const express = require('express');
const router = express.Router();
const { getDb, ensureUserDefaultCategories } = require('../db/database');
const { standardizeError } = require('../middleware/errorFormatter');
const {
  createSubscriptionFromRecommendation,
  decorateSubscription,
  getSubscriptionRecommendations,
  getSubscriptionSummary,
  getSubscriptions,
} = require('../services/subscriptionService');

router.get('/', (req, res) => {
  const db = getDb();
  ensureUserDefaultCategories(req.user.id);
  const subscriptions = getSubscriptions(db, req.user.id);
  res.json({
    summary: getSubscriptionSummary(subscriptions),
    subscriptions,
  });
});

router.get('/recommendations', (req, res) => {
  const db = getDb();
  res.json({
    recommendations: getSubscriptionRecommendations(db, req.user.id),
  });
});

router.post('/recommendations/create', (req, res) => {
  const db = getDb();
  ensureUserDefaultCategories(req.user.id);
  if (req.body?.category_id) {
    const categoryId = parseInt(req.body.category_id, 10);
    const category = Number.isInteger(categoryId)
      ? db.prepare('SELECT id FROM categories WHERE id = ? AND user_id = ? AND deleted_at IS NULL').get(categoryId, req.user.id)
      : null;
    if (!category) {
      return res.status(400).json(standardizeError('category_id is invalid for this user', 'VALIDATION_ERROR', 'category_id'));
    }
  }
  try {
    const created = createSubscriptionFromRecommendation(db, req.user.id, req.body || {});
    res.status(201).json(created);
  } catch (err) {
    res.status(err.status || 400).json(standardizeError(err.message || 'Could not create subscription', err.status ? 'VALIDATION_ERROR' : 'SUBSCRIPTION_CREATE_ERROR', err.field || null));
  }
});

router.patch('/:id', (req, res) => {
  const db = getDb();
  const billId = parseInt(req.params.id, 10);
  if (!Number.isInteger(billId)) {
    return res.status(400).json(standardizeError('bill_id must be an integer', 'VALIDATION_ERROR', 'bill_id'));
  }

  const existing = db.prepare('SELECT * FROM bills WHERE id = ? AND user_id = ? AND deleted_at IS NULL').get(billId, req.user.id);
  if (!existing) return res.status(404).json(standardizeError('Bill not found', 'NOT_FOUND', 'bill_id'));

  const allowedTypes = new Set(['streaming', 'software', 'cloud', 'music', 'news', 'fitness', 'gaming', 'utilities', 'insurance', 'other']);
  const next = {
    is_subscription: req.body.is_subscription !== undefined ? (req.body.is_subscription ? 1 : 0) : existing.is_subscription,
    subscription_type: req.body.subscription_type !== undefined
      ? (allowedTypes.has(req.body.subscription_type) ? req.body.subscription_type : 'other')
      : existing.subscription_type,
    reminder_days_before: req.body.reminder_days_before !== undefined
      ? Number(req.body.reminder_days_before)
      : existing.reminder_days_before,
    active: req.body.active !== undefined ? (req.body.active ? 1 : 0) : existing.active,
  };

  if (!Number.isInteger(next.reminder_days_before) || next.reminder_days_before < 0 || next.reminder_days_before > 30) {
    return res.status(400).json(standardizeError('reminder_days_before must be between 0 and 30', 'VALIDATION_ERROR', 'reminder_days_before'));
  }

  db.prepare(`
    UPDATE bills
    SET is_subscription = ?,
        subscription_type = ?,
        reminder_days_before = ?,
        active = ?,
        updated_at = datetime('now')
    WHERE id = ? AND user_id = ?
  `).run(next.is_subscription, next.subscription_type, next.reminder_days_before, next.active, billId, req.user.id);

  const updated = db.prepare(`
    SELECT b.*, c.name AS category_name
    FROM bills b
    LEFT JOIN categories c ON c.id = b.category_id AND c.user_id = b.user_id AND c.deleted_at IS NULL
    WHERE b.id = ? AND b.user_id = ?
  `).get(billId, req.user.id);

  res.json(decorateSubscription(updated));
});

module.exports = router;