/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {CldrData, CldrLocaleData} from './cldr-data';
import {fileHeader} from './file-header';
import {BaseCurrencies} from './locale-base-currencies';
import {generateLocale} from './locale-file';

interface ClosureLocale {
  /** Closure-supported locale names that resolve to this locale. */
  closureLocaleNames: string[];
  /** Canonical locale name that is used to resolve the CLDR data. */
  canonicalLocaleName: string;
  /** Locale data. Can have a different locale name if this captures an aliased locale. */
  data: CldrLocaleData;
}

/**
 * Locales used by closure that need to be captured within the Closure Locale file. Extracted from:
 * https://github.com/google/closure-library/blob/c7445058af72f679ef3273274e936d5d5f40b55a/closure/goog/i18n/datetimepatterns.js#L2450
 */
const closureLibraryLocales = [
  'af',    'am',    'ar',    'ar-DZ', 'az',    'be',    'bg',      'bn',         'br',      'bs',
  'ca',    'chr',   'cs',    'cy',    'da',    'de',    'de-AT',   'de-CH',      'el',      'en-AU',
  'en-CA', 'en-GB', 'en-IE', 'en-IN', 'en-SG', 'en-ZA', 'es',      'es-419',     'es-MX',   'es-US',
  'et',    'eu',    'fa',    'fi',    'fr',    'fr-CA', 'ga',      'gl',         'gsw',     'gu',
  'haw',   'hi',    'hr',    'hu',    'hy',    'id',    'is',      'it',         'he',      'ja',
  'ka',    'kk',    'km',    'kn',    'ko',    'ky',    'ln',      'lo',         'lt',      'lv',
  'mk',    'ml',    'mn',    'ro-MD', 'mr',    'ms',    'mt',      'my',         'ne',      'nl',
  'nb',    'or',    'pa',    'pl',    'pt',    'pt-PT', 'ro',      'ru',         'sr-Latn', 'si',
  'sk',    'sl',    'sq',    'sr',    'sv',    'sw',    'ta',      'te',         'th',      'fil',
  'tr',    'uk',    'ur',    'uz',    'vi',    'zh',    'zh-Hans', 'zh-Hant-HK', 'zh-Hant', 'zu'
] as const;

/** Union type matching possible Closure Library locales. */
type ClosureLibraryLocaleName = typeof closureLibraryLocales[number];

/**
 * Locale ID aliases to support deprecated locale ids used by Closure. Maps locales supported
 * by Closure library to a list of aliases that match the same locale data.
 */
const closureLibraryAliases: {[l in ClosureLibraryLocaleName]?: string[]} = {
  'id': ['in'],
  'he': ['iw'],
  'ro-MD': ['mo'],
  'nb': ['no', 'no-NO'],
  'sr-Latn': ['sh'],
  'fil': ['tl'],
  'pt': ['pt-BR'],
  'zh-Hans': ['zh-Hans-CN', 'zh-CN'],
  'zh-Hant-HK': ['zh-HK'],
  'zh-Hant': ['zh-Hant-TW', 'zh-TW'],
};


/**
 * Generate a file that contains all locale to import for closure.
 * Tree shaking will only keep the data for the `goog.LOCALE` locale.
 */
export function generateClosureLocaleFile(cldrData: CldrData, baseCurrencies: BaseCurrencies) {
  const locales: ClosureLocale[] = closureLibraryLocales.map(localeName => {
    const data = cldrData.getLocaleData(localeName);

    if (data === null) {
      throw Error(`Missing locale data for Closure locale: ${localeName}`);
    }

    return {
      data,
      canonicalLocaleName: localeName,
      closureLocaleNames: computeEquivalentLocaleNames(localeName),
    };
  });

  return `${fileHeader}

import {registerLocaleData} from '../src/i18n/locale_data';

const u = undefined;

${locales.map(locale => generateLocaleConstants(locale)).join('\n')}

let l: any;
let locales: string[] = [];

switch (goog.LOCALE) {
${locales.map(locale => generateCase(locale)).join('')}}

if (l) {
  locales.forEach(locale => registerLocaleData(l, locale));
}
`;

  /**
   * Generates locale data constants for all locale names within the specified
   * Closure Library locale.
   */
  function generateLocaleConstants(locale: ClosureLocale): string {
    // Closure Locale names contain both the dashed and underscore variant. We filter out
    // the dashed variant as otherwise we would end up with the same constant twice. e.g.
    // https://github.com/google/closure-library/blob/c7445058af72f679ef3273274e936d5d5f40b55a/closure/goog/i18n/datetimepatternsext.js#L11659-L11660.
    const localeConstantNames = locale.closureLocaleNames.filter(d => !d.includes('-'))
                                    .map(d => `locale_${formatLocale(d)}`);
    const dataConstantName = localeConstantNames[0];
    const otherAliasConstantNames = localeConstantNames.slice(1);

    // We only generate the locale data once. All other constants just refer to the
    // first constant with the actual locale data. This reduces the Closure Locale file
    // size and potentially speeds up compilation with Closure Compiler.
    return `
${generateLocaleConstant(locale, dataConstantName)}
${otherAliasConstantNames.map(d => `export const ${d} = ${dataConstantName};`).join('\n')}`;
  }

  /** Generates a locale data constant for the specified locale. */
  function generateLocaleConstant(locale: ClosureLocale, constantName: string): string {
    return generateLocale(locale.canonicalLocaleName, locale.data, baseCurrencies)
        .replace(`${fileHeader}\n`, '')
        .replace('export default ', `export const ${constantName} = `)
        .replace('function plural', `function plural_${constantName}`)
        .replace(/,\s+plural/, `, plural_${constantName}`)
        .replace(/\s*const u = undefined;\s*/, '');
  }

  /** Generates a TypeScript `switch` case for the specified locale. */
  function generateCase(locale: ClosureLocale): string {
    return `
${locale.closureLocaleNames.map(l => `case '${l}':`).join('\n')}
  l = locale_${formatLocale(locale.canonicalLocaleName)};
  locales = [${locale.closureLocaleNames.map(n => `"${n}"`).join(', ')}];
  break;`;
  }
}

function computeEquivalentLocaleNames(localeName: ClosureLibraryLocaleName): string[] {
  const equivalents = new Set<string>([localeName]);

  if (localeName.includes('-')) {
    equivalents.add(localeName.replace(/-/g, '_'));
  }

  const aliases = closureLibraryAliases[localeName];
  if (aliases !== undefined) {
    aliases.forEach(aliasName => {
      equivalents.add(aliasName);

      if (aliasName.includes('-')) {
        equivalents.add(aliasName.replace(/-/g, '_'));
      }
    });
  }

  return Array.from(equivalents);
}

function formatLocale(locale: string): string {
  return locale.replace(/-/g, '_');
}