#!/bin/sh
#
# Run a Perl script for iRODS.
#
# Usage is:
#	./runPerlScript [options]
#
# This shell script starts a Perl script set on the command-line.
# It looks for Perl on the user's path and in standard locations
# on UNIX and Windows Cygwin, then invokes Perl with the given
# arguments.
#
# Options are:
#	--script script		the name of the Perl script to run
#	--dir directory		the name of the directory to run from
#
# All other options are passed to the Perl script unchanged.
#





#
# @brief	Print error messages in red.
#
# The given text is printed in red using standard xterm/vt100
# escape codes to set the text color.
#
# @param	text
#	the text to print
#
printError( )
{
	echo "$1"
}





#
# @brief	Find the path to Perl on this system.
#
# The system is searched for the Perl executable with the highest
# version number.  When found, PERL_PATH is set.  Otherwise
# PERL_PATH is the empty string.
#
PERLPATH=""

findPerl( )
{
	# On many systems there is just one Perl installed.  But
	# sometimes a system may have one version that came with
	# the OS in /usr/bin, and a more recent version installed
	# by the sysadmin in /usr/local.  We'd prefer to use the
	# more recent version.

	# Below we build a list of all Perls found in standard
	# locations.  Each one is written to a temporary results
	# file, one per row.  Each row starts with the version
	# number reported by that Perl, followed by the path to it.

	# When we're done searching, if there is only one entry
	# in the file, we use it.  Otherwise the file is sorted
	# numerically and we use the entry with the highest
	# version number.
	RESULTSFILE="/tmp/irods_$$.txt"

	# While "perl -v" reports version information for the program,
	# this is hard to parse.  Instead, we use the following
	# one line program:
	PERLPROG="'print $]'"

	# Check standard top-level directories, such as /, /opt,
	# /sw, and /cygwin.
	#
	# Then look in all the standard places.
	#	UNIX standard directories:
	#		/bin /sbin /usr/bin /usr/sbin
	#		/usr/local /usr/local/bin
	#		/usr/share /usr/share/bin
	#	Solaris added directories:
	#		/usr/ucb
	#	MacPorts directories:
	#		/opt/bin /opt/sbin /opt/usr/bin /opt/usr/sbin
	#		/opt/usr/local/bin /opt/usr/share/bin
	#	Fink directories:
	#		/sw/bin /sw/sbin /sw/usr/bin /sw/usr/sbin /sw/usr/local/bin
	#		/sw/usr/share/bin
	#	Cygwin directories:
	#		/cygwin/bin /cygwin/sbin /cygwin/usr/bin /cygwin/usr/sbin
	#		/cygwin/usr/local/bin /cygwin/usr/share/bin
	foundany="0"

#
# First, we include the user's prefered perl, in case it's the best.
# This is needed at NMI B&T for example, where the path is adjusted to
# select preferred versions of commands.
#
	foundWhich=`which perl`
	if [ $? -eq 0 ]; then
		PERL_PATH="$foundWhich"
		# It's a file.  Runnable?
		$PERL_PATH -v > /dev/null 2>&1
		if [ $? -eq 0 ]; then
			# Record working perl
			PERL_VERSION=`echo 'print $]' | $PERL_PATH`
			echo "$PERL_VERSION	$PERL_PATH" >> $RESULTSFILE
			foundany="1"
		fi
	fi
#
# Now we check other locations for more recent Perl's.
#
	for prefix in "/" "/opt" "/sw" "/cygwin"; do

		if [ ! -d $prefix ]; then
			continue	# No such prefix directory
		fi

		# Look in standard UNIX directories
		for dir in "bin" "sbin" "usr/bin" "usr/sbin" "usr/udb" \
			"usr/local" "usr/local/bin" "usr/share" "usr/share/bin" ; do

			if [ ! -d $prefix/$dir ]; then
				continue	# No such directory
			fi

			# Is $prefix/$dir/perl there?
			PERL_PATH="$prefix/$dir/perl"
			if [ -f $PERL_PATH ]; then
				# It's a file.  Runnable?
				$PERL_PATH -v > /dev/null 2>&1
				if [ $? -eq 0 ]; then
					# Record working perl
					PERL_VERSION=`echo 'print $]' | $PERL_PATH`
					echo "$PERL_VERSION	$PERL_PATH" >> $RESULTSFILE
					foundany="1"
				fi
			fi

			# Get all other perls ending with a number.  Often
			# these are separate older versions of Perl, or
			# directories for different Perl versions.
			foundLocal=`ls -d $prefix/$dir/perl[0-9]* 2> /dev/null`
			if [ $? -ne 0 ]; then
				continue	# No perl in directory
			fi

			for found in $foundLocal; do
				# Is it a file?
				PERL_PATH="$found"
				if [ -f $PERL_PATH ]; then
					# It's a file.  Runnable?
					$PERL_PATH -v > /dev/null 2>&1
					if [ $? -eq 0 ]; then
						# Record working perl
						PERL_VERSION=`echo 'print $]' | $PERL_PATH`
						echo "$PERL_VERSION	$PERL_PATH" >> $RESULTSFILE
						foundany="1"
					fi
					continue
				fi

				# Is it a directory?
				if [ -d $PERL_PATH ]; then
					# It's a directory.  Contains 'perl'?
					PERL_PATH="$found/perl"
					if [ -f $PERL_PATH ]; then
						# It's a file.  Runnable?
						$PERL_PATH -v > /dev/null 2>&1
						if [ $? -eq 0 ]; then
							# Record working perl
							PERL_VERSION=`echo 'print $]' | $PERL_PATH`
							echo "$PERL_VERSION	$PERL_PATH" >> $RESULTSFILE
							foundany="1"
						fi
					fi

					# Contains 'bin/perl'?
					PERL_PATH="$found/bin/perl"
					if [ -f $PERL_PATH ]; then
						# It's a file.  Runnable?
						$PERL_PATH -v > /dev/null 2>&1
						if [ $? -eq 0 ]; then
							# Record working perl
							PERL_VERSION=`echo 'print $]' | $PERL_PATH`
							echo "$PERL_VERSION	$PERL_PATH" >> $RESULTSFILE
							foundany="1"
						fi
					fi
					continue
				fi
			done

		done
	done

	# Were any found?
	if [ "$foundany" -ne "0" ]; then
		# Sort the results numerically.
		SORTEDRESULTSFILE="/tmp/irods_$$_2.txt"
		sort -rn $RESULTSFILE > $SORTEDRESULTSFILE
		rm -f $RESULTSFILE

		# Take the first one.  Use this loop approach
		# to get the 2nd word in the file instead of
		# using awk so that we don't require that awk
		# be installed on this system.
		gotfirst="0"
		for word in `cat $SORTEDRESULTSFILE`; do
			if [ "$gotfirst" -eq "0" ]; then
				gotfirst="1"
				continue
			fi
			PERL_PATH="$word"
			rm -f $SORTEDRESULTSFILE
			return
		done
		PERL_PATH=""
		rm -f $SORTEDRESULTSFILE
		return
	fi
	rm -f $RESULTSFILE

	# Nope.  None of the standard directories had it.
	# Perhaps the user has it on their path?

	# Is Perl on the user's path?
	perl -v > /dev/null 2>&1
	if [ $? -eq 0 ]; then
		# Yup.  Use it.
		PERL_PATH="perl"
		return
	fi

	# Can 'which' find it?  Technically, this just searches the user's
	# path, so it should be no better than the above.  However, it also
	# looks at aliases and resets the path to that found in the user's
	# .cshrc, so it can un-do changes caused to the user's current
	# environment.  It's worth a try.
	foundWhich=`which perl`
	if [ $? -eq 0 ]; then
		# Yup.  Use it.
		PERL_PATH="$foundWhich"
		return
	fi

	# Nothing.
	PERL_PATH=""
	return
}



# Parse the command-line and separate out arguments for
# this script, and those for the Perl script to be invoked.
PERL_SCRIPT=""
PERL_RUN_DIRECTORY="."
PERL_SCRIPT_ARGUMENTS=""
THIS_SCRIPT="$0"
THIS_COMMAND_LINE="$*"

while [ $# -ne 0 ]; do
	case $1 in
	--script)	shift
			PERL_SCRIPT=$1
			;;
	--dir)		shift
			PERL_RUN_DIRECTORY=$1
			;;
	*)
			PERL_SCRIPT_ARGUMENTS="$PERL_SCRIPT_ARGUMENTS $1"
			;;
	esac
	shift
done





# Make sure the script and directory exist
if [ ! -d "$PERL_RUN_DIRECTORY" ]; then
	printError "Programmer error:"
	printError "    The '$PERL_RUN_DIRECTORY' directory does not exist."
	printError " "
	printError "    The '$THIS_SCRIPT' script was probably invoked with a bad"
	printError "    --dir argument."
	printError "        Command line:  $THIS_SCRIPT $THIS_COMMAND_LINE"
	printError " "
	printError "Abort."
	exit 1
fi
if [ ! -f "$PERL_SCRIPT" ]; then
	if [ ! -f "$PERL_RUN_DIRECTORY/$PERL_SCRIPT" ]; then
		printError "Programmer error:"
		printError "    The '$PERL_SCRIPT' Perl script does not exist."
		printError " "
		printError "    The '$THIS_SCRIPT' script was probably invoked with a bad"
		printError "    --script argument."
		printError "        Command line:  $THIS_SCRIPT $THIS_COMMAND_LINE"
		printError " "
		printError "Abort."
		exit 1
	fi
fi





# Find perl
findPerl
if [ "$PERL_PATH" = "" ]; then
	printError "Configuration problem:" 
	printError "    This script requires Perl, but Perl cannot be found on"
	printError "    your system.  You can get the latest version of Perl from:"
	printError "        http://perl.org/"
	printError " "
	printError "Abort.  Please re-run this script after installing Perl."
	exit 1
fi






# Run the script
cd $PERL_RUN_DIRECTORY
$PERL_PATH $PERL_SCRIPT $PERL_SCRIPT_ARGUMENTS
ExitCode="$?"
exit $ExitCode