commands = [
  "if",
  "elseif",
  "else",
  "endif",
  "foreach",
  "endforeach",
  "while",
  "endwhile",
  "function",
  "endfunction",
  "macro",
  "endmacro",
  "message",
];
if_args = [
  "1",
  "ON",
  "YES",
  "TRUE",
  "Y",
  "0",
  "OFF",
  "NO",
  "FALSE",
  "N",
  "IGNORE",
  "NOTFOUND",
  "NOT",
  "AND",
  "OR",
  "COMMAND",
  "POLICY",
  "TARGET",
  "TEST",
  "DEFINED",
  "CACHE",
  "ENV",
  "IN_LIST",
  "EXISTS",
  "IS_NEWER_THAN",
  "IS_DIRECTORY",
  "IS_SYMLINK",
  "IS_ABSOLUTE",
  "MATCHES",
  "LESS",
  "GREATER",
  "EQUAL",
  "LESS_EQUAL",
  "GREATER_EQUAL",
  "STRLESS",
  "STRGREATER",
  "STREQUAL",
  "STRLESS_EQUAL",
  "STRGREATER_EQUAL",
  "VERSION_LESS",
  "VERSION_GREATER",
  "VERSION_EQUAL",
  "VERSION_LESS_EQUAL",
  "VERSION_GREATER_EQUAL",
];
foreach_args = ["IN", "RANGE", "ZIP_LISTS", "LISTS", "ITEMS"];
message_args = [
  "FATAL_ERROR",
  "SEND_ERROR",
  "WARNING",
  "AUTHOR_WARNING",
  "DEPRECATION",
  "NOTICE",
  "STATUS",
  "VERBOSE",
  "DEBUG",
  "TRACE",
  "CHECK_START",
  "CHECK_PASS",
  "CHECK_FAIL",
];

module.exports = grammar({
  name: "cmake",

  externals: ($) => [$.bracket_argument],
  extras: ($) => [/[\s\n\r]/, $.comment],

  rules: {
    source_file: ($) => repeat($._command_invocation),

    escape_sequence: ($) => choice($._escape_identity, $._escape_encoded, $._escape_semicolon),
    _escape_identity: (_) => /\\[^A-Za-z0-9;]/,
    _escape_encoded: (_) => choice("\\t", "\\r", "\\n"),
    _escape_semicolon: (_) => ";",

    variable: ($) => prec.left(repeat1(choice(/[a-zA-Z0-9/_.+-]/, $.escape_sequence))),
    variable_ref: ($) => choice($.normal_var, $.env_var, $.cache_var),
    normal_var: ($) => seq("${", $.variable, "}"),
    env_var: ($) => seq("$ENV", "{", $.variable, "}"),
    cache_var: ($) => seq("$CACHE", "{", $.variable, "}"),

    argument: ($) => choice($.bracket_argument, $.quoted_argument, $.unquoted_argument),

    quoted_argument: ($) => seq('"', optional($.quoted_element), '"'),
    quoted_element: ($) => repeat1(choice($.variable_ref, /[^\\"]/, $.escape_sequence)),

    unquoted_argument: ($) => prec.right(repeat1(choice($.variable_ref, /[^\s\n\r()#\"\\]/, $.escape_sequence))),

    if_command: ($) => command($.if, repeat(choice($.argument, ...if_args))),
    elseif_command: ($) => command($.elseif, repeat(choice($.argument, ...if_args))),
    else_command: ($) => command($.else, optional(choice($.argument, ...if_args))),
    endif_command: ($) => command($.endif, optional(choice($.argument, ...if_args))),
    if_condition: ($) =>
      seq($.if_command, repeat(choice($._command_invocation, $.elseif_command, $.else_command)), $.endif_command),

    foreach_command: ($) => command($.foreach, repeat(choice($.argument, ...foreach_args))),
    endforeach_command: ($) => command($.endforeach, optional($.argument)),
    foreach_loop: ($) => seq($.foreach_command, repeat($._command_invocation), $.endforeach_command),

    while_command: ($) => command($.while, repeat(choice($.argument, ...if_args))),
    endwhile_command: ($) => command($.endwhile, optional(choice($.argument, ...if_args))),
    while_loop: ($) => seq($.while_command, repeat($._command_invocation), $.endwhile_command),

    function_command: ($) => command($.function, repeat($.argument)),
    endfunction_command: ($) => command($.endfunction, repeat($.argument)),
    function_def: ($) => seq($.function_command, repeat($._command_invocation), $.endfunction_command),

    macro_command: ($) => command($.macro, repeat($.argument)),
    endmacro_command: ($) => command($.endmacro, repeat($.argument)),
    macro_def: ($) => seq($.macro_command, repeat($._command_invocation), $.endmacro_command),

    message_command: ($) => command($.message, optional(repeat(choice($.argument, ...message_args)))),

    normal_command: ($) => command($.identifier, repeat($.argument)),

    _command_invocation: ($) =>
      choice(
        $.normal_command,
        $.if_condition,
        $.foreach_loop,
        $.while_loop,
        $.function_def,
        $.macro_def,
        $.message_command
      ),

    comment: ($) => seq("#", choice($.bracket_argument)),

    ...commandNames(...commands),
    identifier: (_) => /[A-Za-z_][A-Za-z0-9_]*/,
    integer: (_) => /[+-]*\d+/,
  },
});

function iregex(s) {
  return new RegExp(Array.from(s).reduce((acc, value) => acc + `[${value.toLowerCase()}${value.toUpperCase()}]`, ""));
}

function commandName(name) {
  return { [name]: (_) => iregex(name) };
}

function commandNames(...names) {
  return Object.assign({}, ...names.map(commandName));
}

function command(name_rule, arg_rule) {
  return seq(name_rule, "(", arg_rule, ")");
}