content: -- Copyright (c) 2016-present, Facebook, Inc.
  -- All rights reserved.
  --
  -- This source code is licensed under the BSD-style license found in the
  -- LICENSE file in the root directory of this source tree.
  
  
  {-# LANGUAGE GADTs #-}
  {-# LANGUAGE OverloadedStrings #-}
  {-# LANGUAGE NoRebindableSyntax #-}
  
  module Duckling.Numeral.Rules
    ( rules
    ) where
  
  import Prelude
  
  import Duckling.Dimensions.Types
  import Duckling.Numeral.Helpers
  import Duckling.Regex.Types
  import Duckling.Types
  
  ruleIntegerNumeric :: Rule
  ruleIntegerNumeric = Rule
    { name = "integer (numeric)"
    , pattern =
      [ regex "(\\d{1,18})"
      ]
    , prod = \tokens -> case tokens of
        (Token RegexMatch (GroupMatch (match:_)):_) ->
          toInteger <$> parseInt match >>= integer
        _ -> Nothing
    }
  
  ruleFractions :: Rule
  ruleFractions = Rule
    { name = "fractional number"
    , pattern =
      [ regex "(\\d+)/(\\d+)"
      ]
    , prod = \tokens -> case tokens of
        (Token RegexMatch (GroupMatch (numerator:denominator:_)):_) -> do
          n <- parseDecimal False numerator
          d <- parseDecimal False denominator
          divide n d >>= notOkForAnyTime
        _ -> Nothing
    }
  
  rules :: [Rule]
  rules =
    [ ruleIntegerNumeric
    , ruleFractions
    ]
  