/// <reference types="tree-sitter-cli/dsl" />
// @ts-check

export default grammar({
  name: 'fsm',
  rules: {
    source_file: $ => repeat($.statement),
    _type: $ => seq(
      '<',
      field('type', $.expression_type),
      '>'
    ),
    expression: $ => choice(
      $.symbol_expression,
      $.prop_expression,
      $.pointer_expression,
      $.or_expression,
      $.reflect_expression,
      $.string_expression
    ),
    expression_type: $ => choice(
      'Expression',
      $.pointer_expression_type,
      $.symbol_expression_type,
      $.string_expression_type,
      $.or_expression_type,
      $.reflect_expression_type
    ),
    string_expression: $ => prec(-10, /[a-zA-Z0-9]+/),
    string_expression_type: $ => 'String',
    symbol_expression: $ => prec(10, seq(
      ':',
      field('expression', $.expression)
    )),
    symbol_expression_type: $ => 'Symbol',
    prop_expression: $ => seq(
      '[',
      field('expression', $.expression),
      ']'
    ),
    pointer_expression: $ => prec(10, choice(
      $.action_pointer_expression,
      $.prop_pointer_expression
    )),
    pointer_expression_type: $ => choice(
      'Pointer',
      $.action_pointer_expression_type,
      $.prop_pointer_expression_type
    ),
    prop_pointer_expression: $ => seq(
      '[[',
      field('expression', $.expression),
      ']]'
    ),
    prop_pointer_expression_type: $ => 'PropPointer',
    action_pointer_expression: $ => prec(10, seq(
      '*',
      field('expression', $.expression)
    )),
    action_pointer_expression_type: $ => 'ActionPointer',
    reflect_expression: $ => prec(20, seq(
      '(',
      field('expression', $.expression),
      ')'
    )),
    reflect_expression_type: $ => 'ReflectExpression',
    or_expression: $ => prec.left(5, seq(
      field('prefer', $.expression),
      '?',
      field('fallback', $.expression)
    )),
    or_expression_type: $ => 'OrExpression',
    statement: $ => choice(
      $.route_statement,
      $.on_statement,
      $.block_statement,
      $.move_statement,
      $.actions_statement,
      $.action_statement,
      $.prop_statement,
      $.optional_prop_statement,
      $.await_statement,
      $.reflect_statement,
      $.or_assign_statement
    ),
    route_statement: $ => seq(
      'route',
      field('name', $.expression),
      field('procedure', $.statement)
    ),
    or_assign_statement: $ => prec.left(5, seq(
      field('operand', $.expression),
      '?=',
      field('default', $.expression)
    )),
    on_statement: $ => seq(
      'on',
      field('state', $.expression),
      field('procedure', $.statement)
    ),
    block_statement: $ => seq(
      'do',
        field('procedure', repeat($.statement)),
      'end'
    ),
    actions_statement: $ => prec.right(seq(
      'actions',
      field('expressions', repeat($.expression))
    )),
    action_statement: $ => seq(
      '*',
      field('expression', $.expression)
    ),
    prop_statement: $ => seq(
      'prop',
      field('name', $.expression),
      field('type', $._type)
    ),
    optional_prop_statement: $ => seq(
      'prop?',
      field('name', $.expression),
      field('type', $._type)
    ),
    move_statement: $ => seq(
      '=>', 
      field('to', $.expression)
    ),
    await_statement: $ => seq(
     'await',
     field('action', $.expression),
     field('resolved', $.statement),
     '!',
     field('rejected', $.statement),
    ),
    reflect_statement: $ => seq(
      '(',
      field('statement', $.statement),
      ')'
    )
  }
});