feat: add HttpRequestBody.contentLength() (#174)

Author: stainless-app[bot]

finch-java-client-okhttp/src/main/kotlin/com/tryfinch/api/client/okhttp/OkHttpClient.kt

@@ -115,12 +115,17 @@ private constructor(private val okHttpClient: okhttp3.OkHttpClient, private val
 
     private fun HttpRequestBody.toRequestBody(): RequestBody {
         val mediaType = contentType()?.toMediaType()
+        val length = contentLength()
 
         return object : RequestBody() {
             override fun contentType(): MediaType? {
                 return mediaType
             }
 
+            override fun contentLength(): Long {
+                return length
+            }
+
             override fun isOneShot(): Boolean {
                 return !repeatable()
             }

finch-java-core/src/main/kotlin/com/tryfinch/api/core/http/HttpRequestBody.kt

@@ -10,6 +10,8 @@ interface HttpRequestBody : Closeable {
 
     fun contentType(): String?
 
+    fun contentLength(): Long
+
     /**
      * Determines if a request can be repeated in a meaningful way, for example before doing a
      * retry.

finch-java-core/src/main/kotlin/com/tryfinch/api/services/HttpRequestBodies.kt

@@ -5,6 +5,7 @@ package com.tryfinch.api.services
 import com.fasterxml.jackson.databind.json.JsonMapper
 import com.tryfinch.api.core.http.HttpRequestBody
 import com.tryfinch.api.errors.FinchException
+import java.io.ByteArrayOutputStream
 import java.io.OutputStream
 import org.apache.hc.client5.http.entity.mime.MultipartEntityBuilder
 
@@ -14,16 +15,31 @@ internal inline fun <reified T> json(
     value: T,
 ): HttpRequestBody {
     return object : HttpRequestBody {
-        override fun writeTo(outputStream: OutputStream) {
+        private var cachedBytes: ByteArray? = null
+
+        private fun serialize(): ByteArray {
+            if (cachedBytes != null) return cachedBytes!!
+
+            val buffer = ByteArrayOutputStream()
             try {
-                return jsonMapper.writeValue(outputStream, value)
+                jsonMapper.writeValue(buffer, value)
+                cachedBytes = buffer.toByteArray()
+                return cachedBytes!!
             } catch (e: Exception) {
                 throw FinchException("Error writing request", e)
             }
         }
 
+        override fun writeTo(outputStream: OutputStream) {
+            outputStream.write(serialize())
+        }
+
         override fun contentType(): String = "application/json"
 
+        override fun contentLength(): Long {
+            return serialize().size.toLong()
+        }
+
         override fun repeatable(): Boolean = true
 
         override fun close() {}
@@ -49,6 +65,8 @@ internal fun multipartFormData(
 
         override fun contentType(): String = entity.contentType
 
+        override fun contentLength(): Long = -1
+
         override fun repeatable(): Boolean = entity.isRepeatable
 
         override fun close() = entity.close()