#!/bin/bash

CFG_FILE=$HOME/.config/ssh-check.list
TIMEOUT=5 # seconds

read -d '' SSH_OPTIONS <<END
-o ConnectTimeout=$TIMEOUT
-o ControlPath=none
-o PasswordAuthentication=no
-o StrictHostKeyChecking=yes
END

quietly()
{
    "$@" </dev/null >/dev/null 2>&1
}

match()
{
    local search_text="$1" search_pattern invert=
    shift
    for search_pattern in "$@"
    do
        if [[ "$search_pattern" = '!'* ]]
        then
            invert=y
        fi
        if  (set +e
            [[ $search_text = ${search_pattern#!} ]]
            [ $? ${invert:+ !}= 0 ])
        then
            return
        fi
    done
    false
}

main()
{
    local h
    declare -a hosts=()
    declare -i max_found_host_length=0
    while read h cmd
    do
        if [ ${#h} -gt $max_found_host_length ]
        then
            max_found_host_length=${#h}
        fi
        hosts+=("$h $cmd")
    done < "$CFG_FILE"
    while true
    do
        {
            default_hostcmd=uptime
            for h in "${hosts[@]}"
            do
                host=${h%% *}
                hostcmd=${h#* }
                [ "$host" ] || continue
                [ $# = 0 ] || match "$host" "$@" || continue
                (
                    #.........."1234567890123456"
                    successpat=" Success:       %-${max_found_host_length}s  %s\n"
                    failurepat="*FAILURE:       %-${max_found_host_length}s  %s\n"
                    command_stderr=$(mktemp)
                    if command_stdout=$(ssh -n $SSH_OPTIONS -- \
                            "$host" \
                            "${hostcmd:-$default_hostcmd}" \
                            2>"$command_stderr")
                    then
                        if [ "$hostcmd" ]
                        then
                            logtail=${command_stdout: -40 }
                        else
                            logtail=${command_stdout: 1 : 40 }
                        fi
                        printf "$successpat" "$host" "${logtail@Q}"
                    else
                        REPLY=
                        while read
                        do
                                REPLY=${REPLY%$'\r'}
                                printf "$failurepat" "$host" "${REPLY@Q}"
                        done <"$command_stderr" >&2
                        logtail=${REPLY: -40 }
                        printf "$failurepat" "$host" "${logtail@Q}"
                    fi
                    rm "$command_stderr"
                ) &
            done
            wait
        } | column -t -s'$'
        tty -s && break
        sleep 5
    done
}

edit_config()
{
    set -e
    f=$(mktemp)
    if [ -e "$CFG_FILE" ]
    then
        cp "$CFG_FILE" "$f"
    fi
    touch -r "$f" "$f".timestamp
    $EDITOR "$f"
    [ -e "$f" -a "$f" -nt "$f".timestamp ]
    mv "$f" "$CFG_FILE"
    set +e
    rm "$f".timestamp
}

usage()
{
    cat <<EOF
Usage: $0 [--help | -h] [--verbose | -v] [--edit] [--run] [--] [host pattern] [...]
EOF
}

unset run_anyway do_edit
while [ $# -gt 0 ]
do
    case "$1" in
        --edit) do_edit=y;;
        --run) run_anyway=y;;
        --help | -h) usage; exit;;
        --command) REMOTE_COMMAND=$2; shift 2;;
        --verbose | -v) VERBOSE=y; shift;;
        --) shift; break;;
        -*) usage >&2; exit 1 ;;
        *) break;;
    esac
    shift
done

if [ "$do_edit" ]
then
    edit_config
    r=$?
    if ! [ "${run_anyway}" ]
    then
        exit $r
    fi
elif [ ! -e "$CFG_FILE" -a -t 0 ]
then
    edit_config
fi

main "$@"