Paginator.ts

export interface Paginator {
    getPageDatas(page: number): Promise<any[]>;
    getNbPages(): Promise<number>;
    getNbRowsPerPage(): Promise<number>;
}

import { Paginator } from "./paginator.interface";


export class StaticPaginator implements Paginator {

    private datas: any[];
    private rowsPerPage = 10;

    constructor(datas: any[]) {
        this.datas = datas;
    }

    getPageDatas(page: number): any[] {
        if (page <= 0 || page > this.getNbPages()) {
            return [];
        }
        
        const firstIndex = (page - 1) * this.getNbRowsPerPage();
        const lastIndex = firstIndex + this.getNbRowsPerPage();

        return this.datas.slice(firstIndex, lastIndex);
    }

    getNbPages(): number {
        return Math.ceil(this.datas.length / this.getNbRowsPerPage());
    }

    getNbRowsPerPage(): number {
        return this.rowsPerPage;
    }

    setNbRowsPerPage(nbRows: number): void {
        if (nbRows <= 0) {
            throw "invalid rows number: nb rows per page must be positive";
        }

        this.rowsPerPage = nbRows;
    }
}