// 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 SIMPLE_LANGUAGE_REGEXP = /^\s*([^\s\-;]+)(?:-([^\s;]+))?\s*(?:;(.*))?$/;
function parseLanguage(str, i) {
  const match = SIMPLE_LANGUAGE_REGEXP.exec(str);
  if (!match) {
    return undefined;
  }
  const [, prefix, suffix] = match;
  if (!prefix) {
    return undefined;
  }
  const full = suffix ? `${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) {
  const accepts = accept.split(",");
  const result = [];
  for (const [i, accept] of accepts.entries()){
    const language = parseLanguage(accept.trim(), i);
    if (language) {
      result.push(language);
    }
  }
  return result;
}
function specify(language, spec, i) {
  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, accepted, index) {
  let priority = {
    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) {
  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)]);
}
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