/**
 * Begin license text.
 * Copyright 2020 Inrupt Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
 * Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * End license text.Source Distributions
 */

import { Store } from "./util/localStorage";
import { CONTEXT_KEY_PREFERRED_FALLBACK_LANGUAGE } from "./VocabContext";
import { NO_LANGUAGE_TAG } from "./VocabMultiLingualLiteral";

/**
 * Simple registry of terms (and their associated meta-data (like labels,
 * comment, message)) in multiple languages.
 *
 * We use localStorage to store all term meta-data, which can only store
 * strings (so we need to expand out the meta-data for each term).
 */
class VocabTermRegistry {
  private store: Store;

  constructor(store: Store) {
    this.store = store;
  }

  lookupLabel(termIri: string, language: string) {
    return this.lookupItem(termIri, language, "label");
  }

  updateLabel(termIri: string, language: string, label: string) {
    this.updateItem(termIri, language, label, "label");
  }

  lookupComment(termIri: string, language: string) {
    return this.lookupItem(termIri, language, "comment");
  }

  updateComment(termIri: string, language: string, label: string) {
    this.updateItem(termIri, language, label, "comment");
  }

  lookupMessage(termIri: string, language: string) {
    return this.lookupItem(termIri, language, "message");
  }

  updateMessage(termIri: string, language: string, label: string) {
    this.updateItem(termIri, language, label, "message");
  }

  private updateItem(
    termIri: string,
    language: string,
    label: string,
    item: string,
  ) {
    this.store.setItem(`${termIri}-${item}-${language}`, label);
  }

  private lookupItem(termIri: string, language: string, item: string) {
    return this.lookupFullTerm(`${termIri}-${item}-`, language);
  }

  /**
   * Looks up the specified vocabulary term in the specified language. If no
   * value found, will lookup again using the fallback language (as set in our
   * context). If not found again, will fallback to looking up the term in
   * English.
   *
   * @param term
   * @param language
   * @returns {string}
   */
  lookupFullTerm(term: string, language: string): string | undefined {
    const fallbackLanguage =
      this.store.getItem(CONTEXT_KEY_PREFERRED_FALLBACK_LANGUAGE) ?? "en";

    return this.lookupFullTermFallback(term, language, [
      fallbackLanguage,
      "en",
      NO_LANGUAGE_TAG,
    ]);
  }

  /**
   * Looks up the specified vocabulary term in the specified language. If no
   * value found, will lookup again using the provided fallback values one by
   * one until a value is found or there are no additional fallbacks.
   *
   * @param term {string}
   * @param language {string}
   * @param fallback {string[]}
   *
   * @returns {string | undefined}
   */
  lookupFullTermFallback(
    term: string,
    language: string,
    fallback: string[],
  ): string | undefined {
    const result = this.store.getItem(`${term}${language}`);

    if (result) {
      return result;
    } else if (fallback.length > 0) {
      return this.lookupFullTermFallback(term, fallback[0], fallback.slice(1));
    } else {
      return undefined;
    }
  }
}

export { VocabTermRegistry };