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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license./*! * Adapted directly from negotiator at https://github.com/jshttp/negotiator/ * which is licensed as follows: * * (The MIT License) * * Copyright (c) 2012-2014 Federico Romero * Copyright (c) 2012-2014 Isaac Z. Schlueter * Copyright (c) 2014-2015 Douglas Christopher Wilson * * 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. */
import { compareSpecs, isQuality, type Specificity } from "./common.ts";
interface LanguageSpecificity extends Specificity {  prefix: string;  suffix?: string;  full: string;}
const SIMPLE_LANGUAGE_REGEXP = /^\s*([^\s\-;]+)(?:-([^\s;]+))?\s*(?:;(.*))?$/;
function parseLanguage(  str: string,  i: number,): LanguageSpecificity | undefined {  const match = SIMPLE_LANGUAGE_REGEXP.exec(str);  if (!match) {    return undefined;  }
  const [, prefix, suffix] = match;  if (!prefix) {    return undefined;  }
  const full = suffix ? `${prefix}-${suffix}` : prefix;
  let q = 1;  if (match[3]) {    const params = match[3].split(";");    for (const param of params) {      const [key, value] = param.trim().split("=");      if (key === "q" && value) {        q = parseFloat(value);        break;      }    }  }
  return { prefix, suffix, full, q, i };}
function parseAcceptLanguage(accept: string): LanguageSpecificity[] {  const accepts = accept.split(",");  const result: LanguageSpecificity[] = [];
  for (const [i, accept] of accepts.entries()) {    const language = parseLanguage(accept.trim(), i);    if (language) {      result.push(language);    }  }  return result;}
function specify(  language: string,  spec: LanguageSpecificity,  i: number,): Specificity | undefined {  const p = parseLanguage(language, i);  if (!p) {    return undefined;  }  let s = 0;  if (spec.full.toLowerCase() === p.full.toLowerCase()) {    s |= 4;  } else if (spec.prefix.toLowerCase() === p.prefix.toLowerCase()) {    s |= 2;  } else if (spec.full.toLowerCase() === p.prefix.toLowerCase()) {    s |= 1;  } else if (spec.full !== "*") {    return;  }
  return { i, o: spec.i, q: spec.q, s };}
function getLanguagePriority(  language: string,  accepted: LanguageSpecificity[],  index: number,): Specificity {  let priority: Specificity = { i: -1, o: -1, q: 0, s: 0 };  for (const accepts of accepted) {    const spec = specify(language, accepts, index);    if (      spec &&      ((priority.s ?? 0) - (spec.s ?? 0) || priority.q - spec.q ||          (priority.o ?? 0) - (spec.o ?? 0)) < 0    ) {      priority = spec;    }  }  return priority;}
export function preferredLanguages(  accept = "*",  provided?: string[],): string[] {  const accepts = parseAcceptLanguage(accept);
  if (!provided) {    return accepts      .filter(isQuality)      .sort(compareSpecs)      .map((spec) => spec.full);  }
  const priorities = provided    .map((type, index) => getLanguagePriority(type, accepts, index));
  return priorities    .filter(isQuality)    .sort(compareSpecs)    .map((priority) => provided[priorities.indexOf(priority)]!);}