use re
use str

fn is-ipv4 [arg]{
  if (not (re:match '^([0-9]{1,3}\.){3}[0-9]{1,3}$' $arg)) {
    put $false
  } else {
    use ./list
    not (str:split '.' $arg | list:contains [p]{ > $p 255 })
  }
}

fn is-ipv6 [arg]{
  var p     = '[0-9a-fA-F]{1,4}'
  var g1 g2 = '('$p':)' '(:'$p')'
  var cases = [
    $g1'{7,7}'$p
    $g1'{1,7}:'
    $g1'{1,6}:'$p
    $g1'{1,5}'$g2'{1,2}'
    $g1'{1,4}'$g2'{1,3}'
    $g1'{1,3}'$g2'{1,4}'
    $g1'{1,2}'$g2'{1,5}'
    $p':'$g2'{1,6}'
    ':'$g2'{1,7}'
    '::'
  ]
  var r = '^('(str:join '|'  $cases)')$'
  put (re:match $r $arg)
}

fn is-ip [arg]{ or (is-ipv4 $arg) (is-ipv6 $arg) }

fn -long-part6 [p]{
  use str
  set p = (str:to-lower $p)
  var c = (- 4 (count $p))
  put (repeat $c '0' | str:join '')$p
}

fn -middle-part6 [p]{
  while (and (> (count $p) 1) (eq $p[0] 0)) {
    set p = $p[1..]
  }
  put $p
}

fn -find-max0 [parts]{
  use ./list
  var idx s   = -1 1
  var ci cs f = -1 0 $false
  list:loop [i p]{
    if (eq $p 0) {
      condition:call $f { set cs = (+ $cs 1) } { set ci cs f = $i 1 $true }
    } elif $f {
      set f = $false
      if (> $cs $s) {
        set idx s = $ci $cs
      }
    }
  } $parts
  if (and $f (> $cs $s)) {
    set idx s = $ci $cs
  }
  put $idx $s
}

fn long6 [ip]{
  if (not (is-ipv6 $ip)) {
    fail 'Not an IPv6'
  }
  if (eq $ip '::') {
    repeat 8 '0000' | str:join ':'
    return
  }
  var c = (- 7 (str:count $ip ':'))
  if (> $c 0) {
    var i = (str:index $ip '::')
    var z = (repeat $c ':' | str:join '')
    set ip    = (str:join '' [$ip[..$i] $z $ip[{$i}..]])
  }
  str:split ':' $ip | each $-long-part6~ | str:join ':'
}

fn middle6 [ip]{
  str:split ':' (long6 $ip) | each $-middle-part6~ | str:join ':'
}

fn short6 [ip]{
  var parts = [(str:split ':' (middle6 $ip))]
  var i s   = (-find-max0 $parts)
  if (>= $i 0) {
    var left right = $parts[..$i] $parts[(+ $i $s)..]
    if (== (count $left) 0) {
      set left = ['']
    }
    if (== (count $right) 0)  {
      set right = ['']
    }
    set parts = [$@left '' $@right]
  }
  str:join ':' $parts
}

fn is-ip [arg]{ or (is-ipv4 $arg) (is-ipv6 $arg) }

fn -cmp [e1 e2]{
  use ./list
  use ./condition
  var c = 0
  list:loop [i p1]{
    var p2 = $e2[$i]
    set c = (condition:cset (< $p1 $p2) -1 (condition:cset (> $p1 $p2) 1 0))
    if (!= $c 0) {
      break
    }
  } $e1
  put $c
}

fn cmp4 [ip1 ip2]{
  if (or (not (is-ipv4 $ip1)) (not (is-ipv4 $ip2))) {
    fail 'Not an IPv4 '$ip1' → '$ip2
  }
  -cmp [(str:split . $ip1)] [(str:split . $ip2)]
}

fn cmp6 [ip1 ip2]{
  if (or (not (is-ipv6 $ip1)) (not (is-ipv6 $ip2))) {
    fail 'Not an IPv6: '$ip1' → '$ip2
  }
  -cmp [(str:split : (middle6 $ip1))] [(str:split : (middle6 $ip2))]
}

fn cmp [ip1 ip2]{
  if (is-ipv4 $ip1) {
    if (is-ipv4 $ip2) {
      cmp4 $ip1 $ip2
    } else {
      put -1
    }
  } elif (is-ipv6 $ip1) {
    if (is-ipv4 $ip2) {
      put 1
    } elif (is-ipv6 $ip2) {
      cmp6 $ip1 $ip2
    } else {
      put -1
    }
  } else {
    fail 'Not an IP: '$ip1' → '$ip2
  }
}