#!/bin/sh
# diycron: Script to be running (as a root daemon) as a (non-conflicting) cron alternative which simply works.
# Note: Except when required by the shell, we use 0=false, 1=true for internal commands, for consistency.

If() { test "$1" = 1 && return 0 || return 1; }
Ifn() { test "$1" = 0 && return 0 || return 1; }

GetDaySeconds() { echo "$(date -d "1970-01-01 UTC $(date +%T)" +%s)"; }
IsDayMin() { test $(($(GetDaySeconds)>$1)) = 1 && test $(($(GetDaySeconds)<$1+60)) = 1 && echo 1 || echo 0; }
IsHourMin() { test "$1" = "$(date +%M)" && echo 1 || echo 0; }
hm2s() { echo $((($1*60*60) + ($2*60))); }

# Setting variables (that always have a "Job" prefix) for each job, to prevent multiple execution.
ResetJobs() {
	for Job in \
		1 2
	do eval "Job$Job=0"
	done
}

echo "------------------------------------------"
echo "[ $(date "+%F | %T") ] diycron started."

set -x # Enable command echo
ResetJobs

while true
do
	# Inside here, declaration of all cronjobs like normal shell commands, made easy thanks to integrated functions.

	# Trinity rotation backup system: each of the following scripts is executed every 3 days, in a rotation where at least 1 script runs every night at 3:00
		Ifn $Job2 && If $(IsDayMin $(hm2s 3 0)) && test $(($(date +%s) / 86400 % 3)) = 0 && Job2=1 && sleep 60 && /Server/Scripts/Backup/ExternalDataBackup.sh #& # Local backup of external data
		Ifn $Job2 && If $(IsDayMin $(hm2s 3 0)) && test $(($(date +%s) / 86400 % 3)) = 1 && Job2=1 && sleep 60 && /Server/Scripts/Backup/ServerDataBackup.sh #& # Big backup of local services data
		Ifn $Job2 && If $(IsDayMin $(hm2s 3 0)) && test $(($(date +%s) / 86400 % 3)) = 2 && Job2=1 && sleep 60 && /Server/Scripts/Backup/CloudBackup.sh #& # Cloud backup of the locally backed-up data

	# System reboot every X days at 4:30 AM
		#If $(IsDayMin $(hm2s 4 30)) && test $(($(date +%s) / 86400 % 2)) = 0 && sleep 60 && reboot # System reboot every 2 days (every even day)
		If $(IsDayMin $(hm2s 4 30)) && sleep 60 && reboot # System reboot every night

	# Status of all jobs is reset at one time of the day, before or after all execute or have executed (in time).
		If $(IsDayMin $(hm2s 0 0)) && ResetJobs
	# Cooldown to wait at each cycle, to save on resources (Should always be less than 60 seconds!).
	sleep 5
done