#!/bin/bash -e

# lifetime, in minutes
lifetime=15
keysuffix=root

hostopt=""
[ -z "$hostopt" ] && hostopt="${HOSTNAME}"
[ -z "$hostopt" ] && hostopt=`uname -n 2>/dev/null || echo unknown`

function usage
{
    echo "Usage: $0 [-H hostname] [-k keysuffix] [-l lifetime] command"
    echo
    echo "Available commands:"
    echo "    add"
    echo "    list"
    echo "    destroy"
    echo "    shell"
    echo "    ssh [args]"
    echo "    [cmd]"
}

while getopts ":H:k:l:h" opt; do
    case "$opt" in
    H)  hostopt="$OPTARG";;
    k)  keysuffix="$OPTARG";;
    l)  lifetime="$OPTARG";;
    h)  usage; exit 0;;
    \?) usage >&2; exit 1;;
    esac
done
shift $(($OPTIND - 1))

keys="$HOME/.ssh/id_rsa_$keysuffix"
keychain_host="$hostopt-$keysuffix"

function with-keys
{
    unset SSH_AUTH_SOCK SSH_AGENT_PID
    vars=$(keychain --timeout "$lifetime" --eval --host "$keychain_host" $keys)
    eval "$vars"
    export SSHROOT=1
    exec "$@"
}

function with-agent
{
    unset SSH_AUTH_SOCK SSH_AGENT_PID
    vars=$(keychain --timeout "$lifetime" --eval --host "$keychain_host")
    eval "$vars"
    export SSHROOT=1
    echo with-agent: Running: "$@"
    exec "$@"
}

command="$1"
shift

case "$command" in
    init)
        echo "Loading default keys (lifetime $lifetime)..."
        with-agent ssh-add -t "${lifetime}m" "$@" $keys
        ;;
    add)
        echo "Loading keys (lifetime $lifetime):" "$@"
        with-agent ssh-add -t "${lifetime}m" "$@"
        ;;
    list)
        with-agent ssh-add -l
        ;;
    destroy)
        with-agent ssh-add -D
        ;;
    shell)
        with-keys "$SHELL" "$@"
        ;;
    ssh)
        #with-keys ssh -l root "$@"
        with-keys ssh "$@"
        ;;
    *)
        if [ -z "$command" ]; then
            usage >&2
        else
            echo Executing: "$command" "$@"
            with-agent "$command" "$@"
        fi
        ;;
esac