import {
  createParser,
  type ParsedEvent,
  type ReconnectInterval,
} from "eventsource-parser";
import { Configuration, OpenAIApi } from "openai-edge";

const configuration = new Configuration({
  apiKey: process.env.OPENAI_API_KEY,
});

export const openai = new OpenAIApi(configuration);

if (!process.env.OPENAI_API_KEY) {
  throw new Error("Missing env var from OpenAI");
}

export async function OpenAIStream(res: Response) {
  const encoder = new TextEncoder();
  const decoder = new TextDecoder();

  let counter = 0;

  const stream = new ReadableStream({
    async start(controller) {
      function onParse(event: ParsedEvent | ReconnectInterval) {
        if (event.type === "event") {
          const data = event.data;
          if (data === "[DONE]") {
            controller.close();
            return;
          }
          try {
            const json = JSON.parse(data) as {
              choices: any;
            };
            const text =
              json.choices[0]?.delta?.content ?? json.choices[0]?.text ?? "";

            if (counter < 2 && (text.match(/\n/) || []).length) {
              return;
            }

            const queue = encoder.encode(JSON.stringify(text) + "\n");
            controller.enqueue(queue);
            counter++;
          } catch (e) {
            controller.error(e);
          }
        }
      }

      const parser = createParser(onParse);

      for await (const chunk of res.body as any) {
        parser.feed(decoder.decode(chunk));
      }
    },
  });

  return stream;
}