http4k AzureSdkHttpClient adapter

AzureSdkHttpClient.kt

import com.azure.core.http.HttpClient
import com.azure.core.http.HttpHeader
import com.azure.core.http.HttpHeaders
import com.azure.core.http.HttpRequest
import com.azure.core.http.HttpResponse
import org.http4k.core.Body
import org.http4k.core.Body.Companion.EMPTY
import org.http4k.core.HttpHandler
import org.http4k.core.Method
import org.http4k.core.Request
import org.http4k.core.Response
import reactor.core.publisher.Flux
import reactor.core.publisher.Mono
import java.nio.ByteBuffer
import java.nio.ByteBuffer.allocate
import java.nio.charset.Charset
import java.util.stream.Collectors

fun AzureSdkHttpClient(http4k: HttpHandler): HttpClient = HttpClient { request ->
    Mono.fromCallable { Http4kAzureResponse(http4k(request.toHttp4k()), request) }
}

private fun HttpRequest.toHttp4k() = Request(Method.valueOf(httpMethod.name), url.toExternalForm())
    .headers(headers.toMap().toList())
    .body(body
            .collect(Collectors.reducing { a, b ->
                allocate(a.remaining() + b.remaining()).put(a).put(b)
            })
            .block()
            ?.map { Body(it) }
            ?.orElse(EMPTY)
            ?: EMPTY
    )

class Http4kAzureResponse(private val http4k: Response, request: HttpRequest) : HttpResponse(request) {
    override fun getStatusCode() = http4k.status.code

    override fun getHeaderValue(name: String) = http4k.header(name)

    override fun getHeaders() = HttpHeaders(http4k.headers.map { HttpHeader(it.first, it.second) })

    override fun getBody(): Flux<ByteBuffer> = Flux.just(http4k.body.payload)

    override fun getBodyAsByteArray(): Mono<ByteArray> = Mono.just(http4k.body.payload.array())

    override fun getBodyAsString(): Mono<String> = Mono.just(http4k.bodyString())

    override fun getBodyAsString(charset: Charset): Mono<String> = bodyAsByteArray.map { String(it, charset) }
}

build.gradle

implementation group: 'com.azure', name: 'azure-core', version: '1.16.0'