feat(api): user authentication

src/auth/auth.service.ts

@@ -0,0 +1,47 @@
+import { Injectable } from "@nestjs/common";
+import { User } from "../users/user.entity";
+import { UsersService } from "../users/users.service";
+import { LoginDto } from "./dto/login.dto";
+import { JwtService } from "@nestjs/jwt";
+
+@Injectable()
+export class AuthService {
+  constructor(
+    private readonly usersService: UsersService,
+    private readonly jwtService: JwtService
+  ) {}
+
+  async spotifyLogin({
+    accessToken,
+    refreshToken,
+    profile
+  }: LoginDto): Promise<User> {
+    const user = await this.usersService.createOrUpdate({
+      displayName: profile.displayName,
+      photo: profile.photos.length > 0 ? profile.photos[0] : null,
+      spotify: {
+        id: profile.id,
+        accessToken,
+        refreshToken
+      }
+    });
+
+    return user;
+  }
+
+  async createToken(user: User): Promise<{ accessToken }> {
+    const payload = {
+      sub: user.id,
+      name: user.displayName,
+      picture: user.photo
+    };
+
+    const token = await this.jwtService.signAsync(payload);
+
+    return { accessToken: token };
+  }
+
+  async findUser(id: string): Promise<User> {
+    return this.usersService.findById(id);
+  }
+}