PixelDroid-App-Android/app/src/main/java/com/h/pixeldroid/posts/feeds/cachedFeeds/notifications/NotificationsRemoteMediator.kt

87 lines
3.2 KiB
Kotlin

/*
* Copyright (C) 2020 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
*
* http://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.h.pixeldroid.posts.feeds.cachedFeeds.notifications
import androidx.paging.*
import androidx.room.withTransaction
import com.h.pixeldroid.utils.db.AppDatabase
import com.h.pixeldroid.utils.di.PixelfedAPIHolder
import com.h.pixeldroid.utils.api.objects.Notification
import retrofit2.HttpException
import java.io.IOException
import java.lang.NullPointerException
import javax.inject.Inject
/**
* RemoteMediator for the notifications.
*
* A [RemoteMediator] defines a set of callbacks used to incrementally load data from a remote
* source into a local source wrapped by a [PagingSource], e.g., loading data from network into
* a local db cache.
*/
@OptIn(ExperimentalPagingApi::class)
class NotificationsRemoteMediator @Inject constructor(
private val apiHolder: PixelfedAPIHolder,
private val db: AppDatabase
) : RemoteMediator<Int, Notification>() {
override suspend fun load(loadType: LoadType, state: PagingState<Int, Notification>): MediatorResult {
val (max_id, min_id) = when (loadType) {
LoadType.REFRESH -> {
Pair<String?, String?>(null, null)
}
LoadType.PREPEND -> {
//No prepend for the moment, might be nice to add later
return MediatorResult.Success(endOfPaginationReached = true)
}
LoadType.APPEND -> {
Pair<String?, String?>(state.lastItemOrNull()?.id, null)
}
}
try {
val user = db.userDao().getActiveUser()
?: return MediatorResult.Error(NullPointerException("No active user exists"))
val api = apiHolder.api ?: apiHolder.setToCurrentUser()
val apiResponse = api.notifications(
max_id = max_id,
min_id = min_id,
limit = state.config.pageSize.toString(),
)
apiResponse.forEach{it.user_id = user.user_id; it.instance_uri = user.instance_uri}
val endOfPaginationReached = apiResponse.isEmpty()
db.withTransaction {
// clear table in the database
if (loadType == LoadType.REFRESH) {
db.notificationDao().clearFeedContent()
}
db.notificationDao().insertAll(apiResponse)
}
return MediatorResult.Success(endOfPaginationReached = endOfPaginationReached)
} catch (exception: IOException) {
return MediatorResult.Error(exception)
} catch (exception: HttpException) {
return MediatorResult.Error(exception)
}
}
}