Added a database working in LRU (#43)

Co-authored-by: Joachim Dunant <joachim.dunant@epfl.ch>

app/build.gradle

@@ -44,7 +44,7 @@ android {
 
     }
 
-
+    apply plugin: 'kotlin-kapt'
 }
 
 dependencies {
@@ -65,6 +65,10 @@ dependencies {
     implementation "androidx.browser:browser:1.2.0"
     implementation 'com.google.android.material:material:1.1.0'
 
+    def room_version = "2.2.4"
+    implementation "androidx.room:room-runtime:$room_version"
+    kapt "androidx.room:room-compiler:$room_version"
+    implementation "androidx.room:room-ktx:$room_version"
 
     implementation("com.github.bumptech.glide:glide:4.11.0") {
         exclude group: "com.android.support"

app/src/androidTest/java/com/h/pixeldroid/AppDatabaseTest.kt

@@ -0,0 +1,69 @@
+package com.h.pixeldroid
+
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.h.pixeldroid.db.AppDatabase
+import com.h.pixeldroid.db.PostDao
+import com.h.pixeldroid.db.PostEntity
+import com.h.pixeldroid.utils.*
+import org.junit.After
+import org.junit.Assert
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+import java.util.Calendar
+
+@RunWith(AndroidJUnit4::class)
+class AppDatabaseTest {
+    private var postDao: PostDao? = null
+    private var db: AppDatabase? = null
+    private var postTest = PostEntity(1, "test", date= Calendar.getInstance().time)
+
+    @Before
+    fun setup() {
+        AppDatabase.TEST_MODE = true
+        db = AppDatabase.getDatabase(ApplicationProvider.getApplicationContext())
+        postDao = db?.postDao()
+        postDao?.insertAll(postTest)
+    }
+
+    @After
+    fun tearDown() {
+
+    }
+
+    @Test
+    fun testInsertPostItem() {
+        Assert.assertEquals(postTest.domain, postDao?.getById(postTest.uid)!!.domain)
+    }
+
+    @Test
+    fun testDeleteAll(){
+        postDao?.deleteAll()
+        Assert.assertEquals(postDao?.getPostsCount(), 0)
+    }
+
+    @Test
+    fun testUtilsInsertAll() {
+        val postTest2 = PostEntity(2, "test", date= Calendar.getInstance().time)
+        DatabaseUtils.insertAllPosts(db!!, postTest, postTest2)
+
+        Assert.assertEquals(postTest.domain, postDao?.getById(postTest.uid)!!.domain)
+        Assert.assertEquals(postTest2.domain, postDao?.getById(postTest2.uid)!!.domain)
+    }
+
+    @Test
+    fun testUtilsLRU() {
+        for(i in 1..db!!.MAX_NUMBER_OF_POSTS) {
+            DatabaseUtils.insertAllPosts(db!!, PostEntity(i, i.toString(), date= Calendar.getInstance().time))
+        }
+
+        Assert.assertEquals("1", postDao?.getById(1)!!.domain)
+        Assert.assertEquals(db?.MAX_NUMBER_OF_POSTS, postDao?.getPostsCount())
+
+        DatabaseUtils.insertAllPosts(db!!, PostEntity(0, "0", date= Calendar.getInstance().time))
+        Assert.assertEquals(db?.MAX_NUMBER_OF_POSTS, postDao?.getPostsCount())
+        val eldestPost = postDao?.getById(1)
+        Assert.assertEquals(null, eldestPost)
+    }
+}

app/src/main/java/com/h/pixeldroid/MainActivity.kt

@@ -1,5 +1,6 @@
 package com.h.pixeldroid
 
+import android.app.Activity
 import android.content.Intent
 import android.os.Bundle
 import android.view.MenuItem
@@ -19,6 +20,7 @@ import com.h.pixeldroid.motions.OnSwipeListener
 class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelectedListener {
 
     private lateinit var drawerLayout: DrawerLayout
+    private val newPostsActivityRequestCode = Activity.RESULT_OK
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -69,7 +71,7 @@ class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelecte
         supportFragmentManager.beginTransaction().replace(R.id.fragment_container, fragment).commit()
     }
 
-    /*
+    /**
     When clicking in the drawer menu, go to the corresponding activity
      */
     override fun onNavigationItemSelected(@NonNull item: MenuItem): Boolean {
@@ -83,7 +85,7 @@ class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelecte
         return true
     }
 
-    /*
+    /**
     Launches the given activity and put it as the current one
      */
     private fun launchActivity(activity: AppCompatActivity) {
@@ -91,8 +93,8 @@ class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelecte
         startActivity(intent)
     }
 
-    /*
-    Closes the drawer if we are clicking behind it
+    /**
+    Closes the drawer if it is open, when we press the back button
      */
     override fun onBackPressed() {
         if(drawerLayout.isDrawerOpen(GravityCompat.START)){

app/src/main/java/com/h/pixeldroid/db/AppDatabase.kt

@@ -0,0 +1,41 @@
+package com.h.pixeldroid.db
+
+import android.content.Context
+import androidx.room.Database
+import androidx.room.Room
+import androidx.room.RoomDatabase
+import androidx.room.TypeConverters
+
+@Database(entities = [PostEntity::class], version = 1)
+@TypeConverters(Converters::class)
+abstract class AppDatabase : RoomDatabase() {
+    abstract fun postDao(): PostDao
+    val MAX_NUMBER_OF_POSTS = 100
+
+    companion object {
+        // Singleton prevents multiple instances of database opening at the
+        // same time.
+        @Volatile
+        private var INSTANCE: AppDatabase? = null
+        var TEST_MODE = false
+
+        fun getDatabase(context: Context): AppDatabase {
+
+            return INSTANCE ?: synchronized(this) {
+                var instance: AppDatabase? = null
+
+                // To be able to create a temporary database that flushes when tests are over
+                instance = if (TEST_MODE) {
+                    Room.inMemoryDatabaseBuilder(context, AppDatabase::class.java).allowMainThreadQueries().build()
+                } else {
+                    Room.databaseBuilder(
+                        context.applicationContext, AppDatabase::class.java, "posts_database"
+                    ).build()
+                }
+
+                INSTANCE = instance
+                return instance
+            }
+        }
+    }
+}

app/src/main/java/com/h/pixeldroid/db/Converters.kt

@@ -0,0 +1,16 @@
+package com.h.pixeldroid.db
+
+import androidx.room.TypeConverter
+import java.util.Date
+
+class Converters {
+    @TypeConverter
+    fun fromTimestamp(value: Long?): Date? {
+        return value?.let { Date(it) }
+    }
+
+    @TypeConverter
+    fun dateToTimestamp(date: Date?): Long? {
+        return date?.time?.toLong()
+    }
+}

app/src/main/java/com/h/pixeldroid/db/PostDao.kt

@@ -0,0 +1,36 @@
+package com.h.pixeldroid.db
+
+import androidx.lifecycle.LiveData
+import androidx.room.Dao
+import androidx.room.Delete
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy.REPLACE
+import androidx.room.Query
+import java.util.Date
+
+@Dao
+interface PostDao {
+    @Query("SELECT * FROM posts")
+    fun getAll(): LiveData<List<PostEntity>>
+
+    @Query("SELECT * FROM posts WHERE uid = :postId")
+    fun getById(postId: Int): PostEntity
+
+    @Query("SELECT count(*) FROM posts")
+    fun getPostsCount(): Int
+
+    @Query("UPDATE posts SET date = :date WHERE uid = :postId")
+    fun addDateToPost(postId: Int, date: Date)
+
+    @Query("DELETE FROM posts")
+    fun deleteAll()
+
+    @Query("DELETE FROM posts WHERE date IN (SELECT min(date) FROM posts) ")
+    fun deleteOldestPost(): Int
+
+    @Insert(onConflict = REPLACE)
+    fun insertAll(vararg posts: PostEntity)
+
+    @Delete
+    fun delete(post: PostEntity)
+}

app/src/main/java/com/h/pixeldroid/db/PostEntity.kt

@@ -0,0 +1,17 @@
+package com.h.pixeldroid.db
+
+import androidx.room.ColumnInfo;
+import androidx.room.Entity;
+import androidx.room.PrimaryKey;
+import java.util.Date
+
+@Entity(tableName= "posts")
+data class PostEntity(
+    @PrimaryKey val uid: Int,
+    @ColumnInfo(name = "domain") val domain: String? = "",
+    @ColumnInfo(name = "username") val username: String? = "",
+    @ColumnInfo(name = "display name") val displayName: String? = "",
+    @ColumnInfo(name = "accountID") val accountID: Int? = -1,
+    @ColumnInfo(name = "image url") val ImageURL: String? = "",
+    @ColumnInfo(name = "date") val date: Date?
+)

app/src/main/java/com/h/pixeldroid/utils/DatabaseUtils.kt

@@ -0,0 +1,45 @@
+package com.h.pixeldroid.utils
+
+import com.h.pixeldroid.db.AppDatabase
+import com.h.pixeldroid.db.PostEntity
+import java.util.Calendar
+
+class DatabaseUtils {
+    companion object {
+        /**
+         * Inserts one post into the specified database,
+         * after it has checked the LRU
+         */
+        fun insertPost(db: AppDatabase, post: PostEntity) {
+            if (!IsInsertable(db)) {
+                removeEldestPost(db)
+            }
+
+            db.postDao().addDateToPost(post.uid, Calendar.getInstance().time)
+            db.postDao().insertAll(post)
+        }
+
+        /**
+         * Inserts multiple posts into the specified database
+         */
+        fun insertAllPosts(db: AppDatabase, vararg posts: PostEntity) {
+            posts.forEach { insertPost(db, it) }
+        }
+
+        /**
+         * Checks if we can add one post into the database
+         * or if it is full
+         */
+        private fun IsInsertable(db: AppDatabase): Boolean {
+            return db.postDao().getPostsCount() + 1 <= db.MAX_NUMBER_OF_POSTS
+        }
+
+        /**
+         * Removes the eldest post from the database
+         */
+        private fun removeEldestPost(db: AppDatabase) {
+            db.postDao().deleteOldestPost()
+        }
+    }
+
+}

app/src/main/res/drawable/ic_add_black_24dp.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24.0"
+        android:viewportHeight="24.0">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M19,13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z"/>
+</vector>

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

@@ -17,4 +17,12 @@
 
     <style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />
 
+    <style name="posts_title">
+        <item name="android:layout_width">match_parent</item>
+        <item name="android:layout_marginBottom">8dp</item>
+        <item name="android:paddingLeft">8dp</item>
+        <item name="android:background">@android:color/holo_orange_light</item>
+        <item name="android:textAppearance">@android:style/TextAppearance.Large</item>
+    </style>
+
 </resources>