module Maskable where

import Bit
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 oct (Maskbits maskbits)
        | maskbits == 8 = oct
        | maskbits == 7 = oct { b8 = Zero }
        | maskbits == 6 = oct { b8 = Zero, b7 = Zero }
        | maskbits == 5 = oct { b8 = Zero, b7 = Zero, b6 = Zero }
        | maskbits == 4 = oct { b8 = Zero, b7 = Zero, b6 = Zero, b5 = Zero }
        | maskbits == 3 = oct { b8 = Zero, b7 = Zero, b6 = Zero, b5 = Zero, b4 = Zero }
        | maskbits == 2 = oct { b8 = Zero, b7 = Zero, b6 = Zero, b5 = Zero, b4 = Zero, b3 = Zero }
        | maskbits == 1 = oct { b8 = Zero, b7 = Zero, b6 = Zero, b5 = Zero, b4 = Zero, b3 = Zero, b2 = Zero }
        | maskbits == 0 = min_octet
        | otherwise = Octet.None



instance Maskable IPv4Address where
    apply_mask _ Maskbits.None = IPv4Address.None
    apply_mask addr (Maskbits mask)
        | mask == 32 = ipv4address_from_octets oct1 oct2 oct3 oct4
        | mask == 31 = ipv4address_from_octets oct1 oct2 oct3 (apply_mask oct4 (Maskbits 1))
        | mask == 30 = ipv4address_from_octets oct1 oct2 oct3 (apply_mask oct4 (Maskbits 2))
        | mask == 29 = ipv4address_from_octets oct1 oct2 oct3 (apply_mask oct4 (Maskbits 3))
        | mask == 28 = ipv4address_from_octets oct1 oct2 oct3 (apply_mask oct4 (Maskbits 4))
        | mask == 27 = ipv4address_from_octets oct1 oct2 oct3 (apply_mask oct4 (Maskbits 5))
        | mask == 26 = ipv4address_from_octets oct1 oct2 oct3 (apply_mask oct4 (Maskbits 6))
        | mask == 25 = ipv4address_from_octets oct1 oct2 oct3 (apply_mask oct4 (Maskbits 7))
        | mask == 24 = ipv4address_from_octets oct1 oct2 oct3 (min_octet)
        | mask == 23 = ipv4address_from_octets oct1 oct2 (apply_mask oct3 (Maskbits 1)) (min_octet)
        | mask == 22 = ipv4address_from_octets oct1 oct2 (apply_mask oct3 (Maskbits 2)) (min_octet)
        | mask == 21 = ipv4address_from_octets oct1 oct2 (apply_mask oct3 (Maskbits 3)) (min_octet)
        | mask == 20 = ipv4address_from_octets oct1 oct2 (apply_mask oct3 (Maskbits 4)) (min_octet)
        | mask == 19 = ipv4address_from_octets oct1 oct2 (apply_mask oct3 (Maskbits 5)) (min_octet)
        | mask == 18 = ipv4address_from_octets oct1 oct2 (apply_mask oct3 (Maskbits 6)) (min_octet)
        | mask == 17 = ipv4address_from_octets oct1 oct2 (apply_mask oct3 (Maskbits 7)) (min_octet)
        | mask == 16 = ipv4address_from_octets oct1 oct2 (min_octet) (min_octet)
        | mask == 15 = ipv4address_from_octets oct1 (apply_mask oct2 (Maskbits 1)) (min_octet) (min_octet)
        | mask == 14 = ipv4address_from_octets oct1 (apply_mask oct2 (Maskbits 2)) (min_octet) (min_octet)
        | mask == 13 = ipv4address_from_octets oct1 (apply_mask oct2 (Maskbits 3)) (min_octet) (min_octet)
        | mask == 12 = ipv4address_from_octets oct1 (apply_mask oct2 (Maskbits 4)) (min_octet) (min_octet)
        | mask == 11 = ipv4address_from_octets oct1 (apply_mask oct2 (Maskbits 5)) (min_octet) (min_octet)
        | mask == 10 = ipv4address_from_octets oct1 (apply_mask oct2 (Maskbits 6)) (min_octet) (min_octet)
        | mask == 9 = ipv4address_from_octets oct1 (apply_mask oct2 (Maskbits 7)) (min_octet) (min_octet)
        | mask == 8 = ipv4address_from_octets oct1 (min_octet) (min_octet) (min_octet)
        | mask == 7 = ipv4address_from_octets (apply_mask oct1 (Maskbits 1)) (min_octet) (min_octet) (min_octet)
        | mask == 6 = ipv4address_from_octets (apply_mask oct1 (Maskbits 2)) (min_octet) (min_octet) (min_octet)
        | mask == 5 = ipv4address_from_octets (apply_mask oct1 (Maskbits 3)) (min_octet) (min_octet) (min_octet)
        | mask == 4 =  ipv4address_from_octets (apply_mask oct1 (Maskbits 4)) (min_octet) (min_octet) (min_octet)
        | mask == 3 = ipv4address_from_octets (apply_mask oct1 (Maskbits 5)) (min_octet) (min_octet) (min_octet)
        | mask == 2 = ipv4address_from_octets (apply_mask oct1 (Maskbits 6)) (min_octet) (min_octet) (min_octet)
        | mask == 1 = ipv4address_from_octets (apply_mask oct1 (Maskbits 7)) (min_octet) (min_octet) (min_octet)
        | mask == 0 = 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)