          viewModel,
+          urlLauncher
+        )
+      }
+    },
+    floatingActionButton = { LobsterFAB(showSaved, viewModel) },
+  )
+}
+
+@Composable
+private fun LobsterFAB(
+  showSaved: MutableState<Boolean>,
+  viewModel: LobstersViewModel
+) {
+  val animatedYOffset = animate(if (showSaved.value) 100.dp else 0.dp)
+
+  FloatingActionButton(
+    onClick = { viewModel.refreshPosts() },
+    modifier = Modifier.offset(y = animatedYOffset)
+  ) {
+    IconResource(resourceId = R.drawable.ic_refresh_24px)
+  }
+}
+
+@Composable
+private fun LobsterList(
+  showSaved: MutableState<Boolean>,
+  savedPostsState: State<List<LobstersPost>>,
+  hottestPostsState: State<List<LobstersPost>>,
+  lastIndex: Int,
+  viewModel: LobstersViewModel,
+  urlLauncher: UrlLauncher
+) {
+  val hottestPostsListState = rememberLazyListState()
+  val savedPostsListState = rememberLazyListState()
+
   LazyColumnForIndexed(
-          items = state.value,
+    items = if (showSaved.value) savedPostsState.value else hottestPostsState.value,
+    state = if (showSaved.value) savedPostsListState else hottestPostsListState,
     modifier = Modifier.padding(horizontal = 8.dp)
   ) { index, item ->
-          if (lastIndex == index) {
+    if (lastIndex == index && !showSaved.value) {
       viewModel.getMorePosts()
     }
     LobstersItem(
       item,
       linkOpenAction = { post -> urlLauncher.launch(post.url.ifEmpty { post.commentsUrl }) },
       commentOpenAction = { post -> urlLauncher.launch(post.commentsUrl) },
+      saveAction = { post -> if (!showSaved.value) viewModel.savePost(post) },
     )
   }
+}
+
+@Composable
+private fun LobsterEmptyList(showSaved: MutableState<Boolean>) {
+  Column(
+    modifier = Modifier.fillMaxSize(),
+    verticalArrangement = Arrangement.Center,
+    horizontalAlignment = Alignment.CenterHorizontally,
+  ) {
+    if (!showSaved.value) {
+      IconResource(R.drawable.ic_sync_problem_24px, modifier = Modifier.padding(16.dp))
+      Text(stringResource(R.string.loading))
+    } else {
+      Icon(Icons.Default.FavoriteBorder, tint = savedTitleColor, modifier = Modifier.padding(16.dp))
+      Text(stringResource(R.string.no_saved_posts))
     }
-    },
-    floatingActionButton = {
-      FloatingActionButton(onClick = { viewModel.refreshPosts() }) {
-        IconResource(resourceId = R.drawable.ic_refresh_24px)
   }
-    },
+}
+
+@Composable
+private fun LobsterTopAppbar(showSaved: MutableState<Boolean>) {
+  TopAppBar {
+    Box(modifier = Modifier.fillMaxWidth()) {
+      Text(
+        text = if (showSaved.value) "Saved" else "Home",
+        modifier = Modifier.padding(16.dp).align(Alignment.CenterStart),
+        style = MaterialTheme.typography.h6,
+      )
+      IconToggleButton(
+        checked = showSaved.value,
+        onCheckedChange = { showSaved.value = !showSaved.value },
+        modifier = Modifier.padding(8.dp).align(Alignment.CenterEnd),
+      ) {
+        Icon(
+          asset = if (showSaved.value) Icons.Default.Favorite else Icons.Default.FavoriteBorder,
+          tint = savedTitleColor,
         )
+      }
+    }
+  }
 }

app/src/main/java/dev/msfjarvis/lobsters/data/LobstersViewModel.kt

@@ -10,6 +10,7 @@ import kotlinx.coroutines.CoroutineExceptionHandler
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.launch
 import java.net.SocketTimeoutException
 import java.net.UnknownHostException
@@ -20,14 +21,16 @@ class LobstersViewModel @ViewModelInject constructor(
 ) : ViewModel() {
   private var apiPage = 1
   private val _posts = MutableStateFlow<List<LobstersPost>>(emptyList())
-  private val dao = database.postsDao()
+  private val _savedPosts = MutableStateFlow<List<LobstersPost>>(emptyList())
+  private val postsDao = database.postsDao()
+  private val savedPostsDao = database.savedPostsDao()
   private val coroutineExceptionHandler = CoroutineExceptionHandler { _, throwable ->
     when (throwable) {
       // Swallow known network errors that can be recovered from.
       is UnknownHostException, is SocketTimeoutException -> {
         if (_posts.value.isEmpty()) {
           viewModelScope.launch {
-            dao.loadPosts().collectLatest { _posts.value = it }
+            postsDao.loadPosts().collectLatest { _posts.value = it }
           }
         }
       }
@@ -35,9 +38,17 @@ class LobstersViewModel @ViewModelInject constructor(
     }
   }
   val posts: StateFlow<List<LobstersPost>> get() = _posts
+  val savedPosts: StateFlow<List<LobstersPost>> get() = _savedPosts
 
   init {
     getMorePostsInternal(true)
+    getSavedPosts()
+  }
+
+  private fun getSavedPosts() {
+    viewModelScope.launch {
+      savedPostsDao.loadPosts().collectLatest { _savedPosts.value = it }
+    }
   }
 
   fun getMorePosts() {
@@ -54,12 +65,24 @@ class LobstersViewModel @ViewModelInject constructor(
       val newPosts = lobstersApi.getHottestPosts(apiPage)
       if (firstLoad) {
         _posts.value = newPosts
-        dao.deleteAllPosts()
+        postsDao.deleteAllPosts()
       } else {
         _posts.value += newPosts
       }
       apiPage += 1
-      dao.insertPosts(*_posts.value.toTypedArray())
+      postsDao.insertPosts(*_posts.value.toTypedArray())
+    }
+  }
+
+  fun savePost(post: LobstersPost) {
+    viewModelScope.launch {
+      val tempList = _posts.value
+      _posts.value = tempList.map {
+        if (it.shortId == post.shortId) it.isLiked = true
+        it
+      }
+      savedPostsDao.insertPosts(post)
+      getSavedPosts()
     }
   }
 }

app/src/main/java/dev/msfjarvis/lobsters/ui/LobstersItem.kt

@@ -1,5 +1,6 @@
 package dev.msfjarvis.lobsters.ui
 
+import androidx.compose.animation.animate
 import androidx.compose.foundation.Text
 import androidx.compose.foundation.background
 import androidx.compose.foundation.clickable
@@ -13,6 +14,8 @@ import androidx.compose.foundation.lazy.LazyColumnFor
 import androidx.compose.foundation.lazy.LazyItemScope
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
@@ -31,18 +34,27 @@ fun LazyItemScope.LobstersItem(
   modifier: Modifier = Modifier,
   linkOpenAction: (LobstersPost) -> Unit,
   commentOpenAction: (LobstersPost) -> Unit,
+  saveAction: (LobstersPost) -> Unit,
 ) {
+  val liked = remember { mutableStateOf(false) }
+  val titleColor = if (post.isLiked || liked.value) savedTitleColor else titleColor
+
   Column(
     modifier = modifier
       .fillParentMaxWidth()
       .clickable(
         onClick = { linkOpenAction.invoke(post) },
-        onLongClick = { commentOpenAction.invoke(post) }
+        onLongClick = { commentOpenAction.invoke(post) },
+        onDoubleClick = {
+          post.isLiked = true
+          liked.value = true
+          saveAction.invoke(post)
+        },
       ),
   ) {
     Text(
       text = post.title,
-      color = Color(0xFF7395D9),
+      color = titleColor,
       fontWeight = FontWeight.Bold,
       modifier = Modifier.padding(top = 4.dp)
     )
@@ -106,11 +118,15 @@ fun PreviewLobstersItem() {
       null,
       null,
     ),
-    listOf("openbsd")
+    listOf("openbsd"),
   )
   LobstersTheme {
     LazyColumnFor(items = listOf(post)) { item ->
-      LobstersItem(post = item, linkOpenAction = {}, commentOpenAction = {})
+      LobstersItem(
+        post = item,
+        linkOpenAction = {},
+        commentOpenAction = {},
+        saveAction = {})
     }
   }
 }

app/src/main/java/dev/msfjarvis/lobsters/ui/Theme.kt

@@ -5,6 +5,9 @@ import androidx.compose.material.darkColors
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.graphics.Color
 
+val titleColor = Color(0xFF7395D9)
+val savedTitleColor = Color(0xFFD97373)
+
 val darkColors = darkColors(
   primary = Color.White,
   secondary = Color(0xFF6C0000),

app/src/main/res/values/strings.xml

@@ -1,4 +1,5 @@
 <resources>
     <string name="app_name">lobste.rs</string>
     <string name="loading">Loading posts…</string>
+    <string name="no_saved_posts">You don\'t have any saved posts</string>
 </resources>

data/src/main/java/dev/msfjarvis/lobsters/data/source/PostsDao.kt

@@ -6,6 +6,7 @@ import androidx.room.Insert
 import androidx.room.OnConflictStrategy
 import androidx.room.Query
 import androidx.room.Transaction
+import androidx.room.Update
 import dev.msfjarvis.lobsters.data.model.LobstersEntity
 import dev.msfjarvis.lobsters.model.LobstersPost
 import kotlinx.coroutines.flow.Flow
@@ -15,6 +16,15 @@ abstract class PostsDao {
   @Query("SELECT * FROM lobsters_posts")
   abstract fun loadPosts(): Flow<List<LobstersPost>>
 
+  @Update
+  suspend fun updatePost(vararg posts: LobstersPost) {
+    updatePosts(posts.map { LobstersEntity(it) })
+  }
+
+  @Update(onConflict = OnConflictStrategy.IGNORE)
+  protected abstract suspend fun updatePosts(posts: List<LobstersEntity>)
+
+
   @Transaction
   open suspend fun insertPosts(vararg posts: LobstersPost) {
     insertPosts(posts.map { LobstersEntity(it) })

data/src/main/java/dev/msfjarvis/lobsters/data/source/PostsDatabase.kt

@@ -4,12 +4,14 @@ import androidx.room.Database
 import androidx.room.RoomDatabase
 import androidx.room.TypeConverters
 import dev.msfjarvis.lobsters.data.model.LobstersEntity
+import dev.msfjarvis.lobsters.data.model.SavedLobstersEntity
 
 @Database(
   entities = [
     LobstersEntity::class,
+    SavedLobstersEntity::class
   ],
-  version = 1,
+  version = 2,
   exportSchema = false,
 )
 @TypeConverters(
@@ -17,4 +19,5 @@ import dev.msfjarvis.lobsters.data.model.LobstersEntity
 )
 abstract class PostsDatabase : RoomDatabase() {
   abstract fun postsDao(): PostsDao
+  abstract fun savedPostsDao(): SavedPostsDao
 }

model/src/main/java/dev/msfjarvis/lobsters/model/LobstersPost.kt

@@ -22,5 +22,6 @@ class LobstersPost(
   val commentsUrl: String,
   @Json(name = "submitter_user")
   val submitterUser: Submitter,
-  val tags: List<String>
+  val tags: List<String>,
+  var isLiked: Boolean = false,
 )