#! /bin/bash
# vim: set tabstop=4 shiftwidth=4 expandtab filetype=sh:

# called by udev as:
# ttyusbhandler [add|remove] ttyUSBname

# depending on what port ttyUSB adapter was added or removed from,
# automatically launches or kills ADTPro as needed
# restarts getty as needed

# remove:
# kill any ADTPro for this port
# if a getty is on this port, do nothing here, it will be killed and respawn
#   iteself

# add:
# stagger adds by port number to prevent problems during simultaneous add at startup
# if lower port, solo adapter on lower port USB hub, or lower port of any USB hub,
#   kill any ADTPro, rescan for getty if sleeping, and launch adtPro
# if upper port, solo adapter on upper port USB hub, or higher port of any USB hub,
#   rescan for getty

if [[ $1 == "remove" ]]; then
    rm /tmp/udev-$2-removed &> /dev/null
    touch /tmp/udev-$2-removed
    pkill -f "$2.*ADTPro"
elif [[ $1 == "add" ]]; then
    [[ $2 == "ttyUSBlower" ]] && sleep 1.5
    [[ ${#2} -gt 11 ]] && sleep "${2:15:2}"
    if [[ $2 == "ttyUSBlower" || \
          $2 == $(ls -1 /dev/ttyUSBlower_hub* 2> /dev/null | head -1 | cut -c 6-) || \
          ( ${2:0:12} == "ttyUSBlower_" && $2 != $(ls -1 /dev/ttyUSBupper_hub* 2> /dev/null | tail -1 | cut -c 6-) ) \
       ]]; then
        rm /tmp/udev-ttyUSBlower-added &> /dev/null
        touch /tmp/udev-ttyUSBlower-added
        pkill -f "[A]DTPro"
        pkill -f "[u]sbgetty"
        exec echo "/usr/local/adtpro/adtpro.sh headless serial" | at -M now
    else # ttyUSBupper
        rm /tmp/udev-ttyUSBupper-added &> /dev/null
        touch /tmp/udev-ttyUSBupper-added
        pkill -f "[g]etty.*ttyUSB"
        if [[ -f /bin/systemctl ]]; then # if systemd
            # if USB-to-serial adapter is directly attached to upper port
            if [[ -c /dev/ttyUSBupper ]]; then
                ttyUSB=ttyUSBupper
            # if hub in upper port, use highest numbered port on hub
            elif [[ $(ls -1 /dev/ttyUSBupper_hub* 2> /dev/null | wc -l) -gt 0 ]]; then
                ttyUSB=$(ls -1 /dev/ttyUSBupper_hub* 2> /dev/null | tail -1 | cut -c 6-)
            # if hub in lower port with multiple adapters, use highest numbered port on hub
            elif [[ $(ls -1 /dev/ttyUSBlower_hub* 2> /dev/null | wc -l) -gt 1 ]]; then
                ttyUSB=$(ls -1 /dev/ttyUSBlower_hub* 2> /dev/null | tail -1 | cut -c 6-)
            else
            # by definition, this shouldn't happen
                ttyUSB=
            fi
            exec systemctl restart usbgetty@$ttyUSB
        fi
    fi
else
    exit 2
fi