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/** * Adapted directly from content-disposition.js at * https://github.com/Rob--W/open-in-browser/blob/master/extension/content-disposition.js * which is licensed as: * * (c) 2017 Rob Wu <rob@robwu.nl> (https://robwu.nl) * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
import { toParamRegExp, unquote } from "./headers.ts";
let needsEncodingFixup = false;
function fixupEncoding(value: string): string {  if (needsEncodingFixup && /[\x80-\xff]/.test(value)) {    value = textDecode("utf-8", value);    if (needsEncodingFixup) {      value = textDecode("iso-8859-1", value);    }  }  return value;}
const FILENAME_STAR_REGEX = toParamRegExp("filename\\*", "i");const FILENAME_START_ITER_REGEX = toParamRegExp(  "filename\\*((?!0\\d)\\d+)(\\*?)",  "ig",);const FILENAME_REGEX = toParamRegExp("filename", "i");
function rfc2047decode(value: string): string {  // deno-lint-ignore no-control-regex  if (!value.startsWith("=?") || /[\x00-\x19\x80-\xff]/.test(value)) {    return value;  }  return value.replace(    /=\?([\w-]*)\?([QqBb])\?((?:[^?]|\?(?!=))*)\?=/g,    (_: string, charset: string, encoding: string, text: string) => {      if (encoding === "q" || encoding === "Q") {        text = text.replace(/_/g, " ");        text = text.replace(          /=([0-9a-fA-F]{2})/g,          (_, hex) => String.fromCharCode(parseInt(hex, 16)),        );        return textDecode(charset, text);      }      try {        text = atob(text);        // deno-lint-ignore no-empty      } catch {}      return textDecode(charset, text);    },  );}
function rfc2231getParam(header: string): string {  const matches: [string, string][] = [];  let match: RegExpExecArray | null;  while ((match = FILENAME_START_ITER_REGEX.exec(header))) {    const [, ns, quote, part] = match;    const n = parseInt(ns, 10);    if (n in matches) {      if (n === 0) {        break;      }      continue;    }    matches[n] = [quote, part];  }  const parts: string[] = [];  for (let n = 0; n < matches.length; ++n) {    if (!(n in matches)) {      break;    }    let [quote, part] = matches[n];    part = unquote(part);    if (quote) {      part = unescape(part);      if (n === 0) {        part = rfc5987decode(part);      }    }    parts.push(part);  }  return parts.join("");}
function rfc5987decode(value: string): string {  const encodingEnd = value.indexOf(`'`);  if (encodingEnd === -1) {    return value;  }  const encoding = value.slice(0, encodingEnd);  const langValue = value.slice(encodingEnd + 1);  return textDecode(encoding, langValue.replace(/^[^']*'/, ""));}
function textDecode(encoding: string, value: string): string {  if (encoding) {    try {      const decoder = new TextDecoder(encoding, { fatal: true });      const bytes = Array.from(value, (c) => c.charCodeAt(0));      if (bytes.every((code) => code <= 0xFF)) {        value = decoder.decode(new Uint8Array(bytes));        needsEncodingFixup = false;      }      // deno-lint-ignore no-empty    } catch {}  }  return value;}
export function getFilename(header: string): string {  needsEncodingFixup = true;
  // filename*=ext-value ("ext-value" from RFC 5987, referenced by RFC 6266).  let matches = FILENAME_STAR_REGEX.exec(header);  if (matches) {    const [, filename] = matches;    return fixupEncoding(      rfc2047decode(rfc5987decode(unescape(unquote(filename)))),    );  }
  // Continuations (RFC 2231 section 3, referenced by RFC 5987 section 3.1).  // filename*n*=part  // filename*n=part  const filename = rfc2231getParam(header);  if (filename) {    return fixupEncoding(rfc2047decode(filename));  }
  // filename=value (RFC 5987, section 4.1).  matches = FILENAME_REGEX.exec(header);  if (matches) {    const [, filename] = matches;    return fixupEncoding(rfc2047decode(unquote(filename)));  }
  return "";}