feat: add simple login logic

src/modules/otp/otp.entity.ts

@@ -0,0 +1,45 @@
+import {
+  BeforeInsert,
+  Column,
+  CreateDateColumn,
+  Entity,
+  Index,
+  PrimaryGeneratedColumn,
+} from 'typeorm';
+
+@Entity()
+@Index(['phone', 'used'])
+export class OTP {
+  @PrimaryGeneratedColumn()
+  id: number;
+
+  @Index()
+  @Column({
+    type: 'varchar',
+    length: 11,
+    nullable: false,
+  })
+  phone: string;
+
+  @Column({
+    type: 'varchar',
+    length: 5,
+    nullable: false,
+  })
+  code: string;
+
+  @CreateDateColumn()
+  createdAt: Date;
+
+  @Index()
+  @Column({ type: 'timestamptz' })
+  expiredAt: Date;
+
+  @Column({ type: 'boolean', default: false })
+  used: boolean;
+
+  @BeforeInsert()
+  setExpiry() {
+    this.expiredAt = new Date(Date.now() + 2 * 60 * 1000);
+  }
+}

src/modules/otp/otp.module.ts

@@ -0,0 +1,10 @@
+import { Module } from '@nestjs/common';
+import { OtpService } from './providers/otp.service';
+import { TypeOrmModule } from '@nestjs/typeorm';
+import { OTP } from './otp.entity';
+
+@Module({
+  imports: [TypeOrmModule.forFeature([OTP])],
+  providers: [OtpService],
+})
+export class OtpModule {}

src/modules/otp/providers/otp.service.ts

@@ -0,0 +1,39 @@
+import { Injectable } from '@nestjs/common';
+import { Repository } from 'typeorm';
+import { OTP } from '../otp.entity';
+import { InjectRepository } from '@nestjs/typeorm';
+
+@Injectable()
+export class OtpService {
+  constructor(
+    /**
+     * Inject OTP Repository
+     */
+    @InjectRepository(OTP)
+    private readonly otpRepository: Repository<OTP>,
+  ) {}
+
+  /**
+   * Generate OTP 5-digit code
+   */
+  private generateOTPCode(): string {
+    return Math.floor(10_000 + Math.random() * 90_000).toString();
+  }
+
+  /**
+   * Create new OTP record
+   */
+  public async createOTP(phone: string): Promise<string> {
+    // OTP request Rate limit
+    const lastOTP = await this.otpRepository.findOne({
+      where: { phone },
+      order: { createdAt: 'DESC' },
+    });
+
+    if (lastOTP && Date.now() - lastOTP.createdAt.getTime() < 60_000) {
+      //   throw new TooMany();
+    }
+
+    return '';
+  }
+}