import { ViewArray } from './view-array';


export class ViewArrayImpl implements ViewArray {

  public isVisible: boolean;
  public visibleEntries: any[];
  public hasEntries: boolean;
  public entries: any[];
  public hasHiddenEntries: boolean;
  public timerRef_: any;
  public currentIndex_: number;

  constructor(private interval: any, private additionalCount: number) {
    this.isVisible = false;
    this.visibleEntries = null;
    this.hasEntries = false;
    this.entries = [];
    this.hasHiddenEntries = false;
    this.timerRef_ = null;
    this.currentIndex_ = 0;
  }

  public length(): number {
    return this.entries.length;
  }

  public get(index: number): any {
    return this.entries[index];
  }

  public push(elem: any): void {
    this.entries.push(elem);
    this.hasEntries = true;

    if (this.isVisible) {
      this.startTimer_();
    }
  }

  public toggle(): void {
    this.setVisible(!this.isVisible);
  }

  public setVisible(newState: boolean): void {
    this.isVisible = newState;

    this.visibleEntries = [];
    this.currentIndex_ = 0;

    if (newState) {
      this.showAdditionalEntries_();
      this.startTimer_();
    }
    else {
      this.stopTimer_();
    }
  }

  public showAdditionalEntries_(): void {
    var i: number = 0;
    for (i = this.currentIndex_; i < (this.currentIndex_ + this.additionalCount) && i < this.entries.length; ++i) {
      this.visibleEntries.push(this.entries[i]);
    }

    this.currentIndex_ = i;
    this.hasHiddenEntries = this.currentIndex_ < this.entries.length;
    if (this.currentIndex_ >= this.entries.length) {
      this.stopTimer_();
    }
  }

  public startTimer_(): void {
    if (this.timerRef_) {
      return;
    }

    var that = this;
    this.timerRef_ = this.interval(function() {
      that.showAdditionalEntries_();
    }, 10);
  }

  public stopTimer_(): void {
    if (this.timerRef_) {
      this.interval.cancel(this.timerRef_);
      this.timerRef_ = null;
    }
  }
}