refactoring

Resolve #7779

packages/backend/src/services/validate-email-for-account.ts

@@ -0,0 +1,34 @@
+import validateEmail from 'deep-email-validator';
+import { UserProfiles } from '@/models';
+
+export async function validateEmailForAccount(emailAddress: string): Promise<{
+	available: boolean;
+	reason: null | 'used' | 'format' | 'disposable' | 'mx' | 'smtp';
+}> {
+	const exist = await UserProfiles.count({
+		emailVerified: true,
+		email: emailAddress,
+	});
+
+	const validated = await validateEmail({
+		email: emailAddress,
+		validateRegex: true,
+		validateMx: true,
+		validateTypo: false, // TLDを見ているみたいだけどclubとか弾かれるので
+		validateDisposable: true, // 捨てアドかどうかチェック
+		validateSMTP: false, // 日本だと25ポートが殆どのプロバイダーで塞がれていてタイムアウトになるので
+	});
+
+	const available = exist === 0 && validated.valid;
+
+	return {
+		available,
+		reason: available ? null :
+			exist !== 0 ? 'used' :
+			validated.reason === 'regex' ? 'format' :
+			validated.reason === 'disposable' ? 'disposable' :
+			validated.reason === 'mx' ? 'mx' :
+			validated.reason === 'smtp' ? 'smtp' :
+			null,
+	};
+}