import { parseYamlConfig } from './yaml-config.mjs'
import { createRequire } from 'node:module'
import { pathToFileURL } from 'node:url'
import { dirname, resolve as resolvePath, join } from 'node:path'

/**
 * Resolve the `mysql2/promise` driver from the TARGET PROJECT directory.
 *
 * ESM resolves a bare specifier relative to the importing module — and this helper
 * lives inside the PLUGIN, not the project being scaffolded. A plain
 * `import('mysql2/promise')` here would therefore look in the plugin's own
 * node_modules and never see a target-project `npm i mysql2`. We instead build a
 * `require` rooted at the target project so the documented "install mysql2 in your
 * project" actually takes effect. Throws (MODULE_NOT_FOUND) when it is absent.
 *
 * @param {string} [baseDir] target project root (defaults to cwd)
 * @returns {string} absolute path to the resolved mysql2/promise entry
 */
export function resolveMysql2Path(baseDir = process.cwd()) {
  const require = createRequire(pathToFileURL(join(baseDir, 'package.json')).href)
  return require.resolve('mysql2/promise')
}

/**
 * Apply a DDL file to a MySQL database using mysql2/promise.
 * DB credentials are read from config-vars.yaml's `database:` section.
 *
 * @param {{configPath: string, ddlPath: string}} opts
 * @returns {Promise<void>}
 */
export async function applyDDL({ configPath, ddlPath }) {
  const { readFileSync } = await import('node:fs')

  const config = parseYamlConfig(readFileSync(configPath, 'utf8'))
  const ddl = readFileSync(ddlPath, 'utf8')
  const { host, port, user, password, database } = resolveDbConfig(config, configPath)

  let mysql
  try {
    // 从目标项目（config-vars.yaml 所在目录）解析 mysql2，而非插件自身目录（见 resolveMysql2Path）。
    const resolved = resolveMysql2Path(dirname(resolvePath(configPath)))
    ;({ default: mysql } = await import(pathToFileURL(resolved).href))
  } catch {
    throw new MysqlUnavailableError()
  }

  const conn = await mysql.createConnection({
    host,
    port,
    user,
    password,
    database,
    multipleStatements: true,
  })
  try {
    await conn.query(ddl)
  } finally {
    await conn.end()
  }
}

/**
 * Resolve mysql2 connection settings from a parsed config-vars.yaml object,
 * reading its `database:` section directly. Pure (no I/O), so it is
 * unit-testable without mysql2 installed.
 *
 * Throws if no schema resolves — V1 has no USE/CREATE DATABASE.
 *
 * @param {Record<string, any>} config  parsed config-vars.yaml
 * @param {string} [cfgPath] only used to make the error message actionable
 * @returns {{host:string, port:number, user:string, password:string, database:string}}
 */
export function resolveDbConfig(config, cfgPath = 'config-vars.yaml') {
  const db = (config && config.database) || {}
  const host = db.host || '127.0.0.1'
  const port = Number(db.port || 3306)
  const user = db.user || 'root'
  const password = db.password || ''
  const database = db.schema || undefined
  if (!database) {
    throw new Error(`apply-ddl: 缺数据库名 — 请在 ${cfgPath} 的 database.schema 填写`)
  }
  if (!Number.isInteger(port) || port <= 0 || port > 65535) {
    throw new Error(`apply-ddl: 端口非法 — ${cfgPath} 的 database.port 必须是 1..65535 的整数`)
  }
  // DDL-7：lib 自保护——拒绝把未填的「【人工填写】」凭据占位直连 MySQL。
  // db-init 步骤 B 已用 LLM 文本检查把关，这里在真正建连的那一层再加一道防御（占位文本绝不应连库）。
  for (const [k, v] of [['host', host], ['user', user], ['password', password], ['schema', database]]) {
    if (typeof v === 'string' && v.includes('【人工填写')) {
      throw new Error(`apply-ddl: ${cfgPath} 的 database.${k} 仍是「【人工填写】」占位 — 请先填真实凭据`)
    }
  }
  return { host, port, user, password, database }
}

/** Distinct error type so the CLI can emit a friendly install hint. */
export class MysqlUnavailableError extends Error {
  constructor() {
    super('mysql2 is not installed')
    this.name = 'MysqlUnavailableError'
  }
}

// CLI entry guard：pathToFileURL 规范化 argv[1] 以匹配 import.meta.url（路径含空格 / 非 ASCII / Windows 反斜杠时字面比较会失配）
if (process.argv[1] && import.meta.url === pathToFileURL(process.argv[1]).href) {
  const [configPath, ddlPath] = process.argv.slice(2)
  if (!configPath || !ddlPath) {
    console.error('usage: node lib/apply-ddl.mjs <configPath> <ddlPath>')
    process.exit(2)
  }
  // DDL-6：缺文件属用法/路径错 → 退出码 2（与 db-init C.2 文档「2 = 用法错（路径找不到）」及 validate-ddl 对齐）。
  const { existsSync } = await import('node:fs')
  if (!existsSync(configPath)) { console.error(`apply-ddl: 配置文件不存在: ${configPath}`); process.exit(2) }
  if (!existsSync(ddlPath)) { console.error(`apply-ddl: DDL 文件不存在: ${ddlPath}`); process.exit(2) }
  try {
    await applyDDL({ configPath, ddlPath })
    console.log(`apply-ddl: applied ${ddlPath} using ${configPath}`)
  } catch (e) {
    if (e instanceof MysqlUnavailableError) {
      console.error('apply-ddl: mysql2 not found. Please run `npm i mysql2` in the target project.')
      process.exit(1)
    }
    console.error(`apply-ddl: failed — ${e?.message || e}`)
    process.exit(1)
  }
}