Marketplace on Next.js 16 (App Router), MySQL 8 and Better Auth

import { drizzle } from "drizzle-orm/mysql2";
import mysql from "mysql2/promise";

// ponytail: single module-level pool; the runtime + mysql2's pool handle concurrency,
// so no globalThis singleton dance needed.
const pool = mysql.createPool(process.env.DATABASE_URL!);

export const db = drizzle({ client: pool });

import { boolean, mysqlTable, text, timestamp, varchar } from "drizzle-orm/mysql-core";

export const user = mysqlTable("user", {
  id: varchar("id", { length: 255 }).primaryKey(),
  name: text("name").notNull(),
  email: varchar("email", { length: 255 }).notNull().unique(),
  emailVerified: boolean("email_verified").notNull().default(false),
  image: text("image"),
  createdAt: timestamp("created_at").notNull().defaultNow(),
  updatedAt: timestamp("updated_at").notNull().defaultNow(),
});

export const session = mysqlTable("session", {
  id: varchar("id", { length: 255 }).primaryKey(),
  expiresAt: timestamp("expires_at").notNull(),
  token: varchar("token", { length: 255 }).notNull().unique(),
  createdAt: timestamp("created_at").notNull().defaultNow(),
  updatedAt: timestamp("updated_at").notNull(),
  ipAddress: text("ip_address"),
  userAgent: text("user_agent"),
  userId: varchar("user_id", { length: 255 })
    .notNull()
    .references(() => user.id, { onDelete: "cascade" }),
});

export const account = mysqlTable("account", {
  id: varchar("id", { length: 255 }).primaryKey(),
  accountId: text("account_id").notNull(),
  providerId: text("provider_id").notNull(),
  userId: varchar("user_id", { length: 255 })
    .notNull()
    .references(() => user.id, { onDelete: "cascade" }),
  accessToken: text("access_token"),
  refreshToken: text("refresh_token"),
  idToken: text("id_token"),
  accessTokenExpiresAt: timestamp("access_token_expires_at"),
  refreshTokenExpiresAt: timestamp("refresh_token_expires_at"),
  scope: text("scope"),
  password: text("password"),
  createdAt: timestamp("created_at").notNull().defaultNow(),
  updatedAt: timestamp("updated_at").notNull(),
});

export const verification = mysqlTable("verification", {
  id: varchar("id", { length: 255 }).primaryKey(),
  identifier: text("identifier").notNull(),
  value: text("value").notNull(),
  expiresAt: timestamp("expires_at").notNull(),
  createdAt: timestamp("created_at").notNull().defaultNow(),
  updatedAt: timestamp("updated_at").notNull().defaultNow(),
});

// Better Auth instance (self-hosted, Next.js 16 (App Router)).
import { betterAuth } from "better-auth";
import { drizzleAdapter } from "better-auth/adapters/drizzle";
// Reuse the SAME postgres-js/Drizzle client the db slice exported in
// src/lib/db.ts — Better Auth shares the pooled `DATABASE_URL` connection.
import { db } from "./db";
import * as authSchema from "@/db/auth-schema";

export const auth = betterAuth({
  // Drizzle adapter over the shared client. The schema is passed HERE (not into
  // drizzle()) — it is the only consumer that needs it, so the db client stays
  // schema-less. ponytail: do NOT enable experimental.joins; it is the one option
  // that would make the adapter reach into db._.fullSchema.
  // ponytail: usePlural stays false (the default) — with it true Better Auth would
  // look for `sessions`/`accounts` and could bind to the analytics/ledger app-type tables.
  database: drizzleAdapter(db, { provider: "mysql", schema: authSchema }),
  // ponytail: email+password is the shortest real auth that works out of
  // the box — add socialProviders / plugins here when the app needs them.
  emailAndPassword: { enabled: true },
  secret: process.env.BETTER_AUTH_SECRET,
  baseURL: process.env.BETTER_AUTH_URL,
});

export type Session = typeof auth.$Infer.Session;

// Mount Better Auth on Next's route layer.
import { toNextJsHandler } from "better-auth/next-js";
import { auth } from "@/lib/auth";

export const { GET, POST } = toNextJsHandler(auth);

// Session-protection proxy for Next.js 16 (App Router) (Next 16 renamed middleware.ts → proxy.ts).
// ponytail: getSessionCookie only checks the cookie EXISTS (no DB hit at
// the Edge runtime) — do the real auth.api.getSession() check inside
// protected Server Components / route handlers. This just bounces
// logged-out users before render.
import { NextResponse, type NextRequest } from "next/server";
import { getSessionCookie } from "better-auth/cookies";

export function proxy(request: NextRequest) {
  const sessionCookie = getSessionCookie(request);
  if (!sessionCookie) {
    return NextResponse.redirect(new URL("/sign-in", request.url));
  }
  return NextResponse.next();
}

export const config = {
  // ponytail: guard the SaaS app surface; widen the matcher per app-type.
  matcher: ["/dashboard/:path*", "/settings/:path*"],
};

// === file: src/db/schema.ts ===
import { relations, sql } from "drizzle-orm";
import {
  bigint,
  check,
  index,
  int,
  mysqlTable,
  text,
  timestamp,
  unique,
  varchar,
} from "drizzle-orm/mysql-core";
// Better Auth owns identity; we only reference its `user` table by id.
import { user } from "./auth-schema";

export type SellerStatus = "pending" | "active" | "suspended";
export type ListingStatus = "draft" | "active" | "sold" | "archived";
export type OrderStatus =
  | "pending"
  | "paid"
  | "shipped"
  | "completed"
  | "refunded"
  | "canceled";
export type PayoutStatus = "scheduled" | "processing" | "paid" | "failed";

/** Supply side: a user who sells. One seller profile per user. */
export const sellers = mysqlTable(
  "sellers",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    // Better Auth's user.id is text — match it as varchar(255).
    userId: varchar("user_id", { length: 255 })
      .notNull()
      .references(() => user.id, { onDelete: "cascade" }),
    displayName: text("display_name").notNull(),
    // ponytail: opaque payout-provider account id (Stripe Connect / PayPal) —
    // no provider FK needed; nullable until onboarding completes.
    payoutAccountId: text("payout_account_id"),
    status: varchar("status", { length: 32 })
      .$type<SellerStatus>()
      .notNull()
      .default("pending"),
    createdAt: timestamp("created_at").notNull().defaultNow(),
  },
  (t) => [
    // One seller profile per identity.
    unique("sellers_user_unique").on(t.userId),
    index("idx_seller_status").on(t.status),
    check(
      "sellers_status_check",
      sql`${t.status} in ('pending','active','suspended')`,
    ),
  ],
);

/** Catalog: each listing belongs to a seller. priceCents keeps money integer. */
export const listings = mysqlTable(
  "listings",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    sellerId: varchar("seller_id", { length: 36 })
      .notNull()
      .references(() => sellers.id, { onDelete: "cascade" }),
    title: text("title").notNull(),
    description: text("description"),
    priceCents: int("price_cents").notNull().default(0),
    status: varchar("status", { length: 32 })
      .$type<ListingStatus>()
      .notNull()
      .default("draft"),
    createdAt: timestamp("created_at").notNull().defaultNow(),
  },
  (t) => [
    // Browse a seller's catalog; filter the storefront by live listings.
    index("idx_listing_seller").on(t.sellerId),
    index("idx_listing_status").on(t.status),
    check(
      "listings_status_check",
      sql`${t.status} in ('draft','active','sold','archived')`,
    ),
  ],
);

/** Demand side: a buyer (Better Auth user) purchases a listing. */
export const marketplaceOrders = mysqlTable(
  "marketplace_orders",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    // The buyer is a Better Auth user — text id, like sellers.userId.
    buyerId: varchar("buyer_id", { length: 255 })
      .notNull()
      .references(() => user.id, { onDelete: "cascade" }),
    listingId: varchar("listing_id", { length: 36 })
      .notNull()
      .references(() => listings.id),
    // Captured at purchase time — independent of later listing price edits.
    amountCents: int("amount_cents").notNull(),
    status: varchar("status", { length: 32 })
      .$type<OrderStatus>()
      .notNull()
      .default("pending"),
    createdAt: timestamp("created_at").notNull().defaultNow(),
  },
  (t) => [
    // Buyer's order history; reconcile orders against a listing.
    index("idx_order_buyer").on(t.buyerId),
    index("idx_order_listing").on(t.listingId),
    check(
      "marketplace_orders_status_check",
      sql`${t.status} in ('pending','paid','shipped','completed','refunded','canceled')`,
    ),
  ],
);

/** Money out: a payout settles a seller's earnings for a period. */
export const payouts = mysqlTable(
  "payouts",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    sellerId: varchar("seller_id", { length: 36 })
      .notNull()
      .references(() => sellers.id, { onDelete: "cascade" }),
    // Net amount remitted to the seller (gross minus marketplace fee).
    amountCents: bigint("amount_cents", { mode: "number" }).notNull(),
    status: varchar("status", { length: 32 })
      .$type<PayoutStatus>()
      .notNull()
      .default("scheduled"),
    // Settlement window this payout covers, e.g. "2026-06".
    period: varchar("period", { length: 32 }).notNull(),
    createdAt: timestamp("created_at").notNull().defaultNow(),
  },
  (t) => [
    // One payout per seller per settlement window.
    unique("payouts_seller_period_unique").on(t.sellerId, t.period),
    index("idx_payout_seller").on(t.sellerId),
    index("idx_payout_status").on(t.status),
    check(
      "payouts_status_check",
      sql`${t.status} in ('scheduled','processing','paid','failed')`,
    ),
  ],
);

/** Trust signal: a reviewer (Better Auth user) rates a listing 1-5. */
export const reviews = mysqlTable(
  "reviews",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    listingId: varchar("listing_id", { length: 36 })
      .notNull()
      .references(() => listings.id, { onDelete: "cascade" }),
    // Reviewer is a Better Auth user — text id.
    reviewerId: varchar("reviewer_id", { length: 255 })
      .notNull()
      .references(() => user.id, { onDelete: "cascade" }),
    rating: int("rating").notNull(),
    body: text("body"),
    createdAt: timestamp("created_at").notNull().defaultNow(),
  },
  (t) => [
    // One review per reviewer per listing.
    unique("reviews_listing_reviewer_unique").on(t.listingId, t.reviewerId),
    // Render a listing's reviews + aggregate its rating.
    index("idx_review_listing").on(t.listingId),
    check("reviews_rating_check", sql`${t.rating} between 1 and 5`),
  ],
);

export const sellersRelations = relations(sellers, ({ one, many }) => ({
  user: one(user, { fields: [sellers.userId], references: [user.id] }),
  listings: many(listings),
  payouts: many(payouts),
}));

export const listingsRelations = relations(listings, ({ one, many }) => ({
  seller: one(sellers, {
    fields: [listings.sellerId],
    references: [sellers.id],
  }),
  orders: many(marketplaceOrders),
  reviews: many(reviews),
}));

export const marketplaceOrdersRelations = relations(
  marketplaceOrders,
  ({ one }) => ({
    buyer: one(user, {
      fields: [marketplaceOrders.buyerId],
      references: [user.id],
    }),
    listing: one(listings, {
      fields: [marketplaceOrders.listingId],
      references: [listings.id],
    }),
  }),
);

export const payoutsRelations = relations(payouts, ({ one }) => ({
  seller: one(sellers, {
    fields: [payouts.sellerId],
    references: [sellers.id],
  }),
}));

export const reviewsRelations = relations(reviews, ({ one }) => ({
  listing: one(listings, {
    fields: [reviews.listingId],
    references: [listings.id],
  }),
  reviewer: one(user, {
    fields: [reviews.reviewerId],
    references: [user.id],
  }),
}));

import { drizzle } from "drizzle-orm/mysql2";
import mysql from "mysql2/promise";

// Serverless: a small pool per short-lived instance — many instances × a big pool exhausts MySQL.
export const pool = mysql.createPool({ uri: process.env.DATABASE_URL!, connectionLimit: 2 });
export const db = drizzle({ client: pool });

import { drizzle } from "drizzle-orm/mysql2";
import mysql from "mysql2/promise";

// Long-running process: a real, reused pool (mysql2 manages idle recycling).
export const pool = mysql.createPool({ uri: process.env.DATABASE_URL!, connectionLimit: 10 });
export const db = drizzle({ client: pool });

import { drizzle } from "drizzle-orm/planetscale-serverless";
import { Client } from "@planetscale/database";

// Edge/Workers have NO TCP sockets, so mysql2 cannot run here. PlanetScale's HTTP driver
// speaks MySQL over fetch — the client that works on Workers (the MySQL analog of Neon's HTTP driver).
const client = new Client({ url: process.env.DATABASE_URL! });
export const db = drizzle({ client });