import { Anthropic } from "@anthropic-ai/sdk";

export interface Env {
  ANTHROPIC_API_KEY: string;
}

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    // Handle CORS preflight requests
    if (request.method === "OPTIONS") {
      return new Response(null, {
        headers: {
          "Access-Control-Allow-Origin": "*",
          "Access-Control-Allow-Methods": "GET, POST, OPTIONS",
          "Access-Control-Allow-Headers": "Content-Type",
        },
      });
    }

    if (request.method !== "GET") {
      return new Response("Method Not Allowed", { status: 405 });
    }

    const url = new URL(request.url);
    const instructions = url.searchParams.get("instructions");
    const context = url.searchParams.get("context");

    if (!instructions) {
      return new Response("Missing instructions parameter", { status: 400 });
    }

    const prompt = `You are an intelligent programming assistant. Please respond to the following request concisely:

${instructions}

${context ? `Context:\n${context}\n` : ''}

If your response includes code, please format it using triple backticks (\`\`\`) with the appropriate language identifier. For example:

\`\`\`python
print("Hello, World!")
\`\`\`

Provide a clear and concise explanation along with any code snippets. Keep your response brief and to the point`;

    try { 
      const anthropic = new Anthropic({ apiKey: env.ANTHROPIC_API_KEY });

      const stream = await anthropic.messages.create({
        model: "claude-3-5-sonnet-20240620",
        max_tokens: 1024,
        messages: [{ role: "user", content: prompt }],
        stream: true,
      });

      const encoder = new TextEncoder();

      const streamResponse = new ReadableStream({
        async start(controller) {
          for await (const chunk of stream) {
            if (chunk.type === 'content_block_delta' && chunk.delta.type === 'text_delta') {
              const bytes = encoder.encode(chunk.delta.text);
              controller.enqueue(bytes);
            }
          }
          controller.close();
        },
      });

      return new Response(streamResponse, {
        headers: {
          "Content-Type": "text/plain; charset=utf-8",
          "Access-Control-Allow-Origin": "*",
          "Cache-Control": "no-cache",
          "Connection": "keep-alive",
        },
      });
    } catch (error) {
      console.error("Error:", error);
      return new Response("Internal Server Error", { status: 500 });
    }
  },
};