Translation converters

When the translation files are not in JSON format, they must be converted. To do a conversion, first you have to define the converter function in the module using the NGT_TRANSLATION_CONVERTER token:

// app.module.ts
import { NGT_TRANSLATION_CONVERTER } from 'ng-translation';
import { CustomTranslationConverter } from './custom-translation-converter';

@NgModule({
  providers: [ {
    provide: NGT_TRANSLATION_CONVERTER,
    useClass: CustomTranslationConverter
  } ],
  ...
})
export class AppModule { }

The function has to implement the TranslationConverter interface. The new formats can defined in the convert() method:

// custom-translation-converter.ts
@Injectable()
export class CustomTranslationConverter implements TranslationConverter {

  convert(
    language: string,
    resource: Resource,
    translations: any
  ): object {

    switch (resource.format) {
      case 'format-name':
        return { "key": "text" };
      default:
        return translations;
    }
  }
}

The following example converts .po format translations (where msgctxt contains the translation key) into JSON object:

import { Resource, TranslationConverter } from 'ng-translation';

export class CustomTranslationConverter implements TranslationConverter {

  convert(
    language: string,
    resource: Resource,
    translations: any
  ): object {

    switch (resource.format) {
      case 'po':
        return po2object( language, resource, translations );
      default:
        return translations;
    }
  }
}

function po2object(
  language: string,
  resource: Resource,
  translations: string
): object {

  const result: object = { };
  const lines: Array = translations.match(/^.*((\r\n|\n|\r)|$)/gm);
  let isHeader = true;
  let key = '';
  let text = '';
  let fqp = -1;
  let lqp = -1;

  lines.forEach( line => {
    if (isHeader) {
      if (line.trim() === '') {
        isHeader = false;
        key = '';
        text = '';
      }
    } else {
      if (line.startsWith( 'msgctxt ' )) {
        fqp = line.indexOf( '"' );
        lqp = line.lastIndexOf( '"' );
        if (fqp >= 7 && lqp > fqp) {
          key = line.substring( fqp + 1, lqp );
        }
      } else if (line.startsWith( 'msgstr ' )) {
        fqp = line.indexOf( '"' );
        lqp = line.lastIndexOf( '"' );
        if (fqp > 6 && lqp > fqp) {
          text = line.substring( fqp + 1, lqp );
        }
      } else if (line.trim() === '') {
        if (key && text) {
          let target = result;
          const path: Array = key.split( '.' );
          for (let i = 0; i < path.length; i++) {
            if (target[ path[ i ] ] === undefined) {
              target[ path[ i ] ] = i === path.length - 1 ? text : { };
            }
            target = target[ path[ i ] ];
          }
        }
        key = '';
        text = '';
      }
    }
  } );
  return result;
}