Thumbs-up function 👍

data/firestore/src/commonMain/kotlin/io/github/droidkaigi/confsched2020/data/firestore/Firestore.kt

@@ -6,4 +6,6 @@ import kotlinx.coroutines.flow.Flow
 interface Firestore {
     fun getFavoriteSessionIds(): Flow<List<String>>
     suspend fun toggleFavorite(sessionId: SessionId)
+    fun getThumbsUpCount(sessionId: SessionId): Flow<Int>
+    suspend fun incrementThumbsUpCount(sessionId: SessionId)
 }

data/firestore/src/main/java/io/github/droidkaigi/confsched2020/data/firestore/internal/FirestoreImpl.kt

@@ -1,25 +1,30 @@
 package io.github.droidkaigi.confsched2020.data.firestore.internal
 
+import com.google.android.gms.tasks.Task
+import com.google.android.gms.tasks.Tasks
 import com.google.firebase.auth.FirebaseAuth
 import com.google.firebase.firestore.CollectionReference
 import com.google.firebase.firestore.DocumentReference
 import com.google.firebase.firestore.DocumentSnapshot
+import com.google.firebase.firestore.FieldValue
 import com.google.firebase.firestore.FirebaseFirestore
 import com.google.firebase.firestore.Query
 import com.google.firebase.firestore.QuerySnapshot
 import com.google.firebase.firestore.Source
 import io.github.droidkaigi.confsched2020.data.firestore.Firestore
 import io.github.droidkaigi.confsched2020.model.SessionId
-import javax.inject.Inject
 import kotlinx.coroutines.channels.awaitClose
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.callbackFlow
 import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.mapLatest
 import kotlinx.coroutines.tasks.await
 import timber.log.Timber
 import timber.log.debug
+import javax.inject.Inject
+import kotlin.math.floor
 
 internal class FirestoreImpl @Inject constructor() : Firestore {
 
@@ -35,7 +40,7 @@ internal class FirestoreImpl @Inject constructor() : Firestore {
             emit(favoritesRef)
         }
         val favoritesSnapshotFlow = setupFavorites.flatMapLatest {
-            it.whereEqualTo("favorite", true).toFlow()
+            it.whereEqualTo(FAVORITE_VALUE_KEY, true).toFlow()
         }
         return favoritesSnapshotFlow.mapLatest { favorites ->
             Timber.debug { "favoritesSnapshotFlow onNext" }
@@ -57,12 +62,44 @@ internal class FirestoreImpl @Inject constructor() : Firestore {
         } else {
             Timber.debug { "toggleFavorite: $sessionId document not exits" }
             document.reference
-                .set(mapOf("favorite" to newFavorite))
+                .set(mapOf(FAVORITE_VALUE_KEY to newFavorite))
                 .await()
         }
         Timber.debug { "toggleFavorite: end" }
     }
 
+    override fun getThumbsUpCount(sessionId: SessionId): Flow<Int> {
+        val setupThumbsUp = flow {
+            signInIfNeeded()
+            val counterRef = getThumbsUpCounterRef(sessionId)
+            createShardsIfNeeded(counterRef)
+            emit(counterRef)
+        }
+
+        val thumbsUpSnapshot = setupThumbsUp.flatMapLatest {
+            it.toFlow()
+        }
+
+        return thumbsUpSnapshot.map { shards ->
+            var count = 0
+            shards.forEach { snap ->
+                count += snap.get(SHARDS_COUNT_KEY, Int::class.java) ?: 0
+            }
+            count
+        }
+    }
+
+    override suspend fun incrementThumbsUpCount(sessionId: SessionId) {
+        signInIfNeeded()
+        val counterRef = getThumbsUpCounterRef(sessionId)
+        createShardsIfNeeded(counterRef)
+        val shardId = floor(Math.random() * NUM_SHARDS).toInt()
+        counterRef
+            .document(shardId.toString())
+            .update(SHARDS_COUNT_KEY, FieldValue.increment(1))
+            .await()
+    }
+
     private fun getFavoritesRef(): CollectionReference {
         val firebaseAuth = FirebaseAuth.getInstance()
         val firebaseUserId = firebaseAuth.currentUser?.uid ?: throw RuntimeException(
@@ -83,6 +120,47 @@ internal class FirestoreImpl @Inject constructor() : Firestore {
         firebaseAuth.signInAnonymously().await()
         Timber.debug { "signInIfNeeded end" }
     }
+
+    private fun getThumbsUpCounterRef(sessionId: SessionId): CollectionReference {
+        return FirebaseFirestore
+            .getInstance()
+            .collection("confsched/2020/sessions/${sessionId.id}/thumbsup_counters")
+    }
+
+    private suspend fun createShardsIfNeeded(counterRef: CollectionReference) {
+        val lastShardId = NUM_SHARDS - 1
+        val lastShard = counterRef
+            .document(lastShardId.toString())
+            .get(Source.SERVER)
+            .await()
+
+        if (lastShard.exists()) {
+            Timber.debug { "createShardsIfNeeded shards already exist" }
+            return
+        }
+
+        val tasks = arrayListOf<Task<Void>>()
+        (0 until NUM_SHARDS).forEach {
+            val makeShard = counterRef
+                .document(it.toString())
+                .set(mapOf(SHARDS_COUNT_KEY to 0))
+            tasks.add(makeShard)
+        }
+
+        try {
+            Tasks.whenAll(tasks).await()
+        } catch(e: Exception) {
+            // FIXME: debug code
+            println("⭐" + e.message)
+        }
+        Timber.debug { "createShardsIfNeeded creating shards completed" }
+    }
+
+    companion object {
+        const val NUM_SHARDS = 10
+        const val SHARDS_COUNT_KEY = "shards"
+        const val FAVORITE_VALUE_KEY = "favorite"
+    }
 }
 
 private suspend fun DocumentReference.fastGet(): DocumentSnapshot {

data/repository/src/main/java/io/github/droidkaigi/confsched2020/data/repository/internal/DataSessionRepository.kt

@@ -18,14 +18,14 @@ import io.github.droidkaigi.confsched2020.model.SessionId
 import io.github.droidkaigi.confsched2020.model.SessionList
 import io.github.droidkaigi.confsched2020.model.SpeechSession
 import io.github.droidkaigi.confsched2020.model.repository.SessionRepository
-import javax.inject.Inject
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.filter
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.onEach
 import timber.log.Timber
 import timber.log.debug
+import javax.inject.Inject
 
 internal class DataSessionRepository @Inject constructor(
     private val droidKaigiApi: DroidKaigiApi,
@@ -129,4 +129,12 @@ internal class DataSessionRepository @Inject constructor(
         val response = droidKaigiApi.getSessions()
         sessionDatabase.save(response)
     }
+
+    override fun thumbsUpCounts(sessionId: SessionId): Flow<Int> {
+        return firestore.getThumbsUpCount(sessionId)
+    }
+
+    override suspend fun incrementThumbsUpCount(sessionId: SessionId) {
+        firestore.incrementThumbsUpCount(sessionId)
+    }
 }

feature/session/src/main/java/io/github/droidkaigi/confsched2020/session/ui/SessionDetailFragment.kt

@@ -127,7 +127,8 @@ class SessionDetailFragment : Fragment(R.layout.fragment_session_detail), Inject
                             adapter,
                             session,
                             uiModel.showEllipsis,
-                            uiModel.searchQuery
+                            uiModel.searchQuery,
+                            uiModel.thumbsUpCount
                         )
                     }
             }
@@ -178,13 +179,20 @@ class SessionDetailFragment : Fragment(R.layout.fragment_session_detail), Inject
         adapter: GroupAdapter<ViewHolder<*>>,
         session: Session,
         showEllipsis: Boolean,
-        searchQuery: String?
+        searchQuery: String?,
+        thumbsUpCount: Int
     ) {
         binding.sessionDetailRecycler.transitionName =
             "${session.id}-${navArgs.transitionNameSuffix}"
 
         val items = mutableListOf<Group>()
-        items += sessionDetailTitleItemFactory.create(session, searchQuery)
+        items += sessionDetailTitleItemFactory.create(
+            session,
+            searchQuery,
+            thumbsUpCount
+        ) {
+            sessionDetailViewModel.thumbsUp(session)
+        }
         items += sessionDetailDescriptionItemFactory.create(
             session,
             showEllipsis,

feature/session/src/main/java/io/github/droidkaigi/confsched2020/session/ui/item/SessionDetailTitleItem.kt

@@ -21,7 +21,9 @@ import java.util.regex.Pattern
 
 class SessionDetailTitleItem @AssistedInject constructor(
     @Assisted private val session: Session,
-    @Assisted private val searchQuery: String?
+    @Assisted private val searchQuery: String?,
+    @Assisted private val thumbsUpCount: Int,
+    @Assisted private val thumbsUpListener: () -> Unit
 ) :
     BindableItem<ItemSessionDetailTitleBinding>() {
     override fun getLayout() = R.layout.item_session_detail_title
@@ -59,6 +61,11 @@ class SessionDetailTitleItem @AssistedInject constructor(
 //            Test Code
 //            binding.sessionMessage.text = "セッション部屋がRoom1からRoom3に変更になりました（サンプル）"
 //            binding.sessionMessage.isVisible = true
+
+            binding.thumbsUp.text = thumbsUpCount.toString()
+            binding.thumbsUp.setOnClickListener {
+                thumbsUpListener.invoke()
+            }
         }
     }
 
@@ -87,7 +94,9 @@ class SessionDetailTitleItem @AssistedInject constructor(
     interface Factory {
         fun create(
             session: Session,
-            searchQuery: String? = null
+            searchQuery: String? = null,
+            thumbsUpCount: Int,
+            thumbsUpListener: () -> Unit
         ): SessionDetailTitleItem
     }
 }

feature/session/src/main/java/io/github/droidkaigi/confsched2020/session/ui/viewmodel/SessionDetailViewModel.kt

@@ -11,11 +11,11 @@ import io.github.droidkaigi.confsched2020.ext.combine
 import io.github.droidkaigi.confsched2020.ext.toAppError
 import io.github.droidkaigi.confsched2020.ext.toLoadingState
 import io.github.droidkaigi.confsched2020.model.AppError
-import io.github.droidkaigi.confsched2020.model.TextExpandState
 import io.github.droidkaigi.confsched2020.model.LoadState
 import io.github.droidkaigi.confsched2020.model.LoadingState
 import io.github.droidkaigi.confsched2020.model.Session
 import io.github.droidkaigi.confsched2020.model.SessionId
+import io.github.droidkaigi.confsched2020.model.TextExpandState
 import io.github.droidkaigi.confsched2020.model.repository.SessionRepository
 import kotlinx.coroutines.flow.collect
 import kotlinx.coroutines.flow.map
@@ -32,10 +32,18 @@ class SessionDetailViewModel @AssistedInject constructor(
         val error: AppError?,
         val session: Session?,
         val showEllipsis: Boolean,
-        val searchQuery: String?
+        val searchQuery: String?,
+        val thumbsUpCount: Int
     ) {
         companion object {
-            val EMPTY = UiModel(false, null, null, true, null)
+            val EMPTY = UiModel(
+                isLoading = false,
+                error = null,
+                session = null,
+                showEllipsis = true,
+                searchQuery = null,
+                thumbsUpCount = 0
+            )
         }
     }
 
@@ -55,16 +63,25 @@ class SessionDetailViewModel @AssistedInject constructor(
     private val descriptionTextExpandStateLiveData: MutableLiveData<TextExpandState> =
         MutableLiveData(TextExpandState.COLLAPSED)
 
+    private val thumbsUpCountLiveData: LiveData<Int> = liveData {
+        sessionRepository.thumbsUpCounts(sessionId)
+            .collect { thumbsUpCount ->
+               emit(thumbsUpCount)
+            }
+    }
+
     // Produce UiModel
     val uiModel: LiveData<UiModel> = combine(
         initialValue = UiModel.EMPTY,
         liveData1 = sessionLoadStateLiveData,
         liveData2 = favoriteLoadingStateLiveData,
-        liveData3 = descriptionTextExpandStateLiveData
+        liveData3 = descriptionTextExpandStateLiveData,
+        liveData4 = thumbsUpCountLiveData
     ) { current: UiModel,
         sessionLoadState: LoadState<Session>,
         favoriteState: LoadingState,
-        descriptionTextExpandState: TextExpandState ->
+        descriptionTextExpandState: TextExpandState,
+        thumbsUpCount: Int ->
         val isLoading =
             sessionLoadState.isLoading || favoriteState.isLoading
         val sessions = when (sessionLoadState) {
@@ -87,7 +104,8 @@ class SessionDetailViewModel @AssistedInject constructor(
                     .toAppError(),
             session = sessions,
             showEllipsis = showEllipsis,
-            searchQuery = searchQuery
+            searchQuery = searchQuery,
+            thumbsUpCount = thumbsUpCount
         )
     }
 
@@ -107,6 +125,17 @@ class SessionDetailViewModel @AssistedInject constructor(
         descriptionTextExpandStateLiveData.value = TextExpandState.EXPANDED
     }
 
+    fun thumbsUp(session: Session) {
+        viewModelScope.launch {
+            try {
+                sessionRepository.incrementThumbsUpCount(session.id)
+            } catch (e: Exception) {
+                // TODO: implement
+                println("⭐ " + e.message)
+            }
+        }
+    }
+
     @AssistedInject.Factory
     interface Factory {
         fun create(

feature/session/src/main/res/layout/item_session_detail_title.xml

@@ -99,7 +99,7 @@
         <TextView
             android:id="@+id/session_message"
             android:layout_width="0dp"
-            android:layout_height="wrap_content"
+            android:layout_height="24dp"
             android:layout_marginTop="8dp"
             android:textAppearance="@style/TextAppearance.DroidKaigi.SessionMessage"
             android:visibility="gone"
@@ -119,15 +119,27 @@
             app:layout_constraintTop_toBottomOf="@id/session_message"
             />
 
+        <com.google.android.material.button.MaterialButton
+            android:id="@+id/thumbs_up"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="24dp"
+            style="@style/Widget.MaterialComponents.Button.OutlinedButton"
+            app:layout_constraintStart_toStartOf="@id/guideline_start"
+            app:layout_constraintTop_toBottomOf="@id/tags"
+            app:layout_constraintBottom_toTopOf="@id/divider_survey_and_text"
+            tools:text="thumbs-up"
+            />
+
         <View
             android:id="@+id/divider_survey_and_text"
             android:layout_width="0dp"
             android:layout_height="1dp"
-            android:layout_marginTop="22dp"
+            android:layout_marginTop="24dp"
             android:background="@color/black_alpha_12"
             app:layout_constraintEnd_toEndOf="@id/guideline_end"
             app:layout_constraintStart_toStartOf="@id/guideline_start"
-            app:layout_constraintTop_toBottomOf="@id/tags"
+            app:layout_constraintTop_toBottomOf="@id/thumbs_up"
             />
 
     </androidx.constraintlayout.widget.ConstraintLayout>

model/src/commonMain/kotlin/io/github/droidkaigi/confsched2020/model/repository/SessionRepository.kt

@@ -17,4 +17,6 @@ interface SessionRepository {
         session: SpeechSession,
         sessionFeedback: SessionFeedback
     )
+    fun thumbsUpCounts(sessionId: SessionId): Flow<Int>
+    suspend fun incrementThumbsUpCount(sessionId: SessionId)
 }