// server/utils/db.ts - Prisma Client 单例，当前答题 API 不依赖数据库，保留给后续业务使用
import { PrismaMariaDb } from "@prisma/adapter-mariadb";

import { PrismaClient } from "~~/prisma/generated/client";

/**
 * 将 `DATABASE_URL` 解析为 MariaDB driver 的连接池配置
 *
 * Prisma 7 使用 driver adapter 后，需要显式传入 adapter；
 * 这里不把连接串原样传给前端或日志，只在服务端初始化连接池
 */
const createMariaDbConfig = () => {
  const databaseUrl = process.env.DATABASE_URL;

  if (!databaseUrl) {
    throw new Error("DATABASE_URL is not set.");
  }

  const url = new URL(databaseUrl);

  return {
    host: url.hostname,
    port: Number(url.port || 3306),
    user: decodeURIComponent(url.username),
    password: decodeURIComponent(url.password),
    database: decodeURIComponent(url.pathname.slice(1)),
    connectionLimit: 5,
    connectTimeout: 15_000,
    // 正常情况下连接应立即可用；5s 内拿不到连接说明池已耗尽，快速报错优于无限挂起
    acquireTimeout: 5_000
  };
};

type MariaDbConfig = ReturnType<typeof createMariaDbConfig>;

/**
 * 创建 Prisma Client
 *
 * 连接池超时设置比默认值更宽松，是因为当前数据库是远程 MySQL，
 * 默认超时时间过短时 Node driver 可能还没建好 socket 就失败
 */
const prismaClientSingleton = (config: MariaDbConfig) => {
  const adapter = new PrismaMariaDb(config);
  return new PrismaClient({ adapter });
};

type PrismaClientSingleton = ReturnType<typeof prismaClientSingleton>;

/**
 * 开发环境热更新会反复加载模块
 *
 * 把 Prisma Client 挂到 globalThis 上，可以避免每次 HMR 都新建连接池
 */
const globalForPrisma = globalThis as unknown as {
  prisma: PrismaClientSingleton | undefined;
  prismaConfigSignature: string | undefined;
};

const mariaDbConfig = createMariaDbConfig();
const prismaConfigSignature = JSON.stringify(mariaDbConfig);

/** 全项目唯一 Prisma Client 实例 */
export const prisma =
  globalForPrisma.prisma &&
  globalForPrisma.prismaConfigSignature === prismaConfigSignature
    ? globalForPrisma.prisma
    : prismaClientSingleton(mariaDbConfig);

// 生产环境由进程生命周期管理；开发环境缓存到全局，减少 HMR 连接泄漏
if (process.env.NODE_ENV !== "production") {
  globalForPrisma.prisma = prisma;
  globalForPrisma.prismaConfigSignature = prismaConfigSignature;
}