#! /usr/bin/env bash

set -e
# Arguments 'TO', optional user (can be configured in ~/.ssh/config.d/...), command to run over ssh

# Figure out the IPAddress I need to operate from
# Figure out the interface name to use
# Set the interface to the IP Address if not already setup
# Test with ping
# Connect with SSH

SCRIPT_NAME="${0##*/}"
if [ $# -eq 0 ]; then
    printf '%s\n' \
        "${SCRIPT_NAME} <TO> [<FROM>] [<Interface>]" \
        "" \
        "Configure MacOS iface to connect to <TO> address from <FROM> address" \
        "Default <Interface> is en9" \
        "" \
        "FROM and FROM_SN will be autofilled for the following subnets:" \
        "    10.117.10.0/24" \
        "    192.168.[1 or 2].0/24" \
        "" \
        "for other subnets, you'll need to specify a FROM argument and a FROM_SN env variable" \
        "" \
        "What the script does:" \
        "    1. Attempts a ping to the destination IP." \
        "    2. If unsuccessful:" \
        "       a. if FROM (2nd arg) isn't specified or set to 'dhcp':" \
        "       - tries to guess the FROM and FROM_SN based on known TO ranges." \
        "       b. if FROM was specied - uses FROM/2nd argument and FROM_SN from env" \
        "       c. compares desired FROM and assigned IP on outgoing interface (IFACE env or default: en9)" \
        "       d. if different, asssigns ip address to interface (temporary, using sudo)" \
        "       e. Attempts ping once again" \
        "    3. If ping was successful, tries to grab hostname via ssh" \
        "" \
        "    The entire process will do it's best to communicate error states and" \
        "    recommend possible actions if any steps fail" \
        ""\
        "Predefined CIDR and  aliases" \
        "    10.117.10.254/24  " \
        "    192.168.1.254/24  " \
        "    192.168.2.254/24  " \
        "    169.254.1.15/27   " \
        "    169.254.111.15/27 " \
        "    169.254.3.254/24  " \
        "" \
        "Examples:" \
        "    ${SCRIPT_NAME} 192.168.2.2 # connect to tech port" \
        ""
    exit 2
elif [[ $# -eq 1 && "$1" == "editme" ]]; then
    exec ${VISUAL:-${EDITOR:-vi}} "$(readlink -f "$0")"
    exit 0
fi

TO="${1}"
IFACE="${IFACE:-en9}"
PINGOK=1
CMDs=("${@:2}")

[ "${#CMDs}" -gt 0 ] || CMDs=( hostname )

_myip() {
    lsip | awk "/${IFACE}/"'{split($3, a, "/"); print a[1];}'
}

_ping() {
    ping -c "${PING_C:-3}" -W 250 "${TO}"
}

_log() {
    printf '%s\n' \
            "${@:2}" \
    >&2
    exit ${1} 
}

if _ping &>/dev/null; then
    printf "Connection detected.\n"
else
    PINGOK=0
    if [ "${FROM:-${2:-}}" == "dhcp" ]; then
        FROM=dhcp
        FROM_SN=auto
        SLEEP="${SLEEP:-15s}"
    else
        SLEEP="${SLEEP:-3s}"
        case "${FROM:+__}${TO}" in
            10.117.10.*)
                FROM=10.117.10.254
                FROM_SN=255.255.255.0
                ;;
            192.168.1.*)
                FROM=192.168.1.254
                FROM_SN=255.255.255.0
                ;;
            192.168.2.*)
                FROM=192.168.2.254
                FROM_SN=255.255.255.0
                ;;
            169.254.1.*)
                FROM=169.254.1.15
                FROM_SN=255.255.255.224
                ;;
            169.254.111.*)
                FROM=169.254.111.15
                FROM_SN=255.255.255.224
                ;;
            169.254.3.*)
                FROM=169.254.3.253
                FROM_SN=255.255.255.0
                ;;
            *)
                FROM=${FROM:-${2:?FROM and FROM_SN Must be supplied for unknown IPv4 destination $1}}
                FROM_SN=${FROM_SN:?FROM and FROM_SN Must be supplied for unknown IPv4 destination $1}
                ;;
        esac
    fi

    MYIP=''
    MYIP="$(_myip)"

    if [ "$FROM" == "$MYIP" ]; then
        _log 2 "Already setup with $MYIP, but ping to $TO is failing, you'll need to troubleshoot this."
        exit 2
    fi

    echo "$MYIP detected on $IFACE, Setting up $FROM / $FROM_SN - \`sudo\` might be prompting you for your password"

    if [ "${FROM}" == "dhcp" ]; then
        sudo ipconfig set "${IFACE}" bootp || true
        sudo ipconfig set "${IFACE}" dhcp
    else
        sudo ipconfig set "${IFACE}" manual "${FROM}" "${FROM_SN}"
    fi \
    && printf 'Waiting %s...' "${SLEEP}" \
    && sleep "${SLEEP}" \
    && MYIP="$(_myip)"
fi

if [ $PINGOK -eq 0 ] && _ping &>/dev/null; then
    PINGOK=1
fi

if [ $PINGOK -eq 1 ]; then
    # auto-copy-ssh-id "${TO}"

    ssh-keygen -R "${TO}" || true

    ssh \
        -o PasswordAuthentication=no \
        -o BatchMode=yes \
        -o ConnectTimeout=2 \
        -ttn \
        "${TO}" -- "${CMDs[*]}" \
    || 1>&2 printf '%s\n' \
        "Could not SSH into ${TO}, you might want to run 'pull-vast.id_rsa ${TO}' or 'auto-copy-ssh-id ${TO}'"
else
    _log 2 "Ping faild."
fi

exit