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// Copyright 2018-2022 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, Specificity } from "./common.ts";
interface EncodingSpecificity extends Specificity {  encoding?: string;}
const simpleEncodingRegExp = /^\s*([^\s;]+)\s*(?:;(.*))?$/;
function parseEncoding(  str: string,  i: number,): EncodingSpecificity | undefined {  const match = simpleEncodingRegExp.exec(str);  if (!match) {    return undefined;  }
  const encoding = match[1];  let q = 1;  if (match[2]) {    const params = match[2].split(";");    for (const param of params) {      const p = param.trim().split("=");      if (p[0] === "q") {        q = parseFloat(p[1]);        break;      }    }  }
  return { encoding, q, i };}
function specify(  encoding: string,  spec: EncodingSpecificity,  i = -1,): Specificity | undefined {  if (!spec.encoding) {    return;  }  let s = 0;  if (spec.encoding.toLocaleLowerCase() === encoding.toLocaleLowerCase()) {    s = 1;  } else if (spec.encoding !== "*") {    return;  }
  return {    i,    o: spec.i,    q: spec.q,    s,  };}
function parseAcceptEncoding(accept: string): EncodingSpecificity[] {  const accepts = accept.split(",");  const parsedAccepts: EncodingSpecificity[] = [];  let hasIdentity = false;  let minQuality = 1;
  for (let i = 0; i < accepts.length; i++) {    const encoding = parseEncoding(accepts[i].trim(), i);
    if (encoding) {      parsedAccepts.push(encoding);      hasIdentity = hasIdentity || !!specify("identity", encoding);      minQuality = Math.min(minQuality, encoding.q || 1);    }  }
  if (!hasIdentity) {    parsedAccepts.push({      encoding: "identity",      q: minQuality,      i: accepts.length - 1,    });  }
  return parsedAccepts;}
function getEncodingPriority(  encoding: string,  accepted: Specificity[],  index: number,): Specificity {  let priority: Specificity = { o: -1, q: 0, s: 0, i: 0 };
  for (const s of accepted) {    const spec = specify(encoding, s, index);
    if (      spec &&      (priority.s! - spec.s! || priority.q - spec.q ||          priority.o! - spec.o!) <        0    ) {      priority = spec;    }  }
  return priority;}
/** Given an `Accept-Encoding` string, parse out the encoding returning a * negotiated encoding based on the `provided` encodings otherwise just a * prioritized array of encodings. */export function preferredEncodings(  accept: string,  provided?: string[],): string[] {  const accepts = parseAcceptEncoding(accept);
  if (!provided) {    return accepts      .filter(isQuality)      .sort(compareSpecs)      .map((spec) => spec.encoding!);  }
  const priorities = provided.map((type, index) =>    getEncodingPriority(type, accepts, index)  );
  return priorities    .filter(isQuality)    .sort(compareSpecs)    .map((priority) => provided[priorities.indexOf(priority)]);}