57 lines
1.8 KiB
Kotlin
57 lines
1.8 KiB
Kotlin
package com.github.apognu.otter.repositories
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import android.content.Context
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import com.github.apognu.otter.utils.Cache
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import com.github.apognu.otter.utils.CacheItem
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import kotlinx.coroutines.CoroutineScope
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import kotlinx.coroutines.Dispatchers.IO
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import kotlinx.coroutines.Job
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import kotlinx.coroutines.flow.*
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import java.io.BufferedReader
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interface Upstream<D> {
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fun fetch(size: Int = 0): Flow<Repository.Response<D>>
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}
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abstract class Repository<D : Any, C : CacheItem<D>> {
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protected val scope: CoroutineScope = CoroutineScope(Job() + IO)
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enum class Origin(val origin: Int) {
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Cache(0b01),
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Network(0b10)
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}
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data class Response<D>(val origin: Origin, val data: List<D>, val hasMore: Boolean)
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abstract val context: Context?
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abstract val cacheId: String?
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abstract val upstream: Upstream<D>
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open fun cache(data: List<D>): C? = null
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protected open fun uncache(reader: BufferedReader): C? = null
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fun fetch(upstreams: Int = Origin.Cache.origin and Origin.Network.origin, size: Int = 0): Flow<Response<D>> = flow {
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if (Origin.Cache.origin and upstreams == upstreams) fromCache().collect { emit(it) }
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if (Origin.Network.origin and upstreams == upstreams) fromNetwork(size).collect { emit(it) }
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}
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private fun fromCache() = flow {
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cacheId?.let { cacheId ->
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Cache.get(context, cacheId)?.let { reader ->
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uncache(reader)?.let { cache ->
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emit(Response(Origin.Cache, cache.data, false))
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}
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}
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}
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}.flowOn(IO)
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private fun fromNetwork(size: Int) = flow {
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upstream
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.fetch(size)
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.map { response -> Response(Origin.Network, onDataFetched(response.data), response.hasMore) }
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.collect { response -> emit(Response(Origin.Network, response.data, response.hasMore)) }
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}
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protected open fun onDataFetched(data: List<D>) = data
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}
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