module.exports = grammar({
  name: "d2",

  word: ($) => $._word,

  rules: {
    // TODO: add the actual grammar rules
    source_file: ($) => repeat($._definition),

    _definition: ($) => choice($._root_attribute, $.connection, $.shape),

    connection: ($) =>
      seq(
        $.identifier,
        repeat1(seq($.arrow, $.identifier)),
        optional(seq($._colon, $.label)),
        $._end
      ),

    shape: ($) =>
      seq(
        $.identifier,
        repeat(seq($.dot, $.identifier)),
        choice(
          optional(seq($.dot, $._shape_attribute)),
          optional(seq($._colon, $.label))
        ),
        $._end
      ),

    identifier: ($) => $._identifier,

    label: ($) => choice($.string, $._unquoted_string),

    attr_value: ($) => choice($.string, $._unquoted_string),

    _root_attribute: ($) =>
      seq(alias($._root_attr_key, $.attr_key), $._colon, $.attr_value, $._end),

    _root_attr_key: ($) => "direction",

    _style_attribute: ($) =>
      seq(
        alias("style", $.attr_key),
        $.dot,
        alias($._style_attr_key, $.attr_key),
        $._colon,
        $.attr_value
      ),

    _shape_attribute: ($) =>
      choice(
        seq(alias($._shape_attr_key, $.attr_key), $._colon, $.attr_value),
        $._style_attribute
      ),

    _shape_attr_key: ($) =>
      choice(
        "shape",
        "label",
        // sql
        "constraint",
        // image
        "icon",
        "width",
        "height"
      ),

    _style_attr_key: ($) =>
      choice(
        "opacity",
        "fill",
        "stroke",
        "stroke-width",
        "stroke-dash",
        "border-radius",
        "font-color",
        "shadow",
        "multiple",
        "animated",
        "3d",
        "link"
      ),

    _text_attr_key: ($) => "near",

    _connection_attr_key: ($) => choice("source-arrowhead", "target-arrowhead"),

    _identifier: ($) =>
      prec.right(
        seq(
          repeat(" "),
          optional($._dash),
          choice(
            $._word,
            repeat1(seq($._word, choice(repeat(" "), $._dash), $._word))
          ),
          optional($._dash),
          repeat(" ")
        )
      ),

    _colon: ($) => seq(repeat(" "), ":", repeat(" ")),

    _dash: ($) => token.immediate("-"),

    _word: ($) => /[\w\d]+/,

    arrow: ($) =>
      prec.left(
        choice(
          seq("--", repeat($._dash)),
          seq("<-", repeat($._dash)),
          seq("<-", repeat($._dash), ">"),
          seq(repeat($._dash), "->")
        )
      ),

    _unquoted_string: ($) => token.immediate(/[^'"`\n;{]+/),

    string: ($) =>
      choice(
        seq("'", repeat(token.immediate(/[^'\n]+/)), "'"),
        seq('"', repeat(token.immediate(/[^"\n]+/)), '"'),
        seq("`", repeat(token.immediate(/[^`\n]+/)), "`")
      ),

    _end: ($) => choice(";", "\n", "\0"),

    dot: ($) => ".",
  },
});