SaaS 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 });

// === 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. With Clerk
// the identity-sync mirror occupies this same ./auth-schema slot (src/db/auth-schema.ts).
import { user } from "./auth-schema";

export type MemberRole = "owner" | "admin" | "member";
export type InvitationStatus = "pending" | "accepted" | "revoked";
export type SubscriptionStatus =
  | "trialing"
  | "active"
  | "past_due"
  | "canceled";

/** Tenant boundary: every billable/metered row hangs off an organization. */
export const organizations = mysqlTable(
  "organizations",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    slug: varchar("slug", { length: 255 }).notNull().unique(),
    name: text("name").notNull(),
    createdAt: timestamp("created_at").notNull().defaultNow(),
  },
  (t) => [index("idx_org_slug").on(t.slug)],
);

/** org <-> user join with role. The composite unique is the membership identity. */
export const memberships = mysqlTable(
  "memberships",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    organizationId: varchar("organization_id", { length: 36 })
      .notNull()
      .references(() => organizations.id, { onDelete: "cascade" }),
    // Better Auth's user.id is text — match it as varchar(255).
    userId: varchar("user_id", { length: 255 })
      .notNull()
      .references(() => user.id, { onDelete: "cascade" }),
    role: varchar("role", { length: 32 }).$type<MemberRole>().notNull().default("member"),
    createdAt: timestamp("created_at").notNull().defaultNow(),
  },
  (t) => [
    unique("memberships_org_user_unique").on(t.organizationId, t.userId),
    index("idx_membership_user").on(t.userId),
    check(
      "memberships_role_check",
      sql`${t.role} in ('owner','admin','member')`,
    ),
  ],
);

/** Pending team invitations — how someone who does NOT yet have an account joins an org.
 *
 * Stores a SHA-256 of the invite token, NEVER the token itself. The raw token exists only in the
 * link that was sent, so a database dump (or a stray token in a log) cannot be replayed into org
 * access. The accept path hashes what it was given and looks up by that hash.
 *
 * Org-scoped like every other tenant table: RLS covers it on Postgres, forOrg on MySQL. It holds
 * an invitee's email address BEFORE they are a member of anything, which is exactly the kind of
 * row that must not be readable across tenants.
 */
export const invitations = mysqlTable(
  "invitations",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    organizationId: varchar("organization_id", { length: 36 })
      .notNull()
      .references(() => organizations.id, { onDelete: "cascade" }),
    // Indexed/unique key -> varchar, same rule as slug/role above.
    email: varchar("email", { length: 255 }).notNull(),
    role: varchar("role", { length: 32 }).$type<MemberRole>().notNull().default("member"),
    tokenHash: varchar("token_hash", { length: 64 }).notNull(),
    status: varchar("status", { length: 32 }).$type<InvitationStatus>().notNull().default("pending"),
    // Nullable + ON DELETE SET NULL: the inviter's account going away must not cascade-delete
    // invitations that are still legitimately pending.
    invitedByUserId: varchar("invited_by_user_id", { length: 255 }).references(() => user.id, {
      onDelete: "set null",
    }),
    expiresAt: timestamp("expires_at").notNull(),
    acceptedAt: timestamp("accepted_at"),
    createdAt: timestamp("created_at").notNull().defaultNow(),
  },
  (t) => [
    // The accept path's lookup key: a token must identify at most one invitation.
    unique("invitations_token_hash_unique").on(t.tokenHash),
    // ONE row per (org, email) — re-inviting UPDATEs it rather than accumulating dead rows, which
    // also makes "resend the invite" and "invite again" the same operation instead of two.
    unique("invitations_org_email_unique").on(t.organizationId, t.email),
    index("idx_invitation_org").on(t.organizationId),
    check(
      "invitations_role_check",
      sql`${t.role} in ('owner','admin','member')`,
    ),
    check(
      "invitations_status_check",
      sql`${t.status} in ('pending','accepted','revoked')`,
    ),
  ],
);

/** Append-only record of every privileged action taken inside an organization.
 *
 * Org-scoped like the rest of the tenant surface, and APPEND-ONLY by more than convention: the RLS
 * block REVOKEs UPDATE and DELETE on this table from the application role, so the app physically
 * cannot rewrite its own history even if a future handler tries. A log the app can edit is not
 * evidence of anything, which is the only reason anyone asks for one.
 *
 * `actor_user_id` is nullable with ON DELETE SET NULL: the person who did the thing may later
 * delete their account, and the entry has to survive them — that is the case the log exists for.
 * `action` is a dotted verb ("member.role_changed"), `target` names what it happened to, and
 * `summary` is the sentence a human reads.
 */
export const auditLog = mysqlTable(
  "audit_log",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    organizationId: varchar("organization_id", { length: 36 })
      .notNull()
      .references(() => organizations.id, { onDelete: "cascade" }),
    actorUserId: varchar("actor_user_id", { length: 255 }).references(() => user.id, {
      onDelete: "set null",
    }),
    action: varchar("action", { length: 64 }).notNull(),
    target: text("target"),
    summary: text("summary").notNull(),
    createdAt: timestamp("created_at").notNull().defaultNow(),
  },
  (t) => [index("idx_audit_org_time").on(t.organizationId, t.createdAt)],
);

/** API keys, for programmatic access to this organization's data.
 *
 * Stores a SHA-256 of the key, NEVER the key. It is shown once, at creation, and cannot be
 * recovered afterwards — the same discipline as `invitations.token_hash`, and for the same reason:
 * a database dump must not be a set of working credentials.
 *
 * `prefix` is the leading, non-secret part of the key, kept in clear so the UI can say WHICH key a
 * row is without being able to reconstruct it. Without it a revoke screen lists indistinguishable
 * rows and nobody dares click anything.
 *
 * `revoked_at` rather than a DELETE: a revoked key's usage rows still reference it, and "this key
 * was disabled on the 3rd" is exactly what someone asks after an incident.
 */
export const apiKeys = mysqlTable(
  "api_keys",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    organizationId: varchar("organization_id", { length: 36 })
      .notNull()
      .references(() => organizations.id, { onDelete: "cascade" }),
    name: varchar("name", { length: 255 }).notNull(),
    keyHash: varchar("key_hash", { length: 64 }).notNull(),
    prefix: varchar("prefix", { length: 32 }).notNull(),
    createdByUserId: varchar("created_by_user_id", { length: 255 }).references(() => user.id, {
      onDelete: "set null",
    }),
    lastUsedAt: timestamp("last_used_at"),
    revokedAt: timestamp("revoked_at"),
    createdAt: timestamp("created_at").notNull().defaultNow(),
  },
  (t) => [
    unique("api_keys_hash_unique").on(t.keyHash),
    index("idx_api_keys_org").on(t.organizationId),
  ],
);

/** Catalog of billable plans (seed-managed). priceCents keeps money integer. */
export const plans = mysqlTable("plans", {
  id: varchar("id", { length: 36 }).primaryKey(),
  slug: varchar("slug", { length: 255 }).notNull().unique(), // free | pro | scale
  name: text("name").notNull(),
  priceCents: int("price_cents").notNull().default(0),
  // Monthly included credits; metering checks usage against this.
  monthlyCredits: bigint("monthly_credits", { mode: "number" })
    .notNull()
    .default(0),
});

/** One active subscription per org. Mirrors the billing provider's state. */
export const subscriptions = mysqlTable(
  "subscriptions",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    organizationId: varchar("organization_id", { length: 36 })
      .notNull()
      .references(() => organizations.id, { onDelete: "cascade" }),
    planId: varchar("plan_id", { length: 36 })
      .notNull()
      .references(() => plans.id),
    status: varchar("status", { length: 32 })
      .$type<SubscriptionStatus>()
      .notNull()
      .default("trialing"),
    // The generic billing-sync contract every webhook provider (Polar/Stripe/LemonSqueezy)
    // needs: the provider's subscription id as a UNIQUE idempotency key, plus the last
    // event timestamp as an out-of-order/staleness guard. The billing fragment maps a
    // provider's events onto these — it does NOT redeclare this table (compose, not duplicate).
    providerSubId: varchar("provider_sub_id", { length: 255 }).unique(),
    providerEventAt: timestamp("provider_event_at"),
    currentPeriodEnd: timestamp("current_period_end"),
    createdAt: timestamp("created_at").notNull().defaultNow(),
  },
  (t) => [
    // One live subscription per org (the metering layer reads exactly one).
    unique("subscriptions_org_unique").on(t.organizationId),
    index("idx_sub_status").on(t.status),
    check(
      "subscriptions_status_check",
      sql`${t.status} in ('trialing','active','past_due','canceled')`,
    ),
  ],
);

/** Append-only credit/token meter. Roll up by org+window for quota + billing. */
export const apiUsage = mysqlTable(
  "api_usage",
  {
    id: varchar("id", { length: 36 }).primaryKey(),
    organizationId: varchar("organization_id", { length: 36 })
      .notNull()
      .references(() => organizations.id, { onDelete: "cascade" }),
    // Who/what spent — opaque key id, nullable for org-level system calls.
    apiKeyId: text("api_key_id"),
    creditsUsed: bigint("credits_used", { mode: "number" }).notNull(),
    createdAt: timestamp("created_at").notNull().defaultNow(),
  },
  (t) => [
    // Drives the "credits used this period" rollup query.
    index("idx_usage_org_time").on(t.organizationId, t.createdAt),
  ],
);

export const organizationsRelations = relations(organizations, ({ many }) => ({
  memberships: many(memberships),
  invitations: many(invitations),
  subscriptions: many(subscriptions),
  usage: many(apiUsage),
  auditLog: many(auditLog),
  apiKeys: many(apiKeys),
}));

export const apiKeysRelations = relations(apiKeys, ({ one }) => ({
  organization: one(organizations, {
    fields: [apiKeys.organizationId],
    references: [organizations.id],
  }),
}));

export const auditLogRelations = relations(auditLog, ({ one }) => ({
  organization: one(organizations, {
    fields: [auditLog.organizationId],
    references: [organizations.id],
  }),
  actor: one(user, { fields: [auditLog.actorUserId], references: [user.id] }),
}));

export const invitationsRelations = relations(invitations, ({ one }) => ({
  organization: one(organizations, {
    fields: [invitations.organizationId],
    references: [organizations.id],
  }),
  invitedBy: one(user, {
    fields: [invitations.invitedByUserId],
    references: [user.id],
  }),
}));

export const membershipsRelations = relations(memberships, ({ one }) => ({
  organization: one(organizations, {
    fields: [memberships.organizationId],
    references: [organizations.id],
  }),
  user: one(user, { fields: [memberships.userId], references: [user.id] }),
}));

export const subscriptionsRelations = relations(subscriptions, ({ one }) => ({
  organization: one(organizations, {
    fields: [subscriptions.organizationId],
    references: [organizations.id],
  }),
  plan: one(plans, {
    fields: [subscriptions.planId],
    references: [plans.id],
  }),
}));

export const apiUsageRelations = relations(apiUsage, ({ one }) => ({
  organization: one(organizations, {
    fields: [apiUsage.organizationId],
    references: [organizations.id],
  }),
}));

import { and, eq, isNull, lt, or } from "drizzle-orm";
import { subscriptions } from "@/db/schema";

export type PolarSubscriptionEvent = {
  type: string;
  data: {
    id: string;
    status: string;
    currentPeriodEnd: string | null;
    modifiedAt: string;
    metadata: { organizationId: string; planId: string };
  };
};

const STATUS_MAP: Record<string, "trialing" | "active" | "past_due" | "canceled"> = {
  trialing: "trialing",
  active: "active",
  past_due: "past_due",
  unpaid: "past_due",
  canceled: "canceled",
  revoked: "canceled",
};

// Idempotent + CONCURRENCY-safe sync of a Polar subscription (MySQL). The staleness guard lives
// in the UPDATE's WHERE, so the row lock serializes concurrent retries. MySQL has no RETURNING —
// affectedRows tells us if a row advanced. The insert path catches the unique-key race (a
// concurrent delivery of the same NEW event) as an idempotent no-op, rethrowing every other error.
// Returns changed=true only on a real advance so callers can guard side effects (emails) against
// Polar's duplicate deliveries.
export async function recordPolarEvent(
  // ponytail: loosely typed Drizzle client so the emitted core stays portable.
  db: any,
  event: PolarSubscriptionEvent,
): Promise<{ changed: boolean }> {
  const sub = event.data;
  const status = STATUS_MAP[sub.status];
  if (!status) return { changed: false }; // unknown status — ignore, don't default
  const eventAt = new Date(sub.modifiedAt);
  const currentPeriodEnd = sub.currentPeriodEnd ? new Date(sub.currentPeriodEnd) : null;

  // Guarded UPDATE: applies only when our event is strictly newer than what's stored.
  // No TOCTOU — the comparison is in the WHERE, evaluated under the row lock.
  const updated = await db
    .update(subscriptions)
    .set({ status, currentPeriodEnd, providerEventAt: eventAt })
    .where(
      and(
        eq(subscriptions.providerSubId, sub.id),
        or(isNull(subscriptions.providerEventAt), lt(subscriptions.providerEventAt, eventAt)),
      ),
    );
  if (updated[0].affectedRows > 0) return { changed: true };

  // No row advanced: the row exists but our event is stale (guard rejected it), or it doesn't
  // exist yet. If it exists, this is a stale/duplicate delivery — ignore.
  const [existing] = await db
    .select({ id: subscriptions.id })
    .from(subscriptions)
    .where(eq(subscriptions.providerSubId, sub.id))
    .limit(1);
  if (existing) return { changed: false };

  // The row doesn't exist yet — insert it. A concurrent delivery of the SAME new subscription can
  // win the race between our SELECT and this INSERT; the unique key then rejects ours (ER_DUP_ENTRY)
  // — an idempotent no-op, NOT a change. Any other error is real: rethrow so the webhook fails loud
  // and Polar retries.
  try {
    await db.insert(subscriptions).values({
      id: crypto.randomUUID(),
      organizationId: sub.metadata.organizationId,
      planId: sub.metadata.planId,
      status,
      currentPeriodEnd,
      providerSubId: sub.id,
      providerEventAt: eventAt,
    });
    return { changed: true };
  } catch (err: any) {
    if ((err?.cause?.code ?? err?.code) === "ER_DUP_ENTRY") return { changed: false };
    throw err;
  }
}

import { eq } from "drizzle-orm";
import { memberships, invitations, subscriptions, apiUsage, auditLog, apiKeys } from "@/db/schema";

// MySQL has NO row-level security. Tenant isolation is enforced HERE: route EVERY org-scoped
// read/write through forOrg(db, orgId). Fail-closed — a missing orgId throws rather than running
// unscoped. The global `plans` catalog is intentionally NOT scoped.
export function forOrg(db: any, orgId: string) {
  if (!orgId) throw new Error("forOrg: missing orgId — refusing to run an unscoped tenant query");
  const scoped = (table: any, orgCol: any) => ({
    select: () => db.select().from(table).where(eq(orgCol, orgId)),
    update: (values: Record<string, unknown>) => db.update(table).set(values).where(eq(orgCol, orgId)),
    delete: () => db.delete(table).where(eq(orgCol, orgId)),
  });
  return {
    memberships: scoped(memberships, memberships.organizationId),
    invitations: scoped(invitations, invitations.organizationId),
    subscriptions: scoped(subscriptions, subscriptions.organizationId),
    apiUsage: scoped(apiUsage, apiUsage.organizationId),
    auditLog: scoped(auditLog, auditLog.organizationId),
    apiKeys: scoped(apiKeys, apiKeys.organizationId),
  };
}

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 });