#!/usr/bin/env bash
# Bash completion support for ssh.

export COMP_WORDBREAKS=${COMP_WORDBREAKS/\:/}

_sshcomplete() {
    local CURRENT_PROMPT="${COMP_WORDS[COMP_CWORD]}"
    if [[ ${CURRENT_PROMPT} == *@*  ]] ; then
      local OPTIONS="-P ${CURRENT_PROMPT/@*/}@ -- ${CURRENT_PROMPT/*@/}"
    else
      local OPTIONS=" -- ${CURRENT_PROMPT}"
    fi

    # Parse defined hosts from all ssh configuration files (taking "Include" directives into consideration).
    # The solution relies on ssh printing the configuration files paths in verbose mode.
    #
    # We try to connect to localhost on port 4, which is reserved and should be unused.
    # In case there is an ssh server listening on that port, we ask ssh to "do nothing" by executing "echo" remotely.
    config_files="$(ssh -v 127.0.0.1 -p 4 echo 2>&1 | sed -n '/Reading configuration data/ s/.*Reading configuration data \([^\r]*\).*/\1/gp')"
    for file in $config_files
    do
        COMPREPLY=(${COMPREPLY[@]} $(compgen -W "$(grep ^Host "${file}" | awk '{for (i=2; i<=NF; i++) print $i}' )" ${OPTIONS}) )
    done

    # parse all hosts found in .ssh/known_hosts
    if [ -r "$HOME/.ssh/known_hosts" ]; then
        if grep -v -q -e '^ ssh-rsa' "$HOME/.ssh/known_hosts" ; then
            COMPREPLY=( ${COMPREPLY[@]} $(compgen -W "$( awk '{print $1}' "$HOME/.ssh/known_hosts" | grep -v ^\| | cut -d, -f 1 | sed -e 's/\[//g' | sed -e 's/\]//g' | cut -d: -f1 | grep -v ssh-rsa)" ${OPTIONS}) )
        fi
    fi

    # parse hosts defined in /etc/hosts
    if [ -r /etc/hosts ]; then
        COMPREPLY=( ${COMPREPLY[@]} $(compgen -W "$( grep -v '^[[:space:]]*$' /etc/hosts | grep -v '^#' | awk '{for (i=2; i<=NF; i++) print $i}' )" ${OPTIONS}) )
    fi

    return 0
}

complete -o default -o nospace -F _sshcomplete ssh scp