require('dotenv').config();

const express = require('express');
const cors = require('cors');
const { createStore } = require('./storage');

const PORT = Number(process.env.PORT || 4000);
const CATEGORY_SET = new Set(['KOREAN', 'CHINESE', 'JAPANESE', 'WESTERN', 'OTHER']);

async function main() {
  const { mode, store } = await createStore();

  const app = express();
  app.use(cors());
  app.use(express.json());

  app.get('/v1/health', (_req, res) => {
    res.json({ status: 'ok', mode, time: new Date().toISOString() });
  });

  app.get('/v1/restaurants/nearby', async (req, res) => {
    try {
      const userExternalId = getUserId(req);
      const lat = Number(req.query.lat);
      const lng = Number(req.query.lng);
      const radiusMeters = Number(req.query.radiusMeters || 1000);
      const category = typeof req.query.category === 'string' ? req.query.category : undefined;
      const sort = normalizeSort(req.query.sort);

      if (!Number.isFinite(lat) || !Number.isFinite(lng)) {
        return res.status(400).json({ code: 'INVALID_INPUT', message: 'lat/lng required' });
      }

      if (category && !CATEGORY_SET.has(category)) {
        return res.status(400).json({ code: 'INVALID_INPUT', message: 'invalid category' });
      }

      const items = await store.getNearby({
        userExternalId,
        lat,
        lng,
        radiusMeters,
        category,
        sort,
      });

      return res.json({ items, nextCursor: null });
    } catch (error) {
      return handleError(res, error);
    }
  });

  app.get('/v1/restaurants/:restaurantId', async (req, res) => {
    try {
      const userExternalId = getUserId(req);
      const restaurant = await store.getRestaurantById(
        req.params.restaurantId,
        userExternalId,
      );

      if (!restaurant) {
        return res.status(404).json({ code: 'NOT_FOUND', message: 'restaurant not found' });
      }

      return res.json(restaurant);
    } catch (error) {
      return handleError(res, error);
    }
  });

  app.get('/v1/restaurants/:restaurantId/reviews', async (req, res) => {
    try {
      const userExternalId = getUserId(req);
      const items = await store.getReviews(req.params.restaurantId, userExternalId);
      return res.json({ items, nextCursor: null });
    } catch (error) {
      return handleError(res, error);
    }
  });

  app.post('/v1/restaurants/:restaurantId/reviews', async (req, res) => {
    try {
      const userExternalId = getUserId(req);
      const restaurantId = req.params.restaurantId;
      const rating = Number(req.body?.rating);
      const content = String(req.body?.content || '').trim();

      if (!Number.isInteger(rating) || rating < 1 || rating > 5 || !content) {
        return res.status(400).json({
          code: 'INVALID_INPUT',
          message: 'rating must be 1~5 and content required',
        });
      }

      const result = await store.upsertReview(restaurantId, userExternalId, rating, content);
      if (!result) {
        return res.status(404).json({ code: 'NOT_FOUND', message: 'restaurant not found' });
      }

      return res.json(result);
    } catch (error) {
      return handleError(res, error);
    }
  });

  app.delete('/v1/reviews/:reviewId', async (req, res) => {
    try {
      const userExternalId = getUserId(req);
      const result = await store.deleteReview(req.params.reviewId, userExternalId);

      if (!result.deleted && result.reason === 'NOT_FOUND') {
        return res.status(404).json({ code: 'NOT_FOUND', message: 'review not found' });
      }

      if (!result.deleted && result.reason === 'FORBIDDEN') {
        return res.status(403).json({ code: 'FORBIDDEN', message: 'not your review' });
      }

      return res.status(204).send();
    } catch (error) {
      return handleError(res, error);
    }
  });

  app.post('/v1/restaurants/:restaurantId/like', async (req, res) => {
    try {
      const userExternalId = getUserId(req);
      const result = await store.toggleLike(req.params.restaurantId, userExternalId);

      if (!result) {
        return res.status(404).json({ code: 'NOT_FOUND', message: 'restaurant not found' });
      }

      return res.json(result);
    } catch (error) {
      return handleError(res, error);
    }
  });

  app.get('/v1/users/me/reviews', async (req, res) => {
    try {
      const userExternalId = getUserId(req);
      const items = await store.getMyReviews(userExternalId);
      return res.json({ items, nextCursor: null });
    } catch (error) {
      return handleError(res, error);
    }
  });

  app.listen(PORT, () => {
    console.log(`[lunch-picker-backend] mode=${mode} listening on http://localhost:${PORT}`);
  });
}

main().catch((error) => {
  console.error('[lunch-picker-backend] failed to start', error);
  process.exit(1);
});

function getUserId(req) {
  const value = req.header('x-user-id');
  return value && value.trim() ? value.trim() : 'demo-user-1';
}

function normalizeSort(input) {
  if (typeof input !== 'string') return 'distance';
  if (input === 'rating' || input === 'likes') return input;
  return 'distance';
}

function handleError(res, error) {
  console.error('[api-error]', error);
  return res.status(500).json({ code: 'INTERNAL_ERROR', message: 'unexpected error' });
}