import { Injectable } from '@nestjs/common';
import {
  PageOptions,
  PaginationOptions,
} from 'src/types/pagination.interfaces';

@Injectable()
export class PaginationService {
  public paginate(options: PageOptions, rowCount: number): PaginationOptions {
    const paginationOptions: PaginationOptions = {
      page: options.page || 1,
      pageSize: options.pageSize || 50,
      rowCount,
    };

    // Calculate page count from row count and page size
    paginationOptions.pageCount = Math.ceil(
      rowCount / paginationOptions.pageSize,
    );

    // Limit the page number to 1..pageCount
    paginationOptions.page = Math.max(
      Math.min(paginationOptions.page, paginationOptions.pageCount),
      1,
    );

    // Calculate the offset for the query
    paginationOptions.offset =
      (paginationOptions.page - 1) * paginationOptions.pageSize;

    return paginationOptions;
  }
}