import mysql from 'mysql2/promise'
import pool from './connection'
import { readFileSync } from 'fs'
import { join } from 'path'

async function columnExists(conn: mysql.Connection, table: string, column: string): Promise<boolean> {
  const [rows] = await conn.query(
    `SELECT COUNT(*) as cnt FROM information_schema.COLUMNS WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = ? AND COLUMN_NAME = ?`,
    [table, column]
  )
  return (rows as any[])[0].cnt > 0
}

async function runMigrations(conn: mysql.Connection) {
  console.log('[DB] Checking migrations...')

  // transactions 表添加 user_id
  const hasTxUserId = await columnExists(conn, 'transactions', 'user_id')
  console.log(`[DB] transactions.user_id exists: ${hasTxUserId}`)
  if (!hasTxUserId) {
    console.log('[DB] Migrating: adding user_id to transactions')
    await conn.query('ALTER TABLE transactions ADD COLUMN user_id INT NOT NULL DEFAULT 1 AFTER id')
    await conn.query('ALTER TABLE transactions ADD INDEX idx_user_date (user_id, date)')
    await conn.query('ALTER TABLE transactions ADD INDEX idx_user_type_date (user_id, type, date)')
    console.log('[DB] transactions.user_id added')
  }

  // budgets 表添加 user_id
  const hasBudgetUserId = await columnExists(conn, 'budgets', 'user_id')
  console.log(`[DB] budgets.user_id exists: ${hasBudgetUserId}`)
  if (!hasBudgetUserId) {
    console.log('[DB] Migrating: adding user_id to budgets')
    await conn.query('ALTER TABLE budgets ADD COLUMN user_id INT NOT NULL DEFAULT 1 AFTER id')
    await conn.query('ALTER TABLE budgets ADD UNIQUE KEY uk_user_month (user_id, month)')
    console.log('[DB] budgets.user_id added')
  }
}

export async function initDatabase() {
  const dbName = process.env.DB_NAME || 'xiaocai'

  // 先用不指定数据库的连接，确保数据库存在
  const bootstrap = await mysql.createConnection({
    host: process.env.DB_HOST || 'localhost',
    user: process.env.DB_USER || 'xiaocai',
    password: process.env.DB_PASSWORD || 'xiaocai123',
    multipleStatements: true,
  })

  await bootstrap.query(`CREATE DATABASE IF NOT EXISTS \`${dbName}\` DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci`)
  await bootstrap.end()

  // 用独立连接执行建表和填充（需要 multipleStatements）
  const initConn = await mysql.createConnection({
    host: process.env.DB_HOST || 'localhost',
    user: process.env.DB_USER || 'xiaocai',
    password: process.env.DB_PASSWORD || 'xiaocai123',
    database: dbName,
    multipleStatements: true,
  })

  try {
    const schemaPath = join(__dirname, 'schema.sql')
    const seedPath = join(__dirname, 'seed.sql')

    const schema = readFileSync(schemaPath, 'utf-8')
    const cleanSchema = schema
      .replace(/CREATE DATABASE.*?;/gi, '')
      .replace(/USE\s+\w+;/gi, '')
    await initConn.query(cleanSchema)

    const seed = readFileSync(seedPath, 'utf-8')
    await initConn.query(seed)

    console.log('[DB] Schema and seed applied')
  } catch (err: any) {
    if (err.code === 'ER_DUP_ENTRY' || err.errno === 1062) {
      console.log('[DB] Already initialized, skipping seed')
    } else {
      console.error('[DB] Init warning:', err.message)
    }
  }

  // 始终运行迁移（独立于 schema/seed）
  try {
    await runMigrations(initConn)
    console.log('[DB] Migrations complete')
  } catch (err: any) {
    console.error('[DB] Migration error:', err.message)
  }

  await initConn.end()
  console.log('[DB] Database ready')
}