// MySQL 连接池、建表、字段备注同步
// 表结构写成数据（下面的 TABLES），建表语句和「备注同步」都由它生成，不会两处写法对不上
const fileConfig = require('./read-config.js')
const { COPY } = require('./copy.js')

const settings = {
  host: process.env.PAY_DB_HOST || (fileConfig.db && fileConfig.db.host) || '127.0.0.1',
  port: Number(process.env.PAY_DB_PORT || (fileConfig.db && fileConfig.db.port) || 3306),
  user: process.env.PAY_DB_USER || (fileConfig.db && fileConfig.db.user) || '',
  password: process.env.PAY_DB_PASSWORD || (fileConfig.db && fileConfig.db.password) || '',
  database: process.env.PAY_DB_NAME || (fileConfig.db && fileConfig.db.database) || '',
}

// 默认：配了库名和账号就走 MySQL，否则继续用 JSONL 文件
// PAY_STORE=jsonl / mysql 可以强制指定（自测强制用文件，不碰你的库）
const useMysql = process.env.PAY_STORE ? process.env.PAY_STORE === 'mysql' : Boolean(settings.database && settings.user)

const TABLES = {
  orders: {
    comment: '订单表，金额单位分',
    columns: [
      { name: 'out_trade_no', type: 'VARCHAR(32)', notNull: true, comment: '业务单号，幂等键' },
      { name: 'openid', type: 'VARCHAR(64)', notNull: true, comment: '用户 openid' },
      { name: 'product_id', type: 'VARCHAR(32)', notNull: true, comment: '道具 ID' },
      { name: 'env', type: 'TINYINT', notNull: true, default: '0', comment: '0 现网 1 沙箱' },
      { name: 'amount', type: 'INT', notNull: true, default: '0', comment: '下单金额（分）' },
      { name: 'status', type: 'VARCHAR(16)', notNull: true, default: "'created'", comment: 'created 已下单 delivered 已发货' },
      { name: 'wx_order_id', type: 'VARCHAR(64)', comment: '平台单号，唯一' },
      { name: 'paid_fee', type: 'INT', comment: '实付金额（分）' },
      { name: 'notified', type: 'TINYINT', notNull: true, default: '0', comment: '已通知平台发货' },
      { name: 'refunded', type: 'TINYINT', notNull: true, default: '0', comment: '已退款' },
      { name: 'refund_order_id', type: 'VARCHAR(32)', comment: '退款单号' },
      { name: 'created_at', type: 'DATETIME(3)', notNull: true, comment: '下单时间' },
      { name: 'delivered_at', type: 'DATETIME(3)', comment: '发货时间' },
      { name: 'refunded_at', type: 'DATETIME(3)', comment: '退款时间' },
    ],
    keys: [
      'PRIMARY KEY (out_trade_no)',
      'UNIQUE KEY uniq_wx_order (wx_order_id)',
      'KEY idx_openid (openid)',
      'KEY idx_pending (refunded, created_at)',
    ],
  },
  codes: {
    comment: '激活码表，退款只作废不删行',
    columns: [
      { name: 'code', type: 'VARCHAR(24)', notNull: true, comment: '激活码，主键' },
      { name: 'product_id', type: 'VARCHAR(32)', notNull: true, comment: '道具 ID（等级）' },
      { name: 'out_trade_no', type: 'VARCHAR(32)', comment: '绑定订单号，唯一' },
      { name: 'openid', type: 'VARCHAR(64)', comment: '归属用户 openid' },
      { name: 'env', type: 'TINYINT', notNull: true, default: '0', comment: '0 现网 1 沙箱' },
      { name: 'status', type: 'VARCHAR(16)', notNull: true, default: "'issued'", comment: 'issued 已发出 revoked 已作废' },
      { name: 'batch', type: 'VARCHAR(32)', comment: '批次号，备用' },
      { name: 'created_at', type: 'DATETIME(3)', notNull: true, comment: '生成时间' },
      { name: 'bound_at', type: 'DATETIME(3)', comment: '绑定时间' },
      { name: 'used_at', type: 'DATETIME(3)', comment: '核销时间，暂无核销' },
      { name: 'revoked_at', type: 'DATETIME(3)', comment: '作废时间' },
    ],
    keys: ['PRIMARY KEY (code)', 'UNIQUE KEY uniq_order (out_trade_no)', 'KEY idx_openid (openid)'],
  },
  goods: {
    comment: '道具价目表，价格需与 MP 后台一致',
    columns: [
      { name: 'product_id', type: 'VARCHAR(32)', notNull: true, comment: '道具 ID' },
      { name: 'name', type: 'VARCHAR(64)', notNull: true, comment: '显示名' },
      { name: 'price', type: 'INT', notNull: true, comment: '单价（分）' },
      { name: 'enabled', type: 'TINYINT', notNull: true, default: '1', comment: '0 下架 1 在售' },
      { name: 'admin_only', type: 'TINYINT', notNull: true, default: '0', comment: '1 仅管理员可购买' },
      { name: 'note', type: 'VARCHAR(255)', comment: '购买页提示文案，例如优惠信息' },
      { name: 'updated_at', type: 'DATETIME(3)', notNull: true, comment: '修改时间' },
    ],
    keys: ['PRIMARY KEY (product_id)'],
  },
  users: {
    comment: '用户表，激活码看 codes 表',
    columns: [
      { name: 'openid', type: 'VARCHAR(64)', notNull: true, comment: '用户 openid' },
      { name: 'created_at', type: 'DATETIME(3)', notNull: true, comment: '首次使用时间' },
      { name: 'last_seen_at', type: 'DATETIME(3)', notNull: true, comment: '最近一次活跃' },
      { name: 'is_admin', type: 'TINYINT', notNull: true, default: '0', comment: '0 普通 1 管理员' },
    ],
    keys: ['PRIMARY KEY (openid)', 'KEY idx_created (created_at)'],
  },
  settings: {
    comment: '页面文案配置，改完最多 1 分钟生效',
    columns: [
      { name: 'cfg_key', type: 'VARCHAR(64)', notNull: true, comment: '配置项，如 buy.title' },
      { name: 'cfg_value', type: 'VARCHAR(255)', notNull: true, comment: '文案内容' },
      { name: 'remark', type: 'VARCHAR(255)', comment: '这个配置显示在哪里' },
      { name: 'updated_at', type: 'DATETIME(3)', notNull: true, comment: '修改时间' },
    ],
    keys: ['PRIMARY KEY (cfg_key)'],
  },
}

let pool = null

function getPool() {
  if (pool) return pool
  let mysql
  try {
    mysql = require('mysql2/promise')
  } catch (err) {
    throw new Error('没装 mysql2，请先在 server 目录执行 npm install')
  }
  pool = mysql.createPool(
    Object.assign({}, settings, {
      charset: 'utf8mb4',
      waitForConnections: true,
      connectionLimit: 5,
      supportBigNumbers: true,
      bigNumberStrings: false, // 大整数当数字返回，别变字符串
    })
  )
  return pool
}

const quoteComment = (text) => String(text).replace(/'/g, "''")

function columnSql(column) {
  return [
    `\`${column.name}\` ${column.type}`,
    column.notNull ? 'NOT NULL' : 'NULL',
    column.default === undefined ? '' : `DEFAULT ${column.default}`,
    `COMMENT '${quoteComment(column.comment)}'`,
  ]
    .filter(Boolean)
    .join(' ')
}

// 早期版本用 BIGINT 存毫秒时间戳，这里自动换成 DATETIME(3)，跑一次就没了
async function upgradeTimeColumns(db) {
  const [columns] = await db.query(
    `SELECT TABLE_NAME, COLUMN_NAME FROM information_schema.COLUMNS
     WHERE TABLE_SCHEMA = ? AND DATA_TYPE = 'bigint' AND COLUMN_NAME LIKE '%\\_at'`,
    [settings.database]
  )
  for (const column of columns) {
    const table = column.TABLE_NAME
    const name = column.COLUMN_NAME
    await db.query(`ALTER TABLE \`${table}\` ADD COLUMN \`${name}_new\` DATETIME(3) NULL`)
    await db.query(
      `UPDATE \`${table}\` SET \`${name}_new\` = FROM_UNIXTIME(\`${name}\` / 1000) WHERE \`${name}\` IS NOT NULL`
    )
    await db.query(`ALTER TABLE \`${table}\` DROP COLUMN \`${name}\``)
    await db.query(`ALTER TABLE \`${table}\` CHANGE \`${name}_new\` \`${name}\` DATETIME(3) NULL`)
  }
  return columns.length
}

// 表已经存在时建表语句不会生效，所以单独把「字段备注 + 表备注」同步一遍
// ponytail: 一个 ALTER 会把整表重建，数据量小（几百行）无所谓；真到几十万行再改成按需比对
async function syncComments(db, name, table) {
  const [rows] = await db.query(
    `SELECT COLUMN_NAME, COLUMN_COMMENT FROM information_schema.COLUMNS WHERE TABLE_SCHEMA = ? AND TABLE_NAME = ?`,
    [settings.database, name]
  )
  const current = new Map(rows.map((row) => [row.COLUMN_NAME, row.COLUMN_COMMENT]))
  const stale = table.columns.filter((column) => current.has(column.name) && current.get(column.name) !== column.comment)
  if (stale.length) {
    await db.query(`ALTER TABLE \`${name}\` ${stale.map((column) => 'MODIFY COLUMN ' + columnSql(column)).join(', ')}`)
  }
  const [tableRows] = await db.query(
    `SELECT TABLE_COMMENT FROM information_schema.TABLES WHERE TABLE_SCHEMA = ? AND TABLE_NAME = ?`,
    [settings.database, name]
  )
  if (tableRows.length && tableRows[0].TABLE_COMMENT !== table.comment) {
    await db.query(`ALTER TABLE \`${name}\` COMMENT = '${quoteComment(table.comment)}'`)
  }
  return stale.length
}

// 表已存在时建表语句改不了结构，所以按声明把缺的列补上（只加列，不动已有数据）
// 注意：以后新增 NOT NULL 列一定要带 DEFAULT，否则在非空表上会加不进去
async function addMissingColumns(db, name, table) {
  const [rows] = await db.query(
    `SELECT COLUMN_NAME FROM information_schema.COLUMNS WHERE TABLE_SCHEMA = ? AND TABLE_NAME = ?`,
    [settings.database, name]
  )
  const existing = new Set(rows.map((row) => row.COLUMN_NAME))
  const missing = table.columns.filter((column) => !existing.has(column.name))
  for (const column of missing) {
    await db.query(`ALTER TABLE \`${name}\` ADD COLUMN ${columnSql(column)}`)
  }
  return missing.length
}

async function initSchema(goodsSeed) {
  const db = getPool()
  for (const [name, table] of Object.entries(TABLES)) {
    const columns = table.columns.map(columnSql).join(', ')
    await db.query(
      `CREATE TABLE IF NOT EXISTS \`${name}\` (${columns}, ${table.keys.join(', ')}) ` +
        `ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='${quoteComment(table.comment)}'`
    )
  }

  let added = 0
  for (const [name, table] of Object.entries(TABLES)) added += await addMissingColumns(db, name, table)
  if (added) console.log(`已给已有表补上 ${added} 个字段`)

  const converted = await upgradeTimeColumns(db)
  if (converted) console.log(`已把 ${converted} 个时间列从时间戳改成可读时间`)

  let commented = 0
  for (const [name, table] of Object.entries(TABLES)) commented += await syncComments(db, name, table)
  if (commented) console.log(`已同步 ${commented} 个字段备注`)

  // 价目表空的时候用代码里的价目表播种一次；之后改价直接改库（记得 MP 后台一起改）
  const [rows] = await db.query('SELECT COUNT(*) AS n FROM goods')
  if (rows[0].n === 0) {
    for (const productId of Object.keys(goodsSeed)) {
      const goods = goodsSeed[productId]
      await db.query('INSERT IGNORE INTO goods (product_id, name, price, enabled, updated_at) VALUES (?, ?, ?, 1, ?)', [
        String(productId),
        goods.name,
        goods.price,
        new Date(),
      ])
    }
  }
  // admin_only 以代码里的价目表为准（价格、名称还是以库里为准，方便改价不发版）
  for (const productId of Object.keys(goodsSeed)) {
    await db.query('UPDATE goods SET admin_only = ? WHERE product_id = ?', [
      goodsSeed[productId].adminOnly ? 1 : 0,
      String(productId),
    ])
  }

  // 文案配置：缺哪个补哪个，只刷新备注列，不覆盖你已经改过的 cfg_value
  for (const [key, item] of Object.entries(COPY)) {
    await db.query(
      `INSERT INTO settings (cfg_key, cfg_value, remark, updated_at) VALUES (?, ?, ?, ?)
       ON DUPLICATE KEY UPDATE remark = VALUES(remark)`,
      [key, item.value, item.comment, new Date()]
    )
  }
  return db
}

module.exports = { settings, useMysql, getPool, initSchema }