80 lines
2.1 KiB
Kotlin
80 lines
2.1 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 com.github.apognu.otter.utils.untilNetwork
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import com.google.gson.Gson
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import kotlinx.coroutines.Dispatchers.IO
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import kotlinx.coroutines.GlobalScope
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import kotlinx.coroutines.channels.Channel
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import kotlinx.coroutines.launch
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import java.io.BufferedReader
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interface Upstream<D> {
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fun fetch(size: Int = 0): Channel<Repository.Response<D>>?
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}
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abstract class Repository<D : Any, C : CacheItem<D>> {
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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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private var _channel: Channel<Response<D>>? = null
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private val channel: Channel<Response<D>>
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get() {
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if (_channel?.isClosedForSend ?: true) {
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_channel = Channel(10)
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}
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return _channel!!
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}
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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): Channel<Response<D>> {
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if (Origin.Cache.origin and upstreams == upstreams) fromCache()
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if (Origin.Network.origin and upstreams == upstreams) fromNetwork(size)
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return channel
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}
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private fun fromCache() {
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GlobalScope.launch(IO) {
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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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channel.offer(Response(Origin.Cache, cache.data, false))
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}
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}
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}
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}
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}
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private fun fromNetwork(size: Int) {
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upstream.fetch(size)?.untilNetwork(IO) { data, hasMore ->
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val data = onDataFetched(data)
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cacheId?.let { cacheId ->
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Cache.set(
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context,
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cacheId,
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Gson().toJson(cache(data)).toByteArray()
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)
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}
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channel.offer(Response(Origin.Network, data, hasMore))
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}
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}
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protected open fun onDataFetched(data: List<D>) = data
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}
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