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)}`;
  }
}