Implement recent searches

- Add Repository and Dao for recent searches
- Add recent searches body in the Search UI
- Add relevant tests

core/data-test/src/main/java/com/google/samples/apps/nowinandroid/core/data/test/TestDataModule.kt

@@ -18,10 +18,12 @@ package com.google.samples.apps.nowinandroid.core.data.test
 
 import com.google.samples.apps.nowinandroid.core.data.di.DataModule
 import com.google.samples.apps.nowinandroid.core.data.repository.NewsRepository
+import com.google.samples.apps.nowinandroid.core.data.repository.RecentSearchRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.SearchContentsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.TopicsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.UserDataRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.fake.FakeNewsRepository
+import com.google.samples.apps.nowinandroid.core.data.repository.fake.FakeRecentSearchRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.fake.FakeSearchContentsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.fake.FakeTopicsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.fake.FakeUserDataRepository
@@ -52,6 +54,11 @@ interface TestDataModule {
         userDataRepository: FakeUserDataRepository,
     ): UserDataRepository
 
+    @Binds
+    fun bindsRecentSearchRepository(
+        recentSearchRepository: FakeRecentSearchRepository,
+    ): RecentSearchRepository
+
     @Binds
     fun bindsSearchContentsRepository(
         searchContentsRepository: FakeSearchContentsRepository,

core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/di/DataModule.kt

@@ -16,11 +16,13 @@
 
 package com.google.samples.apps.nowinandroid.core.data.di
 
+import com.google.samples.apps.nowinandroid.core.data.repository.DefaultRecentSearchRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.DefaultSearchContentsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.NewsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.OfflineFirstNewsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.OfflineFirstTopicsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.OfflineFirstUserDataRepository
+import com.google.samples.apps.nowinandroid.core.data.repository.RecentSearchRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.SearchContentsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.TopicsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.UserDataRepository
@@ -50,6 +52,11 @@ interface DataModule {
         userDataRepository: OfflineFirstUserDataRepository,
     ): UserDataRepository
 
+    @Binds
+    fun bindsRecentSearchRepository(
+        recentSearchRepository: DefaultRecentSearchRepository,
+    ): RecentSearchRepository
+
     @Binds
     fun bindsSearchContentsRepository(
         searchContentsRepository: DefaultSearchContentsRepository,

core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/model/RecentSearchQuery.kt

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.core.data.model
+
+import com.google.samples.apps.nowinandroid.core.database.model.RecentSearchQueryEntity
+import kotlinx.datetime.Clock
+import kotlinx.datetime.Instant
+
+data class RecentSearchQuery(
+    val query: String,
+    val queriedDate: Instant = Clock.System.now(),
+)
+
+fun RecentSearchQueryEntity.asExternalModel() = RecentSearchQuery(
+    query = query,
+    queriedDate = queriedDate,
+)

core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/model/SearchResult.kt.kt

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.core.data.model
+
+import com.google.samples.apps.nowinandroid.core.model.data.NewsResource
+import com.google.samples.apps.nowinandroid.core.model.data.Topic
+
+/** */
+data class SearchResult(
+    val topics: List<Topic> = emptyList(),
+    val newsResources: List<NewsResource> = emptyList(),
+)

core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/DefaultRecentSearchRepository.kt

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.core.data.repository
+
+import com.google.samples.apps.nowinandroid.core.data.model.RecentSearchQuery
+import com.google.samples.apps.nowinandroid.core.data.model.asExternalModel
+import com.google.samples.apps.nowinandroid.core.database.dao.RecentSearchQueryDao
+import com.google.samples.apps.nowinandroid.core.database.model.RecentSearchQueryEntity
+import com.google.samples.apps.nowinandroid.core.network.Dispatcher
+import com.google.samples.apps.nowinandroid.core.network.NiaDispatchers.IO
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.withContext
+import kotlinx.datetime.Clock
+import javax.inject.Inject
+
+class DefaultRecentSearchRepository @Inject constructor(
+    private val recentSearchQueryDao: RecentSearchQueryDao,
+    @Dispatcher(IO) private val ioDispatcher: CoroutineDispatcher,
+) : RecentSearchRepository {
+    override suspend fun insertOrReplaceRecentSearch(searchQuery: String) {
+        withContext(ioDispatcher) {
+            recentSearchQueryDao.insertOrReplaceRecentSearchQuery(
+                RecentSearchQueryEntity(
+                    query = searchQuery,
+                    queriedDate = Clock.System.now(),
+                ),
+            )
+        }
+    }
+
+    override fun getRecentSearchQueries(limit: Int): Flow<List<RecentSearchQuery>> {
+        return recentSearchQueryDao.getRecentSearchQueryEntities(limit).map { searchQueries ->
+            searchQueries.map {
+                it.asExternalModel()
+            }
+        }
+    }
+
+    override suspend fun clearRecentSearches() = recentSearchQueryDao.clearRecentSearchQueries()
+}

core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/DefaultSearchContentsRepository.kt

@@ -16,6 +16,7 @@
 
 package com.google.samples.apps.nowinandroid.core.data.repository
 
+import com.google.samples.apps.nowinandroid.core.data.model.SearchResult
 import com.google.samples.apps.nowinandroid.core.database.dao.NewsResourceDao
 import com.google.samples.apps.nowinandroid.core.database.dao.NewsResourceFtsDao
 import com.google.samples.apps.nowinandroid.core.database.dao.TopicDao
@@ -29,7 +30,6 @@ import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.flatMapLatest
-import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.mapLatest
 import kotlinx.coroutines.withContext
 import javax.inject.Inject

core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/RecentSearchRepository.kt

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.core.data.repository
+
+import com.google.samples.apps.nowinandroid.core.data.model.RecentSearchQuery
+import kotlinx.coroutines.flow.Flow
+
+/**
+ * Data layer interface for the recent searches.
+ */
+interface RecentSearchRepository {
+
+    /**
+     * Get the recent search queries up to the number of queries specified as [limit].
+     */
+    fun getRecentSearchQueries(limit: Int): Flow<List<RecentSearchQuery>>
+
+    /**
+     * Insert or replace the [searchQuery] as part of the recent searches.
+     */
+    suspend fun insertOrReplaceRecentSearch(searchQuery: String)
+
+    /**
+     * Clear the recent searches.
+     */
+    suspend fun clearRecentSearches()
+}

core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/SearchContentsRepository.kt

@@ -16,8 +16,7 @@
 
 package com.google.samples.apps.nowinandroid.core.data.repository
 
-import com.google.samples.apps.nowinandroid.core.model.data.NewsResource
+import com.google.samples.apps.nowinandroid.core.data.model.SearchResult
-import com.google.samples.apps.nowinandroid.core.model.data.Topic
 import kotlinx.coroutines.flow.Flow
 
 /**
@@ -35,8 +34,3 @@ interface SearchContentsRepository {
      */
     fun searchContents(searchQuery: String): Flow<SearchResult>
 }
-
-data class SearchResult(
-    val topics: List<Topic> = emptyList(),
-    val newsResources: List<NewsResource> = emptyList(),
-)

core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/fake/FakeRecentSearchRepository.kt

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.core.data.repository.fake
+
+import com.google.samples.apps.nowinandroid.core.data.model.RecentSearchQuery
+import com.google.samples.apps.nowinandroid.core.data.repository.RecentSearchRepository
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.flowOf
+import javax.inject.Inject
+
+/**
+ * Fake implementation of the [RecentSearchRepository]
+ */
+class FakeRecentSearchRepository @Inject constructor() : RecentSearchRepository {
+    override suspend fun insertOrReplaceRecentSearch(searchQuery: String) { /* no-op */ }
+
+    override fun getRecentSearchQueries(limit: Int): Flow<List<RecentSearchQuery>> =
+        flowOf(emptyList())
+
+    override suspend fun clearRecentSearches() { /* no-op */ }
+}

core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/repository/fake/FakeSearchContentsRepository.kt

@@ -16,9 +16,10 @@
 
 package com.google.samples.apps.nowinandroid.core.data.repository.fake
 
+import com.google.samples.apps.nowinandroid.core.data.model.SearchResult
 import com.google.samples.apps.nowinandroid.core.data.repository.SearchContentsRepository
-import com.google.samples.apps.nowinandroid.core.data.repository.SearchResult
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.flowOf
 import javax.inject.Inject
 
 /**
@@ -26,8 +27,6 @@ import javax.inject.Inject
  */
 class FakeSearchContentsRepository @Inject constructor() : SearchContentsRepository {
 
-    override suspend fun populateFtsData() {}
+    override suspend fun populateFtsData() { /* no-op */ }
-    override fun searchContents(searchQuery: String): Flow<SearchResult> {
+    override fun searchContents(searchQuery: String): Flow<SearchResult> = flowOf()
-        TODO("Not yet implemented")
-    }
 }

core/database/schemas/com.google.samples.apps.nowinandroid.core.database.NiaDatabase/14.json

@@ -0,0 +1,308 @@
+{
+  "formatVersion": 1,
+  "database": {
+    "version": 14,
+    "identityHash": "51271b81bde7c7997d67fb23c8f31780",
+    "entities": [
+      {
+        "tableName": "news_resources",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` TEXT NOT NULL, `title` TEXT NOT NULL, `content` TEXT NOT NULL, `url` TEXT NOT NULL, `header_image_url` TEXT, `publish_date` INTEGER NOT NULL, `type` TEXT NOT NULL, PRIMARY KEY(`id`))",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "title",
+            "columnName": "title",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "content",
+            "columnName": "content",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "url",
+            "columnName": "url",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "headerImageUrl",
+            "columnName": "header_image_url",
+            "affinity": "TEXT",
+            "notNull": false
+          },
+          {
+            "fieldPath": "publishDate",
+            "columnName": "publish_date",
+            "affinity": "INTEGER",
+            "notNull": true
+          },
+          {
+            "fieldPath": "type",
+            "columnName": "type",
+            "affinity": "TEXT",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": [
+            "id"
+          ]
+        },
+        "indices": [],
+        "foreignKeys": []
+      },
+      {
+        "tableName": "news_resources_topics",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`news_resource_id` TEXT NOT NULL, `topic_id` TEXT NOT NULL, PRIMARY KEY(`news_resource_id`, `topic_id`), FOREIGN KEY(`news_resource_id`) REFERENCES `news_resources`(`id`) ON UPDATE NO ACTION ON DELETE CASCADE , FOREIGN KEY(`topic_id`) REFERENCES `topics`(`id`) ON UPDATE NO ACTION ON DELETE CASCADE )",
+        "fields": [
+          {
+            "fieldPath": "newsResourceId",
+            "columnName": "news_resource_id",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "topicId",
+            "columnName": "topic_id",
+            "affinity": "TEXT",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": [
+            "news_resource_id",
+            "topic_id"
+          ]
+        },
+        "indices": [
+          {
+            "name": "index_news_resources_topics_news_resource_id",
+            "unique": false,
+            "columnNames": [
+              "news_resource_id"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_news_resources_topics_news_resource_id` ON `${TABLE_NAME}` (`news_resource_id`)"
+          },
+          {
+            "name": "index_news_resources_topics_topic_id",
+            "unique": false,
+            "columnNames": [
+              "topic_id"
+            ],
+            "orders": [],
+            "createSql": "CREATE INDEX IF NOT EXISTS `index_news_resources_topics_topic_id` ON `${TABLE_NAME}` (`topic_id`)"
+          }
+        ],
+        "foreignKeys": [
+          {
+            "table": "news_resources",
+            "onDelete": "CASCADE",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "news_resource_id"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          },
+          {
+            "table": "topics",
+            "onDelete": "CASCADE",
+            "onUpdate": "NO ACTION",
+            "columns": [
+              "topic_id"
+            ],
+            "referencedColumns": [
+              "id"
+            ]
+          }
+        ]
+      },
+      {
+        "ftsVersion": "FTS4",
+        "ftsOptions": {
+          "tokenizer": "simple",
+          "tokenizerArgs": [],
+          "contentTable": "",
+          "languageIdColumnName": "",
+          "matchInfo": "FTS4",
+          "notIndexedColumns": [],
+          "prefixSizes": [],
+          "preferredOrder": "ASC"
+        },
+        "contentSyncTriggers": [],
+        "tableName": "newsResourcesFts",
+        "createSql": "CREATE VIRTUAL TABLE IF NOT EXISTS `${TABLE_NAME}` USING FTS4(`newsResourceId` TEXT NOT NULL, `title` TEXT NOT NULL, `content` TEXT NOT NULL)",
+        "fields": [
+          {
+            "fieldPath": "newsResourceId",
+            "columnName": "newsResourceId",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "title",
+            "columnName": "title",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "content",
+            "columnName": "content",
+            "affinity": "TEXT",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": []
+        },
+        "indices": [],
+        "foreignKeys": []
+      },
+      {
+        "tableName": "topics",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`id` TEXT NOT NULL, `name` TEXT NOT NULL, `shortDescription` TEXT NOT NULL, `longDescription` TEXT NOT NULL DEFAULT '', `url` TEXT NOT NULL DEFAULT '', `imageUrl` TEXT NOT NULL DEFAULT '', PRIMARY KEY(`id`))",
+        "fields": [
+          {
+            "fieldPath": "id",
+            "columnName": "id",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "name",
+            "columnName": "name",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "shortDescription",
+            "columnName": "shortDescription",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "longDescription",
+            "columnName": "longDescription",
+            "affinity": "TEXT",
+            "notNull": true,
+            "defaultValue": "''"
+          },
+          {
+            "fieldPath": "url",
+            "columnName": "url",
+            "affinity": "TEXT",
+            "notNull": true,
+            "defaultValue": "''"
+          },
+          {
+            "fieldPath": "imageUrl",
+            "columnName": "imageUrl",
+            "affinity": "TEXT",
+            "notNull": true,
+            "defaultValue": "''"
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": [
+            "id"
+          ]
+        },
+        "indices": [],
+        "foreignKeys": []
+      },
+      {
+        "ftsVersion": "FTS4",
+        "ftsOptions": {
+          "tokenizer": "simple",
+          "tokenizerArgs": [],
+          "contentTable": "",
+          "languageIdColumnName": "",
+          "matchInfo": "FTS4",
+          "notIndexedColumns": [],
+          "prefixSizes": [],
+          "preferredOrder": "ASC"
+        },
+        "contentSyncTriggers": [],
+        "tableName": "topicsFts",
+        "createSql": "CREATE VIRTUAL TABLE IF NOT EXISTS `${TABLE_NAME}` USING FTS4(`topicId` TEXT NOT NULL, `name` TEXT NOT NULL, `shortDescription` TEXT NOT NULL, `longDescription` TEXT NOT NULL)",
+        "fields": [
+          {
+            "fieldPath": "topicId",
+            "columnName": "topicId",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "name",
+            "columnName": "name",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "shortDescription",
+            "columnName": "shortDescription",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "longDescription",
+            "columnName": "longDescription",
+            "affinity": "TEXT",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": []
+        },
+        "indices": [],
+        "foreignKeys": []
+      },
+      {
+        "tableName": "recentSearchQueries",
+        "createSql": "CREATE TABLE IF NOT EXISTS `${TABLE_NAME}` (`query` TEXT NOT NULL, `queriedDate` INTEGER NOT NULL, PRIMARY KEY(`query`))",
+        "fields": [
+          {
+            "fieldPath": "query",
+            "columnName": "query",
+            "affinity": "TEXT",
+            "notNull": true
+          },
+          {
+            "fieldPath": "queriedDate",
+            "columnName": "queriedDate",
+            "affinity": "INTEGER",
+            "notNull": true
+          }
+        ],
+        "primaryKey": {
+          "autoGenerate": false,
+          "columnNames": [
+            "query"
+          ]
+        },
+        "indices": [],
+        "foreignKeys": []
+      }
+    ],
+    "views": [],
+    "setupQueries": [
+      "CREATE TABLE IF NOT EXISTS room_master_table (id INTEGER PRIMARY KEY,identity_hash TEXT)",
+      "INSERT OR REPLACE INTO room_master_table (id,identity_hash) VALUES(42, '51271b81bde7c7997d67fb23c8f31780')"
+    ]
+  }
+}

core/database/src/main/java/com/google/samples/apps/nowinandroid/core/database/DaosModule.kt

@@ -18,6 +18,7 @@ package com.google.samples.apps.nowinandroid.core.database
 
 import com.google.samples.apps.nowinandroid.core.database.dao.NewsResourceDao
 import com.google.samples.apps.nowinandroid.core.database.dao.NewsResourceFtsDao
+import com.google.samples.apps.nowinandroid.core.database.dao.RecentSearchQueryDao
 import com.google.samples.apps.nowinandroid.core.database.dao.TopicDao
 import com.google.samples.apps.nowinandroid.core.database.dao.TopicFtsDao
 import dagger.Module
@@ -47,4 +48,9 @@ object DaosModule {
     fun providesNewsResourceFtsDao(
         database: NiaDatabase,
     ): NewsResourceFtsDao = database.newsResourceFtsDao()
+
+    @Provides
+    fun providesRecentSearchQueryDao(
+        database: NiaDatabase,
+    ): RecentSearchQueryDao = database.recentSearchQueryDao()
 }

core/database/src/main/java/com/google/samples/apps/nowinandroid/core/database/NiaDatabase.kt

@@ -22,11 +22,13 @@ import androidx.room.RoomDatabase
 import androidx.room.TypeConverters
 import com.google.samples.apps.nowinandroid.core.database.dao.NewsResourceDao
 import com.google.samples.apps.nowinandroid.core.database.dao.NewsResourceFtsDao
+import com.google.samples.apps.nowinandroid.core.database.dao.RecentSearchQueryDao
 import com.google.samples.apps.nowinandroid.core.database.dao.TopicDao
 import com.google.samples.apps.nowinandroid.core.database.dao.TopicFtsDao
 import com.google.samples.apps.nowinandroid.core.database.model.NewsResourceEntity
 import com.google.samples.apps.nowinandroid.core.database.model.NewsResourceFtsEntity
 import com.google.samples.apps.nowinandroid.core.database.model.NewsResourceTopicCrossRef
+import com.google.samples.apps.nowinandroid.core.database.model.RecentSearchQueryEntity
 import com.google.samples.apps.nowinandroid.core.database.model.TopicEntity
 import com.google.samples.apps.nowinandroid.core.database.model.TopicFtsEntity
 import com.google.samples.apps.nowinandroid.core.database.util.InstantConverter
@@ -39,8 +41,9 @@ import com.google.samples.apps.nowinandroid.core.database.util.NewsResourceTypeC
         NewsResourceFtsEntity::class,
         TopicEntity::class,
         TopicFtsEntity::class,
+        RecentSearchQueryEntity::class,
     ],
-    version = 13,
+    version = 14,
     autoMigrations = [
         AutoMigration(from = 1, to = 2),
         AutoMigration(from = 2, to = 3, spec = DatabaseMigrations.Schema2to3::class),
@@ -54,6 +57,7 @@ import com.google.samples.apps.nowinandroid.core.database.util.NewsResourceTypeC
         AutoMigration(from = 10, to = 11, spec = DatabaseMigrations.Schema10to11::class),
         AutoMigration(from = 11, to = 12, spec = DatabaseMigrations.Schema11to12::class),
         AutoMigration(from = 12, to = 13),
+        AutoMigration(from = 13, to = 14),
     ],
     exportSchema = true,
 )
@@ -66,4 +70,5 @@ abstract class NiaDatabase : RoomDatabase() {
     abstract fun newsResourceDao(): NewsResourceDao
     abstract fun topicFtsDao(): TopicFtsDao
     abstract fun newsResourceFtsDao(): NewsResourceFtsDao
+    abstract fun recentSearchQueryDao(): RecentSearchQueryDao
 }

core/database/src/main/java/com/google/samples/apps/nowinandroid/core/database/dao/RecentSearchQueryDao.kt

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.core.database.dao
+
+import androidx.room.Dao
+import androidx.room.Query
+import androidx.room.Upsert
+import com.google.samples.apps.nowinandroid.core.database.model.RecentSearchQueryEntity
+import kotlinx.coroutines.flow.Flow
+
+/**
+ * DAO for [RecentSearchQueryEntity] access
+ */
+@Dao
+interface RecentSearchQueryDao {
+    @Query(value = "SELECT * FROM recentSearchQueries ORDER BY queriedDate DESC LIMIT :limit")
+    fun getRecentSearchQueryEntities(limit: Int): Flow<List<RecentSearchQueryEntity>>
+
+    @Upsert
+    suspend fun insertOrReplaceRecentSearchQuery(recentSearchQuery: RecentSearchQueryEntity)
+
+    @Query(value = "DELETE FROM recentSearchQueries")
+    suspend fun clearRecentSearchQueries()
+}

core/database/src/main/java/com/google/samples/apps/nowinandroid/core/database/model/RecentSearchQueryEntity.kt

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.core.database.model
+
+import androidx.room.ColumnInfo
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+import kotlinx.datetime.Instant
+
+/**
+ * Defines an database entity that stored recent search queries.
+ */
+@Entity(
+    tableName = "recentSearchQueries",
+)
+data class RecentSearchQueryEntity(
+    @PrimaryKey
+    val query: String,
+    @ColumnInfo
+    val queriedDate: Instant,
+)

core/domain/src/main/java/com/google/samples/apps/nowinandroid/core/domain/GetRecentSearchQueriesUseCase.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.core.domain
+
+import com.google.samples.apps.nowinandroid.core.data.model.RecentSearchQuery
+import com.google.samples.apps.nowinandroid.core.data.repository.RecentSearchRepository
+import kotlinx.coroutines.flow.Flow
+import javax.inject.Inject
+
+/**
+ * A use case which returns the recent search queries.
+ */
+class GetRecentSearchQueriesUseCase @Inject constructor(
+    private val recentSearchRepository: RecentSearchRepository,
+) {
+    operator fun invoke(limit: Int = 10): Flow<List<RecentSearchQuery>> =
+        recentSearchRepository.getRecentSearchQueries(limit)
+}

core/domain/src/main/java/com/google/samples/apps/nowinandroid/core/domain/GetSearchContentsUseCase.kt

@@ -16,11 +16,12 @@
 
 package com.google.samples.apps.nowinandroid.core.domain
 
+import com.google.samples.apps.nowinandroid.core.data.model.SearchResult
 import com.google.samples.apps.nowinandroid.core.data.repository.SearchContentsRepository
-import com.google.samples.apps.nowinandroid.core.data.repository.SearchResult
 import com.google.samples.apps.nowinandroid.core.data.repository.UserDataRepository
 import com.google.samples.apps.nowinandroid.core.domain.model.FollowableTopic
 import com.google.samples.apps.nowinandroid.core.domain.model.UserNewsResource
+import com.google.samples.apps.nowinandroid.core.domain.model.UserSearchResult
 import com.google.samples.apps.nowinandroid.core.model.data.UserData
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.combine
@@ -41,7 +42,7 @@ class GetSearchContentsUseCase @Inject constructor(
             .mapToUserSearchResult(userDataRepository.userData)
 }
 
-fun Flow<SearchResult>.mapToUserSearchResult(userDataStream: Flow<UserData>): Flow<UserSearchResult> =
+private fun Flow<SearchResult>.mapToUserSearchResult(userDataStream: Flow<UserData>): Flow<UserSearchResult> =
     combine(userDataStream) { searchResult, userData ->
         UserSearchResult(
             topics = searchResult.topics.map { topic ->
@@ -58,8 +59,3 @@ fun Flow<SearchResult>.mapToUserSearchResult(userDataStream: Flow<UserData>): Fl
             },
         )
     }
-
-data class UserSearchResult(
-    val topics: List<FollowableTopic> = emptyList(),
-    val newsResources: List<UserNewsResource> = emptyList(),
-)

core/domain/src/main/java/com/google/samples/apps/nowinandroid/core/domain/model/UserSearchResult.kt

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.core.domain.model
+
+import com.google.samples.apps.nowinandroid.core.data.model.SearchResult
+
+/**
+ * An entity of [SearchResult] with additional user information such as whether the user is
+ * following a topic.
+ */
+data class UserSearchResult(
+    val topics: List<FollowableTopic> = emptyList(),
+    val newsResources: List<UserNewsResource> = emptyList(),
+)

core/testing/src/main/java/com/google/samples/apps/nowinandroid/core/testing/repository/TestRecentSearchRepository.kt

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.core.testing.repository
+
+import com.google.samples.apps.nowinandroid.core.data.model.RecentSearchQuery
+import com.google.samples.apps.nowinandroid.core.data.repository.RecentSearchRepository
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.flow
+
+class TestRecentSearchRepository : RecentSearchRepository {
+
+    private val cachedRecentSearches: MutableList<RecentSearchQuery> = mutableListOf()
+
+    override fun getRecentSearchQueries(limit: Int): Flow<List<RecentSearchQuery>> {
+        return flow {
+            emit(cachedRecentSearches.sortedByDescending { it.queriedDate }.take(limit))
+        }
+    }
+
+    override suspend fun insertOrReplaceRecentSearch(searchQuery: String) {
+        cachedRecentSearches.add(RecentSearchQuery(searchQuery))
+    }
+
+    override suspend fun clearRecentSearches() {
+        cachedRecentSearches.clear()
+    }
+}

core/testing/src/main/java/com/google/samples/apps/nowinandroid/core/testing/repository/TestSearchContentsRepository.kt

@@ -16,8 +16,8 @@
 
 package com.google.samples.apps.nowinandroid.core.testing.repository
 
+import com.google.samples.apps.nowinandroid.core.data.model.SearchResult
 import com.google.samples.apps.nowinandroid.core.data.repository.SearchContentsRepository
-import com.google.samples.apps.nowinandroid.core.data.repository.SearchResult
 import com.google.samples.apps.nowinandroid.core.model.data.NewsResource
 import com.google.samples.apps.nowinandroid.core.model.data.Topic
 import kotlinx.coroutines.flow.Flow
@@ -28,10 +28,9 @@ class TestSearchContentsRepository : SearchContentsRepository {
     private val cachedTopics: MutableList<Topic> = mutableListOf()
     private val cachedNewsResources: MutableList<NewsResource> = mutableListOf()
 
-    override suspend fun populateFtsData() {}
+    override suspend fun populateFtsData() { /* no-op */ }
 
-    override fun searchContents(searchQuery: String): Flow<SearchResult> {
+    override fun searchContents(searchQuery: String): Flow<SearchResult> = flowOf(
-        return flowOf(
         SearchResult(
             topics = cachedTopics.filter {
                 it.name.contains(searchQuery) ||
@@ -44,7 +43,6 @@ class TestSearchContentsRepository : SearchContentsRepository {
             },
         ),
     )
-    }
 
     /**
      * Test only method to add the topics to the stored list in memory

core/ui/src/main/java/com/google/samples/apps/nowinandroid/core/ui/NewsFeed.kt

@@ -51,6 +51,7 @@ fun LazyGridScope.newsFeed(
     feedState: NewsFeedUiState,
     onNewsResourcesCheckedChanged: (String, Boolean) -> Unit,
     onTopicClick: (String) -> Unit,
+    onExpandedCardClick: () -> Unit = {},
 ) {
     when (feedState) {
         NewsFeedUiState.Loading -> Unit
@@ -67,6 +68,7 @@ fun LazyGridScope.newsFeed(
                     userNewsResource = userNewsResource,
                     isBookmarked = userNewsResource.isSaved,
                     onClick = {
+                        onExpandedCardClick()
                         analyticsHelper.logNewsResourceOpened(
                             newsResourceId = userNewsResource.id,
                             newsResourceTitle = userNewsResource.title,

feature/search/src/androidTest/java/com/google/samples/apps/nowinandroid/feature/search/SearchScreenTest.kt

@@ -23,8 +23,9 @@ import androidx.compose.ui.test.assertIsFocused
 import androidx.compose.ui.test.junit4.createAndroidComposeRule
 import androidx.compose.ui.test.onAllNodesWithContentDescription
 import androidx.compose.ui.test.onNodeWithContentDescription
+import androidx.compose.ui.test.onNodeWithTag
 import androidx.compose.ui.test.onNodeWithText
-import androidx.compose.ui.test.onParent
+import com.google.samples.apps.nowinandroid.core.data.model.RecentSearchQuery
 import com.google.samples.apps.nowinandroid.core.domain.model.UserNewsResource
 import com.google.samples.apps.nowinandroid.core.model.data.DarkThemeConfig.DARK
 import com.google.samples.apps.nowinandroid.core.model.data.ThemeBrand.ANDROID
@@ -47,6 +48,7 @@ class SearchScreenTest {
     private lateinit var clearSearchContentDesc: String
     private lateinit var followButtonContentDesc: String
     private lateinit var unfollowButtonContentDesc: String
+    private lateinit var clearRecentSearchesContentDesc: String
     private lateinit var topicsString: String
     private lateinit var updatesString: String
     private lateinit var tryAnotherSearchString: String
@@ -64,6 +66,7 @@ class SearchScreenTest {
     fun setup() {
         composeTestRule.activity.apply {
             clearSearchContentDesc = getString(R.string.clear_search_text_content_desc)
+            clearRecentSearchesContentDesc = getString(R.string.clear_recent_searches_content_desc)
             followButtonContentDesc =
                 getString(interestsR.string.card_follow_button_content_desc)
             unfollowButtonContentDesc =
@@ -82,10 +85,7 @@ class SearchScreenTest {
         }
 
         composeTestRule
-            .onNodeWithContentDescription(clearSearchContentDesc)
+            .onNodeWithTag("searchTextField")
-            // The parent of the IconButton whose contentDescription matches the clearSearchText
-            // should be the TextField for search
-            .onParent()
             .assertIsFocused()
     }
 
@@ -93,7 +93,7 @@ class SearchScreenTest {
     fun emptySearchResult_emptyScreenIsDisplayed() {
         composeTestRule.setContent {
             SearchScreen(
-                uiState = SearchResultUiState.Success(),
+                searchResultUiState = SearchResultUiState.Success(),
             )
         }
 
@@ -106,7 +106,7 @@ class SearchScreenTest {
     fun searchResultWithTopics_allTopicsAreVisible_followButtonsVisibleForTheNumOfFollowedTopics() {
         composeTestRule.setContent {
             SearchScreen(
-                uiState = SearchResultUiState.Success(topics = followableTopicTestData),
+                searchResultUiState = SearchResultUiState.Success(topics = followableTopicTestData),
             )
         }
 
@@ -135,7 +135,7 @@ class SearchScreenTest {
     fun searchResultWithNewsResources_firstNewsResourcesIsVisible() {
         composeTestRule.setContent {
             SearchScreen(
-                uiState = SearchResultUiState.Success(
+                searchResultUiState = SearchResultUiState.Success(
                     newsResources = newsResourcesTestData.map {
                         UserNewsResource(
                             newsResource = it,
@@ -153,4 +153,29 @@ class SearchScreenTest {
             .onNodeWithText(newsResourcesTestData[0].title)
             .assertIsDisplayed()
     }
+
+    @Test
+    fun emptyQuery_notEmptyRecentSearches_verifyClearSearchesButton_displayed() {
+        val recentSearches = listOf("kotlin", "testing")
+        composeTestRule.setContent {
+            SearchScreen(
+                searchResultUiState = SearchResultUiState.EmptyQuery,
+                recentSearchesUiState = RecentSearchQueriesUiState.Success(
+                    recentQueries = recentSearches.map {
+                        RecentSearchQuery(it)
+                    },
+                ),
+            )
+        }
+
+        composeTestRule
+            .onNodeWithContentDescription(clearRecentSearchesContentDesc)
+            .assertIsDisplayed()
+        composeTestRule
+            .onNodeWithText("kotlin")
+            .assertIsDisplayed()
+        composeTestRule
+            .onNodeWithText("testing")
+            .assertIsDisplayed()
+    }
 }

feature/search/src/main/java/com/google/samples/apps/nowinandroid/feature/search/RecentSearchQueriesUiState.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.samples.apps.nowinandroid.feature.search
+
+import com.google.samples.apps.nowinandroid.core.data.model.RecentSearchQuery
+
+sealed interface RecentSearchQueriesUiState {
+    object Loading : RecentSearchQueriesUiState
+
+    data class Success(
+        val recentQueries: List<RecentSearchQuery> = emptyList(),
+    ) : RecentSearchQueriesUiState
+}

feature/search/src/main/java/com/google/samples/apps/nowinandroid/feature/search/SearchScreen.kt

@@ -29,11 +29,15 @@ import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.safeDrawing
 import androidx.compose.foundation.layout.windowInsetsBottomHeight
 import androidx.compose.foundation.layout.windowInsetsTopHeight
+import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.grid.GridCells.Adaptive
 import androidx.compose.foundation.lazy.grid.LazyVerticalGrid
 import androidx.compose.foundation.lazy.grid.rememberLazyGridState
+import androidx.compose.foundation.lazy.items
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.text.ClickableText
+import androidx.compose.foundation.text.KeyboardActions
+import androidx.compose.foundation.text.KeyboardOptions
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
@@ -46,21 +50,29 @@ import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
+import androidx.compose.ui.ExperimentalComposeUiApi
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.focus.FocusRequester
 import androidx.compose.ui.focus.focusRequester
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.input.key.Key
+import androidx.compose.ui.input.key.key
+import androidx.compose.ui.input.key.onKeyEvent
+import androidx.compose.ui.platform.LocalSoftwareKeyboardController
 import androidx.compose.ui.platform.testTag
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.AnnotatedString
 import androidx.compose.ui.text.SpanStyle
 import androidx.compose.ui.text.buildAnnotatedString
+import androidx.compose.ui.text.font.FontFamily
 import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.input.ImeAction
 import androidx.compose.ui.text.style.TextDecoration
 import androidx.compose.ui.text.withStyle
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.tooling.preview.PreviewParameter
 import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import com.google.samples.apps.nowinandroid.core.designsystem.icon.NiaIcons
@@ -88,18 +100,22 @@ internal fun SearchRoute(
     searchViewModel: SearchViewModel = hiltViewModel(),
     forYouViewModel: ForYouViewModel = hiltViewModel(),
 ) {
-    val uiState by searchViewModel.searchResultUiState.collectAsStateWithLifecycle()
+    val recentSearchQueriesUiState by searchViewModel.recentSearchQueriesUiState.collectAsStateWithLifecycle()
+    val searchResultUiState by searchViewModel.searchResultUiState.collectAsStateWithLifecycle()
     val searchQuery by searchViewModel.searchQuery.collectAsStateWithLifecycle()
     SearchScreen(
         modifier = modifier,
         onBackClick = onBackClick,
+        onClearRecentSearches = searchViewModel::clearRecentSearches,
         onFollowButtonClick = interestsViewModel::followTopic,
         onInterestsClick = onInterestsClick,
         onSearchQueryChanged = searchViewModel::onSearchQueryChanged,
+        onSearchTriggered = searchViewModel::onSearchTriggered,
         onTopicClick = onTopicClick,
         onNewsResourcesCheckedChanged = forYouViewModel::updateNewsResourceSaved,
+        recentSearchesUiState = recentSearchQueriesUiState,
         searchQuery = searchQuery,
-        uiState = uiState,
+        searchResultUiState = searchResultUiState,
     )
 }
 
@@ -107,13 +123,16 @@ internal fun SearchRoute(
 internal fun SearchScreen(
     modifier: Modifier = Modifier,
     onBackClick: () -> Unit = {},
+    onClearRecentSearches: () -> Unit = {},
     onFollowButtonClick: (String, Boolean) -> Unit = { _, _ -> },
     onInterestsClick: () -> Unit = {},
     onNewsResourcesCheckedChanged: (String, Boolean) -> Unit = { _, _ -> },
     onSearchQueryChanged: (String) -> Unit = {},
+    onSearchTriggered: (String) -> Unit = {},
     onTopicClick: (String) -> Unit = {},
     searchQuery: String = "",
-    uiState: SearchResultUiState = SearchResultUiState.Loading,
+    recentSearchesUiState: RecentSearchQueriesUiState = RecentSearchQueriesUiState.Loading,
+    searchResultUiState: SearchResultUiState = SearchResultUiState.Loading,
 ) {
     TrackScreenViewEvent(screenName = "Search")
     Column(modifier = modifier) {
@@ -121,26 +140,42 @@ internal fun SearchScreen(
         SearchToolbar(
             onBackClick = onBackClick,
             onSearchQueryChanged = onSearchQueryChanged,
+            onSearchTriggered = onSearchTriggered,
             searchQuery = searchQuery,
         )
-        when (uiState) {
+        when (searchResultUiState) {
             SearchResultUiState.Loading,
             SearchResultUiState.LoadFailed,
-            SearchResultUiState.EmptyQuery,
             -> Unit
+            SearchResultUiState.EmptyQuery,
+            -> {
+                if (recentSearchesUiState is RecentSearchQueriesUiState.Success) {
+                    RecentSearchesBody(
+                        onClearRecentSearches = onClearRecentSearches,
+                        onRecentSearchClicked = {
+                            onSearchQueryChanged(it)
+                            onSearchTriggered(it)
+                        },
+                        recentSearchQueries = recentSearchesUiState.recentQueries.map { it.query },
+                    )
+                }
+            }
+
             is SearchResultUiState.Success -> {
-                if (uiState.isEmpty()) {
+                if (searchResultUiState.isEmpty()) {
                     EmptySearchResultBody(
                         onInterestsClick = onInterestsClick,
                         searchQuery = searchQuery,
                     )
                 } else {
                     SearchResultBody(
-                        topics = uiState.topics,
+                        topics = searchResultUiState.topics,
                         onFollowButtonClick = onFollowButtonClick,
                         onNewsResourcesCheckedChanged = onNewsResourcesCheckedChanged,
+                        onSearchTriggered = onSearchTriggered,
                         onTopicClick = onTopicClick,
-                        newsResources = uiState.newsResources,
+                        newsResources = searchResultUiState.newsResources,
+                        searchQuery = searchQuery,
                     )
                 }
             }
@@ -151,7 +186,7 @@ internal fun SearchScreen(
 
 @Composable
 fun EmptySearchResultBody(
-    onInterestsClick: () -> Unit = {},
+    onInterestsClick: () -> Unit,
     searchQuery: String,
 ) {
     Column(horizontalAlignment = Alignment.CenterHorizontally) {
@@ -206,8 +241,10 @@ private fun SearchResultBody(
     topics: List<FollowableTopic>,
     newsResources: List<UserNewsResource>,
     onFollowButtonClick: (String, Boolean) -> Unit,
-    onNewsResourcesCheckedChanged: (String, Boolean) -> Unit = { _, _ -> },
+    onNewsResourcesCheckedChanged: (String, Boolean) -> Unit,
-    onTopicClick: (String) -> Unit = {},
+    onSearchTriggered: (String) -> Unit,
+    onTopicClick: (String) -> Unit,
+    searchQuery: String = "",
 ) {
     if (topics.isNotEmpty()) {
         Text(
@@ -220,7 +257,11 @@ private fun SearchResultBody(
         )
         TopicsTabContent(
             topics = topics,
-            onTopicClick = onTopicClick,
+            onTopicClick = {
+                // Pass the current search query to ViewModel to save it as recent searches
+                onSearchTriggered(searchQuery)
+                onTopicClick(it)
+            },
             onFollowButtonClick = onFollowButtonClick,
             withBottomSpacer = false,
         )
@@ -252,17 +293,83 @@ private fun SearchResultBody(
                 feedState = NewsFeedUiState.Success(feed = newsResources),
                 onNewsResourcesCheckedChanged = onNewsResourcesCheckedChanged,
                 onTopicClick = onTopicClick,
+                onExpandedCardClick = {
+                    onSearchTriggered(searchQuery)
+                },
+            )
+        }
+    }
+}
+
+@Composable
+private fun RecentSearchesBody(
+    onClearRecentSearches: () -> Unit,
+    onRecentSearchClicked: (String) -> Unit,
+    recentSearchQueries: List<String>,
+) {
+    Column {
+        Row(
+            horizontalArrangement = Arrangement.SpaceBetween,
+            verticalAlignment = Alignment.CenterVertically,
+            modifier = Modifier.fillMaxWidth(),
+        ) {
+            Text(
+                text = buildAnnotatedString {
+                    withStyle(style = SpanStyle(fontWeight = FontWeight.Bold)) {
+                        append(stringResource(id = searchR.string.recent_searches))
+                    }
+                },
+                modifier = Modifier.padding(horizontal = 16.dp, vertical = 8.dp),
+            )
+            if (recentSearchQueries.isNotEmpty()) {
+                IconButton(
+                    onClick = {
+                        onClearRecentSearches()
+                    },
+                    modifier = Modifier.padding(horizontal = 16.dp),
+                ) {
+                    Icon(
+                        imageVector = NiaIcons.Close,
+                        contentDescription = stringResource(
+                            id = searchR.string.clear_recent_searches_content_desc,
+                        ),
+                        tint = MaterialTheme.colorScheme.onSurface,
                     )
                 }
             }
+        }
+        LazyColumn(modifier = Modifier.padding(horizontal = 16.dp)) {
+            items(recentSearchQueries) { recentSearch ->
+                ClickableText(
+                    text = buildAnnotatedString {
+                        withStyle(
+                            style = SpanStyle(
+                                fontSize = 28.sp,
+                                fontFamily = FontFamily.SansSerif,
+                            ),
+                        ) {
+                            append(recentSearch)
+                        }
+                    },
+                    onClick = {
+                        onRecentSearchClicked(recentSearch)
+                    },
+                    modifier = Modifier
+                        .padding(vertical = 16.dp)
+                        .fillMaxWidth(),
+                )
+            }
+        }
+    }
 }
 
 @Composable
 private fun SearchToolbar(
     modifier: Modifier = Modifier,
-    onBackClick: () -> Unit = {},
+    onBackClick: () -> Unit,
-    onSearchQueryChanged: (String) -> Unit = {},
+    onSearchQueryChanged: (String) -> Unit,
     searchQuery: String = "",
+    onSearchTriggered: (String) -> Unit,
 ) {
     Row(
         verticalAlignment = Alignment.CenterVertically,
@@ -278,18 +385,27 @@ private fun SearchToolbar(
         }
         SearchTextField(
             onSearchQueryChanged = onSearchQueryChanged,
+            onSearchTriggered = onSearchTriggered,
             searchQuery = searchQuery,
         )
     }
 }
 
-@OptIn(ExperimentalMaterial3Api::class)
+@OptIn(ExperimentalMaterial3Api::class, ExperimentalComposeUiApi::class)
 @Composable
 private fun SearchTextField(
     onSearchQueryChanged: (String) -> Unit,
     searchQuery: String,
+    onSearchTriggered: (String) -> Unit,
 ) {
     val focusRequester = remember { FocusRequester() }
+    val keyboardController = LocalSoftwareKeyboardController.current
+
+    val onSearchExplicitlyTriggered = {
+        keyboardController?.hide()
+        onSearchTriggered(searchQuery)
+    }
+
     TextField(
         colors = TextFieldDefaults.textFieldColors(
             focusedIndicatorColor = Color.Transparent,
@@ -306,9 +422,12 @@ private fun SearchTextField(
             )
         },
         trailingIcon = {
-            IconButton(onClick = {
+            if (searchQuery.isNotEmpty()) {
+                IconButton(
+                    onClick = {
                         onSearchQueryChanged("")
-            }) {
+                    },
+                ) {
                     Icon(
                         imageVector = NiaIcons.Close,
                         contentDescription = stringResource(
@@ -317,16 +436,37 @@ private fun SearchTextField(
                         tint = MaterialTheme.colorScheme.onSurface,
                     )
                 }
+            }
         },
         onValueChange = {
+            if (!it.contains("\n")) {
                 onSearchQueryChanged(it)
+            }
         },
         modifier = Modifier
             .fillMaxWidth()
             .padding(16.dp)
-            .focusRequester(focusRequester),
+            .focusRequester(focusRequester)
+            .onKeyEvent {
+                if (it.key == Key.Enter) {
+                    onSearchExplicitlyTriggered()
+                    true
+                } else {
+                    false
+                }
+            }.testTag("searchTextField"),
         shape = RoundedCornerShape(32.dp),
         value = searchQuery,
+        keyboardOptions = KeyboardOptions(
+            imeAction = ImeAction.Search,
+        ),
+        keyboardActions = KeyboardActions(
+            onSearch = {
+                onSearchExplicitlyTriggered()
+            },
+        ),
+        maxLines = 1,
+        singleLine = true,
     )
     LaunchedEffect(Unit) {
         focusRequester.requestFocus()
@@ -337,7 +477,11 @@ private fun SearchTextField(
 @Composable
 private fun SearchToolbarPreview() {
     NiaTheme {
-        SearchToolbar()
+        SearchToolbar(
+            onBackClick = {},
+            onSearchQueryChanged = {},
+            onSearchTriggered = {},
+        )
     }
 }
 
@@ -345,7 +489,22 @@ private fun SearchToolbarPreview() {
 @Composable
 private fun EmptySearchResultColumnPreview() {
     NiaTheme {
-        EmptySearchResultBody(searchQuery = "C++")
+        EmptySearchResultBody(
+            onInterestsClick = {},
+            searchQuery = "C++",
+        )
+    }
+}
+
+@Preview
+@Composable
+private fun RecentSearchesBodyPreview() {
+    NiaTheme {
+        RecentSearchesBody(
+            onClearRecentSearches = {},
+            onRecentSearchClicked = {},
+            recentSearchQueries = listOf("kotlin", "jetpack compose", "testing"),
+        )
     }
 }
 
@@ -356,6 +515,6 @@ private fun SearchScreenPreview(
     searchResultUiState: SearchResultUiState,
 ) {
     NiaTheme {
-        SearchScreen(uiState = searchResultUiState)
+        SearchScreen(searchResultUiState = searchResultUiState)
     }
 }

feature/search/src/main/java/com/google/samples/apps/nowinandroid/feature/search/SearchViewModel.kt

@@ -19,8 +19,11 @@ package com.google.samples.apps.nowinandroid.feature.search
 import androidx.lifecycle.SavedStateHandle
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import com.google.samples.apps.nowinandroid.core.data.repository.RecentSearchRepository
+import com.google.samples.apps.nowinandroid.core.domain.GetRecentSearchQueriesUseCase
 import com.google.samples.apps.nowinandroid.core.domain.GetSearchContentsUseCase
-import com.google.samples.apps.nowinandroid.feature.search.SearchResultUiState.LoadFailed
+import com.google.samples.apps.nowinandroid.core.result.Result
+import com.google.samples.apps.nowinandroid.core.result.asResult
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
@@ -28,31 +31,42 @@ import kotlinx.coroutines.flow.flatMapLatest
 import kotlinx.coroutines.flow.flowOf
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.stateIn
+import kotlinx.coroutines.launch
 import javax.inject.Inject
 
 @HiltViewModel
 class SearchViewModel @Inject constructor(
     // TODO: Add GetSearchContentsCountUseCase to check if the fts tables are populated
     getSearchContentsUseCase: GetSearchContentsUseCase,
+    recentSearchQueriesUseCase: GetRecentSearchQueriesUseCase,
+    private val recentSearchRepository: RecentSearchRepository,
     private val savedStateHandle: SavedStateHandle,
 ) : ViewModel() {
 
-    val searchQuery = savedStateHandle.getStateFlow("searchQuery", "")
+    val searchQuery = savedStateHandle.getStateFlow(SEARCH_QUERY, "")
 
     val searchResultUiState: StateFlow<SearchResultUiState> =
         searchQuery.flatMapLatest { query ->
-            if (query.length < 2) {
+            if (query.length < SEARCH_QUERY_MIN_LENGTH) {
                 flowOf(SearchResultUiState.EmptyQuery)
             } else {
-                try {
+                getSearchContentsUseCase(query).asResult().map {
-                    getSearchContentsUseCase(query).map {
+                    when (it) {
+                        is Result.Success -> {
                             SearchResultUiState.Success(
-                            topics = it.topics,
+                                topics = it.data.topics,
-                            newsResources = it.newsResources,
+                                newsResources = it.data.newsResources,
                             )
                         }
-                } catch (exception: Exception) {
+
-                    flowOf(LoadFailed)
+                        is Result.Loading -> {
+                            SearchResultUiState.Loading
+                        }
+
+                        is Result.Error -> {
+                            SearchResultUiState.LoadFailed
+                        }
+                    }
                 }
             }
         }.stateIn(
@@ -61,7 +75,39 @@ class SearchViewModel @Inject constructor(
             initialValue = SearchResultUiState.Loading,
         )
 
+    val recentSearchQueriesUiState: StateFlow<RecentSearchQueriesUiState> =
+        recentSearchQueriesUseCase().map {
+            RecentSearchQueriesUiState.Success(it)
+        }.stateIn(
+            scope = viewModelScope,
+            started = SharingStarted.WhileSubscribed(5_000),
+            initialValue = RecentSearchQueriesUiState.Loading,
+        )
+
     fun onSearchQueryChanged(query: String) {
-        savedStateHandle["searchQuery"] = query
+        savedStateHandle[SEARCH_QUERY] = query
+    }
+
+    /**
+     * Called when the search action is explicitly triggered by the user. For example, when the
+     * search icon is tapped in the IME or when the enter key is pressed in the search text field.
+     *
+     * The search results are displayed on the fly as the user types, but to explicitly save the
+     * search query in the search text field, defining this method.
+     */
+    fun onSearchTriggered(query: String) {
+        viewModelScope.launch {
+            recentSearchRepository.insertOrReplaceRecentSearch(query)
+        }
+    }
+
+    fun clearRecentSearches() {
+        viewModelScope.launch {
+            recentSearchRepository.clearRecentSearches()
+        }
     }
 }
+
+/** Minimum length where search query is considered as [SearchResultUiState.EmptyQuery] */
+const val SEARCH_QUERY_MIN_LENGTH = 2
+const val SEARCH_QUERY = "searchQuery"

feature/search/src/main/java/com/google/samples/apps/nowinandroid/feature/search/navigation/SearchNavigation.kt

@@ -31,7 +31,7 @@ fun NavController.navigateToSearch(navOptions: NavOptions? = null) {
 fun NavGraphBuilder.searchScreen(
     onBackClick: () -> Unit,
     onInterestsClick: () -> Unit,
-    onTopicClick: (String) -> Unit = {},
+    onTopicClick: (String) -> Unit,
 ) {
     // TODO: Handle back stack for each top-level destination. At the moment each top-level
     // destination may have own search screen's back stack.

feature/search/src/main/res/values/strings.xml

@@ -23,4 +23,6 @@
     <string name="to_browse_topics"> to browse topics</string>
     <string name="topics">Topics</string>
     <string name="updates">Updates</string>
+    <string name="recent_searches">Recent searches</string>
+    <string name="clear_recent_searches_content_desc">Clear searches</string>
 </resources>

feature/search/src/test/java/com/google/samples/apps/nowinandroid/feature/search/SearchViewModelTest.kt

@@ -17,12 +17,15 @@
 package com.google.samples.apps.nowinandroid.feature.search
 
 import androidx.lifecycle.SavedStateHandle
+import com.google.samples.apps.nowinandroid.core.domain.GetRecentSearchQueriesUseCase
 import com.google.samples.apps.nowinandroid.core.domain.GetSearchContentsUseCase
 import com.google.samples.apps.nowinandroid.core.testing.data.newsResourcesTestData
 import com.google.samples.apps.nowinandroid.core.testing.data.topicsTestData
+import com.google.samples.apps.nowinandroid.core.testing.repository.TestRecentSearchRepository
 import com.google.samples.apps.nowinandroid.core.testing.repository.TestSearchContentsRepository
 import com.google.samples.apps.nowinandroid.core.testing.repository.TestUserDataRepository
 import com.google.samples.apps.nowinandroid.core.testing.util.MainDispatcherRule
+import com.google.samples.apps.nowinandroid.feature.search.RecentSearchQueriesUiState.Success
 import com.google.samples.apps.nowinandroid.feature.search.SearchResultUiState.EmptyQuery
 import com.google.samples.apps.nowinandroid.feature.search.SearchResultUiState.Loading
 import kotlinx.coroutines.flow.collect
@@ -33,6 +36,7 @@ import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
 import kotlin.test.assertEquals
+import kotlin.test.assertIs
 
 /**
  * To learn more about how this test handles Flows created with stateIn, see
@@ -49,13 +53,17 @@ class SearchViewModelTest {
         searchContentsRepository = searchContentsRepository,
         userDataRepository = userDataRepository,
     )
+    private val recentSearchRepository = TestRecentSearchRepository()
+    private val getRecentQueryUseCase = GetRecentSearchQueriesUseCase(recentSearchRepository)
     private lateinit var viewModel: SearchViewModel
 
     @Before
     fun setup() {
         viewModel = SearchViewModel(
             getSearchContentsUseCase = getSearchContentsUseCase,
+            recentSearchQueriesUseCase = getRecentQueryUseCase,
             savedStateHandle = SavedStateHandle(),
+            recentSearchRepository = recentSearchRepository,
         )
     }
 
@@ -76,7 +84,7 @@ class SearchViewModelTest {
 
     @Test
     fun emptyResultIsReturned_withNotMatchingQuery() = runTest {
-        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.searchQuery.collect() }
+        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.searchResultUiState.collect() }
 
         viewModel.onSearchQueryChanged("XXX")
         searchContentsRepository.addNewsResources(newsResourcesTestData)
@@ -88,4 +96,15 @@ class SearchViewModelTest {
 
         collectJob.cancel()
     }
+
+    @Test
+    fun recentSearches() = runTest {
+        val collectJob = launch(UnconfinedTestDispatcher()) { viewModel.recentSearchQueriesUiState.collect() }
+        viewModel.onSearchTriggered("kotlin")
+
+        val result = viewModel.recentSearchQueriesUiState.value
+        assertIs<Success>(result)
+
+        collectJob.cancel()
+    }
 }