RestApi.kt

class RestApi(private val pets: PetService) {

    companion object {
        val petIdLens = Path.long().of("petId")
        val petLens = Body.auto<Pet>().toLens()
        val nameLens = Query.nonEmptyString().required("name")

        const val petsPath = "/pet"
        val petPath = "/pet/${petIdLens}"
        val uploadImagePath = "/pet/${petIdLens}/uploadImage"
    }

    private fun getPet(request: Request): Response {
        val id = petIdLens(request)
        val pet = pets.get(id) ?: return Response(Status.NOT_FOUND)

        return Response(Status.OK).with(petLens of pet)
    }

    private fun createPet(request: Request): Response {
        val name = nameLens(request)

        val pet = pets.create(name = name)

        return Response(Status.OK).with(petLens of pet)
    }

    private fun uploadImage(request: Request): Response {
        val contentType = Header.CONTENT_TYPE(request) ?: return Response(Status.BAD_REQUEST)
        val petId = petIdLens(request)

        val updatedPet = request.body.use { body ->
            pets.uploadImage(petId, contentType.value, body.stream)
        } ?: return Response(Status.NOT_FOUND)

        return Response(Status.OK).with(petLens of updatedPet)
    }

    fun toHttpHandler() : HttpHandler {
        val routes = routes(
            petPath bind Method.GET to ::getPet,
            petsPath bind Method.POST to ::createPet,
            uploadImagePath bind Method.POST to ::uploadImage
        )

        return ServerFilters.CatchLensFailure().then(routes)
    }
}