import { Router } from "express";
import { getSession, addMessage, getConversationForAPI } from "../services/sessionStore.js";

const router = Router();
const ANTHROPIC_API_URL = "https://api.anthropic.com";

/**
 * Build entity context string for the system prompt
 */
function buildEntityContext(entities) {
  if (!entities || entities.length === 0) {
    return "\n\nThe diagram is currently empty.";
  }

  const entityList = entities.map(e => {
    const shape = e.template?.replace('#', '').replace('-template', '') || 'unknown';
    const pos = e.position || { x: 0, y: 0, z: 0 };
    return `- ${e.text || '(no label)'} (${shape}, ${e.color || 'unknown'}) at (${pos.x?.toFixed(1)}, ${pos.y?.toFixed(1)}, ${pos.z?.toFixed(1)})`;
  }).join('\n');

  return `\n\n## Current Diagram State\nThe diagram currently contains ${entities.length} entities:\n${entityList}`;
}

// Express 5 uses named parameters for wildcards
router.post("/*path", async (req, res) => {
  const apiKey = process.env.ANTHROPIC_API_KEY;

  if (!apiKey) {
    return res.status(500).json({ error: "API key not configured" });
  }

  // Get the path after /api/claude (e.g., /v1/messages)
  // Express 5 returns path segments as an array
  const pathParam = req.params.path;
  const path = "/" + (Array.isArray(pathParam) ? pathParam.join("/") : pathParam || "");

  // Check for session-based request
  const { sessionId, ...requestBody } = req.body;
  let modifiedBody = requestBody;

  if (sessionId) {
    const session = getSession(sessionId);
    if (session) {
      console.log(`[Claude API] Session ${sessionId}: ${session.entities.length} entities, ${session.conversationHistory.length} messages in history`);

      // Inject entity context into system prompt
      if (modifiedBody.system) {
        const entityContext = buildEntityContext(session.entities);
        console.log(`[Claude API] Entity context:`, entityContext);
        modifiedBody.system += entityContext;
      }

      // Get conversation history and merge with current messages
      const historyMessages = getConversationForAPI(sessionId);
      if (historyMessages.length > 0 && modifiedBody.messages) {
        // Filter out any duplicate messages (in case client sent history too)
        const currentContent = modifiedBody.messages[modifiedBody.messages.length - 1]?.content;
        const filteredHistory = historyMessages.filter(msg => msg.content !== currentContent);
        modifiedBody.messages = [...filteredHistory, ...modifiedBody.messages];
        console.log(`[Claude API] Merged ${filteredHistory.length} history messages with ${modifiedBody.messages.length - filteredHistory.length} new messages`);
      }
    } else {
      console.log(`[Claude API] Session ${sessionId} not found`);
    }
  }

  try {
    const response = await fetch(`${ANTHROPIC_API_URL}${path}`, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        "x-api-key": apiKey,
        "anthropic-version": "2023-06-01",
      },
      body: JSON.stringify(modifiedBody),
    });

    const data = await response.json();

    // If session exists and response is successful, store messages
    if (sessionId && response.ok && data.content) {
      const session = getSession(sessionId);
      if (session) {
        // Store the user message if it was new (only if it's a string, not tool results)
        const userMessage = requestBody.messages?.[requestBody.messages.length - 1];
        if (userMessage && userMessage.role === 'user' && typeof userMessage.content === 'string') {
          addMessage(sessionId, {
            role: 'user',
            content: userMessage.content
          });
        }

        // Store the assistant response (text only, not tool use blocks)
        const assistantContent = data.content
          .filter(c => c.type === 'text')
          .map(c => c.text)
          .join('\n');

        if (assistantContent) {
          addMessage(sessionId, {
            role: 'assistant',
            content: assistantContent
          });
        }
      }
    }

    res.status(response.status).json(data);
  } catch (error) {
    console.error("Claude API error:", error.message);
    res.status(500).json({ error: "Failed to proxy request to Claude API" });
  }
});

export default router;