#!/bin/sh

runningUserID="$(id -u)"
if [ ! "$runningUserID" -eq 0 ]; then
	echo "docker-entrypoint.sh needs to be run as root, exiting..."
	exit 1
fi


# set the PULL_LOCATION env var if not set already
if [ -z "$PULL_LOCATION" ]; then  # if the env var is not set, set the default
	PULL_LOCATION="/to-pull"
	echo "PULL_LOCATION environment variable not set. Defaulting to /to-pull"
fi
if [ ! -d "$PULL_LOCATION" ]; then  # if the folder to pull does not exist
	echo "'$PULL_LOCATION' does not exist, exiting..."
	exit 1
fi


# check if PULL_LOCATION is a valid git repo
git config --global --add safe.directory "$PULL_LOCATION"  # make git trust this folder to check if it is a repo
current_dir=$PWD; cd "$PULL_LOCATION"; is_git_repo="$(git rev-parse --is-inside-work-tree 2>/dev/null)"; cd "$current_dir";
if [ ! "$is_git_repo" ]; then
	echo "'$PULL_LOCATION' is no git repository, exiting..."
	exit 1
fi


# Some PULL_INTERVAL env var checks
# check if the var is even set; and if it is set, check if it is an integer
# integer check found here: https://www.baeldung.com/linux/bash-variable-is-numeric 
if [ -z "$PULL_INTERVAL" ]; then
	PULL_INTERVAL=60  # every minute by default
	echo "PULL_INTERVAL environment variable not set. Defaulting to [every] 60 [seconds]"
fi
if [[ ! "$PULL_INTERVAL" =~ '^[0-9]+([.][0-9]+)?$' ]]; then
	PULL_INTERVAL=60
	echo "PULL_INTERVAL must be an integer, defaulting to [every] 60 [seconds] now"
fi
if [ "$PULL_INTERVAL" -lt 5 ]; then  # if the PULL_INTERVAL is too low (more than every 5 seconds)
	echo "PULL_INTERVAL must not be lower than 5 (every 5 seconds). Now set to 5."
	PULL_INTERVAL=5
fi


# now the user management (for permissions, security)
if [ -z "$PULLER_UID" ]; then 
	PULLER_UID=1000
	echo "PULLER_UID environment variable has not been set, defaulting to 1000..."
fi
if [[ ! "$PULLER_UID" =~ '^[0-9]+([.][0-9]+)?$' ]]; then  # check that PULLER_UID is a number
        PULLER_UID=1000  # set to roots uid
        echo "PULLER_UID must be an integer, defaulting to 1000 now."
fi
if [ ! "$PULLER_UID" = "0" ]; then
	# create a new user (for running the git pull; for security reasons)
	adduser -g gitpuller -s /bin/sh -u $PULLER_UID -D gitpuller  # user needs home dir for git config (see below)
	echo "Added user 'gitpuller' with UID $PULLER_UID"
	PULLER_USER="gitpuller"
	su $PULLER_USER -c "cd $PULL_LOCATION; git config --global --add safe.directory '$PULL_LOCATION';"
else
	PULLER_USER="root"
	# no need for git config ... as this is already done for the root user (see 'check if PULL_LOCATION is a valid git repo')
fi

#print log size info
if [ "$GIT_OUTPUT" = "0" ]; then
	echo "Not logging git outputs exept those to stderr (reducing the log size)"
else
	echo "INFO: logging all git outputs; you can reduce log size by setting the env var GIT_OUTPUT to 0"
fi

echo ""
echo "-----"
echo "Starting docker-git-puller with '$PULL_LOCATION' as the pull location."
echo "Pulling every $PULL_INTERVAL seconds."
echo "-----"
echo ""



while true; do
	# if $GIT_OUTPUT is 0, do not write the 'git pull' output to stdout; for any other value, do it
	if [ "$GIT_OUTPUT" = "0" ]; then
		su $PULLER_USER -c "cd $PULL_LOCATION; git pull > /dev/null;"
	else
		echo "[$(date)] Pulling git repo..."
		su $PULLER_USER -c "cd $PULL_LOCATION; git pull"
		echo "Waiting $PULL_INTERVAL seconds for next pull"
		echo "-----"
		echo ""
	fi
	sleep $PULL_INTERVAL
done