feat: add modular services and repositories for improved code organization

Introduce repository pattern across multiple services, including `favorites`, `tags`, `sessions`, `reports`, `auth`, and more. Decouple crypto functionalities into modular services like `HashingService`, `JwtService`, and `EncryptionService`. Improve testability and maintainability by simplifying dependencies and consolidating utility logic.

backend/src/users/repositories/users.repository.ts

@@ -0,0 +1,158 @@
+import { Injectable } from "@nestjs/common";
+import { and, eq, lte, sql } from "drizzle-orm";
+import { DatabaseService } from "../../database/database.service";
+import { users, contents, favorites } from "../../database/schemas";
+import type { UpdateUserDto } from "../dto/update-user.dto";
+
+@Injectable()
+export class UsersRepository {
+	constructor(private readonly databaseService: DatabaseService) {}
+
+	async create(data: {
+		username: string;
+		email: string;
+		passwordHash: string;
+		emailHash: string;
+	}) {
+		const [newUser] = await this.databaseService.db
+			.insert(users)
+			.values(data)
+			.returning();
+		return newUser;
+	}
+
+	async findByEmailHash(emailHash: string) {
+		const result = await this.databaseService.db
+			.select({
+				uuid: users.uuid,
+				username: users.username,
+				email: users.email,
+				passwordHash: users.passwordHash,
+				status: users.status,
+				isTwoFactorEnabled: users.isTwoFactorEnabled,
+			})
+			.from(users)
+			.where(eq(users.emailHash, emailHash))
+			.limit(1);
+		return result[0] || null;
+	}
+
+	async findOneWithPrivateData(uuid: string) {
+		const result = await this.databaseService.db
+			.select({
+				uuid: users.uuid,
+				username: users.username,
+				email: users.email,
+				displayName: users.displayName,
+				status: users.status,
+				isTwoFactorEnabled: users.isTwoFactorEnabled,
+				createdAt: users.createdAt,
+				updatedAt: users.updatedAt,
+			})
+			.from(users)
+			.where(eq(users.uuid, uuid))
+			.limit(1);
+		return result[0] || null;
+	}
+
+	async countAll() {
+		const result = await this.databaseService.db
+			.select({ count: sql<number>`count(*)` })
+			.from(users);
+		return Number(result[0].count);
+	}
+
+	async findAll(limit: number, offset: number) {
+		return await this.databaseService.db
+			.select({
+				uuid: users.uuid,
+				username: users.username,
+				displayName: users.displayName,
+				status: users.status,
+				createdAt: users.createdAt,
+			})
+			.from(users)
+			.limit(limit)
+			.offset(offset);
+	}
+
+	async findByUsername(username: string) {
+		const result = await this.databaseService.db
+			.select({
+				uuid: users.uuid,
+				username: users.username,
+				displayName: users.displayName,
+				createdAt: users.createdAt,
+			})
+			.from(users)
+			.where(eq(users.username, username))
+			.limit(1);
+		return result[0] || null;
+	}
+
+	async findOne(uuid: string) {
+		const result = await this.databaseService.db
+			.select()
+			.from(users)
+			.where(eq(users.uuid, uuid))
+			.limit(1);
+		return result[0] || null;
+	}
+
+	async update(uuid: string, data: any) {
+		return await this.databaseService.db
+			.update(users)
+			.set({ ...data, updatedAt: new Date() })
+			.where(eq(users.uuid, uuid))
+			.returning();
+	}
+
+	async getTwoFactorSecret(uuid: string) {
+		const result = await this.databaseService.db
+			.select({
+				secret: users.twoFactorSecret,
+			})
+			.from(users)
+			.where(eq(users.uuid, uuid))
+			.limit(1);
+		return result[0]?.secret || null;
+	}
+
+	async getUserContents(uuid: string) {
+		return await this.databaseService.db
+			.select()
+			.from(contents)
+			.where(eq(contents.userId, uuid));
+	}
+
+	async getUserFavorites(uuid: string) {
+		return await this.databaseService.db
+			.select()
+			.from(favorites)
+			.where(eq(favorites.userId, uuid));
+	}
+
+	async softDeleteUserAndContents(uuid: string) {
+		return await this.databaseService.db.transaction(async (tx) => {
+			const userResult = await tx
+				.update(users)
+				.set({ status: "deleted", deletedAt: new Date() })
+				.where(eq(users.uuid, uuid))
+				.returning();
+
+			await tx
+				.update(contents)
+				.set({ deletedAt: new Date() })
+				.where(eq(contents.userId, uuid));
+
+			return userResult;
+		});
+	}
+
+	async purgeDeleted(before: Date) {
+		return await this.databaseService.db
+			.delete(users)
+			.where(and(eq(users.status, "deleted"), lte(users.deletedAt, before)))
+			.returning();
+	}
+}