import {Injectable, Pipe, PipeTransform, ChangeDetectorRef, OnDestroy} from '@angular/core';
import {Subject} from 'rxjs/Subject';
import {LangChangeEvent, TranslateService} from '@ngx-translate/core';

@Injectable()
@Pipe({
    name: 'CollectionTranslation',
    pure: false
})

export class CollectionPipe implements PipeTransform, OnDestroy {
    value: string;
    lastKey: string;

    onLangChange: Subject<LangChangeEvent>;

    constructor(private translate: TranslateService, private _ref:   ChangeDetectorRef) {

    }

    updateValue(key: string, lang: string) {
        this.value = this.collectionTranslation(key, lang);
        this.lastKey = key;
        this._ref.markForCheck();
    }

    transform(collectionParam: string) {
        // lang parameter is just here to execute the pipe each time the current lang is changed.
        // it's not used in the pipe

        if (this.lastKey === collectionParam) {
            return this.value;
        }

        this.updateValue(collectionParam, localStorage.getItem('kia.language'));

        if (!this.onLangChange) {
            this.onLangChange = this.translate.onLangChange.subscribe((event: LangChangeEvent) => {
                if (this.lastKey) {
                    this.lastKey = null; // we want to make sure it doesn't return the same value until it's been updated
                    this.updateValue(collectionParam, event.lang);
                }
            });
        }

        return this.value;
    }

    private collectionTranslation(collectionParam: string, lang: string): string {
        let collection = '';
        if (collectionParam === null || collectionParam === undefined) {
            return '';
        }

        const coll = collectionParam.toUpperCase();
        if (lang === 'fr') {
            collection = coll.startsWith('E') || coll.startsWith('S') ? 'ETE ' : 'HIVER ';
        } else {
            // Lang EN
            collection = coll.startsWith('E') || coll.startsWith('S') ? 'SUMMER ' : 'WINTER ';
        }

        collection = collection + coll.substring(coll.length - 2);

        return collection;
    }

    _dispose(): void {
        if (typeof this.onLangChange !== 'undefined') {
            this.onLangChange.unsubscribe();
            this.onLangChange = undefined;
        }
    }

    ngOnDestroy(): void {
        this._dispose();
    }
}