import { Location } from "@angular/common";
import { inject, Injectable } from "@angular/core";
import { MatSnackBar } from "@angular/material/snack-bar";
import { ActivatedRoute } from "@angular/router";
import { BehaviorSubject, Observable } from "rxjs";
import { Publication } from "../../core/rest-services/publications/model/publication";
import { PublicationRestService } from "../../core/rest-services/publications/publication.rest-service";
import { copy } from '../../core/utils/ObjectUtils';

const DEFAULT_PUBLICATION: Publication = {
    id: '',
    key: '',
    title: '',
    text: '',
    parsedText: '',
    description: '',
    creationDate: new Date(),
    illustrationId: '',
    categoryId: '',
    author: {
        id: '',
        name: '',
        image: ''
    }
};

@Injectable()
export class PublicationEditionService {
    private activatedRoute = inject(ActivatedRoute);
    private publicationRestService = inject(PublicationRestService);
    private location = inject(Location);
    private snackBar = inject(MatSnackBar);

    private isLoadingSubject = new BehaviorSubject<boolean>(false);
    private publicationSubject = new BehaviorSubject<Publication>(copy(DEFAULT_PUBLICATION));

    private get _publication(): Publication {
        return this.publicationSubject.value;
    }

    private _save(publication: Publication): void {
        this.publicationSubject.next(publication);    
    }

    get isLoading$(): Observable<boolean> {
        return this.isLoadingSubject.asObservable();
    }

    get publication$(): Observable<Publication> {
        return this.publicationSubject.asObservable();
    }

    loadPublication(): void {
        this.isLoadingSubject.next(true);
        
        this.activatedRoute.paramMap.subscribe(params => {
            const publicationId = params.get('publicationId');
            if (publicationId == undefined) {
                this.snackBar.open('A technical error occurred while loading publication data.', 'Close', {duration: 5000});
                this.location.back();
            } else {
                this.publicationRestService.getById(publicationId)
                .then(publication => {
                    this.publicationSubject.next(publication);
                })
                .catch(error => {
                    const errorMessage = 'A technical error occurred while loading publication data.';
                    this.snackBar.open(errorMessage, 'Close', {duration: 5000});
                    console.error(errorMessage, error)
                })
                .finally(() => this.isLoadingSubject.next(false));
            }
          });
    }

    editTitle(title: string): void {
        const publication = this._publication;
        publication.title = title;
        this._save(publication);
    }

    editDescription(description: string): void {
        const publication = this._publication;
        publication.description = description;
        this._save(publication);
    }

    editText(text: string): void {
        const publication = this._publication;
        publication.text = text;
        this._save(publication);
    }
}