import { LanguageService } from './LanguageService';
import { StringTypes } from './StringTypes';

type LangInfo = {[id: string]: string};
type LangData = {[id: string]: LangInfo};
type LangObject = {[id: string]: LangData}

export class LocalizedStrings {

  private document: Document = document;

  constructor (private service: LanguageService, private i18nData: LangObject, private listenToChange = false) {
    if(this.listenToChange) {
      service.registerLanguageChangeListener( () => {
        this.updateTagText();
      });
    }
  }

  getString (id: string, type: string): string {
    let i18nObj = this.i18nData[this.service.getLang()];
    if (!!!i18nObj) {
      console.warn(`Internal Error. The language set at ivprog.lang is not valid: ${this.service.getLang()}`);
      i18nObj = this.i18nData[this.service.getDefaultLang()];
    }
    if (!!!i18nObj[type]) {
      return "{MISSING_I18N_TYPE_IDENTIFIER}";
    } else if (!!!i18nObj[type][id]) {
      return "{MISSING_I18N_IDENTIFIER}";
    } else {
      return i18nObj[type][id];
    }
  }

  getOR (): String {
    return this.getUI('string_join_or');
  }

  getError (id: string, context: [] = []) {
    const text = this.getString(id, StringTypes.ERROR);
    return this.processString(text, context)
  }

  getMessage (id: string, context: [] = []) {
    const text = this.getString(id, StringTypes.MESSAGE);
    return this.processString(text, context)
  }

  getUI (id: string, context: [] = []) {
    const text = this.getString(id, StringTypes.UI);
    return this.processString(text, context)
  }

  processString (text: string, context: []) {
    for (let i = 0; i < context.length; i++) {
      const v = context[i];
      text = text.replace('\$' + i, v);
    }
    return text;
  }

  updateTagText (func: ((str: string | null) => string) | null = null): void {
    if (this.document !== null) {
      const list = this.document.querySelectorAll("data.i18n");
      list.forEach(node => {
        if (func === null) {
          node.innerHTML = this.processTagTex(node.getAttribute("value"));
        } else {
          node.innerHTML = func(node.getAttribute("value"));
        }
      })
    }
  }

  processTagTex (text: string | null): string {
    if (text === null) {
      return "<Invalid i18n identifier>";
    }
    const opts = text.split(':');
    const type = opts[0].toLowerCase();
    const id = opts[1];
    if (StringTypes.ERROR === type) {
      return this.getError(id);
    } else if (StringTypes.MESSAGE === type) {
      return this.getMessage(id);
    } else if (StringTypes.UI === type) {
      return this.getUI(id);
    } else {
      console.warn(" A string has been passed to the i18n helper function that was not in the form type:id -> " + text);
      return this.getString(id, type);
    }
  }

}