feat: add simple login logic

src/modules/auth/providers/auth.service.ts

@@ -0,0 +1,45 @@
+import { UsersService } from '@/modules/users/providers/users.service';
+import { Injectable, UnauthorizedException } from '@nestjs/common';
+import { LoginDTO } from '../dtos/login.dto';
+
+@Injectable()
+export class AuthService {
+  constructor(
+    /**
+     * Inject Users Service
+     */
+    private readonly usersService: UsersService,
+  ) {}
+
+  public async logIn(loginDto: LoginDTO) {
+    const { phone, password } = loginDto;
+    const user = await this.usersService.findOneByPhone(phone);
+
+    if (!user) {
+      // TODO: Send OTP
+
+      return {
+        newUser: true,
+        message: `Otp sent to ${phone}`,
+      };
+    }
+
+    if (!password) {
+      return {
+        newUser: false,
+        message: 'Please send password',
+      };
+    }
+
+    // TODO: Hash password and compare
+    if (password === user.password) {
+      // TODO: Create JWT
+
+      return { access: 'ACCESS_TOKEN', refresh: 'REFRESH_TOKEN' };
+    }
+
+    throw new UnauthorizedException(
+      'Entered phone number or password is wrong.',
+    );
+  }
+}