[kotlin][client] fix encoding of individual parts of a multipart request (#11911)

* [kotlin][client] fix encoding (and Content-Type headers) of individual parts of a multipart request

* [kotlin][client] fix incorrect handling of binary downloads

* [kotlin][client] update samples

samples/client/petstore/kotlin-string/.openapi-generator/FILES

@@ -27,6 +27,7 @@ src/main/kotlin/org/openapitools/client/infrastructure/Errors.kt
 src/main/kotlin/org/openapitools/client/infrastructure/LocalDateAdapter.kt
 src/main/kotlin/org/openapitools/client/infrastructure/LocalDateTimeAdapter.kt
 src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+src/main/kotlin/org/openapitools/client/infrastructure/PartConfig.kt
 src/main/kotlin/org/openapitools/client/infrastructure/RequestConfig.kt
 src/main/kotlin/org/openapitools/client/infrastructure/RequestMethod.kt
 src/main/kotlin/org/openapitools/client/infrastructure/ResponseExtensions.kt

samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt

@@ -34,6 +34,7 @@ import org.openapitools.client.infrastructure.ClientError
 import org.openapitools.client.infrastructure.ServerException
 import org.openapitools.client.infrastructure.ServerError
 import org.openapitools.client.infrastructure.MultiValueMap
+import org.openapitools.client.infrastructure.PartConfig
 import org.openapitools.client.infrastructure.RequestConfig
 import org.openapitools.client.infrastructure.RequestMethod
 import org.openapitools.client.infrastructure.ResponseType
@@ -532,7 +533,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     fun updatePetWithFormWithHttpInfo(petId: kotlin.Long, name: kotlin.String?, status: kotlin.String?) : ApiResponse<Unit?> {
         val localVariableConfig = updatePetWithFormRequestConfig(petId = petId, name = name, status = status)
 
-        return request<Map<String, Any?>, Unit>(
+        return request<Map<String, PartConfig<*>>, Unit>(
             localVariableConfig
         )
     }
@@ -545,8 +546,10 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     * @param status Updated status of the pet (optional)
     * @return RequestConfig
     */
-    fun updatePetWithFormRequestConfig(petId: kotlin.Long, name: kotlin.String?, status: kotlin.String?) : RequestConfig<Map<String, Any?>> {
-        val localVariableBody = mapOf("name" to name, "status" to status)
+    fun updatePetWithFormRequestConfig(petId: kotlin.Long, name: kotlin.String?, status: kotlin.String?) : RequestConfig<Map<String, PartConfig<*>>> {
+        val localVariableBody = mapOf(
+            "name" to PartConfig(body = name, headers = mutableMapOf()),
+            "status" to PartConfig(body = status, headers = mutableMapOf()),)
         val localVariableQuery: MultiValueMap = mutableMapOf()
         val localVariableHeaders: MutableMap<String, String> = mutableMapOf("Content-Type" to "application/x-www-form-urlencoded")
         
@@ -607,7 +610,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     fun uploadFileWithHttpInfo(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: java.io.File?) : ApiResponse<ModelApiResponse?> {
         val localVariableConfig = uploadFileRequestConfig(petId = petId, additionalMetadata = additionalMetadata, file = file)
 
-        return request<Map<String, Any?>, ModelApiResponse>(
+        return request<Map<String, PartConfig<*>>, ModelApiResponse>(
             localVariableConfig
         )
     }
@@ -620,8 +623,10 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     * @param file file to upload (optional)
     * @return RequestConfig
     */
-    fun uploadFileRequestConfig(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: java.io.File?) : RequestConfig<Map<String, Any?>> {
-        val localVariableBody = mapOf("additionalMetadata" to additionalMetadata, "file" to file)
+    fun uploadFileRequestConfig(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: java.io.File?) : RequestConfig<Map<String, PartConfig<*>>> {
+        val localVariableBody = mapOf(
+            "additionalMetadata" to PartConfig(body = additionalMetadata, headers = mutableMapOf()),
+            "file" to PartConfig(body = file, headers = mutableMapOf()),)
         val localVariableQuery: MultiValueMap = mutableMapOf()
         val localVariableHeaders: MutableMap<String, String> = mutableMapOf("Content-Type" to "multipart/form-data")
         localVariableHeaders["Accept"] = "application/json"

samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt

@@ -33,6 +33,7 @@ import org.openapitools.client.infrastructure.ClientError
 import org.openapitools.client.infrastructure.ServerException
 import org.openapitools.client.infrastructure.ServerError
 import org.openapitools.client.infrastructure.MultiValueMap
+import org.openapitools.client.infrastructure.PartConfig
 import org.openapitools.client.infrastructure.RequestConfig
 import org.openapitools.client.infrastructure.RequestMethod
 import org.openapitools.client.infrastructure.ResponseType

samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt

@@ -33,6 +33,7 @@ import org.openapitools.client.infrastructure.ClientError
 import org.openapitools.client.infrastructure.ServerException
 import org.openapitools.client.infrastructure.ServerError
 import org.openapitools.client.infrastructure.MultiValueMap
+import org.openapitools.client.infrastructure.PartConfig
 import org.openapitools.client.infrastructure.RequestConfig
 import org.openapitools.client.infrastructure.RequestMethod
 import org.openapitools.client.infrastructure.ResponseType

samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt

@@ -10,6 +10,7 @@ import okhttp3.ResponseBody
 import okhttp3.MediaType.Companion.toMediaTypeOrNull
 import okhttp3.Request
 import okhttp3.Headers
+import okhttp3.Headers.Companion.toHeaders
 import okhttp3.MultipartBody
 import okhttp3.Call
 import okhttp3.Callback
@@ -65,53 +66,46 @@ open class ApiClient(val baseUrl: String) {
         return contentType ?: "application/octet-stream"
     }
 
-    protected inline fun <reified T> requestBody(content: T, mediaType: String = JsonMediaType): RequestBody =
+    protected inline fun <reified T> requestBody(content: T, mediaType: String?): RequestBody =
         when {
-            content is File -> content.asRequestBody(mediaType.toMediaTypeOrNull())
-            mediaType == FormDataMediaType -> {
+            mediaType == FormDataMediaType ->
                 MultipartBody.Builder()
                     .setType(MultipartBody.FORM)
                     .apply {
-                        // content's type *must* be Map<String, Any?>
+                        // content's type *must* be Map<String, PartConfig<*>>
                         @Suppress("UNCHECKED_CAST")
-                        (content as Map<String, Any?>).forEach { (key, value) ->
-                            if (value is File) {
-                                val partHeaders = Headers.headersOf(
-                                    "Content-Disposition",
-                                    "form-data; name=\"$key\"; filename=\"${value.name}\""
-                                )
-                                val fileMediaType = guessContentTypeFromFile(value).toMediaTypeOrNull()
-                                addPart(partHeaders, value.asRequestBody(fileMediaType))
-                            } else {
-                                val partHeaders = Headers.headersOf(
-                                    "Content-Disposition",
-                                    "form-data; name=\"$key\""
-                                )
-                                addPart(
-                                    partHeaders,
-                                    parameterToString(value).toRequestBody(null)
-                                )
+                        (content as Map<String, PartConfig<*>>).forEach { (name, part) ->
+                            val contentType = part.headers.remove("Content-Type")
+                            val bodies = if (part.body is Iterable<*>) part.body else listOf(part.body)
+                            bodies.forEach { body ->
+                                val headers = part.headers.toMutableMap() +
+                                    ("Content-Disposition" to "form-data; name=\"$name\"" + if (body is File) "; filename=\"${body.name}\"" else "")
+                                addPart(headers.toHeaders(),
+                                    requestSingleBody(body, contentType))
                             }
                         }
                     }.build()
-            }
+            else -> requestSingleBody(content, mediaType)
+        }
+
+    protected inline fun <reified T> requestSingleBody(content: T, mediaType: String?): RequestBody =
+        when {
+            content is File -> content.asRequestBody((mediaType ?: guessContentTypeFromFile(content)).toMediaTypeOrNull())
             mediaType == FormUrlEncMediaType -> {
                 FormBody.Builder().apply {
-                    // content's type *must* be Map<String, Any?>
+                    // content's type *must* be Map<String, PartConfig<*>>
                     @Suppress("UNCHECKED_CAST")
-                    (content as Map<String, Any?>).forEach { (key, value) ->
-                        add(key, parameterToString(value))
+                    (content as Map<String, PartConfig<*>>).forEach { (name, part) ->
+                        add(name, parameterToString(part.body))
                     }
                 }.build()
             }
-            mediaType.startsWith("application/") && mediaType.endsWith("json") ->
+            mediaType == null || mediaType.startsWith("application/") && mediaType.endsWith("json") ->
                 if (content == null) {
                     EMPTY_REQUEST
                 } else {
                     Serializer.moshi.adapter(T::class.java).toJson(content)
-                        .toRequestBody(
-                            mediaType.toMediaTypeOrNull()
-                        )
+                        .toRequestBody((mediaType ?: JsonMediaType).toMediaTypeOrNull())
                 }
             mediaType == XmlMediaType -> throw UnsupportedOperationException("xml not currently supported.")
             // TODO: this should be extended with other serializers
@@ -123,22 +117,20 @@ open class ApiClient(val baseUrl: String) {
         if(body == null) {
             return null
         }
-        val bodyContent = body.string()
-        if (bodyContent.isEmpty()) {
-            return null
-        }
         if (T::class.java == File::class.java) {
             // return tempfile
             // Attention: if you are developing an android app that supports API Level 25 and bellow, please check flag supportAndroidApiLevel25AndBelow in https://openapi-generator.tech/docs/generators/kotlin#config-options
             val f = java.nio.file.Files.createTempFile("tmp.org.openapitools.client", null).toFile()
             f.deleteOnExit()
-            val out = BufferedWriter(FileWriter(f))
-            out.write(bodyContent)
-            out.close()
+            body.byteStream().use { java.nio.file.Files.copy(it, f.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING) }
             return f as T
         }
+        val bodyContent = body.string()
+        if (bodyContent.isEmpty()) {
+            return null
+        }
         return when {
-        mediaType==null || (mediaType.startsWith("application/") && mediaType.endsWith("json")) ->
+            mediaType==null || (mediaType.startsWith("application/") && mediaType.endsWith("json")) ->
                 Serializer.moshi.adapter<T>().fromJson(bodyContent)
             else ->  throw UnsupportedOperationException("responseBody currently only supports JSON body.")
         }

samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/infrastructure/PartConfig.kt

@@ -0,0 +1,11 @@
+package org.openapitools.client.infrastructure
+
+/**
+ * Defines a config object for a given part of a multi-part request.
+ * NOTE: Headers is a Map<String,String> because rfc2616 defines
+ *       multi-valued headers as csv-only.
+ */
+data class PartConfig<T>(
+    val headers: MutableMap<String, String> = mutableMapOf(),
+    val body: T? = null
+)