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 || n8nWebhookUrl.trim() === '') {
      console.error("N8N_WEBHOOK_URL not configured. Environment check:", {
        hasUrl: !!process.env.N8N_WEBHOOK_URL,
        urlValue: process.env.N8N_WEBHOOK_URL || '(empty)',
        nodeEnv: process.env.NODE_ENV,
      });
      return NextResponse.json({
        reply: getFallbackResponse(userMessage),
      });
    }

    // Ensure URL doesn't have trailing slash before adding /webhook/chat
    const baseUrl = n8nWebhookUrl.replace(/\/$/, '');
    const webhookUrl = `${baseUrl}/webhook/chat`;
    console.log(`Sending to n8n: ${webhookUrl}`, {
      hasSecretToken: !!process.env.N8N_SECRET_TOKEN,
      hasApiKey: !!process.env.N8N_API_KEY,
    });

    // 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}`, {
          status: response.status,
          statusText: response.statusText,
          error: errorText,
          webhookUrl: webhookUrl.replace(/\/\/[^:]+:[^@]+@/, '//***:***@'), // Hide credentials in logs
        });
        throw new Error(`n8n webhook failed: ${response.status} - ${errorText.substring(0, 200)}`);
      }

      const data = await response.json();

      console.log("n8n response data (full):", JSON.stringify(data, null, 2));
      console.log("n8n response data type:", typeof data);
      console.log("n8n response is array:", Array.isArray(data));

    // Try multiple ways to extract the reply
    let reply: string | undefined = undefined;

    // Direct fields
    if (data.reply) reply = data.reply;
    else if (data.message) reply = data.message;
    else if (data.response) reply = data.response;
    else if (data.text) reply = data.text;
    else if (data.content) reply = data.content;
    else if (data.answer) reply = data.answer;
    else if (data.output) reply = data.output;
    else if (data.result) reply = data.result;
    
    // Array handling
    else if (Array.isArray(data) && data.length > 0) {
      const firstItem = data[0];
      if (typeof firstItem === 'string') {
        reply = firstItem;
      } else if (typeof firstItem === 'object') {
        reply = firstItem.reply || firstItem.message || firstItem.response || 
                firstItem.text || firstItem.content || firstItem.answer ||
                firstItem.output || firstItem.result;
      }
    }
    
    // Nested structures (common in n8n)
    else if (data && typeof data === "object") {
      // Check nested data field
      if (data.data) {
        if (typeof data.data === 'string') {
          reply = data.data;
        } else if (typeof data.data === 'object') {
          reply = data.data.reply || data.data.message || data.data.response ||
                  data.data.text || data.data.content || data.data.answer;
        }
      }
      
      // Check nested json field
      if (!reply && data.json) {
        if (typeof data.json === 'string') {
          reply = data.json;
        } else if (typeof data.json === 'object') {
          reply = data.json.reply || data.json.message || data.json.response ||
                  data.json.text || data.json.content || data.json.answer;
        }
      }
      
      // Check items array (n8n often wraps in items)
      if (!reply && Array.isArray(data.items) && data.items.length > 0) {
        const firstItem = data.items[0];
        if (typeof firstItem === 'string') {
          reply = firstItem;
        } else if (typeof firstItem === 'object') {
          reply = firstItem.reply || firstItem.message || firstItem.response ||
                  firstItem.text || firstItem.content || firstItem.answer ||
                  firstItem.json?.reply || firstItem.json?.message;
        }
      }
      
      // Last resort: if it's a single string value object, try to extract
      if (!reply && Object.keys(data).length === 1) {
        const value = Object.values(data)[0];
        if (typeof value === 'string') {
          reply = value;
        }
      }
      
      // If still no reply but data exists, stringify it (for debugging)
      if (!reply && Object.keys(data).length > 0) {
        console.warn("n8n response structure not recognized, attempting to extract any string value");
        // Try to find any string value in the object
        const findStringValue = (obj: unknown): string | undefined => {
          if (typeof obj === 'string' && obj.length > 0) return obj;
          if (Array.isArray(obj) && obj.length > 0) {
            return findStringValue(obj[0]);
          }
          if (obj && typeof obj === 'object' && obj !== null) {
            const objRecord = obj as Record<string, unknown>;
            for (const key of ['reply', 'message', 'response', 'text', 'content', 'answer', 'output', 'result']) {
              if (objRecord[key] && typeof objRecord[key] === 'string') {
                return objRecord[key] as string;
              }
            }
            // Recursively search
            for (const value of Object.values(objRecord)) {
              const found = findStringValue(value);
              if (found) return found;
            }
          }
          return undefined;
        };
        reply = findStringValue(data);
      }
    }

    if (!reply) {
      console.error("n8n response missing reply field. Full response:", JSON.stringify(data, null, 2));
      throw new Error("Invalid response format from n8n - no reply field found");
    }

      // 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 (${process.env.N8N_WEBHOOK_URL})` : 'missing',
      hasSecretToken: !!process.env.N8N_SECRET_TOKEN,
      hasApiKey: !!process.env.N8N_API_KEY,
      nodeEnv: process.env.NODE_ENV,
    });

    // 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!";
}