const express = require('express');
const { getDb } = require('../db');
const { createUserNameResolver, normalizeUserKey } = require('../utils/accounting');

const router = express.Router();

function getUsers(db) {
  return db.all('SELECT * FROM users ORDER BY sort_order, id');
}

function findNormalizedUserConflict(users, targetName, excludedId = null) {
  const normalizedTarget = normalizeUserKey(targetName);
  return users.find(
    (user) => user.id !== excludedId && normalizeUserKey(user.name) === normalizedTarget
  );
}

function getRelatedRecordAliases(db, userName) {
  const users = getUsers(db).map((user) => ({ name: user.name }));
  const resolveUserName = createUserNameResolver(users);
  const aliases = db.all('SELECT DISTINCT user FROM records WHERE user IS NOT NULL AND user != ""');

  return aliases
    .map((row) => row.user)
    .filter((name) => resolveUserName(name, '') === userName);
}

router.get('/', (req, res) => {
  res.json(getUsers(getDb()));
});

router.post('/', (req, res) => {
  const db = getDb();
  const name = String(req.body.name ?? '').trim();
  if (!name) {
    return res.status(400).json({ error: '用户名为必填项' });
  }

  const users = getUsers(db);
  const conflict = findNormalizedUserConflict(users, name);
  if (conflict) {
    return res.status(400).json({ error: '用户名已存在，或与现有用户名仅空格不同' });
  }

  const maxOrder = db.get('SELECT MAX(sort_order) AS max_order FROM users')?.max_order || 0;
  const result = db.run('INSERT INTO users (name, sort_order) VALUES (?, ?)', name, maxOrder + 1);
  db.run('INSERT INTO user_balance_settings (user_name, initial_balance) VALUES (?, 0)', name);

  res.status(201).json(db.get('SELECT * FROM users WHERE id = ?', result.lastInsertRowid));
});

router.put('/:id', (req, res) => {
  const db = getDb();
  const id = Number.parseInt(req.params.id, 10);
  const name = String(req.body.name ?? '').trim();

  if (!name) {
    return res.status(400).json({ error: '用户名为必填项' });
  }

  const user = db.get('SELECT * FROM users WHERE id = ?', id);
  if (!user) {
    return res.status(404).json({ error: '用户不存在' });
  }

  const users = getUsers(db);
  const conflict = findNormalizedUserConflict(users, name, id);
  if (conflict) {
    return res.status(400).json({ error: '用户名已存在，或与现有用户名仅空格不同' });
  }

  const aliases = getRelatedRecordAliases(db, user.name);

  db.run('UPDATE users SET name = ? WHERE id = ?', name, id);
  db.run('UPDATE user_balance_settings SET user_name = ? WHERE user_name = ?', name, user.name);

  aliases.forEach((alias) => {
    db.run('UPDATE records SET user = ? WHERE user = ?', name, alias);
  });

  res.json(db.get('SELECT * FROM users WHERE id = ?', id));
});

router.delete('/:id', (req, res) => {
  const db = getDb();
  const id = Number.parseInt(req.params.id, 10);
  const user = db.get('SELECT * FROM users WHERE id = ?', id);

  if (!user) {
    return res.status(404).json({ error: '用户不存在' });
  }

  const aliases = getRelatedRecordAliases(db, user.name);
  const recordCount = aliases.reduce((total, alias) => {
    const count = db.get('SELECT COUNT(*) AS count FROM records WHERE user = ?', alias)?.count || 0;
    return total + count;
  }, 0);

  if (recordCount > 0) {
    return res.status(400).json({ error: `该用户还有 ${recordCount} 条记录，无法删除` });
  }

  db.run('DELETE FROM users WHERE id = ?', id);
  db.run('DELETE FROM user_balance_settings WHERE user_name = ?', user.name);

  res.json({ message: '删除成功' });
});

module.exports = router;