Use Drizzle adapter and Drizzle CLI auth migrations

lib/auth.ts

@@ -1,18 +1,13 @@
 import { betterAuth } from 'better-auth';
-import { getMigrations } from 'better-auth/db';
+import { drizzleAdapter } from 'better-auth/adapters/drizzle';
 import { nextCookies } from 'better-auth/next-js';
 import { admin, magicLink, organization } from 'better-auth/plugins';
-import { Pool } from 'pg';
-
-declare global {
-  // eslint-disable-next-line no-var
-  var __fiscalAuthPgPool: Pool | undefined;
-}
+import { db } from '@/lib/server/db';
+import { authSchema } from '@/lib/server/db/schema';
 
 type BetterAuthInstance = ReturnType<typeof betterAuth>;
 
 let authInstance: BetterAuthInstance | null = null;
-let migrationPromise: Promise<void> | null = null;
 
 function parseCsvList(value: string | undefined) {
   return (value ?? '')
@@ -21,80 +16,6 @@ function parseCsvList(value: string | undefined) {
     .filter((entry) => entry.length > 0);
 }
 
-function isPostgresConnectionString(value: string | undefined) {
-  if (!value) {
-    return false;
-  }
-
-  try {
-    const protocol = new URL(value).protocol.toLowerCase();
-    return protocol === 'postgres:' || protocol === 'postgresql:';
-  } catch {
-    return /^postgres(?:ql)?:\/\//i.test(value);
-  }
-}
-
-function splitSqlStatements(sqlText: string) {
-  return sqlText
-    .split(';')
-    .map((statement) => statement.trim())
-    .filter((statement) => statement.length > 0);
-}
-
-function buildPostgresMigrationPlan(sqlText: string) {
-  const immediateStatements: string[] = [];
-  const deferredIndexStatements: string[] = [];
-  const addIndexPattern = /^alter table\s+([^\s]+)\s+add\s+index\s+([^\s]+)\s+\((.+)\)$/i;
-
-  for (const rawStatement of splitSqlStatements(sqlText)) {
-    const statement = rawStatement.replace(/\s+/g, ' ').trim();
-    const match = statement.match(addIndexPattern);
-    if (!match) {
-      immediateStatements.push(statement);
-      continue;
-    }
-
-    const [, tableName, indexName, columns] = match;
-    deferredIndexStatements.push(`create index if not exists ${indexName} on ${tableName} (${columns})`);
-  }
-
-  return [...immediateStatements, ...deferredIndexStatements];
-}
-
-async function runPostgresMigrations(pool: Pool, sqlText: string) {
-  const statements = buildPostgresMigrationPlan(sqlText);
-  if (statements.length === 0) {
-    return;
-  }
-
-  const client = await pool.connect();
-  try {
-    await client.query('BEGIN');
-    for (const statement of statements) {
-      await client.query(statement);
-    }
-    await client.query('COMMIT');
-  } catch (error) {
-    await client.query('ROLLBACK');
-    throw error;
-  } finally {
-    client.release();
-  }
-}
-
-function getPool() {
-  const connectionString = process.env.DATABASE_URL?.trim();
-  if (!connectionString) {
-    throw new Error('DATABASE_URL is required for Better Auth PostgreSQL adapter.');
-  }
-
-  if (!globalThis.__fiscalAuthPgPool) {
-    globalThis.__fiscalAuthPgPool = new Pool({ connectionString });
-  }
-
-  return globalThis.__fiscalAuthPgPool;
-}
-
 function buildAuth() {
   const adminUserIds = parseCsvList(process.env.BETTER_AUTH_ADMIN_USER_IDS);
   const trustedOrigins = parseCsvList(process.env.BETTER_AUTH_TRUSTED_ORIGINS);
@@ -104,7 +25,10 @@ function buildAuth() {
   const secret = process.env.BETTER_AUTH_SECRET?.trim() || undefined;
 
   return betterAuth({
-    database: getPool(),
+    database: drizzleAdapter(db, {
+      provider: 'pg',
+      schema: authSchema
+    }),
     baseURL,
     secret,
     emailAndPassword: {
@@ -133,28 +57,5 @@ export function getAuth() {
 }
 
 export async function ensureAuthSchema() {
-  const auth = getAuth();
-  const connectionString = process.env.DATABASE_URL?.trim();
-
-  if (!migrationPromise) {
-    migrationPromise = (async () => {
-      const migrations = await getMigrations(auth.options);
-      if (isPostgresConnectionString(connectionString)) {
-        const sql = await migrations.compileMigrations();
-        await runPostgresMigrations(getPool(), sql);
-        return;
-      }
-
-      await migrations.runMigrations();
-    })();
-  }
-
-  try {
-    await migrationPromise;
-  } catch (error) {
-    migrationPromise = null;
-    throw error;
-  }
-
-  return auth;
+  return getAuth();
 }