#!/bin/bash
#
# Simple launcher script to start a worker script within a service or
# one for every service.
#
# Services are subfolders of the $SERVICE_BASE parameter set below.
# The worker script is an executable file within the service's $TOOLS_BASE
# folder. The launcher supposes that the filename of the worker script
# is the same as the launcher's.
#
# Without command line parameters the launcher enumerates all services
# and launches every service's worker script. Optionally waits between
# launches if is prescribed in $SLEEP_BETWEEN parameter. This operation
# needs to be forced by --doit command line option.
#
# With at least one command line parameter the launcher launches only one
# worker script, which is within the service named in the first parameter.
# If the supposed service or the worker script doesn't exist the script
# silently does nothing.
#
# Normally the launcher starts the worker(s) in background, then exits.
# Using the --wait command line option you may wait for the worker(s)
# and get exit code 1 if any worker has reported some error.
#
# You may call this script from the cron - in this case must be set
# the CRON environment variable in crontab and must be exported to the script.
#
# Author: Kovács Zoltán <kovacs.zoltan@smartfront.hu>
#         Kovács Zoltán <kovacsz@marcusconsulting.hu>
# License: GNU/GPL v3+ (https://www.gnu.org/licenses/gpl-3.0.en.html)
# 2023-06-18 v1.0
# new: forked from the "SMARTERP_skeleton" repository.
# mod: "instance" => "service"
# 2022-08-03 v0.6
# new: it optionally waits for the worker(s) and returns with exit code 1,
#      if it has got at least one non-zero exit code from them.
# 2021-02-15 v0.5
# fix: omits the error message when there is no services at all
# 2021-02-05 v0.4
# fix: proper $PATH settings in Debian environment as well
# 2021-02-04 v0.3
# fix: decimal point trouble in non-english environments (eg. Hungarian)
# 2021-01-05 v0.2
# fix: LANG=C and LC_ALL=C initialisations have removed, because these may
#      interfere with UTF-8 file name encoding in Java calls:
#      https://ogris.de/howtos/java-utf8-filenames.html
# 2020-11-20 v0.1 Initial release

# Accepted environment variables and their defaults.
#
CRON=${CRON-""}                                         # Does it run from cron?
SERVICE_BASE=${SERVICE_BASE-"$HOME/services"}		# Services' folder path
SLEEP_BETWEEN=${SLEEP_BETWEEN-"0"}			# Secs between forks

# There is nothing to configure below (I hope).
###############################################

# Messages.
#
MSG_BADOPT="Invalid option"
MSG_MISSINGDEP="Fatal: missing dependency"
MSG_USAGE="For one service:  $($(which basename) "$0") [--wait] servicename\n"
MSG_USAGE+="For all services: $($(which basename) "$0") [--wait] --doit\n"
MSG_USAGE+="Environment variables:\n"
MSG_USAGE+="  SERVICE_BASE  Absolute path to the folder containing services\n"
MSG_USAGE+="                 (default: \$HOME/services)\n"
MSG_USAGE+="  SLEEP_BETWEEN  Secs (may fraction) to wait between multiple launches\n"
MSG_USAGE+="                 (default: 0.0)"

# Getting command line options.
DOIT=""			# Enables launch processes for all available services.
WAIT=""			# Wait for the result of the actually launched process.
while getopts ":-:" option
do
    case ${option} in
        "-" )
            if   [ "$OPTARG" = "doit" ]; then DOIT="yes"
            elif [ "$OPTARG" = "wait" ]; then WAIT="yes"
            else echo "$MSG_BADOPT --$OPTARG" >&2; exit 1
            fi
        ;;
        \? )
        echo "$MSG_BADOPT -$OPTARG" >&2; exit 1
        ;;
    esac
done; shift $((OPTIND -1))
# Done with options.

# Basic environment settings.
#
# Corrects the PATH if the operating system didn't loaded yet;
# it is a bug with cron pam_env, I think.
if [ -n "$CRON" ]; then
    [[ -r  "/etc/profile" ]] && source "/etc/profile"
    # Ubuntu gets the initial environment from a separate file.
    if [ -r "/etc/environment" ]; then
        # Extracts from this file, strips the right part w/o quotes.
        includepath=$(cat "/etc/environment" | $(which egrep) '^PATH=')
        includepath=${includepath:5}
        includepath="${includepath%\"}"; includepath="${includepath#\"}"
        [[ -n "$includepath" ]] && PATH="$PATH:$includepath"
        unset includepath
    fi
    # We need the $HOME/bin as well.
    PATH="$HOME/bin:$PATH"
fi
# We need also the sbin directories.
if ! [[ "$PATH" =~ '/sbin:' ]]; then PATH="$PATH:/usr/local/sbin:/usr/sbin:/sbin"; fi

# Checks the dependencies.
#
TR=$(which tr 2>/dev/null)
if [ -z "$TR" ]; then echo "$MSG_MISSINGDEP tr."; exit 1 ; fi
#for item in basename df egrep head mail printf sleep
for item in basename printf sleep
do
    if [ -n "$(which $item)" ]
    then export $(echo $item | "$TR" '[:lower:]' '[:upper:]')=$(which $item)
    else echo "$MSG_MISSINGDEP $item." >&2; exit 1; fi
done
# All dependencies are available via "$THECOMMAND" (upper case) call.

# Initializations and sanitizations.
#
if [ -z "$SERVICE_BASE" -o ! -d "$SERVICE_BASE" ]; then exit 1; fi
SLEEP_BETWEEN=$("$PRINTF" '%.2f' "$SLEEP_BETWEEN" 2>/dev/null)	# To float
TOOLS_BASE="tools"					# Relative path
WORKERFILE="$("$BASENAME" "$0")"			# Same filename

# Collects the service(s).
if [ -n "$1" ]; then
    # One service.
    SERVICES="$1/"; shift
elif [ -n "$DOIT" ]; then
    # All services when has forced.
    SERVICES="$(cd "$SERVICE_BASE"; ls -d */ 2>/dev/null)"
else
    echo -e "$MSG_USAGE" >&2; exit 1
fi

# Prepares to save the result codes.
declare -A JOBS
# Eumerates the service folders.
[[ -z "$SERVICES" ]] && exit
for service in $SERVICES ""
do
    # Safety first...
    if [ -n "$service" ]; then
	# Forks the worker if it does exist and does runnable.
	if [ -x "$SERVICE_BASE/$service$TOOLS_BASE/$WORKERFILE" ]; then
	    # Sets PATH and USER, passes all remaining command line parameters.
            [[ -n "$CRON" ]] && export PATH USER
	    "$SERVICE_BASE/$service$TOOLS_BASE/$WORKERFILE" "$@" &
	    PID="$!"
	    # Optionally waits for the worker and saves the result.
	    if [ -n "$WAIT" ]
	    then wait $PID; JOBS["$service"]=$?; fi
	    # Optionally reduces the fork frequency.
	    "$SLEEP" ${SLEEP_BETWEEN//,/.}	# decimal point need
	else
	    # Optionally reports the failure.
	    if [ -n "$WAIT" ]
	    then JOBS["$service"]=1; fi
	fi
    fi
done

# Optionally returns with exit code 1, if it has got at least one
# non-zero exit code from workers.
if [ -n "$WAIT" ]; then
    for key in "${!JOBS[@]}"
    do	[[ "${JOBS[$key]}" -gt 0 ]] && exit 1
    done
fi

# That's all, Folks! :)