#!perl

#####################################################################
# NOTE: This script (cnf2bat.pl) requires sh.exe.                   #
# (Both msys and cygwin ship with sh.exe.)                          #
#                                                                   #
# Provide an executable .bat file from a 3rd party library-config   #
# file. These config files (eg gsl-config, gdlib-config,            #
# taglib-config) are not executable in the cmd.exe shell.           #
# This script provides an executable .bat replacement               #
# (eg gsl-config.bat, gdlib-config.bat, taglib-config.bat).         #
#                                                                   #
# Then when a Makefile.PL does something like:                      #
#                                                                   #
# $libs = chomp(`gsl-config --libs`);                               #
#                                                                   #
# courtesy of gsl-config.bat, $libs will be set to the correct      #
# value - instead of being set to the empty string, and we don't    #
# get hit with the message that 'gsl-config' is not recognized as   #
# an internal or external command, operable program or batch file.  #
#                                                                   #
# Obviously, this relies on the generated .bat file being in either #
# the current directory, or the path.                               #
#                                                                   #
# NOTE: You ought to update the batch file (by re-running) this     #
# script whenever the library in question is updated.               #
#                                                                   #
# Not all options are available in the .bat file - only --prefix,   #
# --libs, --cflags and --version, as these are usually the only     #
# options that a Makefile.PL queries. (Others could easily be added #
# if necessary.)                                                    #
#                                                                   #
# This script takes the following arguments:                        #
#  1) the name (fully qualified name) of the library-config file;   #
#  2) (optionally) the directory into which the generated batch     #
#     file is to be placed. Default is '.' (cwd).                   #
#                                                                   #
# You'll also need to set $sh_location (below) to the location      #
# of sh.exe on your machine.                                        #
#                                                                   #
# NOTE: This script can, itself, be converted to a batch file by    #
# running 'pl2bat cnf2bat.pl'                                       #  
#####################################################################


use warnings;
use strict;
use File::Copy;

die "Usage: 'cnf2bat.pl /full/path/to/lib-config [/full/path/to/dest_dir]'\n"
  unless $ARGV[0];

my $destination = '.';
if($ARGV[1]) {
  die "$ARGV[1] is not an existing directory" unless -d $ARGV[1];
  $destination = $ARGV[1];
}

#################################################
# Hard code this to the location of sh.exe.     #
#################################################
my $sh_location = "C:\\MinGW\\msys\\1.0\\bin";


#################################################
# Make sure that sh.exe is in the path          #
#################################################
$ENV{PATH} .= ";$sh_location";


#################################################
# Check that the config file specified in       #
# $ARGV[0] exists, then run the write_bat_file  #
# subroutine.                                   #
#################################################
if(-e $ARGV[0]) {write_bat_file($ARGV[0], $destination)}
else {die "$ARGV[0]: No such file"}


sub write_bat_file {
#################################################
# Collect the --prefix, --version, --libs and   #
# -cflags values from the library-config file,  #
# and hard code them into the batch file.       #
# The generated batch file has the same name as #
# the library-config file, but with a '.bat'    #
# extension.                                    #
#################################################
  my $lc = $_[0];
  $lc =~ s/\\/\//g;
  my $filename = (split /\//, $lc)[-1];
  my $lc_bat = "${destination}/${filename}.bat";

  my $prefix  = `sh $lc --prefix`;
  my $version = `sh $lc --version`;
  my $cflags  = `sh $lc --cflags`;
  my $libs    = `sh $lc --libs`;

  chomp for ($prefix, $version, $cflags, $libs);

  open(WR, '>', $lc_bat) or die "Can't open $lc_bat for writing: $!";

  print WR "\@echo off\n\n";
  print WR "if \"%1\" == \"--version\" goto VERSION\n";
  print WR "if \"%1\" == \"--prefix\"  goto PREFIX\n";
  print WR "if \"%1\" == \"--cflags\"  goto CFLAGS\n";
  print WR "if \"%1\" == \"--libs\"    goto LIBS\n";
  print WR "if \"%1\" == \"\"          goto USAGE\n\n";
  print WR "echo %1 : Unknown option && echo.\ngoto endofbat\n\n";

  print WR ":VERSION\n";
  print WR "echo $version && echo.\n";
  print WR "goto endofbat\n\n";

  print WR ":CFLAGS\n";
  print WR "echo $cflags && echo.\n";
  print WR "goto endofbat\n\n";

  print WR ":PREFIX\n";
  print WR "echo $prefix && echo.\n";
  print WR "goto endofbat\n\n";

  print WR ":LIBS\n";
  print WR "echo $libs && echo.\n";
  print WR "goto endofbat\n\n";

  print WR ":USAGE\n";
  print WR "echo Usage: %0 --arg (where arg is either version, libs, prefix, or cflags) && echo.\n";
  print WR "goto endofbat\n\n";


  print WR ":endofbat\n\n";

  close WR or die "Can't close $lc_bat after writing: $!";
  print "$lc_bat has been written\n";

}