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apps/api/src/common/base.service.ts

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+import { NotFoundException } from "@nestjs/common";
+import type { IRepository } from "./repository.interface.js";
+import type { IService } from "./service.interface.js";
+
+/**
+ * Generic business layer: delegates to an `IRepository`, translating a
+ * missing row into a `NotFoundException`. Subclasses may override
+ * `notFoundMessage` for a more specific error message.
+ */
+export abstract class BaseService<
+  T,
+  CreateInput,
+  UpdateInput,
+  WhereKey,
+> implements IService<T, CreateInput, UpdateInput, WhereKey> {
+  constructor(
+    protected readonly repository: IRepository<
+      T,
+      CreateInput,
+      UpdateInput,
+      WhereKey
+    >,
+  ) {}
+
+  findAll(): Promise<T[]> {
+    return this.repository.findAll();
+  }
+
+  async findById(where: WhereKey): Promise<T> {
+    const entity = await this.repository.findById(where);
+    if (!entity) {
+      throw new NotFoundException(this.notFoundMessage(where));
+    }
+    return entity;
+  }
+
+  create(data: CreateInput): Promise<T> {
+    return this.repository.create(data);
+  }
+
+  async update(where: WhereKey, data: UpdateInput): Promise<T> {
+    await this.findById(where);
+    return this.repository.update(where, data);
+  }
+
+  async delete(where: WhereKey): Promise<void> {
+    await this.findById(where);
+    await this.repository.delete(where);
+  }
+
+  protected notFoundMessage(where: WhereKey): string {
+    return `Resource not found: ${JSON.stringify(where)}`;
+  }
+}