export async function onRequestPost({ request, env }) {
  try {
    if (!env.GROQ_API_KEY) {
      return Response.json(
        { error: "GROQ_API_KEY is missing." },
        { status: 500 }
      );
    }

    const body = await request.json();

    const messages = Array.isArray(body.messages)
      ? body.messages
          .filter(m =>
            m &&
            ["user", "assistant"].includes(m.role) &&
            typeof m.content === "string" &&
            m.content.trim()
          )
          .map(m => ({
            role: m.role,
            content: m.content.trim()
          }))
      : typeof body.message === "string" && body.message.trim()
        ? [{ role: "user", content: body.message.trim() }]
        : [];

    if (!messages.length) {
      return Response.json(
        { error: "Please enter a message." },
        { status: 400 }
      );
    }

    const totalLength = messages.reduce(
      (sum, item) => sum + item.content.length,
      0
    );

    if (totalLength > 20000) {
      return Response.json(
        { error: "Conversation is too long." },
        { status: 400 }
      );
    }

    const upstream = await fetch(
      "https://api.groq.com/openai/v1/chat/completions",
      {
        method: "POST",
        headers: {
          "Authorization": `Bearer ${env.GROQ_API_KEY}`,
          "Content-Type": "application/json"
        },
        body: JSON.stringify({
          model: "openai/gpt-oss-120b",
          messages: [
            {
              role: "system",
              content:
                "You are NE7IFY AI, an expert assistant and web developer. Follow the user's requirements carefully. When generating code, return complete runnable code and do not omit requested features."
            },
            ...messages
          ],
          max_completion_tokens: 8000,
          stream: body.stream === true
        })
      }
    );

    if (!upstream.ok) {
      const data = await upstream.json().catch(() => ({}));

      return Response.json(
        {
          error:
            data.error?.message ||
            "Groq rejected the request."
        },
        { status: 502 }
      );
    }

    if (body.stream === true) {
      return new Response(upstream.body, {
        headers: {
          "Content-Type": "text/event-stream; charset=utf-8",
          "Cache-Control": "no-cache, no-transform",
          "Connection": "keep-alive"
        }
      });
    }

    const data = await upstream.json();

    return Response.json({
      reply:
        data.choices?.[0]?.message?.content ||
        "",
      finish_reason:
        data.choices?.[0]?.finish_reason ||
        null
    });

  } catch (error) {
    return Response.json(
      { error: "Server error: " + error.message },
      { status: 500 }
    );
  }
}