import { Router } from "express";
import { getSession, addMessage, getConversationForAPI } from "../services/sessionStore.js";
import { trackUsage, getUsageSummary, formatCost, getSessionUsage } from "../services/usageTracker.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 requestStart = Date.now();
  console.log(`[Claude API] ========== REQUEST START ==========`);

  const apiKey = process.env.ANTHROPIC_API_KEY;

  if (!apiKey) {
    console.error(`[Claude API] ERROR: API key not configured`);
    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 || "");
  console.log(`[Claude API] Path: ${path}`);

  // Check for session-based request
  const { sessionId, ...requestBody } = req.body;
  let modifiedBody = requestBody;
  console.log(`[Claude API] Session ID: ${sessionId || 'none'}`);
  console.log(`[Claude API] Model: ${requestBody.model}`);
  console.log(`[Claude API] Messages count: ${requestBody.messages?.length || 0}`);

  if (sessionId) {
    const session = getSession(sessionId);
    if (session) {
      console.log(`[Claude API] Session found: ${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 added (${entityContext.length} chars)`);
        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 + ${modifiedBody.messages.length - filteredHistory.length} new = ${modifiedBody.messages.length} total messages`);
      }
    } else {
      console.log(`[Claude API] WARNING: Session ${sessionId} not found`);
    }
  }

  try {
    console.log(`[Claude API] Sending request to Anthropic API...`);
    const fetchStart = Date.now();

    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 fetchDuration = Date.now() - fetchStart;
    console.log(`[Claude API] Response received in ${fetchDuration}ms, status: ${response.status}`);

    console.log(`[Claude API] Parsing response JSON...`);
    const data = await response.json();
    console.log(`[Claude API] Response parsed. Stop reason: ${data.stop_reason}, content blocks: ${data.content?.length || 0}`);

    // Track and log token usage
    if (data.usage) {
      // Extract content for detailed tracking
      const userMessage = requestBody.messages?.[requestBody.messages.length - 1];
      const inputText = typeof userMessage?.content === 'string' ? userMessage.content : null;

      const outputText = data.content
        ?.filter(c => c.type === 'text')
        .map(c => c.text)
        .join('\n') || null;

      const toolCalls = data.content
        ?.filter(c => c.type === 'tool_use')
        .map(c => ({ name: c.name, input: c.input })) || [];

      const usageRecord = trackUsage(sessionId, modifiedBody.model, data.usage, {
        inputText,
        outputText,
        toolCalls
      });
      console.log(`[Claude API] REQUEST USAGE: ${getUsageSummary(usageRecord)}`);

      // Log cumulative session usage if session exists
      if (sessionId) {
        const sessionStats = getSessionUsage(sessionId);
        if (sessionStats) {
          console.log(`[Claude API] SESSION TOTALS (${sessionStats.requestCount} requests):`);
          console.log(`[Claude API]   Total input:  ${sessionStats.totalInputTokens} tokens`);
          console.log(`[Claude API]   Total output: ${sessionStats.totalOutputTokens} tokens`);
          console.log(`[Claude API]   Total cost:   ${formatCost(sessionStats.totalCost)}`);
        }
      }
    }

    if (data.error) {
      console.error(`[Claude API] API returned error:`, data.error);
    }

    // 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
          });
          console.log(`[Claude API] Stored user message to session`);
        }

        // 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
          });
          console.log(`[Claude API] Stored assistant response to session (${assistantContent.length} chars)`);
        }
      }
    }

    const totalDuration = Date.now() - requestStart;
    console.log(`[Claude API] ========== REQUEST COMPLETE (${totalDuration}ms) ==========`);
    res.status(response.status).json(data);
  } catch (error) {
    const totalDuration = Date.now() - requestStart;
    console.error(`[Claude API] ========== REQUEST FAILED (${totalDuration}ms) ==========`);
    console.error(`[Claude API] Error:`, error);
    console.error(`[Claude API] Error message:`, error.message);
    console.error(`[Claude API] Error stack:`, error.stack);
    res.status(500).json({ error: "Failed to proxy request to Claude API", details: error.message });
  }
});

export default router;