81 lines
3.3 KiB
Kotlin
81 lines
3.3 KiB
Kotlin
/*
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* Copyright (C) 2020 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.pixeldroid.app.posts.feeds.cachedFeeds.postFeeds
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import androidx.paging.ExperimentalPagingApi
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import androidx.paging.LoadType
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import androidx.paging.PagingSource
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import androidx.paging.PagingState
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import androidx.paging.RemoteMediator
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import androidx.room.withTransaction
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import org.pixeldroid.app.utils.db.AppDatabase
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import org.pixeldroid.app.utils.db.entities.PublicFeedStatusDatabaseEntity
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import org.pixeldroid.app.utils.di.PixelfedAPIHolder
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/**
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* RemoteMediator for the public feed.
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*
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* A [RemoteMediator] defines a set of callbacks used to incrementally load data from a remote
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* source into a local source wrapped by a [PagingSource], e.g., loading data from network into
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* a local db cache.
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*/
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@OptIn(ExperimentalPagingApi::class)
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class PublicFeedRemoteMediator(
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private val apiHolder: PixelfedAPIHolder,
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private val db: AppDatabase
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) : RemoteMediator<Int, PublicFeedStatusDatabaseEntity>() {
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override suspend fun load(loadType: LoadType, state: PagingState<Int, PublicFeedStatusDatabaseEntity>): MediatorResult {
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val maxId = when (loadType) {
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LoadType.REFRESH -> null
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LoadType.PREPEND -> {
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// No prepend for the moment, might be nice to add later
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return MediatorResult.Success(endOfPaginationReached = true)
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}
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LoadType.APPEND -> state.lastItemOrNull()?.id
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?: return MediatorResult.Success(endOfPaginationReached = true)
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}
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try {
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val user = db.userDao().getActiveUser()
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?: return MediatorResult.Error(NullPointerException("No active user exists"))
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val api = apiHolder.api ?: apiHolder.setToCurrentUser()
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val apiResponse = api.timelinePublic(
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max_id = maxId,
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limit = state.config.pageSize.toString(),
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)
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val dbObjects = apiResponse.map{
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PublicFeedStatusDatabaseEntity(user.user_id, user.instance_uri, it)
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}
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val endOfPaginationReached = apiResponse.isEmpty() || maxId == apiResponse.sortedBy { it.created_at }.last().id
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db.withTransaction {
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// Clear table in the database
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if (loadType == LoadType.REFRESH) {
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db.publicPostDao().clearFeedContent(user.user_id, user.instance_uri)
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}
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db.publicPostDao().insertAll(dbObjects)
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}
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return MediatorResult.Success(endOfPaginationReached = endOfPaginationReached)
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} catch (exception: Exception) {
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return MediatorResult.Error(exception)
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}
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}
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} |