src/app/shared/components/paginator/paginator.component.ts

import { PageEvent } from '@app/shared/models/PageEvent';

import { Component, OnInit, Input, Output, EventEmitter } from '@angular/core';

@Component({
  selector: 'app-paginator',
  templateUrl: './paginator.component.html',
  styleUrls: ['./paginator.component.scss']
})
export class PaginatorComponent implements OnInit {
  @Input()
  length: number;

  @Input()
  pageSize: number;

  private _totalPages: number;

  @Input()
  public set totalPages(v: number) {
    this._totalPages = v;
    this.init();
  }

  public get totalPages(): number {
    return this._totalPages;
  }

  @Input()
  public currentPage: PageEvent;

  @Input()
  subscribe: number;

  @Input()
  hidePageSize: boolean;

  @Output()
  page: EventEmitter<PageEvent> = new EventEmitter();

  public pageEventItems: PageEvent[];

  public activeEventItem: PageEvent;

  public currentPageIndex: number = 0;
  /**
   * Creates an instance of PaginatorComponent.
   *
   * @author Martin Gardyan <martin.gardyan@pta.de>
   * @memberof PaginatorComponent
   */
  constructor() { }

  ngOnInit() {
  }

  private init() {
    this.pageEventItems = new Array<PageEvent>();
    for (let index = 1; index <= this._totalPages; ++index) {
      this.pageEventItems.push({ pageIndex: index });
    }
    if (this._totalPages > 0) {
      this._setActivePage(this.pageEventItems[0]);
    }

  }

  public setSelectedPage(pageEvent: PageEvent): void {
    this._setActivePage(pageEvent);
    this.page.emit(pageEvent);
  }

  public setNextPage(): void {
    if (this.isLastPage()) {
      return;
    }
    const nextActiveItem = this.pageEventItems[this.currentPageIndex + 1];
    this.setSelectedPage(nextActiveItem);
  }

  public setPreviousPage(): void {
    if (this.isFirstPage()) {
      return;
    }
    const previousActiveItem = this.pageEventItems[this.currentPageIndex - 1];
    this.setSelectedPage(previousActiveItem);
  }

  public isLastPage(): boolean {
    return this.currentPageIndex === this.pageEventItems.length - 1;
  }

  public isFirstPage(): boolean {
    return this.currentPageIndex === 0;
  }

  private _setActivePage(pageEvent: PageEvent): void {
    this.currentPageIndex = this.pageEventItems.indexOf(pageEvent);
    this.activeEventItem = pageEvent;
  }
}