i18next/i18next

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src/LanguageUtils.js

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import baseLogger from './logger.js';

function capitalize(string) {
  return string.charAt(0).toUpperCase() + string.slice(1);
}

class LanguageUtil {
  constructor(options) {
    this.options = options;

    this.supportedLngs = this.options.supportedLngs || false;
    this.logger = baseLogger.create('languageUtils');
  }

  getScriptPartFromCode(code) {
    if (!code || code.indexOf('-') < 0) return null;

    const p = code.split('-');
    if (p.length === 2) return null;
    p.pop();
    if (p[p.length - 1].toLowerCase() === 'x') return null;
    return this.formatLanguageCode(p.join('-'));
  }

  getLanguagePartFromCode(code) {
    if (!code || code.indexOf('-') < 0) return code;

    const p = code.split('-');
    return this.formatLanguageCode(p[0]);
  }

  formatLanguageCode(code) {
    // http://www.iana.org/assignments/language-tags/language-tags.xhtml
    if (typeof code === 'string' && code.indexOf('-') > -1) {
      const specialCases = ['hans', 'hant', 'latn', 'cyrl', 'cans', 'mong', 'arab'];
      let p = code.split('-');

      if (this.options.lowerCaseLng) {
        p = p.map((part) => part.toLowerCase());
      } else if (p.length === 2) {
        p[0] = p[0].toLowerCase();
        p[1] = p[1].toUpperCase();

        if (specialCases.indexOf(p[1].toLowerCase()) > -1) p[1] = capitalize(p[1].toLowerCase());
      } else if (p.length === 3) {
        p[0] = p[0].toLowerCase();

        // if lenght 2 guess it's a country
        if (p[1].length === 2) p[1] = p[1].toUpperCase();
        if (p[0] !== 'sgn' && p[2].length === 2) p[2] = p[2].toUpperCase();

        if (specialCases.indexOf(p[1].toLowerCase()) > -1) p[1] = capitalize(p[1].toLowerCase());
        if (specialCases.indexOf(p[2].toLowerCase()) > -1) p[2] = capitalize(p[2].toLowerCase());
      }

      return p.join('-');
    }

    return this.options.cleanCode || this.options.lowerCaseLng ? code.toLowerCase() : code;
  }

  isSupportedCode(code) {
    if (this.options.load === 'languageOnly' || this.options.nonExplicitSupportedLngs) {
      code = this.getLanguagePartFromCode(code);
    }
    return (
      !this.supportedLngs || !this.supportedLngs.length || this.supportedLngs.indexOf(code) > -1
    );
  }

  getBestMatchFromCodes(codes) {
    if (!codes) return null;

    let found;

    // pick first supported code or if no restriction pick the first one (highest prio)
    codes.forEach((code) => {
      if (found) return;
      let cleanedLng = this.formatLanguageCode(code);
      if (!this.options.supportedLngs || this.isSupportedCode(cleanedLng)) found = cleanedLng;
    });

    // if we got no match in supportedLngs yet - check for similar locales
    // first  de-CH --> de
    // second de-CH --> de-DE
    if (!found && this.options.supportedLngs) {
      codes.forEach((code) => {
        if (found) return;

        let lngOnly = this.getLanguagePartFromCode(code);
        if (this.isSupportedCode(lngOnly)) return (found = lngOnly);

        found = this.options.supportedLngs.find((supportedLng) => {
          if (supportedLng.indexOf(lngOnly) === 0) return supportedLng;
        });
      });
    }

    // if nothing found, use fallbackLng
    if (!found) found = this.getFallbackCodes(this.options.fallbackLng)[0];

    return found;
  }

  getFallbackCodes(fallbacks, code) {
    if (!fallbacks) return [];
    if (typeof fallbacks === 'function') fallbacks = fallbacks(code);
    if (typeof fallbacks === 'string') fallbacks = [fallbacks];
    if (Object.prototype.toString.apply(fallbacks) === '[object Array]') return fallbacks;

    if (!code) return fallbacks.default || [];

    // asume we have an object defining fallbacks
    let found = fallbacks[code];
    if (!found) found = fallbacks[this.getScriptPartFromCode(code)];
    if (!found) found = fallbacks[this.formatLanguageCode(code)];
    if (!found) found = fallbacks[this.getLanguagePartFromCode(code)];
    if (!found) found = fallbacks.default;

    return found || [];
  }

  toResolveHierarchy(code, fallbackCode) {
    const fallbackCodes = this.getFallbackCodes(
      fallbackCode || this.options.fallbackLng || [],
      code,
    );

    const codes = [];
    const addCode = (c) => {
      if (!c) return;
      if (this.isSupportedCode(c)) {
        codes.push(c);
      } else {
        this.logger.warn(`rejecting language code not found in supportedLngs: ${c}`);
      }
    };

    if (typeof code === 'string' && code.indexOf('-') > -1) {
      if (this.options.load !== 'languageOnly') addCode(this.formatLanguageCode(code));
      if (this.options.load !== 'languageOnly' && this.options.load !== 'currentOnly')
        addCode(this.getScriptPartFromCode(code));
      if (this.options.load !== 'currentOnly') addCode(this.getLanguagePartFromCode(code));
    } else if (typeof code === 'string') {
      addCode(this.formatLanguageCode(code));
    }

    fallbackCodes.forEach((fc) => {
      if (codes.indexOf(fc) < 0) addCode(this.formatLanguageCode(fc));
    });

    return codes;
  }
}

export default LanguageUtil;