/**
 * @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 } re
 * @returns {string}
 */
function lookahead(re) {
  return concat('(?=', re, ')');
}

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

function stripOptionsFromArgs(args) {
  const opts = args[args.length - 1];

  if (typeof opts === 'object' && opts.constructor === Object) {
    args.splice(args.length - 1, 1);
    return opts;
  } else {
    return {};
  }
}

/**
 * Any of the passed expresssions may match
 *
 * Creates a huge this | this | that | that match
 * @param {(RegExp | string)[] } args
 * @returns {string}
 */
function either(...args) {
  const opts = stripOptionsFromArgs(args);
  const joined = '(' +
    (opts.capture ? "" : "?:") +
    args.map((x) => source(x)).join("|") + ")";
  return joined;
}

/*
Language: Wren
Description: Think Smalltalk in a Lua-sized package with a dash of Erlang and wrapped up in a familiar, modern syntax.
Category: scripting
Author: @joshgoebel
Maintainer: @joshgoebel
Website: https://wren.io/
*/

/** @type LanguageFn */
function wren(hljs) {
  const IDENT_RE = /[a-zA-Z]\w*/;
  const KEYWORDS = [
    "as",
    "break",
    "class",
    "construct",
    "continue",
    "else",
    "for",
    "foreign",
    "if",
    "import",
    "in",
    "is",
    "return",
    "static",
    "var",
    "while"
  ];
  const LITERALS = [
    "true",
    "false",
    "null"
  ];
  const LANGUAGE_VARS = [
    "this",
    "super"
  ];
  const CORE_CLASSES = [
    "Bool",
    "Class",
    "Fiber",
    "Fn",
    "List",
    "Map",
    "Null",
    "Num",
    "Object",
    "Range",
    "Sequence",
    "String",
    "System"
  ];
  const OPERATORS = [
    "-",
    "~",
    /\*/,
    "%",
    /\.\.\./,
    /\.\./,
    /\+/,
    "<<", ">>",
    ">=", "<=",
    "<", ">",
    /\^/,
    /!=/,
    /!/,
    /\bis\b/,
    "==",
    "&&",
    "&",
    /\|\|/,
    /\|/,
    /\?:/,
    "="
  ];
  const FUNCTION = {
    relevance: 0,
    match: concat(/\b(?!(if|while|for|else|super)\b)/, IDENT_RE, /(?=\s*[({])/),
    className: "title.function"
  };
  const FUNCTION_DEFINITION = {
    match: concat(
      either(
        concat(/\b(?!(if|while|for|else|super)\b)/, IDENT_RE),
        either(...OPERATORS)
      ),
      /(?=\s*\([^)]+\)\s*\{)/),
    className: "title.function",
    starts: {
      contains: [
        {
          begin: /\(/,
          end: /\)/,
          contains: [
            {
              relevance: 0,
              scope: "params",
              match: IDENT_RE
            }
          ]
        }
      ]
    }
  };
  const CLASS_DEFINITION = {
    variants: [
      {
        match: [
          /class\s+/,
          IDENT_RE,
          /\s+is\s+/,
          IDENT_RE
        ]
      },
      {
        match: [
          /class\s+/,
          IDENT_RE
        ]
      }
    ],
    scope: {
      2: "title.class",
      4: "title.class.inherited"
    },
    keywords: KEYWORDS
  };

  const OPERATOR = {
    relevance: 0,
    match: either(...OPERATORS),
    className: "operator"
  };

  const TRIPLE_STRING = {
    className: "string",
    begin: /"""/,
    end: /"""/
  };

  const PROPERTY = {
    className: "property",
    begin: concat(/\./, lookahead(IDENT_RE)),
    end: IDENT_RE,
    excludeBegin: true,
    relevance: 0
  };

  const FIELD = {
    relevance: 0,
    match: concat(/\b_/, IDENT_RE),
    scope: "variable"
  };

  // CamelCase
  const CLASS_REFERENCE = {
    relevance: 0,
    match: /[A-Z]+[a-z]+([A-Z]+[a-z]+)*/,
    scope: "title.class",
    keywords: {
      _: CORE_CLASSES
    }
  };

  // TODO: add custom number modes
  const NUMBER = hljs.C_NUMBER_MODE;

  const SETTER = {
    match: [
      IDENT_RE, /\s*/,
      /=/, /\s*/,
      /\(/, IDENT_RE, /\)\s*\{/
    ],
    scope: {
      1: "title.function",
      3: "operator",
      6: "params"
    }
  };

  const COMMENT_DOCS = hljs.COMMENT(
    /\/\*\*/,
    /\*\//,
    {
      contains: [
        {
          match: /@[a-z]+/,
          scope: "doctag"
        },
        "self"
      ]
    }
  );
  const SUBST = {
    scope: "subst",
    begin: /%\(/,
    end: /\)/,
    contains: [
      NUMBER,
      CLASS_REFERENCE,
      FUNCTION,
      FIELD,
      OPERATOR
    ]
  };
  const STRING = {
    scope: "string",
    begin: /"/,
    end: /"/,
    contains: [
      SUBST,
      {
        scope: "char.escape",
        variants: [
          { match: /\\\\|\\["0%abefnrtv]/ },
          { match: /\\x[0-9A-F]{2}/ },
          { match: /\\u[0-9A-F]{4}/ },
          { match: /\\U[0-9A-F]{8}/ }
        ]
      }
    ]
  };
  SUBST.contains.push(STRING);

  const ALL_KWS = [...KEYWORDS, ...LANGUAGE_VARS, ...LITERALS];
  const VARIABLE = {
    relevance: 0,
    match: concat(
      "\\b(?!",
      ALL_KWS.join("|"),
      "\\b)",
      /[a-zA-Z_]\w*(?:[?!]|\b)/
    ),
    className: "variable"
  };

  // TODO: reconsider this in the future
  const ATTRIBUTE = {
    // scope: "meta",
    scope: "comment",
    variants: [
      {
        begin: [/#!?/, /[A-Za-z_]+(?=\()/],
        beginScope: {
          // 2: "attr"
        },
        keywords: {
          literal: LITERALS
        },
        contains: [
          // NUMBER,
          // VARIABLE
        ],
        end: /\)/
      },
      {
        begin: [/#!?/, /[A-Za-z_]+/],
        beginScope: {
          // 2: "attr"
        },
        end: /$/
      }
    ]
  };

  return {
    name: "Wren",
    keywords: {
      keyword: KEYWORDS,
      "variable.language": LANGUAGE_VARS,
      literal: LITERALS
    },
    contains: [
      ATTRIBUTE,
      NUMBER,
      STRING,
      TRIPLE_STRING,
      COMMENT_DOCS,
      hljs.C_LINE_COMMENT_MODE,
      hljs.C_BLOCK_COMMENT_MODE,
      CLASS_REFERENCE,
      CLASS_DEFINITION,
      SETTER,
      FUNCTION_DEFINITION,
      FUNCTION,
      OPERATOR,
      FIELD,
      PROPERTY,
      VARIABLE
    ]
  };
}

module.exports = wren;