import {filter, merge} from 'rxjs/operators';
import { Injectable, OnDestroy } from '@angular/core';
import { ActivatedRoute, ActivatedRouteSnapshot, ActivationEnd, Router } from '@angular/router';
import { Subscription ,  Observable, of } from 'rxjs';

@Injectable()
export class LabelingService implements OnDestroy {
    private pageName: string;
    private routerSubscription: Subscription;
    constructor(private router: Router, private activatedRoute: ActivatedRoute) {
        this.routerSubscription = router.events.pipe(
            filter(routerEvent => routerEvent instanceof ActivationEnd))
            .pipe(merge(of('init')))
            .subscribe(_ => {
                const pageName = this.getChildMostActivatedRouteSnapshot(activatedRoute.snapshot).data.name;
                this.pageName = pageName || this.computePageNameFromRoute(window.location.pathname);
            });
    }

    getChildMostActivatedRouteSnapshot(activatedRouteSnapshot: ActivatedRouteSnapshot): ActivatedRouteSnapshot {
        return activatedRouteSnapshot.children.length > 0 ?
            this.getChildMostActivatedRouteSnapshot(activatedRouteSnapshot.children[0]) :
            activatedRouteSnapshot;
    }

    ngOnDestroy(): void {
        this.routerSubscription.unsubscribe();
    }

    computePageNameFromRoute(str: string): string {
        if (!str || str === '') {
            return 'global';
        }
        const pascal = str.split('/')
            .filter(s => !/[0-9]/g.test(s))
            .map(substr => {
                return substr.split('-')
                    .map(s => s.charAt(0)
                        .toUpperCase() + s.slice(1))
                        .join('');
            })
            .join('');
        const firstCharacter = pascal.charAt(0)
            .toLowerCase();

        return `${firstCharacter + pascal.slice(1)}Page`;
    }

    label(name: string, actionName: string, prefix: string = 'label'): string {
        return `${this.simplifyActionName(actionName)}.${name}.${prefix}`;
    }

    form(name: string, actionName: string): string {
        return `${this.simplifyActionName(actionName)}.form.${name}`;
    }

    simplifyActionName(actionName: string): string {
        const value = actionName.split('.')
            .reverse()[0];

        return value.charAt(0)
            .toUpperCase()
            + value.slice(1);
    }

    page(name: string): string {
        return `${this.pageName}.${name}`;
    }
}