#!/hgdv/software/IRIX6/bin/perl -w

#
#     Transform csh script into ksh script
#
# Synopsis: csh2ksh infile [outfile]
#
# Knows about and will translate:
#   setenv -> export
#   if, then, else, endif -> if,then,elif,fi
# 
# Knows about and will kill:
#   alias, unalias, complete
#
# Not yet known, but trivial to implement, too:
#   if w/o then
#
# Everything else is unknown and will be retained as is.
#
# Warning:
# the csh script is assumed to be "well-formed"!
# (i.e., nicely written and formatted)
#


if ( @ARGV < 1 || @ARGV > 2 )
{
	die "csh2ksh: Usage: csh2ksh infile [outfile]\n";
}

$infile = shift;
$outfile = shift;

open INF, "$infile"
	or die "csh2ksh: couldn't open infile $infile: $!\n";
if ( defined($outfile) )
{
	open OUTF, ">$outfile"
		or die "csh2ksh: couldn't open outfile $outfile: $!\n";
	select OUTF;
}


# read infile
@_ = <INF>;
$_ = join "", @_;


# delete un-translatable stuff
s/^\s*(alias|unalias|complete).*$//mgo;


# translate known stuff
s/^([ \t]*)setenv\b\s*(\w+)\s*(.*)$/$1export $2=$3/mgo;					# setenv
s/^([ \t]*)if\b\s*\(([^)]*)\)\s*\bthen\b(.*)$/$1if [[$2]]\n$1then/mgo;	# if .. then
s/^([ \t]*)endif\b(.*)$/$1fi$2/mgo;										# endif
s/^([ \t]*)set\b\s*(\w+)\s*=(.*)$/$1$2=$3/mgo;							# set x = ..
s/=\s*\(\s*(.*?)\s*\)/="$1"/mgo;										# set .. = ( .. )
# can't use \s after the ^, b/c that would also match newlines


# "small" translations
s/==/=/go;																# if ( .. == .. )
s/(\bif\b.*)=~/$1=/go;													# if ( .. =~ .. )

s/!\s*\$\?(\w+)/"\$$1" = ""/go;											# if ( ! $?VAR )
s/\$\?(\w+)/"\$$1" != ""/go;											# if ( $?VAR )

#  clean up
s/\belse\b(\s*(\#.*)?\n)*\s*\bfi\b/fi/mgo;								# kill empty else .. fi
s/^([ \t]*)if\b.*\n(\s*(\#.*)?\n)*then(\s*(\#.*)?\n)*\s*\bfi\b//mgo;	# kill empty then .. fi

# output
print;

if ( defined(OUTF) )
{
	close OUTF;
	select STDOUT;
}