#compdef ftp rwho rup xping traceroute host aaaa zone mx ns soa txt

# avoid calling variable "hosts", it's an obvious candidate for use in
#  zstyle -e '*' hosts 'reply=($hosts)'
local expl _hosts tmp useip

if ! zstyle -a ":completion:${curcontext}:hosts" hosts _hosts; then
  if (( $+_cache_hosts == 0 )); then
    # uniquify
    typeset -gUa _cache_hosts
    local ipstrip='[:blank:]#[^[:blank:]]#'

    # This boolean style determines whether hosts completes IP addresses. The
    # default is no (not using IP addresses).
    zstyle -t ":completion:${curcontext}:hosts" use-ip && useip=yes
    [[ -n $useip ]] && ipstrip=
    if (( ${+commands[getent]} )); then
      # pws: we were using the horrible ": ${(A)...:=}" syntax to assign
      # to _cache_hosts, overriding the typeset as well as being unreadable
      # and having obscure splitting behaviour.  Why?  We've just
      # tested _cache_hosts doesn't exist.
      _cache_hosts=(${(s: :)${(ps:\t:)${(f)~~"$(_call_program hosts getent hosts 2>/dev/null)"}##${~ipstrip}}})
    else
      _cache_hosts=(${(s: :)${(ps:\t:)${${(f)~~"$(</etc/hosts)"}%%\#*}##${~ipstrip}}})
      if (( ${+commands[ypcat]} )) &&
    	tmp=$(_call_program hosts ypcat hosts.byname 2>/dev/null); then
        _cache_hosts+=( ${=${(f)tmp}##${~ipstrip}} ) # If you use YP
      fi
    fi

    local khostfile
    typeset -Ua khostfiles

    # This style specifies a list of files to look up for host names and IP
    # addresses, if asked to. The files can contain comma separated host names
    # and IP's, and any text on a line after the first whitespace,| or # is
    # discarded. ssh's known_hosts files are thus supported. This style defaults
    # to the list /etc/ssh/ssh_known_hosts, ~/.ssh/known_hosts
    zstyle -a ":completion:${curcontext}:hosts" known-hosts-files khostfiles ||
    khostfiles=(/etc/ssh/ssh_known_hosts ~/.ssh/known_hosts)

    for khostfile in $khostfiles; do
      if [[ -r $khostfile ]]; then
        khosts=(${(s/,/j/,/u)${(f)"$(<$khostfile)"}%%[ |#]*})

        # known_hosts syntax supports the host being in the form [hostname]:port
        # The filter below extracts the hostname from lines using this format.
        khosts=($(for host ($khosts); do
          if [[ $host =~ "\[(.*)\]:\d*" ]]; then
            echo $match
          else
            echo $host
          fi
        done))

        if [[ -z $useip ]]; then
          khosts=(${${khosts:#(#s)[0-9]##.[0-9]##.[0-9]##.[0-9]##(#e)}:#(#s)[0-9a-f:]##(#e)})
        fi
        _cache_hosts+=($khosts)
      fi
    done
  fi

  _hosts=( "$_cache_hosts[@]" )
fi

_wanted hosts expl host \
    compadd -M 'm:{a-zA-Z}={A-Za-z} r:|.=* r:|=*' -a "$@" - _hosts
