import { Router } from 'express';
import { z } from 'zod';
import { grok } from '../services/llm/GrokHeadlessClient.js';
import { createLogger } from '../lib/logger.js';
import crypto from 'crypto';

const log = createLogger('chat-api');
const router = Router();

const ChatRequestSchema = z.object({
  message: z.string().min(1).max(2000),
  vehicle: z.object({ name: z.string(), rangeKm: z.number() }),
  itinerary: z.any().optional(),
  history: z.array(z.object({ role: z.enum(['user', 'assistant']), content: z.string() })).optional(),
  selectedVariant: z.enum(['fast', 'scenic', 'cheap']).optional(),
  origin: z.string().optional(),
  destination: z.string().optional(),
  travelDates: z.object({
    outbound: z.string().nullable().optional(),
    return: z.string().nullable().optional(),
    travellers: z.number().int().min(1).max(8).optional(),
  }).optional(),
});

router.post('/chat', async (req, res) => {
  const requestId = crypto.randomUUID().slice(0, 8);
  const start = Date.now();

  log.info({ requestId, body: req.body }, '=== INCOMING /api/chat REQUEST ===');

  try {
    const parsed = ChatRequestSchema.safeParse(req.body);
    if (!parsed.success) {
      log.error({ requestId, errors: parsed.error.format() }, 'Invalid request body');
      return res.status(400).json({ error: 'Invalid request' });
    }

    const { message, vehicle, itinerary, history = [], selectedVariant = 'fast', origin, destination, travelDates } = parsed.data;

    log.info({
      requestId,
      userMessage: message,
      vehicle: vehicle.name,
      historyLength: history.length,
      currentItineraryDays: itinerary?.days?.length || 0,
      selectedVariant,
      origin,
      destination,
      travelDates,
    }, 'Parsed chat request');

    // Call Grok (this will produce very detailed logs inside GrokHeadlessClient)
    const result = await grok.chat(
      [...history, { role: 'user' as const, content: message }],
      itinerary,
      vehicle,
      selectedVariant,
      { origin, destination, travelDates },
    );

    const duration = Date.now() - start;

    const payload: any = { reply: result.text };
    if (result.updatedItinerary) {
      payload.itinerary = result.updatedItinerary;
    }
    if (result.variants && Array.isArray(result.variants)) {
      payload.variants = result.variants;
    }
    if (result.selectedVariant) {
      payload.selectedVariant = result.selectedVariant;
    }

    log.info({
      requestId,
      durationMs: duration,
      replyLength: result.text.length,
      itineraryUpdated: !!result.updatedItinerary,
      newDays: result.updatedItinerary?.days?.length || 0,
    }, '=== SENDING RESPONSE TO FRONTEND ===');

    if (result.updatedItinerary) {
      log.debug({ requestId, fullItinerary: result.updatedItinerary }, 'Full updated itinerary being sent');
    }

    res.json(payload);
  } catch (err) {
    log.error({ requestId, err }, 'Chat route crashed');
    res.status(500).json({ reply: "Something went wrong on the server." });
  }
});


router.post('/chat/stream', async (req, res) => {
  const requestId = crypto.randomUUID().slice(0, 8);
  const parsed = ChatRequestSchema.safeParse(req.body);
  if (!parsed.success) {
    return res.status(400).json({ error: 'Invalid request', issues: parsed.error.format() });
  }
  const { message, vehicle, itinerary, history = [], selectedVariant = 'fast', origin, destination, travelDates } = parsed.data;

  res.setHeader('Content-Type', 'text/event-stream');
  res.setHeader('Cache-Control', 'no-cache, no-transform');
  res.setHeader('Connection', 'keep-alive');
  res.setHeader('X-Accel-Buffering', 'no');
  res.flushHeaders();

  const send = (event: string, data: unknown) => {
    res.write(`event: ${event}\n`);
    res.write(`data: ${JSON.stringify(data)}\n\n`);
  };

  log.info({ requestId, userMessage: message, selectedVariant }, '=== STREAMING /api/chat/stream request ===');
  send('open', { requestId, selectedVariant });

  let partialCount = 0;
  let cancelled = false;
  // Only trust res.on('close') with res.writableEnded as a guard to detect
  // a real client disconnect (vs. our own res.end after the stream completes).
  res.on('close', () => {
    if (!res.writableEnded) {
      log.info({ requestId }, 'client disconnected mid-stream');
      cancelled = true;
    }
  });

  try {
    const stream = grok.chatStream(
      [...history, { role: 'user' as const, content: message }],
      itinerary,
      vehicle,
      selectedVariant,
      { origin, destination, travelDates },
    );
    for await (const ev of stream) {
      if (cancelled) break;
      if (ev.type === 'thinking') send('thinking', { message: ev.message });
      else if (ev.type === 'partial') {
        partialCount++;
        send('partial', {
          itinerary: ev.itinerary,
          variants: ev.variants,
          message: ev.message,
          partialIndex: partialCount,
        });
      } else if (ev.type === 'done') {
        send('done', {
          reply: ev.text,
          itinerary: ev.itinerary,
          variants: ev.variants,
          selectedVariant: ev.selectedVariant,
        });
      } else if (ev.type === 'error') {
        send('error', { error: ev.error });
      }
    }
    log.info({ requestId, partialCount }, 'stream complete');
  } catch (err) {
    log.error({ requestId, err: String(err) }, 'streaming chat crashed');
    send('error', { error: 'Stream failed' });
  } finally {
    res.end();
  }
});

router.get('/grok/status', async (_req, res) => {
  try {
    const status = await grok.getStatus();
    res.json(status);
  } catch (err) {
    res.json({
      provider: 'fallback',
      label: 'Fallback',
      detail: 'Basic mode',
      isLocal: false,
      model: 'unknown',
    });
  }
});

export default router;