kotlin-client.infrastructure.ApiClient.kt.mustache Maven / Gradle / Ivy

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package {{packageName}}.infrastructure

import com.squareup.moshi.FromJson
import com.squareup.moshi.Moshi
import com.squareup.moshi.ToJson
import okhttp3.*
import java.io.File
import java.util.*

open class ApiClient(val baseUrl: String) {
    companion object {
        protected const val ContentType = "Content-Type"
        protected const val Accept = "Accept"
        protected const val JsonMediaType = "application/json"
        protected const val FormDataMediaType = "multipart/form-data"
        protected const val XmlMediaType = "application/xml"

        @JvmStatic
        val client by lazy {
            builder.build()
        }

        @JvmStatic
        val builder: OkHttpClient.Builder = OkHttpClient.Builder()

        @JvmStatic
        var defaultHeaders: Map by ApplicationDelegates.setOnce(mapOf(ContentType to JsonMediaType, Accept to JsonMediaType))

        @JvmStatic
        val jsonHeaders: Map = mapOf(ContentType to JsonMediaType, Accept to JsonMediaType)
    }

    protected inline fun  requestBody(content: T, mediaType: String = JsonMediaType): RequestBody =
         when {
             content is File -> RequestBody.create(
                 MediaType.parse(mediaType), content
             )
             mediaType == FormDataMediaType -> {
                 var builder = FormBody.Builder()
                 // content's type *must* be Map
                 @Suppress("UNCHECKED_CAST")
                 (content as Map).forEach { key, value ->
                     builder = builder.add(key, value)
                 }
                 builder.build()
             }
             mediaType == JsonMediaType -> RequestBody.create(
                 MediaType.parse(mediaType), Serializer.moshi.adapter(T::class.java).toJson(content)
             )
             mediaType == XmlMediaType -> TODO("xml not currently supported.")
             // TODO: this should be extended with other serializers
             else -> TODO("requestBody currently only supports JSON body and File body.")
         }

    protected inline fun  responseBody(body: ResponseBody?, mediaType: String = JsonMediaType): T? {
        if(body == null) return null
        return when(mediaType) {
            JsonMediaType -> Moshi.Builder().add(object {
                    @ToJson
                    fun toJson(uuid: UUID) = uuid.toString()
                    @FromJson
                    fun fromJson(s: String) = UUID.fromString(s)
                })
                .add(ByteArrayAdapter())
                .build().adapter(T::class.java).fromJson(body.source())
            else -> TODO()
        }
    }

    protected inline fun  request(requestConfig: RequestConfig, body : Any? = null): ApiInfrastructureResponse {
        val httpUrl = HttpUrl.parse(baseUrl) ?: throw IllegalStateException("baseUrl is invalid.")

        var urlBuilder = httpUrl.newBuilder()
                .addPathSegments(requestConfig.path.trimStart('/'))

        requestConfig.query.forEach { query ->
            query.value.forEach { queryValue ->
                urlBuilder = urlBuilder.addQueryParameter(query.key, queryValue)
            }
        }

        val url = urlBuilder.build()
        val headers = requestConfig.headers + defaultHeaders

        if(headers[ContentType] ?: "" == "") {
            throw kotlin.IllegalStateException("Missing Content-Type header. This is required.")
        }

        if(headers[Accept] ?: "" == "") {
            throw kotlin.IllegalStateException("Missing Accept header. This is required.")
        }

        // TODO: support multiple contentType,accept options here.
        val contentType = (headers[ContentType] as String).substringBefore(";").toLowerCase()
        val accept = (headers[Accept] as String).substringBefore(";").toLowerCase()

        var request : Request.Builder =  when (requestConfig.method) {
            RequestMethod.DELETE -> Request.Builder().url(url).delete()
            RequestMethod.GET -> Request.Builder().url(url)
            RequestMethod.HEAD -> Request.Builder().url(url).head()
            RequestMethod.PATCH -> Request.Builder().url(url).patch(requestBody(body, contentType))
            RequestMethod.PUT -> Request.Builder().url(url).put(requestBody(body, contentType))
            RequestMethod.POST -> Request.Builder().url(url).post(requestBody(body, contentType))
            RequestMethod.OPTIONS -> Request.Builder().url(url).method("OPTIONS", null)
        }

        headers.forEach { header -> request = request.addHeader(header.key, header.value) }

        val realRequest = request.build()
        val response = client.newCall(realRequest).execute()

        // TODO: handle specific mapping types. e.g. Map>
        when {
            response.isRedirect -> return Redirection(
                    response.code(),
                    response.headers().toMultimap()
            )
            response.isInformational -> return Informational(
                    response.message(),
                    response.code(),
                    response.headers().toMultimap()
            )
            response.isSuccessful -> return Success(
                    responseBody(response.body(), accept),
                    response.code(),
                    response.headers().toMultimap()
            )
            response.isClientError -> return ClientError(
                    response.body()?.string(),
                    response.code(),
                    response.headers().toMultimap()
            )
            else -> return ServerError(
                    null,
                    response.body()?.string(),
                    response.code(),
                    response.headers().toMultimap()
            )
        }
    }
}