import { Router } from "express";
import { getSession, addMessage } from "../services/sessionStore.js";
import { trackUsage, getUsageSummary, formatCost, getSessionUsage } from "../services/usageTracker.js";
import {
    getClaudeModel,
    buildLangChainMessages,
    aiMessageToClaudeResponse
} from "../services/langchainModels.js";

const router = Router();

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" });
    }

    const { sessionId, model: modelId, system: systemPrompt, ...requestBody } = req.body;
    console.log(`[Claude API] Session ID: ${sessionId || 'none'}`);
    console.log(`[Claude API] Model: ${modelId}`);
    console.log(`[Claude API] Messages count: ${requestBody.messages?.length || 0}`);

    try {
        // Get LangChain model with tools bound
        const model = getClaudeModel(modelId);

        // Build messages with entity context and history
        const messages = buildLangChainMessages(
            sessionId,
            requestBody.messages,
            systemPrompt
        );

        console.log(`[Claude API] Sending request via LangChain...`);
        const fetchStart = Date.now();

        // Invoke model
        const response = await model.invoke(messages);

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

        // Convert to Claude API format for client compatibility
        const data = aiMessageToClaudeResponse(response, modelId);
        console.log(`[Claude API] Response converted. Stop reason: ${data.stop_reason}, content blocks: ${data.content?.length || 0}`);

        // Track and log token usage
        if (data.usage) {
            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, modelId, data.usage, {
                inputText,
                outputText,
                toolCalls
            });
            console.log(`[Claude API] REQUEST USAGE: ${getUsageSummary(usageRecord)}`);

            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)}`);
                }
            }
        }

        // Store messages to session
        if (sessionId && data.content) {
            const session = getSession(sessionId);
            if (session) {
                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`);
                }

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

export default router;