#!/usr/bin/env bash


###################################################################
#Author       	:Joshua Schmid
#Email         	:jxs@posteo.de
###################################################################

VERSION=0.0.3

red() {
    echo -e "\e[31m${1}\e[0m"
}

green() {
    echo -e "\e[32m${1}\e[0m"
}

yellow() {
    echo -e "\e[33m${1}\e[0m"
}

function checks {
    permission_check
    firewall_check
}

function permission_check {
    if [[ "$(whoami)" != "root" ]]; then
        # the script needs root/sudo
        red "Please run as root or with sudo"
        exit 1
    fi
}

function firewall_check {
    if [[ "$(ufw status)" != "Status: inactive" ]]; then
	red "Using your firewall can cause issues with ffmpeg."
    fi
}

globals() {
    GOPRO_NON_INTERACTIVE=${GOPRO_NON_INTERACTIVE:-0}
    GOPRO_AUTOSTART=${GOPRO_AUTOSTART:-0}
    GOPRO_PREVIEW=${GOPRO_PREVIEW:-0}
    GOPRO_RESOLUTION=${GOPRO_RESOLUTION:-1080}
    GOPRO_FOV_ID=${GOPRO_FOV_ID:-4}
    GOPRO_FOV=${GOPRO_FOV:-linear}
    GOPRO_DEVICE_PATTERN=${GOPRO_DEVICE_PATTERN}
    GOPRO_DEVICE=${GOPRO_DEVICE}
    GOPRO_IP=${GOPRO_IP}
    GOPRO_USER=${GOPRO_USER}
}

DEPS=( "ffmpeg" "curl" )
module="v4l2loopback"
module_cmd="modprobe v4l2loopback exclusive_caps=1 card_label='GoPro' video_nr=42"
module_cmd_unload="modprobe -rf v4l2loopback"

START_PATH="/gp/gpWebcam/START?res="
# TODO: seems buggy atm, though
STOP_PATH="/gp/gpWebcam/STOP"
FOV_PATH="/gp/gpWebcam/SETTINGS?fov="

function run_args {

    >&2 green "Running GoPro Webcam Util for Linux [${VERSION}]"
    >&2 echo ""
    >&2 echo "       Launch Options     "
    >&2 echo "=========================="
    >&2 echo " * Non-interactive:  $GOPRO_NON_INTERACTIVE"
    >&2 echo " * Autostart:        $GOPRO_AUTOSTART"
    >&2 echo " * Preview:          $GOPRO_PREVIEW"
    >&2 echo " * Resolution:       ${GOPRO_RESOLUTION}p"
    >&2 echo " * FOV:              $GOPRO_FOV"
    if [[ $GOPRO_DEVICE ]]; then
    >&2 echo " * Device:           $GOPRO_DEVICE"
    fi 
    if [[ $GOPRO_DEVICE_PATTERN ]]; then
    >&2 echo " * Device Pattern:   $GOPRO_DEVICE_PATTERN"
    fi 
    if [[ $GOPRO_IP ]]; then
    >&2 echo " * IP Address:       $GOPRO_IP"
    fi 
    if [[ $GOPRO_USER ]]; then
    >&2 echo " * User:             $GOPRO_USER"
    fi 
    >&2 echo "=========================="
    >&2 echo ""
}

function validate_arguments {

    if [[ $GOPRO_DEVICE ]] && [[ $GOPRO_DEVICE_PATTERN ]]; then
        red "-p | --device-pattern and -d | --device are mutually exclusive"
        exit 1
    fi

    if [[ $GOPRO_DEVICE ]] || [[ $GOPRO_DEVICE_PATTERN ]] && [[ $GOPRO_IP ]]; then
        yellow "When an IP is provided the options for -p | --device-pattern and -d | --device ignored"
    fi

    if [[ ${GOPRO_AUTOSTART} -eq 1 ]] && [[ ${GOPRO_PREVIEW} -eq 1 ]]; then
        red "-v | --preview and -a | --autostart are mutually exclusive"
        exit 1
    fi

    if [[ ${GOPRO_PREVIEW} -eq 1 ]] && [[ ! $GOPRO_USER ]]; then
        red "-r | --preview needs -u | --user. Please provide it with the mentioned flags"
        exit 1
    fi
    
    if [[ ${GOPRO_FOV} == "wide" ]]; then
        GOPRO_FOV_ID=0
    elif [[ ${GOPRO_FOV} == "linear" ]]; then
        GOPRO_FOV_ID=4
    elif [[ ${GOPRO_FOV} == "narrow" ]]; then
        GOPRO_FOV_ID=6
    else
        red "Please choose either \"wide\", \"linear\", or \"narrow\""
        exit 1
    fi
    
    if [[ ${GOPRO_RESOLUTION} -ne "1080" && ${GOPRO_RESOLUTION} -ne "720" && ${GOPRO_RESOLUTION} -ne "480" ]]; then
        red "Please choose either \"1080\", \"720\", or \"480\""
        exit 1
    fi
}

function usage {
cat << EOF
Usage: $gopro action [options...]
Options:
  -n,  --non-interactive   do not wait for user input. Use this when used in a startup-script/fstab

  -p,  --device-pattern    provide a device pattern i.e. (enx, lsr) in case the script failed
                           to detect one by itself.

  -d,  --device            provide a full device name i.e. (enxenx9245589250e7)
                           USE WITH CAUTION. THIS CHANGES EVERY TIME YOU REBOOT/RECONNECT THE CAMERA
                           THIS OPTION IS NOT SUITABLE FOR AUTOMATION!

  -r,  --resolution        select the resolution you would like the GoPro to output. "1080", "720", or "480."
  
  -f,  --fov               select the FOV you would like to use. "wide", "linear", or "narrow."

  -i,  --ip                provide a IPv4 address to the GoPro i.e. (172.27.187.52)
                           CAUTION! This may change over time.
  
  -a,  --auto-start        automatically start ffmpeg to serve the GoPro as a video device to your operating system.
                           If this flag is omitted, print the corresponding command to run it yourself. 

  -v,  --preview           Just launch a preview in VLC. This will not expose the device to the OS.

  -u,  --user              VLC can't be started as root, please provide a username you want to run it with. (Typically your 'default/home' user)

  -V,  --verbose           echo every command that gets executed

  -h,  --help              display this help
Commands:
  webcam                   start the GoPro in webcam mode
EOF
}

function parse_args {
  # Do not parse a starting --help|-h as an action
  ! [[ $1 =~ ^- ]] && ACTION=$1 && shift

  while [[ $# -gt 0 ]]; do
    key="$1"
    case $key in
      -V|--verbose)
        set -x
        ;;
      -h|--help)
        usage
        exit 0
        ;;
      -n|--non-interactive)
        GOPRO_NON_INTERACTIVE=1
        ;;
      -p|--device-pattern)
        GOPRO_DEVICE_PATTERN=$2
        shift
        ;;
      -d|--device)
        GOPRO_DEVICE=$2
        shift
        ;;
      -r|--resolution)
        GOPRO_RESOLUTION=$2
        shift
        ;;
      -f|--fov)
        GOPRO_FOV=$2
        shift
        ;;
      -i|--ip)
        GOPRO_IP=$2
        shift
        ;;
      -u|--user)
        GOPRO_USER=$2
        shift
        ;;
      -a|--auto-start)
        GOPRO_AUTOSTART=1
        ;;
      -v|--preview)
        DEPS+=('vlc')
        GOPRO_PREVIEW=1
        ;;
      -)
        _EXTRA_ARGS+=("$(cat $2)")
        _RAW_INPUT=1
        shift
        ;;
      --)
        shift
        _EXTRA_ARGS+=("$@")
        break
        ;;
      *)
        _EXTRA_ARGS+=("$1")
        ;;
    esac
    shift
  done

  EXTRA_ARGS="${_EXTRA_ARGS[@]}"

  validate_arguments
}

function test_DEPS {
    # bail out if dependencies are not installed.
    for p in ${DEPS[@]}; do
        if ! command -v ${p} &> /dev/null
        then
            red "${p} could not be found"
            red "Please use you system's packagemanager to install this dependency and re-run this script"
            exit 1
        fi
    done
}

function user_confirmation {
    if [ $GOPRO_NON_INTERACTIVE -ne 1 ] ; then
        read -p "Please plug in your GoPro and switch it on. If it booted successfully (Charger icon on screen), hit Return"
    fi
}

function test_module_probe {
    # load module
    if ${module_cmd} &> /dev/null ; then
        green "${module} was successfully loaded."
        return 0
    else
        red "${module} does not exist. Please either install ${module} or get it from source via https://github.com/umlaeute/v4l2loopback"
        exit 1
    fi
}

function test_module_unload {
    # unload module
    if ${module_cmd_unload} &> /dev/null ; then
        green "${module} was unloaded successfully."
        return 0
    else
        red "${module} could not be unloaded. There is maybe an ffmpeg(or similar) running that uses this module"
        exit 1
    fi

}

function test_module_loaded { 
    # test if module is already loaded
    if lsmod | grep ${module} &> /dev/null ; then
        green "${module} is loaded!"
        test_module_unload
        return 0
    else
        green "${module} is not loaded!"
        return 1
    fi
}

function discover_device {
    local dev
    if [[ -z $GOPRO_DEVICE_PATTERN ]]; then
        echo -e "\n"
        echo "Guessing the GoPro's device name..."
        echo "I can only make an uneducated guess wrt the name of the interface that the GoPro exposes."
        echo "For me the name of the interface is 'enxf64854ee7472'. This script will try to discover the device"
        echo "that was added *last*, as you just plugged in the camera, hence the interface added last should be the one we're looking for."
        dev=$(ip -4 --oneline link | grep -v "state DOWN" | grep -v LOOPBACK | grep -v "NO-CARRIER" | cut -f2 -d":" | tail -1 | xargs)

    else
        echo "Using provided device pattern ${GOPRO_DEVICE_PATTERN}"
        dev=$(ip -4 token | grep ${GOPRO_DEVICE_PATTERN} | tail -1 | sed -e s"/token :: dev//" |  sed -e 's/^[[:space:]]*//')
    fi 

    if [[ -z ${dev} ]]; then
        echo -e "\n"
        echo "Could not discover a interface. Please restart the script by providing the device or the device pattern that the GoPro exposes (use 'ip addr' for that)"
        echo "i.e. gopro webcam -d enx123123123"
        echo "or"
        echo "i.e. gopro webcam -p lxr"
        exit 1
    fi

    green "\nDiscovered: ${dev}."
    GOPRO_DEVICE=${dev}
}

function find_gopro_ip {

    if [[ ! ${GOPRO_IP} ]]; then
        yellow "Using ${GOPRO_DEVICE} to discover the GOPRO_IP."
        ip=$(ip -4 addr show dev ${GOPRO_DEVICE} | grep -Po '(?<=inet )[\d.]+')
        if [[ -z ${ip} ]]; then
            red "Could not automatically discover a valid GOPRO_IP. Use the '-p, -d or -i' option to provide more information. (see --help for more information)"
            exit 1
        fi
        green "Found ${ip}"
        GOPRO_IP=${ip}
    fi

    echo "To control the GoPro, we need to contact another interface (GOPRO_IP ending with .51).. Adapting internally.."
    # For whatever reason the gopro server ends on .51
    mangled_ip=$(echo ${GOPRO_IP} | awk -F"." '{print $1"."$2"."$3".51"}')
    green "Now using this GOPRO_IP internally: ${mangled_ip}"

    GOPRO_INTERFACE_IP=$mangled_ip
}

function start_gopro_webcam_mode {

    local response
    # Switching to the GoPro Webcam mode
    response=$(curl -s ${GOPRO_INTERFACE_IP}${START_PATH}${GOPRO_RESOLUTION})
    if [ $? -ne 0 ]; then
        red "Error while starting the Webcam mode. # TODO Useful message."
        exit 1
    fi 
    echo $response
    if [[ -z "${response}" ]]; then
        red "Did not receive a valid response from your GoPro. Please try again to run this script, timing is sometimes crucial."
        exit 1
    fi
    response=$(curl -s ${GOPRO_INTERFACE_IP}${FOV_PATH}${GOPRO_FOV_ID})
    echo $response
    if [[ -z "${response}" ]]; then
        red "Did not receive a valid response from your GoPro. Please try again to run this script, timing is sometimes crucial."
        exit 1
    fi

    green "Sucessfully started the GoPro Webcam mode. (The icon on the Camera should have changed)"
}

function start_webcam {

    if [[ ! ${GOPRO_DEVICE} ]] && [[ ! ${GOPRO_IP} ]]; then
        discover_device
    fi

    find_gopro_ip

    start_gopro_webcam_mode

    expose_device
}

function expose_device {

    if [[ ${GOPRO_AUTOSTART} -eq 1 ]]; then
        echo "Starting ffmpeg.."
        ffmpeg -nostdin -threads 1 -i 'udp://@0.0.0.0:8554?overrun_nonfatal=1&fifo_size=50000000' -f:v mpegts -fflags nobuffer -vf format=yuv420p -f v4l2 /dev/video42
    elif [[ ${GOPRO_PREVIEW} -eq 1 ]]; then
        echo "Starting preview.."
        start_preview
        exit 0
    else
        info_only
        exit 0
    fi
}

function start_preview {

    echo -e "To test this try this command(vlc needs to be installed): \n"
    sudo -u $GOPRO_USER vlc -vvv --network-caching=300 --sout-x264-preset=ultrafast --sout-x264-tune=zerolatency --sout-x264-vbv-bufsize 0 --sout-transcode-threads 4 --no-audio udp://@:8554
}

function info_only {
    echo -e "\n\nYou should be ready to use your GoPro on your prefered videostreaming tool. Have Fun!"

    echo -e "\n\nIf you want to use the GoPro in your prefered Video conferencing software (browser and apps works alike) pipe the UDP stream to a video device (that was created already) with this command: \n"
    green "ffmpeg -nostdin -threads 1 -i 'udp://@0.0.0.0:8554?overrun_nonfatal=1&fifo_size=50000000' -f:v mpegts -fflags nobuffer -vf format=yuv420p -f v4l2 /dev/video42"
    
    echo -e "\nTo get a preview of the output in vlc you can run this command"
    echo -e "To test this try this command(vlc needs to be installed): \n"
    green "vlc -vvv --network-caching=300 --sout-x264-preset=ultrafast --sout-x264-tune=zerolatency --sout-x264-vbv-bufsize 0 --sout-transcode-threads 4 --no-audio udp://@:8554"
}


main() {

    globals
    parse_args "$@"
    run_args
    case $ACTION in
    help)
        usage
        ;;
    webcam)
        # run checks
        checks

        # If module is loaded already, unload it, to maintain idempotency.
        test_module_loaded

        # modprobe the needed kernel module
        test_module_probe

        # prompt to plug in the cable and turn on the device
        user_confirmation

        # Try to detect the correct interface and start the webcam mode
        start_webcam
        ;;
    version)
        echo version: $VERSION
        exit 0
        ;;
    *)
        usage
        exit 1
        ;;
    esac
}

main "$@"