73 lines
2.6 KiB
Kotlin
73 lines
2.6 KiB
Kotlin
package com.h.pixeldroid.posts.feeds.cachedFeeds.postFeeds
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import androidx.paging.*
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import androidx.room.withTransaction
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import com.h.pixeldroid.utils.db.AppDatabase
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import com.h.pixeldroid.utils.di.PixelfedAPIHolder
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import com.h.pixeldroid.utils.db.entities.HomeStatusDatabaseEntity
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import retrofit2.HttpException
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import java.io.IOException
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import java.lang.NullPointerException
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import javax.inject.Inject
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/**
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* RemoteMediator for the home 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 HomeFeedRemoteMediator @Inject constructor(
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private val apiHolder: PixelfedAPIHolder,
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private val db: AppDatabase,
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) : RemoteMediator<Int, HomeStatusDatabaseEntity>() {
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override suspend fun load(loadType: LoadType, state: PagingState<Int, HomeStatusDatabaseEntity>): MediatorResult {
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val (max_id, min_id) = when (loadType) {
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LoadType.REFRESH -> {
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Pair<String?, String?>(null, null)
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}
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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 -> {
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Pair<String?, String?>(state.lastItemOrNull()?.id, null)
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}
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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.timelineHome(
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max_id= max_id,
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min_id = min_id, limit = state.config.pageSize.toString()
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)
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val dbObjects = apiResponse.map{
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HomeStatusDatabaseEntity(user.user_id, user.instance_uri, it)
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}
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val endOfPaginationReached = apiResponse.isEmpty()
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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.homePostDao().clearFeedContent()
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}
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db.homePostDao().insertAll(dbObjects)
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}
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return MediatorResult.Success(endOfPaginationReached = endOfPaginationReached)
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} catch (exception: IOException) {
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return MediatorResult.Error(exception)
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} catch (exception: HttpException) {
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return MediatorResult.Error(exception)
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}
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}
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} |