{-|
    Module      :  Data.Number.MPFR.Comparison
    Description :  wrappers for comparison functions
    Copyright   :  (c) Aleš Bizjak
    License     :  BSD3

    Maintainer  :  ales.bizjak0@gmail.com
    Stability   :  experimental
    Portability :  non-portable

 Comparison functions. All the functions that return Maybe Ordering return Nothing
 when one of the operands is NaN and  Just _ otherwise.

-}

{-# INCLUDE <mpfr.h> #-}
{-# INCLUDE <chsmpfr.h> #-}

module Data.Number.MPFR.Comparison where

import Data.Number.MPFR.Misc

import Data.Number.MPFR.Internal

import Prelude hiding (isNaN)

import Data.Maybe

cmp         :: MPFR -> MPFR -> Maybe Ordering
cmp mp1 mp2 = if isNaN mp1 || isNaN mp2 then Nothing 
                else Just (compare (withMPFRBB mp1 mp2 mpfr_cmp) 0)

cmpw       :: MPFR -> Word -> Maybe Ordering
cmpw mp1 w = if isNaN mp1 then Nothing else Just (compare (unsafePerformIO go) 0)
    where go = with mp1 $ \p -> mpfr_cmp_ui p (fromIntegral w) 

cmpi       :: MPFR -> Int -> Maybe Ordering
cmpi mp1 i = if isNaN mp1 then Nothing else Just (compare (unsafePerformIO go) 0)
    where go = with mp1 $ \p -> mpfr_cmp_si p (fromIntegral i)

cmpd       :: MPFR -> Double -> Maybe Ordering
cmpd mp1 d = unsafePerformIO go
    where go = do mpfr_clear_erangeflag
                  with mp1 $ \p -> do
                    r1 <- mpfr_cmp_d p (realToFrac d)
                    r2 <- mpfr_erangeflag_p
                    if r2 == 0 then return (Just (compare r1 0))
                      else do mpfr_clear_erangeflag
                              return Nothing
                    
cmp2w       :: MPFR -> Word -> Exp -> Maybe Ordering
cmp2w d w e = unsafePerformIO go
    where go = do mpfr_clear_erangeflag
                  with d $ \p -> do
                    r1 <- mpfr_cmp_ui_2exp p (fromIntegral w) e
                    r2 <- mpfr_erangeflag_p
                    if r2 == 0 then return (Just (compare r1 0))
                      else do mpfr_clear_erangeflag
                              return Nothing

cmp2i       :: MPFR -> Int -> Exp -> Maybe Ordering
cmp2i d w e = unsafePerformIO go
    where go = do mpfr_clear_erangeflag
                  with d $ \p -> do
                    r1 <- mpfr_cmp_si_2exp p (fromIntegral w) e
                    r2 <- mpfr_erangeflag_p
                    if r2 == 0 then return (Just (compare r1 0))
                      else do mpfr_clear_erangeflag
                              return Nothing
cmpabs         :: MPFR -> MPFR -> Maybe Ordering
cmpabs mp1 mp2 = if isNaN mp1 || isNaN mp2 then Nothing 
                   else Just (compare (withMPFRBB mp1 mp2 mpfr_cmpabs) 0)

isNaN   :: MPFR -> Bool
isNaN d = withMPFRB d mpfr_nan_p /= 0

isInfinite   :: MPFR -> Bool
isInfinite d = withMPFRB d mpfr_inf_p /= 0 

isNumber   :: MPFR -> Bool
isNumber d = withMPFRB d mpfr_number_p /= 0 

isZero   :: MPFR -> Bool
isZero d = withMPFRB d mpfr_zero_p /= 0

sgn     :: MPFR -> Maybe Int 
sgn mp1 = case (cmpw mp1 0) of
            Nothing -> Nothing
            Just x -> Just (pred . fromEnum $ x)

-- TODO Maybe Bool????
greater       :: MPFR -> MPFR -> Bool
greater d1 d2 = withMPFRBB d1 d2 mpfr_greater_p /= 0

greatereq       :: MPFR -> MPFR -> Bool
greatereq d1 d2 = withMPFRBB d1 d2 mpfr_greaterequal_p /= 0

less       :: MPFR -> MPFR -> Bool
less d1 d2 = withMPFRBB d1 d2 mpfr_less_p /= 0

lesseq       :: MPFR -> MPFR -> Bool
lesseq d1 d2 = withMPFRBB d1 d2 mpfr_lessequal_p /= 0

lessgreater       :: MPFR -> MPFR -> Maybe Bool
lessgreater d1 d2 = if isNaN d1 || isNaN d2 then Nothing 
                      else Just (withMPFRBB d1 d2 mpfr_lessgreater_p /= 0)

equal       :: MPFR -> MPFR -> Bool
equal d1 d2 = withMPFRBB d1 d2 mpfr_equal_p /= 0

unordered       :: MPFR -> MPFR -> Maybe Bool
unordered d1 d2 = if isNaN d1 || isNaN d2 then Nothing 
                    else Just (withMPFRBB d1 d2 mpfr_unordered_p /= 0)


instance Eq MPFR where
    (==) = equal

instance Ord MPFR where
    compare d d' = fromMaybe GT (cmp d d')
    (<)          = less
    (<=)         = lesseq
    (>)          = greater
    (>=)         = greatereq
    max d d'     = maxD Zero (maxPrec d d') d d'
    min d d'     = minD Zero (maxPrec d d') d d'