import { NextRequest, NextResponse } from "next/server";
import { decodeHtmlEntitiesServer } from "@/lib/html-decode";

export async function POST(request: NextRequest) {
  let userMessage = "";

  try {
    // Rate limiting for n8n chat endpoint
    const ip = request.headers.get('x-forwarded-for') || request.headers.get('x-real-ip') || 'unknown';
    const { checkRateLimit } = await import('@/lib/auth');
    
    if (!checkRateLimit(ip, 20, 60000)) { // 20 requests per minute for chat
      return NextResponse.json(
        { error: 'Rate limit exceeded. Please try again later.' },
        { status: 429 }
      );
    }

    const json = await request.json();
    userMessage = json.message;
    const history = json.history || [];

    if (!userMessage || typeof userMessage !== "string") {
      return NextResponse.json(
        { error: "Message is required" },
        { status: 400 },
      );
    }

    // Call your n8n chat webhook
    const n8nWebhookUrl = process.env.N8N_WEBHOOK_URL;

    if (!n8nWebhookUrl) {
      console.error("N8N_WEBHOOK_URL not configured");
      return NextResponse.json({
        reply: getFallbackResponse(userMessage),
      });
    }

    const webhookUrl = `${n8nWebhookUrl}/webhook/chat`;
    console.log(`Sending to n8n: ${webhookUrl}`);

    // Add timeout to prevent hanging requests
    const controller = new AbortController();
    const timeoutId = setTimeout(() => controller.abort(), 30000); // 30 second timeout

    try {
      const response = await fetch(webhookUrl, {
        method: "POST",
        headers: {
          "Content-Type": "application/json",
          ...(process.env.N8N_SECRET_TOKEN && {
            Authorization: `Bearer ${process.env.N8N_SECRET_TOKEN}`,
          }),
          ...(process.env.N8N_API_KEY && {
            "X-API-Key": process.env.N8N_API_KEY,
          }),
        },
        body: JSON.stringify({
          message: userMessage,
          history: history,
        }),
        signal: controller.signal,
      });

      clearTimeout(timeoutId);

      if (!response.ok) {
        const errorText = await response.text().catch(() => 'Unknown error');
        console.error(`n8n webhook failed with status: ${response.status}`, errorText);
        throw new Error(`n8n webhook failed: ${response.status} - ${errorText}`);
      }

      const data = await response.json();

      console.log("n8n response data:", data);

    const reply =
      data.reply ||
      data.message ||
      data.response ||
      data.text ||
      data.content ||
      (Array.isArray(data) && data[0]?.reply);

    if (!reply) {
      console.warn("n8n response missing reply field:", data);
      // If n8n returns successfully but without a clear reply field,
      // we might want to show the fallback or a generic error,
      // but strictly speaking we shouldn't show "Couldn't process".
      // Let's try to stringify the whole data if it's small, or use fallback.
      if (data && typeof data === "object" && Object.keys(data).length > 0) {
        // It returned something, but we don't know what field to use.
        // Check for common n8n structure
        if (data.output) {
          const decoded = decodeHtmlEntitiesServer(String(data.output));
          return NextResponse.json({ reply: decoded });
        }
        if (data.data) {
          const decoded = decodeHtmlEntitiesServer(String(data.data));
          return NextResponse.json({ reply: decoded });
        }
      }
      throw new Error("Invalid response format from n8n");
    }

      // Decode HTML entities in the reply
      const decodedReply = decodeHtmlEntitiesServer(String(reply));

      return NextResponse.json({
        reply: decodedReply,
      });
    } catch (fetchError: unknown) {
      clearTimeout(timeoutId);
      
      if (fetchError instanceof Error && fetchError.name === 'AbortError') {
        console.error("n8n webhook request timed out");
      } else {
        console.error("n8n webhook fetch error:", fetchError);
      }
      throw fetchError;
    }
  } catch (error: unknown) {
    console.error("Chat API error:", error);
    console.error("Error details:", {
      message: error instanceof Error ? error.message : String(error),
      stack: error instanceof Error ? error.stack : undefined,
      n8nUrl: process.env.N8N_WEBHOOK_URL ? 'configured' : 'missing',
    });

    // Fallback to mock responses
    // Now using the variable captured at the start
    return NextResponse.json({ reply: getFallbackResponse(userMessage) });
  }
}

function getFallbackResponse(message: string): string {
  if (!message || typeof message !== "string") {
    return "I'm having a bit of trouble understanding. Could you try asking again?";
  }

  const lowerMessage = message.toLowerCase();

  if (
    lowerMessage.includes("skill") ||
    lowerMessage.includes("tech") ||
    lowerMessage.includes("stack")
  ) {
    return "I specialize in full-stack development with Next.js, React, and Flutter for mobile. On the DevOps side, I love working with Docker Swarm, Traefik, and CI/CD pipelines. Basically, if it involves code or servers, I'm interested!";
  }

  if (
    lowerMessage.includes("project") ||
    lowerMessage.includes("built") ||
    lowerMessage.includes("work")
  ) {
    return "One of my key projects is Clarity, a Flutter app designed to help people with dyslexia. I also maintain a comprehensive self-hosted infrastructure with Docker Swarm. You can check out more details in the Projects section!";
  }

  if (
    lowerMessage.includes("contact") ||
    lowerMessage.includes("email") ||
    lowerMessage.includes("reach") ||
    lowerMessage.includes("hire")
  ) {
    return "The best way to reach me is through the contact form below or by emailing contact@dk0.dev. I'm always open to discussing new ideas, opportunities, or just chatting about tech!";
  }

  if (
    lowerMessage.includes("location") ||
    lowerMessage.includes("where") ||
    lowerMessage.includes("live")
  ) {
    return "I'm based in Osnabrück, Germany. It's a great place to be a student and work on tech projects!";
  }

  if (
    lowerMessage.includes("hobby") ||
    lowerMessage.includes("free time") ||
    lowerMessage.includes("fun")
  ) {
    return "When I'm not coding or tweaking my servers, I enjoy gaming, going for a jog, or experimenting with new tech. Fun fact: I still use pen and paper for my calendar, even though I automate everything else!";
  }

  if (
    lowerMessage.includes("devops") ||
    lowerMessage.includes("docker") ||
    lowerMessage.includes("server") ||
    lowerMessage.includes("hosting")
  ) {
    return "I'm really into DevOps! I run my own infrastructure on IONOS and OVHcloud using Docker Swarm and Traefik. It allows me to host various services and game servers efficiently while learning a ton about system administration.";
  }

  if (
    lowerMessage.includes("student") ||
    lowerMessage.includes("study") ||
    lowerMessage.includes("education")
  ) {
    return "Yes, I'm currently a student in Osnabrück. I balance my studies with working on personal projects and managing my self-hosted infrastructure. It keeps me busy but I learn something new every day!";
  }

  if (
    lowerMessage.includes("hello") ||
    lowerMessage.includes("hi ") ||
    lowerMessage.includes("hey")
  ) {
    return "Hi there! I'm Dennis's AI assistant (currently in offline mode). How can I help you learn more about Dennis today?";
  }

  // Default response
  return "That's an interesting question! I'm currently operating in fallback mode, so my knowledge is a bit limited right now. But I can tell you that Dennis is a full-stack developer and DevOps enthusiast who loves building with Next.js and Docker. Feel free to ask about his skills, projects, or how to contact him!";
}