TrendingMovie.kt

import com.fasterxml.jackson.core.JsonParser
import com.fasterxml.jackson.databind.DeserializationContext
import com.fasterxml.jackson.databind.JsonDeserializer
import com.fasterxml.jackson.databind.JsonNode
import com.fasterxml.jackson.databind.Module
import com.fasterxml.jackson.databind.module.SimpleModule
import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
import okhttp3.OkHttpClient
import retrofit2.Retrofit
import retrofit2.adapter.rxjava.RxJavaCallAdapterFactory
import retrofit2.converter.jackson.JacksonConverterFactory
import retrofit2.http.GET
import rx.Observable

interface TrendingMovie

interface Movies {
    @GET("movies/trending")
    fun trending(): Observable<List<TrendingMovie>>
}

fun trendingMovieModule(): Module = SimpleModule().apply {
    val deserializer: JsonDeserializer<TrendingMovie> = object : JsonDeserializer<TrendingMovie>() {
        override fun deserialize(p: JsonParser, ctxt: DeserializationContext): TrendingMovie {
            val node = p.codec.readTree<JsonNode>(p)

            return object : TrendingMovie {
                val name = node["movie"]["title"]
                val watchers = node["watchers"].intValue()

                override fun toString(): String = "$name, watchers: $watchers"
            }
        }
    }

    addDeserializer(TrendingMovie::class.java, deserializer)
}

fun main(args: Array<String>) {
    val mapper = jacksonObjectMapper().registerModule(trendingMovieModule())

    val client = OkHttpClient.Builder().addInterceptor {
        it.proceed(it.request().newBuilder()
                           .addHeader("Content-type", "application/json")
                           .addHeader("trakt-api-key", TODO("Enter your API key for api.trakt.tv"))
                           .addHeader("trakt-api-version", "2")
                           .build())
    }.build()

    val r = Retrofit.Builder()
            .client(client)
            .baseUrl("https://api.trakt.tv")
            .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
            .addConverterFactory(JacksonConverterFactory.create(mapper))
            .build().create(Movies::class.java)

    r.trending().flatMap { Observable.from(it) }.forEach(::println)
}