module main

import encoding.binary

type Addr = [4]u8

fn Addr.from_u32(a u32) Addr {
    mut bytes := [4]u8{}
    binary.big_endian_put_u32_fixed(mut bytes, a)
    return Addr(bytes)
}

fn (a Addr) str() string {
    return '${a[0]}.${a[1]}.${a[2]}.${a[3]}'
}

fn (a Addr) u32() u32 {
    return binary.big_endian_u32_fixed(a)
}

struct Net {
    netaddr   Addr
    broadcast Addr
mut:
    h u32
}

fn (mut n Net) next() ?Addr {
    if n.h >= n.broadcast.u32() + 1 {
        return none
    }
    defer {
        n.h++
    }
    return Addr.from_u32(n.h)
}

fn test_main() {
    net := Net{
        netaddr:   Addr([u8(172), 16, 16, 0]!)
        broadcast: Addr([u8(172), 16, 16, 3]!)
        h:         u32(2886733824)
    }
    mut rets := []string{}
    for addr in net {
        rets << addr.str()
    }
    assert rets[0] == '172.16.16.0'
    assert rets[1] == '172.16.16.1'
    assert rets[2] == '172.16.16.2'
    assert rets[3] == '172.16.16.3'
}