-- 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. An additional grant
-- of patent rights can be found in the PATENTS file in the same directory.


{-# LANGUAGE GADTs #-}
{-# LANGUAGE NoRebindableSyntax #-}
{-# LANGUAGE OverloadedStrings #-}

module Duckling.Time.EN.GB.Rules
  ( rules
  ) where

import Data.Maybe
import Prelude

import Duckling.Dimensions.Types
import Duckling.Numeral.Helpers (parseInt)
import Duckling.Regex.Types
import Duckling.Time.Helpers
import Duckling.Time.Types (TimeData (..))
import Duckling.Types

ruleDDMM :: Rule
ruleDDMM = Rule
  { name = "dd/mm"
  , pattern =
    [ regex "(3[01]|[12]\\d|0?[1-9])\\s?[/-]\\s?(0?[1-9]|1[0-2])"
    ]
  , prod = \tokens -> case tokens of
      (Token RegexMatch (GroupMatch (dd:mm:_)):_) -> do
        d <- parseInt dd
        m <- parseInt mm
        tt $ monthDay m d
      _ -> Nothing
  }

ruleDDMMYYYY :: Rule
ruleDDMMYYYY = Rule
  { name = "dd/mm/yyyy"
  , pattern =
    [ regex "(3[01]|[12]\\d|0?[1-9])[/-](0?[1-9]|1[0-2])[-/](\\d{2,4})"
    ]
  , prod = \tokens -> case tokens of
      (Token RegexMatch (GroupMatch (dd:mm:yy:_)):_) -> do
        y <- parseInt yy
        d <- parseInt dd
        m <- parseInt mm
        tt $ yearMonthDay y m d
      _ -> Nothing
  }

ruleThanksgiving :: Rule
ruleThanksgiving = Rule
  { name = "Thanksgiving Day"
  , pattern =
    [ regex "thanks?giving( day)?"
    ]
  , prod = \_ -> tt $ nthDOWOfMonth 4 4 11 -- Fourth Thursday of November
  }

rules :: [Rule]
rules =
  [ ruleDDMM
  , ruleDDMMYYYY
  , ruleThanksgiving
  ]