import {ContentChildren, Component, QueryList, Input, forwardRef, AfterContentInit, OnDestroy} from "@angular/core";
import {AccordionGroup} from "./AccordionGroup";
import {Subscription} from "rxjs";

@Component({
    selector: "accordion",
    template: `
<div class="panel-group" role="tablist" aria-multiselectable="true">
    <ng-content></ng-content>
</div>
`
})
export class Accordion implements AfterContentInit, OnDestroy {

    @Input()
    closeOthers = true;

    @Input()
    showArrows = false;

    @Input()
    expandAll = false;

    @ContentChildren(forwardRef(() => AccordionGroup))
    groups: QueryList<AccordionGroup>;

    /**
     * We need to save old groups to make difference and find newly changed group, to toggle them.
     */
    private oldGroups: AccordionGroup[];

    private subscription: Subscription;

    ngAfterContentInit() {
        if (this.expandAll) {
            this.closeOthers = false;
            this.oldGroups = this.groups.toArray();
            this.oldGroups.forEach(group => {
                group.openOnInitialization();
            });

            // we subscribe for changes, and if new groups are added we open them automatically
            this.subscription = this.groups.changes.subscribe(change => {
                const newGroups = this.groups.toArray().filter(group => {
                    return this.oldGroups.indexOf(group) === -1;
                });
                newGroups.forEach(group => {
                    group.openOnInitialization();
                });
                this.oldGroups = this.groups.toArray();
            });
        }
    }

    ngOnDestroy() {
        if (this.subscription)
            this.subscription.unsubscribe();
    }

    closeAll() {
        this.groups.toArray().forEach(group => {
            group.isOpened = false;
        });
    }

}