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

// Other //
import * as statics from '@fb/statics';

@Component({
    selector: 'fb-items-per-page-dropdown',
    templateUrl: './items-per-page-dropdown.component.html'
})
export class FbItemsPerPageDropdownComponent implements OnInit {
    @Input()
    numberOfItems: number[];

    @Input()
    selectableItemsPerPage: number;

    @Output()
    onNumberOfItemsChange: EventEmitter<number> = new EventEmitter<number>();

    dropdownExpanded: boolean;

    ngOnInit(): void {
        this.checkAttributesBeforeInit();
    }

    expandDropdown(): void {
        this.dropdownExpanded = true;
    }

    setItemsPerPage(numberOfRows: number): void {
        this.onNumberOfItemsChange.emit(numberOfRows);
    }

    private checkAttributesBeforeInit(): void {
        let errorString: string = '';

        if (statics.isUndefined(this.numberOfItems)) {
            errorString += 'Parameter numberOfItems is undefined \n';
        }

        if (statics.isUndefined(this.selectableItemsPerPage)) {
            errorString += 'Parameter selectableItemsPerPage is undefined \n';
        }

        if (errorString !== '') {
            throw new Error(errorString);
        }
    }
}