Update instead of replace user to avoid CASCADE deleting all cached feeds

Previously, every time database entry for the user is updated (as it is
on startup of the app), the tables depending on the user will get wiped.
This includes notifications, public and home feeds, so that breaks quite
a bit of things in a hard to debug way.

app/src/main/java/org/pixeldroid/app/utils/db/DBUtils.kt

@@ -14,7 +14,7 @@ import java.lang.IllegalArgumentException
 
 fun addUser(db: AppDatabase, account: Account, instance_uri: String, activeUser: Boolean = true,
             accessToken: String, refreshToken: String?, clientId: String, clientSecret: String) {
-    db.userDao().insertUser(
+    db.userDao().insertOrUpdate(
             UserDatabaseEntity(
                     user_id = account.id!!,
                     instance_uri = normalizeDomain(instance_uri),

app/src/main/java/org/pixeldroid/app/utils/db/dao/UserDao.kt

@@ -5,8 +5,21 @@ import org.pixeldroid.app.utils.db.entities.UserDatabaseEntity
 
 @Dao
 interface UserDao {
-    @Insert(onConflict = OnConflictStrategy.REPLACE)
-    fun insertUser(user: UserDatabaseEntity)
+    /**
+     * Insert a user, if it already exists return -1
+     */
+    @Insert(onConflict = OnConflictStrategy.IGNORE)
+    fun insertUser(user: UserDatabaseEntity): Long
+
+    @Transaction
+    fun insertOrUpdate(user: UserDatabaseEntity) {
+        if (insertUser(user) == -1L) {
+            updateUser(user)
+        }
+    }
+
+    @Update
+    fun updateUser(user: UserDatabaseEntity)
 
     @Query("UPDATE users SET accessToken = :accessToken, refreshToken = :refreshToken WHERE user_id = :id and instance_uri = :instance_uri")
     fun updateAccessToken(accessToken: String, refreshToken: String, id: String, instance_uri: String)