Update OpenAI with sync/async methods

Author: CJCrafter

src/main/kotlin/com/cjcrafter/openai/MyCallback.kt

@@ -0,0 +1,76 @@
+package com.cjcrafter.openai
+
+import com.cjcrafter.openai.exception.OpenAIError
+import com.cjcrafter.openai.exception.WrappedIOError
+import com.google.gson.JsonObject
+import com.google.gson.JsonParser
+import okhttp3.Call
+import okhttp3.Callback
+import okhttp3.Response
+import java.io.IOException
+import java.util.function.Consumer
+
+internal class MyCallback(
+    private val isStream: Boolean,
+    private val onFailure: Consumer<OpenAIError>,
+    private val onResponse: Consumer<JsonObject>
+) : Callback {
+
+    override fun onFailure(call: Call, e: IOException) {
+        onFailure.accept(WrappedIOError(e))
+    }
+
+    override fun onResponse(call: Call, response: Response) {
+        onResponse(response)
+    }
+
+    fun onResponse(response: Response) {
+        if (isStream) {
+            handleStream(response)
+            return
+        }
+
+        val rootObject = JsonParser.parseString(response.body!!.string()).asJsonObject
+
+        // Sometimes OpenAI will respond with an error code for malformed
+        // requests, timeouts, rate limits, etc. We need to let the dev
+        // know that an error occurred.
+        if (rootObject.has("error")) {
+            onFailure.accept(OpenAIError.fromJson(rootObject.get("error").asJsonObject))
+            return
+        }
+
+        onResponse.accept(rootObject)
+    }
+
+    private fun handleStream(response: Response) {
+        response.body?.source()?.use { source ->
+            while (!source.exhausted()) {
+                var jsonResponse = source.readUtf8()
+
+                // OpenAI returns a json string, but they prepend the content with
+                // "data: " (which is not valid json). In order to parse this into
+                // a JsonObject, we have to strip away this extra string.
+                jsonResponse = jsonResponse.substring("data: ".length)
+
+                // After OpenAI's final message (which already contains a non-null
+                // finish reason), they redundantly send "data: [DONE]". Ignore it.
+                if (jsonResponse == "[DONE]")
+                    continue
+
+                val rootObject = JsonParser.parseString(jsonResponse).asJsonObject
+
+                // Sometimes OpenAI will respond with an error code for malformed
+                // requests, timeouts, rate limits, etc. We need to let the dev
+                // know that an error occurred.
+                if (rootObject.has("error")) {
+                    onFailure.accept(OpenAIError.fromJson(rootObject.get("error").asJsonObject))
+                    continue
+                }
+
+                // Developer defined code to run
+                onResponse.accept(rootObject)
+            }
+        }
+    }
+}