TestKittenDataSource

TestKittenDataSource.kt

internal class TestKittenDataSource(
    private val scheduler: TestScheduler
) : KittenDataSource {
    private var images by AtomicReference<List<String>?>(null)
    private var seed by AtomicInt()

    override fun load(limit: Int, page: Int): Maybe<String> =
        singleFromFunction { images }
            .notNull()
            .map {
                val offset = page * limit
                it.subList(fromIndex = offset, toIndex = offset + limit)
            }
            .mapIterable { it.toJsonObject() }
            .map { JsonArray(it).toString() }
            .onErrorComplete()
            .observeOn(scheduler)

    private fun String.toJsonObject(): JsonObject =
        JsonObject(mapOf("url" to JsonPrimitive(this)))

    fun generateImages(): List<String> {
        val images = List(MAX_IMAGES) { "Img${seed + it}" }
        this.images = images
        seed += MAX_IMAGES

        return images
    }

    private companion object {
        private const val MAX_IMAGES = 50
    }
}