waitTillHdmiConnected.sh

#!/bin/bash

# This scripts wait <TIMEOUTINSECONDS> till hdmi connection got established or shutdown if no tvheadend recording is running, upcomming or some stream is consumed, served by tvheaden
# Howto https://debianisttoll.blogspot.com/2021/07/wait-till-hdmi-is-connected-before.html
# Source https://gist.githubusercontent.com/stesee/9ebb11cc2db6a58e6b42afb2d74e7e7b/raw/7327e42950c449c1153ebf546f60ee1d8e3d0d0d/waitTillHdmiConnected.sh

# install stuff before using this script
#   sudo apt install libxml-xpath-perl curl

# setup systemconfiguration
#   allow current user to execute shutdown and waskup - add this line to /etc/sudoers - replace "username" with your username
#       username ALL = NOPASSWD: /usr/bin/setwakeup.sh, /usr/sbin/pm-suspend

# configure your settings

WARMUPTIMEINMINUTES=2
WARNINGTIMEOUTINSECONDS=800
TIMEOUTINSECONDS=900
POLLINGDURATIONINSECONDS=5
LOGFILE="$HOME/waitTillHdmiConnected.log"

# configure your tvheadend settings
URL=localhost
PORT=9981
USERNAME=kodi
PASSWORD=kodi
# Time this script will wait without shutting down for a planned recording
TIMEBEFORENEXTRECORDINMINUTES=20

#set start conditions, is this some bash magic? seems like SECONDS will be increased by every second without coding anything
SECONDS=0

triggerTimeoutActions(){
    #set next wakeup time
    OUTPUT=$(curl --anyauth -u $USERNAME:$PASSWORD --silent --max-time 5 "http://$URL:$PORT/status.xml")
    NEXTRECORD=$(echo "$OUTPUT" | xpath -q -e "/currentload/recordings[1]/recording/next/text()")
    NEXTRECORD=$(echo "$NEXTRECORD-$WARMUPTIMEINMINUTES"|bc)
    NEXTRECORD_TICKS=$(date '+%s' -d "+ $NEXTRECORD minutes")
    
    #TODO Add sanity check value and fall back to someting reasonable... e.g. 24h in future
    FAILSAFE=`date '+%s' -d '+ 24 hours'`
    #TODO Add sanity check value and fall back to someting reasonable... e.g. 24h in future
    
    sudo /usr/bin/setwakeup.sh "$NEXTRECORD_TICKS"
    
    # e.g. shutdown the system
    echo "Shuting down next wakup set to $NEXTRECORD_TICKS" | tee -a "$LOGFILE"
    echo $(date && echo "shutting realy down") | tee -a "$LOGFILE"
    shutdown +1 | tee -a "$LOGFILE"
    exit
}

triggerHdmiConnectedActions(){
    # e.g. set some overscan hack
    #xrandr --output HDMI-3 --transform 1.05,0,-34,0,1.05,-20,0,0,1
    # e.g. start kodi
    kodi &
    exit
}

isHdmiPortConnected(){
    if xrandr 2> /dev/null | grep -q 'HDMI-[0-9] connected'; then
        echo "HDMI connected" | tee -a "$LOGFILE"
        return 0
    else
        echo "HDMI not connected waiting $POLLINGDURATIONINSECONDS seconds" | tee -a "$LOGFILE"
        return 1
    fi
}

isTvheadenRecordingActive(){
    # check if tvheadend is responding
    OUTPUT=$(curl --anyauth -u $USERNAME:$PASSWORD --silent --max-time 5 "http://$URL:$PORT/status.xml")
    if [ -z "$OUTPUT" ]; then
        echo "Tvheadend is not responding" | tee -a "$LOGFILE"
        return 1
    else
        # check if tvheadend is recording
        if echo "$OUTPUT" | grep "<status>Recording</status>" >/dev/null; then
            echo "Tvheadend is recording" | tee -a "$LOGFILE"
            return 0
        fi
        
        # check if tvheadend recording is upcomming in TIMEBEFORENEXTRECORDINMINUTES
        if echo "$OUTPUT" | grep "<next>" >/dev/null; then
            echo "Tvheadend waiting for an upcomming recording" | tee -a "$LOGFILE"
            echo "$OUTPUT"
            NEXTRECORD=$(echo "$OUTPUT" | xpath -q -e "/currentload/recordings[1]/recording/next/text()")
            echo Next recording starts in "$NEXTRECORD" minutes | tee -a "$LOGFILE"
            if [ "$TIMEBEFORENEXTRECORDINMINUTES" -gt "$NEXTRECORD" ]; then
                echo "Tvheadend will start to record in short time" | tee -a "$LOGFILE"
                return 0
            fi
        fi
        
        # check if tvheadend rcording serving some stream
        if echo "$OUTPUT" | grep "<subscriptions>" >/dev/null; then
            SUBS=$(echo "$OUTPUT" | xpath -q -e "/currentload/subscriptions/text()")
            if [ "$SUBS" -gt 0 ]; then
                echo "$SUBS subscriptions running" | tee -a "$LOGFILE"
                return 0
            echo "No subscriptions" | tee -a "$LOGFILE"
            fi
        fi
    fi
    return 1
}

echo $(date && echo "Start polling") | tee -a "$LOGFILE"

while true
do
    if isHdmiPortConnected; then
        triggerHdmiConnectedActions
    fi
    
    duration=$SECONDS
    
    if isTvheadenRecordingActive; then
        SECONDS=0
    else
        echo "$(($duration / 60)) minutes and $(($duration % 60)) seconds elapsed since first poll." | tee -a "$LOGFILE"
        if [ "$duration" -gt "$WARNINGTIMEOUTINSECONDS" ]; then
            echo "Warning: HDMI connection timeout is about to occure!" | tee -a "$LOGFILE"
            if [ "$duration" -gt "$TIMEOUTINSECONDS" ]; then
                triggerTimeoutActions
            fi
        fi
    fi
    
    sleep $POLLINGDURATIONINSECONDS
done