dspace-angular/src/app/shared/pagination/pagination.component.ts

import {
    ChangeDetectionStrategy,
    Component,
    EventEmitter,
    Input,
    OnDestroy,
    OnInit,
    Output,
    ViewEncapsulation
} from '@angular/core'
import { ActivatedRoute, Router } from '@angular/router';
import { isNumeric } from "rxjs/util/isNumeric";
import 'rxjs/add/operator/switchMap';
import { Observable } from "rxjs";
// It is necessary to use ng2-pagination
import { DEFAULT_TEMPLATE, DEFAULT_STYLES } from 'ng2-pagination/dist/template';

import { HostWindowService } from "../host-window.service";
import { HostWindowState } from "../host-window.reducer";
import { PaginationComponentOptions } from './pagination-component-options.model';
import { SortDirection, SortOptions } from "../../core/cache/models/sort-options.model";

/**
 * The default pagination controls component.
 */
@Component({
    exportAs: 'paginationComponent',
    selector: 'ds-pagination',
    templateUrl: 'pagination.component.html',
    changeDetection: ChangeDetectionStrategy.Default,
    encapsulation: ViewEncapsulation.Emulated
})
export class PaginationComponent implements OnDestroy, OnInit {

    /**
     * Number of items in collection.
     */
    @Input() collectionSize: number;

    /**
     * Configuration for the NgbPagination component.
     */
    @Input() paginationOptions: PaginationComponentOptions;

    /**
     * Sort configuration for this component.
     */
    @Input() sortOptions: SortOptions;

    /**
     * An event fired when the page is changed.
     * Event's payload equals to the newly selected page.
     */
    @Output() pageChange: EventEmitter<number> = new EventEmitter<number>();

    /**
     * An event fired when the page wsize is changed.
     * Event's payload equals to the newly selected page size.
     */
    @Output() pageSizeChange: EventEmitter<number> = new EventEmitter<number>();

    /**
     * An event fired when the sort direction is changed.
     * Event's payload equals to the newly selected sort direction.
     */
    @Output() sortDirectionChange: EventEmitter<SortDirection> = new EventEmitter<SortDirection>();

    /**
     * An event fired when the sort field is changed.
     * Event's payload equals to the newly selected sort field.
     */
    @Output() sortFieldChange: EventEmitter<string> = new EventEmitter<string>();

    /**
     * Current page.
     */
    public currentPage = 1;

    /**
     * Current URL query parameters
     */
    public currentQueryParams = {};

    /**
     * An observable of HostWindowState type
     */
    public hostWindow: Observable<HostWindowState>;

    /**
     * ID for the pagination instance. Only useful if you wish to
     * have more than once instance at a time in a given component.
     */
    private id: string;

    /**
     * A boolean that indicate if is an extra small devices viewport.
     */
    public isXs: boolean;

    /**
     * Number of items per page.
     */
    public pageSize: number = 10;

    /**
     * Declare SortDirection enumeration to use it in the template
     */
    public sortDirections = SortDirection

    /**
     * A number array that represents options for a context pagination limit.
     */
    private pageSizeOptions: Array<number>;

    /**
     * Direction in which to sort: ascending or descending
     */
    public sortDirection: SortDirection = SortDirection.Ascending;

    /**
     * Name of the field that's used to sort by
     */
    public sortField: string = "id";

    /**
     * Local variable, which can be used in the template to access the paginate controls ngbDropdown methods and properties
     */
    public paginationControls;

    /**
     *
     */

    /**
     * Subscriber to observable.
     */
    private routeSubscription: any;

    /**
     * An object that represents pagination details of the current viewed page
     */
    public showingDetail: any = {
        range: null,
        total: null
    };

    /**
     * Subscriber to observable.
     */
    private stateSubscription: any;

    /**
     * Method provided by Angular. Invoked after the constructor.
     */
    ngOnInit() {
        this.stateSubscription = this.hostWindowService.isXs()
            .subscribe((status: boolean) => {
                this.isXs = status;
            });
        this.checkConfig(this.paginationOptions);
        this.id = this.paginationOptions.id || null;
        this.currentPage = this.paginationOptions.currentPage;
        this.pageSize = this.paginationOptions.pageSize;
        this.pageSizeOptions = this.paginationOptions.pageSizeOptions;
        this.sortDirection = this.sortOptions.direction;
        this.sortField = this.sortOptions.field;
        this.routeSubscription = this.route.queryParams
            .map(queryParams => queryParams)
            .subscribe(queryParams => {
                this.currentQueryParams = queryParams;
                if (this.id == queryParams['pageId']
                    && (this.paginationOptions.currentPage != queryParams['page']
                    || this.paginationOptions.pageSize != queryParams['pageSize']
                    || this.sortOptions.direction != queryParams['sortDirection']
                    || this.sortOptions.field != queryParams['sortField'] )
                ) {
                    this.validateParams(queryParams['page'], queryParams['pageSize'], queryParams['sortDirection'], queryParams['sortField']);
                }
            });
        this.setShowingDetail();
    }

    /**
     * Method provided by Angular. Invoked when the instance is destroyed.
     */
    ngOnDestroy() {
        this.stateSubscription.unsubscribe();
        this.routeSubscription.unsubscribe();
    }

    /**
     * @param route
     *    Route is a singleton service provided by Angular.
     * @param router
     *    Router is a singleton service provided by Angular.
     */
    constructor(private route: ActivatedRoute,
                private router: Router,
                public hostWindowService: HostWindowService) {
    }

    /**
     * Method to set set new page and update route parameters
     *
     * @param page
     *    The page being navigated to.
     */
    public doPageChange(page: number) {
        this.currentPage = page;
        this.updateRoute();
        this.setShowingDetail();
        this.pageChange.emit(page);
    }

    /**
     * Method to set set new page size and update route parameters
     *
     * @param pageSize
     *    The new page size.
     */
    public setPageSize(pageSize: number) {
        this.pageSize = pageSize;
        this.updateRoute();
        this.setShowingDetail();
        this.pageSizeChange.emit(pageSize);
    }

    /**
     * Method to set set new sort direction and update route parameters
     *
     * @param sortDirection
     *    The new sort direction.
     */
    public setSortDirection(sortDirection: SortDirection) {
        this.sortDirection = sortDirection;
        this.updateRoute();
        this.setShowingDetail();
        this.sortDirectionChange.emit(sortDirection);
    }

    /**
     * Method to set set new sort field and update route parameters
     *
     * @param sortField
     *    The new sort field.
     */
    public setSortField(field: string) {
        this.sortField = field;
        this.updateRoute();
        this.setShowingDetail();
        this.sortFieldChange.emit(field);
    }

    /**
     * Method to update the route parameters
     */
    private updateRoute() {
        this.router.navigate([], {
            queryParams: Object.assign({}, this.currentQueryParams, {
                pageId: this.id,
                page: this.currentPage,
                pageSize: this.pageSize,
                sortDirection: this.sortDirection,
                sortField: this.sortField
            })
        });
    }

    /**
     * Method to set pagination details of the current viewed page.
     */
    private setShowingDetail() {
        let firstItem;
        let lastItem;
        let lastPage = Math.round(this.collectionSize / this.pageSize);

        firstItem = this.pageSize * (this.currentPage - 1) + 1;
        if (this.currentPage != lastPage) {
            lastItem = this.pageSize * this.currentPage;
        } else {
            lastItem = this.collectionSize;
        }
        this.showingDetail = {
            range: firstItem + ' - ' + lastItem,
            total: this.collectionSize
        }
    }

    /**
     * Validate query params
     *
     * @param page
     *    The page number to validate
     * @param pageSize
     *    The page size to validate
     */
    private validateParams(page: any, pageSize: any, sortDirection: any, sortField: any) {
        let filteredPageSize = this.pageSizeOptions.find(x => x == pageSize);
        if (!isNumeric(page) || !filteredPageSize) {
            let filteredPage = isNumeric(page) ? page : this.currentPage;
            filteredPageSize = (filteredPageSize) ? filteredPageSize : this.pageSize;
            this.router.navigate([{
                pageId: this.id,
                page: filteredPage,
                pageSize: filteredPageSize,
                sortDirection: sortDirection,
                sortField: sortField
            }]);
        } else {
            // (+) converts string to a number
            this.currentPage = +page;
            this.pageSize = +pageSize;
            this.sortDirection = +sortDirection;
            this.sortField = sortField;
            this.pageChange.emit(this.currentPage);
            this.pageSizeChange.emit(this.pageSize);
            this.sortDirectionChange.emit(this.sortDirection);
            this.sortFieldChange.emit(this.sortField);
        }
    }

    /**
     * Ensure options passed contains the required properties.
     *
     * @param paginateOptions
     *    The paginate options object.
     */
    private checkConfig(paginateOptions: any) {
        let required = ['id', 'currentPage', 'pageSize', 'pageSizeOptions'];
        let missing = required.filter(function (prop) {
            return !(prop in paginateOptions);
        });
        if (0 < missing.length) {
            throw new Error("Paginate: Argument is missing the following required properties: " + missing.join(', '));
        }
    }
}