import express from 'express';
import { generateCompletion } from '../ai_engine.js';
import { supabase } from '../config/supabaseClient.js';

const router = express.Router();

// ==========================================
// 🧠 DYNAMIC SYSTEM PROMPT BUILDER
// ==========================================
const buildSystemPrompt = (personaName, personaPrompt) => `
You are an elite communication strategist, negotiator, and ghostwriter.
The user is in an ONGOING conversation and needs you to write their NEXT reply.

You will be given:
- The recent conversation history (showing what each side has said so far)
- The most recent message they received (the one they need to reply to)
- Optionally, a screenshot of the chat

Your job: write the PERFECT next message for the user to send.

PERSONA TO ADOPT:
Identity: ${personaName}
Behavior & Tone: ${personaPrompt}

STRICT RULES:
1. NEVER break character.
2. NEVER start with "As an AI..." or "Here is a response...".
3. Output ONLY the exact reply text — no labels, no quotes, no explanation.
4. Keep it concise and natural for modern texting/messaging.
5. Use the conversation history to stay contextually relevant. Do NOT reply generically.
6. If a screenshot is provided, read it carefully — it is the actual chat. Reply to the last visible message.
7. The reply must feel like a natural continuation of the conversation, not a cold opener. It should always be consistent with the chat history.
8. No hyphens (-) at all.
`;

// ==========================================
// 🗄️ CACHE MANAGEMENT
// ==========================================
let formatsCache = null;
let lastFormatsUpdate = 0;
const CACHE_DURATION = 3600000;

// ==========================================
// 📝 CONVERSATION HISTORY FORMATTER
// ==========================================
// Converts the last N messages into a readable thread for the AI.
// Images are noted but not sent (only the triggering image is sent as vision input).
const formatHistory = (messages =[], maxMessages = 6) => {
  if (!messages.length) return null;

  const recent = messages.slice(-maxMessages); // last 6 messages for context
  const lines = recent.map(m => {
    const role = m.sender === 'user' ? 'ME' : 'THEM';
    if (m.type === 'image') return `${role}: [sent a screenshot]`;
    return `${role}: ${m.content}`;
  });

  return lines.join('\n');
};

// ==========================================
// 🌐 ENDPOINTS
// ==========================================

/**
 * 1. FETCH OFFICIAL FORMATS
 */
router.get('/formats', async (req, res) => {
  try {
    const now = Date.now();
    if (formatsCache && (now - lastFormatsUpdate < CACHE_DURATION)) {
      return res.json({ success: true, data: formatsCache, cached: true });
    }

    const { data, error } = await supabase
      .from('replygenius_vibes')
      .select('id, icon, label, hint, color, mockReply, prompt')
      .order('created_at', { ascending: true });

    if (error) throw error;

    formatsCache = data;
    lastFormatsUpdate = now;

    res.json({ success: true, data, cached: false });
  } catch (err) {
    console.error('[FORMATS ERROR]', err.message);
    res.status(500).json({ success: false, error: err.message });
  }
});

/**
 * 2. GENERATE REPLY
 * Expects body: {
 *   type: 'text' | 'image',
 *   content: string,          // current message text OR base64 image
 *   persona: object,
 *   history: Message[],       // recent messages from the chat session
 *   model: string             // 'seed', 'mistral', or 'grok'
 * }
 */
router.post('/generate', async (req, res) => {
  try {
    // 💡 Extract 'model' from the request, default to 'seed' if missing
    const { type, content, persona, history =[], model = 'seed' } = req.body;

    if (!content) throw new Error('No content provided to analyze.');
    if (!persona || !persona.label) throw new Error('Persona context is missing.');

    console.log(`[REPLY GEN] Analyzing ${type} using persona: ${persona.label} | Model: ${model}`);

    const aiSystemPrompt = buildSystemPrompt(
      persona.label,
      persona.prompt || 'Be highly intelligent, strategic, polite, and persuasive.'
    );

    // Build the conversation thread string (text messages only, images noted as placeholder)
    const conversationHistory = formatHistory(history, 6);

    // 💡 Map frontend model IDs to your actual ai_engine identifiers
    const MODEL_MAP = {
      'seed': 'bytedance-1.6',
      'mistral': 'mistral-small',    // Update this to your actual Mistral engine ID if different
      'grok': 'grok-4.3'           // Update this to your actual Grok engine ID if different
    };

    const modelToUse = MODEL_MAP[model] || MODEL_MAP['seed'];

    let imagesPayload =[];
    let userPrompt = '';

    if (type === 'image') {
      // Only send the triggering image to the vision model — prior images stay on device
      imagesPayload = [content];

      userPrompt = conversationHistory
        ? `Here is our conversation so far:\n${conversationHistory}\n\nI've also attached the latest screenshot. Read it and write my next reply. Output ONLY the reply text.`
        : `Analyze this chat screenshot and write my next reply. Output ONLY the reply text.`;

    } else {
      userPrompt = conversationHistory
        ? `Here is our conversation so far:\n${conversationHistory}\n\nTheir latest message: "${content}"\n\nWrite my next reply. Output ONLY the reply text, nothing else.`
        : `Write my reply to this message. Output ONLY the reply text, nothing else.\n\nMessage:\n"${content}"`;
    }

    const aiResult = await generateCompletion({
      model: modelToUse,
      prompt: userPrompt,
      system_prompt: aiSystemPrompt,
      images: imagesPayload,
      forceJson: false,
    });

    if (!aiResult.success) throw new Error(aiResult.error);

    let finalReply = (aiResult.data || '').trim();

    // Strip any wrapping quotes the model might add
    if (finalReply.startsWith('"') && finalReply.endsWith('"')) {
      finalReply = finalReply.slice(1, -1).trim();
    }
    // Strip markdown bold/italic wrappers
    finalReply = finalReply.replace(/^\*+|\*+$/g, '').trim();

    if (!finalReply) throw new Error('AI returned an empty reply.');

    res.json({ success: true, reply: finalReply });

  } catch (err) {
    console.error('[REPLY GEN ERROR]', err.message);
    res.status(500).json({ success: false, error: err.message });
  }
});

/**
 * 3. FORCE CACHE CLEAR (Admin)
 */
router.post('/clear-cache', (req, res) => {
  formatsCache = null;
  lastFormatsUpdate = 0;
  res.json({ success: true, message: 'Formats cache cleared.' });
});

export default router;