#!/bin/bash

: ${2?"Not enough parameters. Usage: $FUNCNAME CMD SCRIPT [PARAMS]"}

BIN=$(which bash)
CMD=$1; shift
SCRIPT=$1; shift
SCRIPT_PARAMS=$@
SCRIPT_NAME=$(basename $SCRIPT)
[[ ! $USER ]] && USER=nobody
LOCKDIR="/tmp/locks-$USER"
STALE_AGE=4 #hours
PIDFILE=$LOCKDIR/$SCRIPT_NAME/pid
LOCKFILE=$LOCKDIR/$SCRIPT_NAME/lock
LOGFILE=$LOCKDIR/$SCRIPT_NAME/log


fail() { local m=$1; echo $m 1>&2 && exit 1; }
clean() { local f=$1; rm -rf $f; }

[[ ! -d ${LOCKDIR} ]] && \
    if ! mkdir ${LOCKDIR} 2>&1 &>/dev/null; then
        fail "[$(date +%s)]: Can't create locks dir [$LOCKDIR]"
    fi

if mkdir $LOCKDIR/$SCRIPT_NAME &> /dev/null; then
    eval "$CMD $SCRIPT $SCRIPT_PARAMS &"  2>&1 &>$LOGFILE #\
        || fail "Error while starting script $SCRIPT"
    PID=$!
    echo $!>$PIDFILE
    touch $LOCKFILE
    if wait "$PID"; then
        echo "[$(date +%s)]: Success" &>$LOGFILE
        clean $LOCKDIR/$SCRIPT_NAME
    else
        fail "[$(date +%s)]: Something went wrong, see log: $LOGFILE"
    fi
    exit 0
else
    PID=$(cat $PIDFILE)
    if ! kill -s 0 $PID 2>&1 &>/dev/null; then
        echo "[$(date +%s)]: Process not found, try to restarting $SCRIPT" 1>&2
        clean $LOCKDIR/$SCRIPT_NAME
        $BIN $0 $CMD $SCRIPT $SCRIPT_PARAMS &&
            exit 0
        fail "[$(date +%s)]: Can't to start script $SCRIPT"
    else
        echo "[$(date +%s)]: Process already run with pid $PID" &>>$LOGFILE
    fi
    if [[ $(($(date +%s) - $(stat -c %Y $LOCKFILE) )) -gt $(( $STALE_AGE *60 *60 )) ]]; then
        echo "[$(date +%s)]: File $LOCKFILE staled, try to restart script $SCRIPT" 1>&2
        echo "[$(date +%s)]: killing $PID" 1>&2
        if ! kill -15 $PID &> /dev/null; then
            fail "[$(date +%s)]: Can't killing process with pid $PID"
        fi
        echo "[$(date +%s)]: Removing stale lock folder: $LOCKDIR/$SCRIPT_NAME" 1>&2
        clean $LOCKDIR/$SCRIPT_NAME
        $BIN $0 $CMD $SCRIPT $SCRIPT_PARAMS
    fi
fi