module Maskable where

import Test.HUnit

import qualified Bit as B
import IPv4Address
import Maskbits
import Octet

-- Any string of bits should be maskable by some number of netmask
-- bits. The convention of the Maskable typeclass follows CIDR
-- notation, where the number of mask bits (the number after the
-- slash) denotes how many bits are reserved for the network.
--
-- So, a mask of 32 applied to an address of 127.0.0.1 will again
-- return 127.0.0.1. Likewise, 31 mask bits applied to 127.0.0.1
-- should return 127.0.0.0, since 127.0.0.1/31 matches both 127.0.0.0
-- and 127.0.0.1. In this case, the final '0' or '1' is the host
-- part of the address. The '127.0.0' is thus the network part.
class Maskable a where
    apply_mask :: a -> Maskbits -> a


instance Maskable Octet where
    apply_mask _ Maskbits.None = Octet.None
    apply_mask Octet.None _    = Octet.None
    apply_mask oct mask
        | mask == Eight = oct
        | mask == Seven = oct { b8 = B.Zero }
        | mask == Six = oct { b8 = B.Zero, b7 = B.Zero }
        | mask == Five = oct { b8 = B.Zero, b7 = B.Zero, b6 = B.Zero }
        | mask == Four = oct { b8 = B.Zero, b7 = B.Zero, b6 = B.Zero, b5 = B.Zero }
        | mask == Three = oct { b8 = B.Zero, b7 = B.Zero, b6 = B.Zero, b5 = B.Zero, b4 = B.Zero }
        | mask == Two = oct { b8 = B.Zero, b7 = B.Zero, b6 = B.Zero, b5 = B.Zero, b4 = B.Zero, b3 = B.Zero }
        | mask == One = oct { b8 = B.Zero, b7 = B.Zero, b6 = B.Zero, b5 = B.Zero, b4 = B.Zero, b3 = B.Zero, b2 = B.Zero }
        | mask == Zero = min_octet
        | otherwise = Octet.None



instance Maskable IPv4Address where
    apply_mask _ Maskbits.None = IPv4Address.None
    apply_mask addr mask
        | mask == ThirtyTwo = ipv4address_from_octets oct1 oct2 oct3 oct4
        | mask == ThirtyOne = ipv4address_from_octets oct1 oct2 oct3 (apply_mask oct4 Seven)
        | mask == Thirty = ipv4address_from_octets oct1 oct2 oct3 (apply_mask oct4 Six)
        | mask == TwentyNine = ipv4address_from_octets oct1 oct2 oct3 (apply_mask oct4 Five)
        | mask == TwentyEight = ipv4address_from_octets oct1 oct2 oct3 (apply_mask oct4 Four)
        | mask == TwentySeven = ipv4address_from_octets oct1 oct2 oct3 (apply_mask oct4 Three)
        | mask == TwentySix = ipv4address_from_octets oct1 oct2 oct3 (apply_mask oct4 Two)
        | mask == TwentyFive = ipv4address_from_octets oct1 oct2 oct3 (apply_mask oct4 One)
        | mask == TwentyFour = ipv4address_from_octets oct1 oct2 oct3 (min_octet)
        | mask == TwentyThree = ipv4address_from_octets oct1 oct2 (apply_mask oct3 Seven) (min_octet)
        | mask == TwentyTwo = ipv4address_from_octets oct1 oct2 (apply_mask oct3 Six) (min_octet)
        | mask == TwentyOne = ipv4address_from_octets oct1 oct2 (apply_mask oct3 Five) (min_octet)
        | mask == Twenty = ipv4address_from_octets oct1 oct2 (apply_mask oct3 Four) (min_octet)
        | mask == Nineteen = ipv4address_from_octets oct1 oct2 (apply_mask oct3 Three) (min_octet)
        | mask == Eighteen = ipv4address_from_octets oct1 oct2 (apply_mask oct3 Two) (min_octet)
        | mask == Seventeen = ipv4address_from_octets oct1 oct2 (apply_mask oct3 One) (min_octet)
        | mask == Sixteen = ipv4address_from_octets oct1 oct2 (min_octet) (min_octet)
        | mask == Fifteen = ipv4address_from_octets oct1 (apply_mask oct2 Seven) (min_octet) (min_octet)
        | mask == Fourteen = ipv4address_from_octets oct1 (apply_mask oct2 Six) (min_octet) (min_octet)
        | mask == Thirteen = ipv4address_from_octets oct1 (apply_mask oct2 Five) (min_octet) (min_octet)
        | mask == Twelve = ipv4address_from_octets oct1 (apply_mask oct2 Four) (min_octet) (min_octet)
        | mask == Eleven = ipv4address_from_octets oct1 (apply_mask oct2 Three) (min_octet) (min_octet)
        | mask == Ten = ipv4address_from_octets oct1 (apply_mask oct2 Two) (min_octet) (min_octet)
        | mask == Nine = ipv4address_from_octets oct1 (apply_mask oct2 One) (min_octet) (min_octet)
        | mask == Eight = ipv4address_from_octets oct1 (min_octet) (min_octet) (min_octet)
        | mask == Seven = ipv4address_from_octets (apply_mask oct1 Seven) (min_octet) (min_octet) (min_octet)
        | mask == Six = ipv4address_from_octets (apply_mask oct1 Six) (min_octet) (min_octet) (min_octet)
        | mask == Five = ipv4address_from_octets (apply_mask oct1 Five) (min_octet) (min_octet) (min_octet)
        | mask == Four =  ipv4address_from_octets (apply_mask oct1 Four) (min_octet) (min_octet) (min_octet)
        | mask == Three = ipv4address_from_octets (apply_mask oct1 Three) (min_octet) (min_octet) (min_octet)
        | mask == Two = ipv4address_from_octets (apply_mask oct1 Two) (min_octet) (min_octet) (min_octet)
        | mask == One = ipv4address_from_octets (apply_mask oct1 One) (min_octet) (min_octet) (min_octet)
        | mask == Zero = ipv4address_from_octets (min_octet) (min_octet) (min_octet) (min_octet)
        | otherwise = IPv4Address.None
        where
          oct1 = (octet1 addr)
          oct2 = (octet2 addr)
          oct3 = (octet3 addr)
          oct4 = (octet4 addr)



-- HUnit Tests

test_octet_mask1 =
    TestCase $ assertEqual "The network bits of 255/4 should equal 240" oct2 (apply_mask oct1 Four)
    where
      oct1 = octet_from_int 255
      oct2 = octet_from_int 240


test_octet_mask2 =
    TestCase $ assertEqual "The network bits of 255/1 should equal 128" oct2 (apply_mask oct1 One)
    where
      oct1 = octet_from_int 255
      oct2 = octet_from_int 128


maskable_tests = [ test_octet_mask1,
                   test_octet_mask2 ]