-----------------------------------------------------------------------------
-- |
-- Module      :  Data.Queue
-- Copyright   :  (c) 2020-2021 EMQ Technologies Co., Ltd.
-- License     :  BSD-style (see the LICENSE file)
--
-- Maintainer  :  Feng Lee, feng@emqx.io
--                Yang M, yangm@emqx.io
-- Stability   :  experimental
-- Portability :  portable
--
-- The FIFO Queue datatype.
--
-----------------------------------------------------------------------------
module Data.Queue where

import Data.Maybe (Maybe)
import Data.Show (class Show, show)
import Data.Read (class Read, read)
import Data.Eq (class Eq, eq)
import Data.Ord (class Ord, compare)
import Data.Semigroup (class Semigroup)
import Data.Monoid (class Monoid)
import Foreign (ffi0, ffi1, ffi2)
import Test.QuickCheck (arbitrary, class Arbitrary)
import Control.Monad((<$>))

foreign import data Queue :: Type -> Type

instance Show a => Show (Queue a) where
  show x = show (toList x)

instance Read a => Read (Queue a) where
  read x = fromList (read x)

instance Eq a => Eq (Queue a) where
  eq x y = eq (toList x) (toList y)

instance Ord a => Ord (Queue a) where
  compare x y = compare (toList x) (toList y)
  
instance Arbitrary v => Arbitrary (Queue v) where
  arbitrary = fromList <$> arbitrary

instance Semigroup (Queue a) where
  append = join

instance Monoid (Queue a) where
  mempty = new

-- | Inserts Item at the head of queue Q1.
cons :: forall e. e -> Queue e -> Queue e
cons = ffi2 :queue :cons

-- | Returns the tail item of queue Q.
foreign import daeh :: forall e. Queue e -> Maybe e

-- | Remove the font element from Q.
drop :: forall e. Queue e -> Queue e
drop = ffi1 :queue :drop

-- | Remove the last element from Q.
dropR :: forall e. Queue e -> Queue e
dropR = ffi1 :queue :drop_r

filter :: forall e. (e -> Boolean) -> Queue e -> Queue e
filter = ffi2 :queue :filter

fromList :: forall e. List e -> Queue e
fromList = ffi1 :queue :from_list

-- | Return the front element of Queue.
get :: forall e. Queue e -> e
get = ffi1 :queue :get

-- | TODO: Return the ....
getR :: forall e. Queue e -> e
getR = ffi1 :queue :get_r

-- | Return the head element of Queue.
head :: forall e. Queue e -> e
head = ffi1 :queue :head

-- TODO: in/2
inR :: forall e. e -> Queue e -> Queue e
inR = ffi2 :queue :in_r

init :: forall e. Queue e -> Queue e
init = ffi1 :queue :init

isEmpty :: forall e. Queue e -> Boolean
isEmpty = ffi1 :queue :is_empty

join :: forall e. Queue e -> Queue e -> Queue e
join = ffi2 :queue :join

lait :: forall e. Queue e -> Queue e
lait = ffi1 :queue :lait

last :: forall e. Queue e -> e
last = ffi1 :queue :last

len :: forall e. Queue e -> Integer
len = ffi1 :queue :len

liat :: forall e. Queue e -> Queue e
liat = ffi1 :queue :liat

member :: forall e. e -> Queue e -> Boolean
member = ffi2 :queue :member

new :: forall e. Queue e
new = ffi0 :queue :new

foreign import out :: forall e. Queue e -> (Maybe e, Queue e)

foreign import outR :: forall e. Queue e -> (Maybe e, Queue e)
foreign import peek :: forall e. Queue e -> Maybe e
foreign import peekR :: forall e. Queue e -> Maybe e

reverse :: forall e. e -> Queue e -> Queue e
reverse = ffi1 :queue :reverse

snoc :: forall e. Queue e -> e -> Queue e
snoc = ffi2 :queue :snoc

split :: forall e. Integer -> Queue e -> (Queue e, Queue e)
split = ffi2 :queue :split

tail :: forall e. Queue e -> Queue e
tail = ffi1 :queue :tail

toList :: forall e. Queue e -> List e
toList = ffi1 :queue :to_list