/**
 * @param {string} value
 * @returns {RegExp}
 * */

/**
 * @param {RegExp | string } re
 * @returns {string}
 */
function source(re) {
  if (!re) return null;
  if (typeof re === "string") return re;

  return re.source;
}

/**
 * @param {...(RegExp | string) } args
 * @returns {string}
 */
function concat(...args) {
  const joined = args.map((x) => source(x)).join("");
  return joined;
}

/*
Language: Bash
Author: vah <vahtenberg@gmail.com>
Contributrors: Benjamin Pannell <contact@sierrasoftworks.com>
Website: https://www.gnu.org/software/bash/
Category: common
*/

/** @type LanguageFn */
function bash(hljs) {
  const VAR = {};
  const BRACED_VAR = {
    begin: /\$\{/,
    end:/\}/,
    contains: [
      "self",
      {
        begin: /:-/,
        contains: [ VAR ]
      } // default values
    ]
  };
  Object.assign(VAR,{
    className: 'variable',
    variants: [
      {begin: concat(/\$[\w\d#@][\w\d_]*/,
        // negative look-ahead tries to avoid matching patterns that are not
        // Perl at all like $ident$, @ident@, etc.
        `(?![\\w\\d])(?![$])`) },
      BRACED_VAR
    ]
  });

  const SUBST = {
    className: 'subst',
    begin: /\$\(/, end: /\)/,
    contains: [hljs.BACKSLASH_ESCAPE]
  };
  const HERE_DOC = {
    begin: /<<-?\s*(?=\w+)/,
    starts: {
      contains: [
        hljs.END_SAME_AS_BEGIN({
          begin: /(\w+)/,
          end: /(\w+)/,
          className: 'string'
        })
      ]
    }
  };
  const QUOTE_STRING = {
    className: 'string',
    begin: /"/, end: /"/,
    contains: [
      hljs.BACKSLASH_ESCAPE,
      VAR,
      SUBST
    ]
  };
  SUBST.contains.push(QUOTE_STRING);
  const ESCAPED_QUOTE = {
    className: '',
    begin: /\\"/

  };
  const APOS_STRING = {
    className: 'string',
    begin: /'/, end: /'/
  };
  const ARITHMETIC = {
    begin: /\$\(\(/,
    end: /\)\)/,
    contains: [
      { begin: /\d+#[0-9a-f]+/, className: "number" },
      hljs.NUMBER_MODE,
      VAR
    ]
  };
  const SH_LIKE_SHELLS = [
    "fish",
    "bash",
    "zsh",
    "sh",
    "csh",
    "ksh",
    "tcsh",
    "dash",
    "scsh",
  ];
  const KNOWN_SHEBANG = hljs.SHEBANG({
    binary: `(${SH_LIKE_SHELLS.join("|")})`,
    relevance: 10
  });
  const FUNCTION = {
    className: 'function',
    begin: /\w[\w\d_]*\s*\(\s*\)\s*\{/,
    returnBegin: true,
    contains: [hljs.inherit(hljs.TITLE_MODE, {begin: /\w[\w\d_]*/})],
    relevance: 0
  };

  const KEYWORDS = [
    "if",
    "then",
    "else",
    "elif",
    "fi",
    "for",
    "while",
    "in",
    "do",
    "done",
    "case",
    "esac",
    "function"
  ];

  const LITERALS = [
    "true",
    "false"
  ];

  return {
    name: 'Bash',
    aliases: ['sh'],
    keywords: {
      $pattern: /\b[a-z._-]+\b/,
      keyword: KEYWORDS,
      literal: LITERALS,
      built_in:
        // Shell built-ins
        // http://www.gnu.org/software/bash/manual/html_node/Shell-Builtin-Commands.html
        'break cd continue eval exec exit export getopts hash pwd readonly return shift test times ' +
        'trap umask unset ' +
        // Bash built-ins
        'alias bind builtin caller command declare echo enable help let local logout mapfile printf ' +
        'read readarray source type typeset ulimit unalias ' +
        // Shell modifiers
        'set shopt ' +
        // Zsh built-ins
        'autoload bg bindkey bye cap chdir clone comparguments compcall compctl compdescribe compfiles ' +
        'compgroups compquote comptags comptry compvalues dirs disable disown echotc echoti emulate ' +
        'fc fg float functions getcap getln history integer jobs kill limit log noglob popd print ' +
        'pushd pushln rehash sched setcap setopt stat suspend ttyctl unfunction unhash unlimit ' +
        'unsetopt vared wait whence where which zcompile zformat zftp zle zmodload zparseopts zprof ' +
        'zpty zregexparse zsocket zstyle ztcp'
    },
    contains: [
      KNOWN_SHEBANG, // to catch known shells and boost relevancy
      hljs.SHEBANG(), // to catch unknown shells but still highlight the shebang
      FUNCTION,
      ARITHMETIC,
      hljs.HASH_COMMENT_MODE,
      HERE_DOC,
      QUOTE_STRING,
      ESCAPED_QUOTE,
      APOS_STRING,
      VAR
    ]
  };
}

export default bash;
