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/*! * 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, Specificity } from "./common.ts";
interface CharsetSpecificity extends Specificity {  charset: string;}
const SIMPLE_CHARSET_REGEXP = /^\s*([^\s;]+)\s*(?:;(.*))?$/;
function parseCharset(str: string, i: number): CharsetSpecificity | undefined {  const match = SIMPLE_CHARSET_REGEXP.exec(str);  if (!match) {    return;  }
  const [, charset] = match;  let q = 1;  if (match[2]) {    const params = match[2].split(";");    for (const param of params) {      const [key, value] = param.trim().split("=");      if (key === "q") {        q = parseFloat(value);        break;      }    }  }
  return { charset, q, i };}
function parseAcceptCharset(accept: string): CharsetSpecificity[] {  const accepts = accept.split(",");  const result: CharsetSpecificity[] = [];
  for (let i = 0; i < accepts.length; i++) {    const charset = parseCharset(accepts[i].trim(), i);    if (charset) {      result.push(charset);    }  }  return result;}
function specify(  charset: string,  spec: CharsetSpecificity,  i: number,): Specificity | undefined {  let s = 0;  if (spec.charset.toLowerCase() === charset.toLocaleLowerCase()) {    s |= 1;  } else if (spec.charset !== "*") {    return;  }
  return { i, o: spec.i, q: spec.q, s };}
function getCharsetPriority(  charset: string,  accepted: CharsetSpecificity[],  index: number,): Specificity {  let priority: Specificity = { i: -1, o: -1, q: 0, s: 0 };  for (const accepts of accepted) {    const spec = specify(charset, 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 preferredCharsets(accept = "*", provided?: string[]): string[] {  const accepts = parseAcceptCharset(accept);
  if (!provided) {    return accepts      .filter(isQuality)      .sort(compareSpecs)      .map((spec) => spec.charset);  }
  const priorities = provided    .map((type, index) => getCharsetPriority(type, accepts, index));
  return priorities    .filter(isQuality)    .sort(compareSpecs)    .map((priority) => provided[priorities.indexOf(priority)]);}