/*
 * Copyright (C) 2020-2021 StApps
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation, version 3.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <https://www.gnu.org/licenses/>.
 */

import {Injectable, OnDestroy} from '@angular/core';
import {LangChangeEvent, TranslateService} from '@ngx-translate/core';
import {SCLanguage, SCThings, SCThingTranslator, SCThingType, SCTranslations} from '@openstapps/core';
import {Subscription} from 'rxjs';
import {isDefined, ThingTranslateParser} from './thing-translate.parser';

// export const DEFAULT_LANGUAGE = new InjectionToken<string>('DEFAULT_LANGUAGE');

// tslint:disable: member-ordering prefer-function-over-method newline-per-chained-call completed-docs

@Injectable({
  providedIn: 'root',
})
export class ThingTranslateService implements OnDestroy {

  onLangChange: Subscription;
  translator: SCThingTranslator;

  /**
   *
   * @param translateService Instance of Angular TranslateService
   * @param parser An instance of the parser currently used
   * @param language TODO
   */
  constructor(private readonly translateService: TranslateService,
              public parser: ThingTranslateParser){

    this.translator = new SCThingTranslator('de' ?? this.translateService.currentLang as keyof SCTranslations<SCLanguage>);

    /** set the default language from configuration */
    this.onLangChange = this.translateService.onLangChange.subscribe((event: LangChangeEvent) => {
      this.translator.language = event.lang as keyof SCTranslations<SCLanguage>;
    });

  }

  /**
   * Returns the parsed result of the translations
   */
  // tslint:disable-next-line: no-any
  getParsedResult(target: object, key: string): any {
    return this.parser.getValueFromKeyPath(target, key);
  }

  /**
   * Gets the translated value of a key (or an array of keys)
   * @returns the translated key, or an object of translated keys
   */
  public get(thing: SCThings, keyPath: string | string[]): string | number | boolean | object  {
    if (!isDefined(keyPath) || keyPath.length === 0) {
      throw new Error(`Parameter "keyPath" required`);
    }
    if (keyPath instanceof Array) {
      return this.getParsedResult(this.translator.translate(thing), keyPath.join('.'));
    }

    return this.getParsedResult(this.translator.translate(thing), keyPath);
  }

  /**
   * Gets the translated value of a key (or an array of keys)
   * @returns the translated key, or an object of translated keys
   */
  public getPropertyName(type: SCThingType, keyPath: string | string[]): string  {
    const translatedPropertyNames = this.translator.translatedPropertyNames(type);
    if (!isDefined(translatedPropertyNames)) {
      throw new Error(`Parameter "type" is an invalid SCThingType`);
    }
    if (!isDefined(keyPath) || keyPath.length === 0) {
      throw new Error(`Parameter "keyPath" required`);
    }
    if (keyPath instanceof Array) {
      return this.getParsedResult(translatedPropertyNames!, keyPath.join('.'));
    }

    return this.getParsedResult(translatedPropertyNames!, keyPath);
  }

  // tslint:disable-next-line: completed-docs
  ngOnDestroy() {
    if (!this.onLangChange.closed) {
      this.onLangChange.unsubscribe();
    }
  }
}