// 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 } from "./common.ts";
const simpleEncodingRegExp = /^\s*([^\s;]+)\s*(?:;(.*))?$/;
function parseEncoding(str, i) {
  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" && p[1]) {
        q = parseFloat(p[1]);
        break;
      }
    }
  }
  return {
    encoding,
    q,
    i
  };
}
function specify(encoding, spec, i = -1) {
  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) {
  const accepts = accept.split(",");
  const parsedAccepts = [];
  let hasIdentity = false;
  let minQuality = 1;
  for (const [i, accept] of accepts.entries()){
    const encoding = parseEncoding(accept.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, accepted, index) {
  let priority = {
    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, provided) {
  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)]);
}
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