#compdef netstat

local Wopt Xopt nopt="[don't resolve addresses to names]"
local lopt='[show only listening sockets]'
local zopt='-z[reset statistic counters after displaying them]'
local popt='(-f)-p+[filter by protocol]:protocol:compadd -a plist'
local Iopt='(-i)-I+[show information about the specified interface]:interface:_net_interfaces'
local set sel tblopt
local -A sets
local -a Mopts families flist plist args sockets extend interval verbose
local -a {sel_,}{bpf,dhcp,groups,interfaces,masquerade,media,memory,multicast,pcb,queues,rdomains,routing,statistics,wireless}

case $OSTYPE in
  linux-gnu)
    families=(
      '(-4 --inet)'{-4,--inet}
      '(-6 --inet)'{-4,--inet6}
      '(-A --protocol)'{-A+,--protocol=}':protocol:_sequence compadd - inet inet6 unix ipx ax25 netrom ddp bluetooth'
      --unix -x --ip --tcpip --ax25 --x25 --rose --ash
      --bluetooth --ipx --netrom --ddp --appletalk --econet --ec
    )
    extend=( \*{-e,--extend}'[show additional information]' )
    verbose=( '(-v --verbose)'{-v,--verbose}'[show what is going on]' )
    args=(
      '(-c --continuous)'{-c,--continuous}'[repeat information every second]'
      '!(-n --numeric)'{-N,--symbolic}
      '(-n --numeric)'{-n,--numeric}"$nopt"
      --numeric-hosts --numeric-ports --numeric-users
      '1: :_guard "[0-9]#" "repeat interval (seconds)"'
      - '(help)'
      '(- 1)'{-h,--help}'[display usage information]'
      '(- 1)'{-V,--version}'[display version information]'
    )
    sets=(
      routing    '(--route|-[^-]#r*)'
      groups     '(--groups|-[^-]#g*)'
      interfaces '(--interfaces|-[^-]#[iI]*)'
      statistics '(--statistics|-[^-]#s*)'
      masquerade '(--masquerade|-[^-]#M*)'
    )

    sel_routing=( '(-r --route)'{-r,--route}'[display routing table]' )
    sel_interfaces=(
      '(-I --interfaces)-i[display interface table]'
      '(-i -I --interfaces)'{--interface=-,-I=-}'[display interface table]::interface:_net_interfaces'
    )
    sel_groups=( '(-g --groups)'{-g,--groups}'[display multicast group memberships]' )
    sel_masquerade=( '(-M --masquerade)'{-M,--masquerade}'[display masqueraded connections]' )
    [[ -e /proc/net/ip_masquerade ]] || sel_masquerade=( \!${^sel_masquerade} )
    sel_statistics=( '(-s --statistics -c --continuous -n --numeric --numeric-hosts --numeric-ports --numeric-users)'{-s,--statistics}'[display networking statistics]' )

    sockets=(
      $families $verbose
      --tcp -t --udp -u --udplite -U --sctp -S --raw -w
      '(-2 --l2cap)'{-2,--l2cap}
      '(-f --rfcomm)'{-f,--rfcomm}
      '(-a --all -l --listening)'{-l,--listening}$lopt
      '(-a --all -l --listening)'{-a,--all}'[show all sockets]'
      --symbolic -N --extend -e
      '(--timers -o)'{--timers,-o}'[show information on networking timers]'
      '(--program -p)'{--program,-p}'[show process id and program name for sockets]'
      '(--wide -W)'{--wide,-W}"[don't truncate IP addresses in output]"
      '(-Z --context)'{-Z,--context}'[display SELinux security context for sockets]'
    )
    routing=(
      $families $extend $verbose
      '-C[display routing cache instead of FIB]'
    )
    interfaces=(
      $extend $verbose
      '(-a --all)'{-a,--all}'[show interfaces that are not up]'
    )
    groups=()
    masquerade=( $extend )
    statistics=( $families )
  ;;
  solaris*|darwin*|dragonfly*|freebsd*)
    families=( '(-p -4 -6)-f+[specify address family]:address family:compadd -a flist' )
  ;|
  freebsd*)
    families+=(
      '(-6 -f)-4[show IPv4 only]'
      '(-4 -f)-6[show IPv6 only]'
    )
  ;|
  (open|net)bsd*)
    popt='(-f)-p+[filter by protocol]:protocol:compadd - ${(M)${(f)"$(</etc/protocols)"}##[a-z0-9]#}'
    families=(
      '(-u)-f+[specify address family]:address family:_sequence compadd - -a flist'
      '(-f)-u[limit reports to the unix address family]' # undocumented on NetBSD
    )
  ;|
  *) # everything except linux
    sets=(
      routing    '-[^-]#r*'
      groups     '-[^-]#g*'
      interfaces '-[^-]#[iIw]*'
      memory     '-[^-]#m*'
      statistics '-[^-]#s*'
    )
    flist=( inet inet6 unix )
    verbose=( '-v[verbose]' )
    sel_routing=( '-r[display routing table]' )
    sel_groups=( '-g[display multicast group memberships]' )
    sel_interfaces=( $Iopt '-i[display interface table]' )
    sel_statistics=( '*-s[display per protocol statistics]' )
    sockets=( $families -n$nopt '-a[show all sockets]' )
    routing=( -n$nopt )
    interfaces=( $families -n$nopt )
    statistics=( $families )
  ;|
  (open|net)bsd*)
    sets+=( pcb '-[^-]#P*' )
    sel_pcb=( '-P+[display contents of the protocol control block]:pcb' )
    routing+=( $verbose '(-L)-s[show routing statistics]' )
    groups+=( $families
      '(-s)-l[display wider fields for the IPv6 multicast routing table]'
      '(-l)-s[show multicast routing statistics]'
    )
    interfaces+=(
      '(-p)-s[show interface statistics]'
    )
  ;|
  darwin*|dragonfly*|(net|free|open)bsd*)
    sockets+=( '-A[show address of a PCB associated with sockets]' )
    interfaces+=(
      '-b[show the number of bytes in and out]'
      '-d[show the number of dropped packets]'
      '1: :_guard "[0-9]#" "repeat interval (seconds)"'
    )
    routing=( $families )
    sel_memory=( '-m[display statistics recorded by the memory management routines]' )
    sel_interfaces+=( '(1 -a -f -i -p -s -u)-w+[display packet traffic at intervals]:interval (seconds)' )
  ;|
  darwin*|dragonfly*|(net|free)bsd*)
    interfaces+=( '-a[show multicast addresses currently in use]' )
  ;|
  dragonfly*|(net|free|open)bsd*)
    Mopts=(
      '-M+[extract values from specified core]:core file:_files'
      '-N+[extract name list from specified system image]:system image:_files'
    )
    interfaces+=(
      '-h[print all counters in human readable form]'
    )
    sockets+=( $Mopts )
  ;|
  darwin*|dragonfly*|freebsd*)
    Wopt='-W+[avoid truncating fields even if it causes overflow]'
    sockets+=( $Wopt
      '-L[show size of listen queues]'
    )
    groups+=( $Wopt )
  ;|
  dragonfly*|netbsd*|freebsd*)
    sockets+=( '(-n)-S[show network addresses as numbers but show ports symbolically]' )
  ;|
  netbsd*|freebsd*)
    sets+=( bpf '-[^-]#B*' )
    sel_bpf=( '-B[display statistics about bpf(4) peers]' )
  ;|
  dragonfly*|freebsd*)
    plist=( divert icmp igmp ip ipsec pim tcp udp icmp6 ip6 rip6 tcp udp pfkey ctrl data )
    sockets+=( $popt )
    statistics+=( $popt $zopt $Mopts )
    memory+=( $Mopts )
    routing+=( $Mopts $zopt
      '(-A -a -f -l -n -W)*-s[show routing statistics]'
      '-W[show path MTU for each route]'
    )
    groups+=( $families $Mopts
    '(-W)*-s[show multicast routing statistics; repeat to suppress those with zero counters]'
    )
  ;|

  solaris2.<11->)
    sets+=( dcache '-[^-]#d*' )
    sel_dcache=( '-d[display the destination cache entry table]' )
    dcache=( $families )
    args=( '-T+[specify time format]:time format:((u\:seconds\ since\ epoch d\:standard\ date\ format))' )
    sockets+=(
      '-u[list user, pid and program that created network endpoint]'
      '-k[show only sockets with kernel data path bypass enabled]'
      '-L[only show state of sockets using SO_REUSEPORT load balancing]'
    )
  ;&
  solaris*)
    args=( -A '-*' $args )
    interval=(
      '1: :_guard "[0-9]#" "repeat interval (seconds)"'
      '2: :_guard "[0-9]#" "count"'
    )
    sets+=(
      dhcp      '-[^-]#D*'
      media     '-[^-]#p*'
      multicast '-[^-]#M*'
    )
    sel_media=( '-p[display net to media tables]' )
    sel_memory=( '-m[display STREAMS memory statistics]' )
    sel_multicast=( '-M[display multicast routing tables]' )
    sel_dhcp=( '-D[display status of DHCP configured interfaces]' )
    sockets+=(
      $verbose
      '-R[show extended security attributes]'
      '-P[specify protocol]:protocol:(ip ipv6 icmp icmpv6 igmp udp tcp rawip)'
    )
    routing+=( $verbose
      '*-f+[filter routing table]:rule:_values -S \: "filter rule" $flist
	"af[specify address family]\:family\:(inet inet6 unix)"
        "outif[specify output interface]\:interface\:_net_interfaces"
        "dst[specify destination IP]\:IP address"
        "flags[select routes tagged with flags]\:flags"' \
      '-a[show state of all routing tables]'
      '-R[show extended security attributes]'
    )
    groups+=( $families -n$nopt $verbose )
    interfaces+=( $interval
      '-a[show state of all interfaces]'
    )
    statistics+=(
      '-P[specify protocol]:protocol:(ip ipv6 icmp icmpv6 igmp udp tcp rawip)'
    )
    media=( -n$nopt $families )
    memory+=( $verbose $interval )
    multicast+=(
      -n$nopt $families
      '-s[show per protocol statistics]'
    )
    dhcp=( $families $Iopt )
  ;;
  darwin*)
    sets+=( queues '-[^-]#q*' )
    sel_queues=( '*-q[display network interface send queue statistics]' )
    sel_memory=( \*$sel_memory )
    sockets+=(
      '-l[show full IPv6 address]'
      '-W[avoid truncating addresses]'
    )
    routing+=( '-l[show mtu and use wider display]' )
    interfaces+=(
      '(-x)-R[show reachability information]'
      '-S[show interface link status and state]'
      '(-R)-x[show extended reachability information]'
    )
    queues=( $Iopt
      '-c+[limit statistics to specified queue]:queue'
    )
    groups+=( $families
      '*-v[show link-layer memberships; repeat for timers and counters]'
    )
  ;;
  dragonfly*)
    plist+=( carp )
    sockets+=(
      '-P[show additional protocol-specific information]'
      '-c+[access cpu specific route table]:cpu'
    )
    interfaces+=( $zopt
      '-B[show maximum buffer sizes instead of current buffer usage]'
      '-t[show the contents of watchdog timers]'
      '(-a -B -b -d -h -n -t -w)*-s[show protocol statistics; repeat to suppress those with zero counters]'
    )
    routing+=(
      '-A[show contents of internal Patricia tree structures]'
      '-a[show protocol-cloned routes]'
    )
  ;;
  openbsd*)
    sets+=( wireless '-W*' rdomains '-R' )
    sel_rdomains=( '-R[show all rdomains with associated interfaces and routing tables]' )
    sel_wireless=( '-W+[display per-interface IEEE 802.11 wireless statistics]:interface' )
    flist+=( local mpls )
    tblopt='-T+[select an alternate routing table to query]:routing table:_routing_tables'
    sockets+=( -l$lopt $tblopt '-B[show buffer sizes for TCP sockets]' )
    routing+=( $Mopts $tblopt
      '-A[show the internal addresses of the routing table]'
      '-F[only show routes with gateway in the same address family as the destination]'
    )
    interfaces+=(
      '-c+[show specified number of updates, then exit]:count'
      '-e[show only the number of errors on the interface]'
      '-q[only show interfaces that have seen packets]'
    )
    statistics+=( $popt '-r[display routing statistics]' )
    groups+=( -n$nopt )
    pcb+=( $Mopts $verbose )
  ;;
  netbsd*)
    popt='(-f)-p+[filter by protocol]:protocol:compadd - ${(M)${(f)"$(</etc/protocols)"}##[a-z0-9]#}'
    Xopt='-X[force use of sysctl(3) when retrieving information]'
    flist+=( arp ns atalk mpls local )
    sets+=( queues '-[^-]#q*' )
    sel_queues=( '-q[display software interrupt queue details for all protocols]' )
    routing+=( $Xopt
      "(-s)-L[don't show link-level routes]"
      '-T[show MPLS tags for the routing tables]'
    )
    bpf+=( $Xopt $Iopt
      '-s[show bpf(4) statistics]'
    )
    interfaces+=( $Xopt )
    memory+=( $Xopt) statistics+=( $Xopt )
    pcb+=( $Mopts $popt )
  ;;
  freebsd<13->.*)
    sockets+=(
      '-c[show TCP stack used for each session]'
      '-C[show TCP congestion control algorithm and diagnostic]'
    )
  ;&
  freebsd<11->.*)
    routing+=( '-F+[show specified routing table]:routing table' )
    bpf=( '-z[reset statistic counters after displaying them]' )
    statistics+=( $bpf[-1] )
  ;&
  freebsd*)
    flist+=( pfkey netgraph ng link )
    plist+=( sctp ipsec6 pfkey )

    sets+=( netisr  '-[^-]#Q*' )
    sel_netisr=( '-Q[display netisr(9) statistics]' )
    sockets+=(
      '-R[show flowid and flowtype for each socket]'
      '-T[show diagnostic information from the TCP control block]'
      '-x[show socket buffer and TCP timer statistics]'
    )
    interfaces+=(
      $popt $Mopts $Iopt $Wopt
      '-q+[exit after specified number of outputs]:number'
    )
    bpf+=( $Iopt $zopt )
  ;;
esac

# Ignore display specific options except the default (socket) display until a
# display has been selected. This is not strictly correct (options can be in
# any order) but makes the completion much more useful. Descriptions for
# options that select a specific display (option set) typically start with
# "display" to set them apart from other options.
sock=''
for set in ${(k)sets}; do
  sel=sel_$set
  if [[ -z $words[(r)$~sets[$set]] ]]; then
    ign='!'
  else
    sock='!'
    ign=''
  fi
  args+=( - "$set" ${(P)sel} ${ign}${(P)^set} )
done
args+=( - sockets ${sock}${sockets} )

_arguments -s -S $args