Daggering kotlin-android: AppModule.kt

ApiService.kt

interface ApiService {

    @GET("api")
    fun getUsers(@Query("result") result: Int): Observable<RandomUserResponse>
}

AppModule.kt

@Module
class AppModule {

    @Provides
    @Singleton
    fun file(application: Application): File {
        val file = File(application.cacheDir, "OkHttpCache")
        file.mkdirs()
        return file
    }

    @Provides
    @Singleton
    fun cache(file: File): Cache {
        return Cache(file, 10 * 1000 * 1000) // 10 mb cache file
    }

    @Singleton
    @Provides
    fun provideHttpLoggingInterceptor(): HttpLoggingInterceptor {
        val logging = HttpLoggingInterceptor(HttpLoggingInterceptor.Logger { message -> Timber.tag("OkHttp").d(message) })
        logging.level = HttpLoggingInterceptor.Level.BODY
        return logging
    }

    @Provides
    @Singleton
    fun okHttpClient(cache: Cache, httpLoggingInterceptor: HttpLoggingInterceptor): OkHttpClient {
        return OkHttpClient.Builder()
                .cache(cache)
                .addInterceptor(httpLoggingInterceptor)
                .build()
    }

    @Singleton
    @Provides
    fun provideRetrofit(okHttpClient: OkHttpClient): Retrofit {
        return Retrofit.Builder()
                .baseUrl(BuildConfig.BASE_URL)
                .client(okHttpClient)
                .addConverterFactory(GsonConverterFactory.create())
                .build()
    }

    @Singleton
    @Provides
    fun provideApiService(retrofit: Retrofit): ApiService {
        return retrofit.create(ApiService::class.java)
    }
}