#!/usr/bin/env perl

if($#ARGV < 0){&Usage();exit;}

$classname = "__nada__";
foreach $arg (@ARGV){
	if($arg eq "-plugin"){
		$is_plugin=1;
	}else{
		$classname = $arg;
	}
}

if($classname eq "__nada__"){&Usage();exit;}

print "\n";
print "Generating files for event processor $classname ....\n";

$dhfile = $fname = "DEventProcessor_${classname}.h";
open(FILE,">$dhfile");
&PrintFileHeader();
&PrintClass();
close(FILE);
print " - $dhfile\n";

$ccfile = $fname = "DEventProcessor_${classname}.cc";
open(FILE,">$ccfile");
&PrintFileHeader();
&PrintMethods($is_plugin);
close(FILE);
print " - $ccfile\n";

	print "\n"; 
if($is_plugin!=0){
	print "CAUTION: Code has been added to allow this to be compiled as a plugin.\n";
	print "If mulitple processors exist in this same directory, only one should\n";
	print "include the \"InitPlugin\" routine. Other processors will need to be\n";
	print "added to the single InitPlugin routine by hand.\n";
}
print "\n";

###############
# PrintFileHeader
###############
sub PrintFileHeader()
{
	# print a few lines at the very top of the file
	$uname = `uname -nprs`;
	chomp($uname);
	print FILE "// \$Id\$\n";
	print FILE "//\n";
	print FILE "//    File: $fname\n";
	print FILE "// Created: ".`date`;
	print FILE "// Creator: ".$ENV{"USER"}." (on $uname)\n";
	print FILE "//\n";
}


###############
# PrintClass
###############
sub PrintClass()
{
	$content = "
\#ifndef _DEventProcessor_${classname}_
\#define _DEventProcessor_${classname}_

\#include <JANA/JEventProcessor.h>

class DEventProcessor_${classname}:public jana::JEventProcessor{
	public:
		DEventProcessor_${classname}();
		~DEventProcessor_${classname}();
		const char* className(void){return \"DEventProcessor_${classname}\";}

	private:
		jerror_t init(void);						///< Called once at program start.
		jerror_t brun(jana::JEventLoop *eventLoop, int runnumber);	///< Called everytime a new run number is detected.
		jerror_t evnt(jana::JEventLoop *eventLoop, int eventnumber);	///< Called every event.
		jerror_t erun(void);						///< Called everytime run number changes, provided brun has been called.
		jerror_t fini(void);						///< Called after last event of last event source has been processed.
};

\#endif // _DEventProcessor_${classname}_

";
	print FILE $content;
	
}

###############
# PrintMethods
###############
sub PrintMethods
{
	$content = "
\#include \"DEventProcessor_${classname}.h\"
using namespace jana;

";

	# If first argument is non-zero, then add code to make this a plugin
	if($_[0]!=0){
		$content = $content."
// Routine used to create our DEventProcessor
\#include \<JANA/JApplication.h\>
extern \"C\"{
void InitPlugin(JApplication *app){
	InitJANAPlugin(app);
	app->AddProcessor(new DEventProcessor_${classname}());
}
} // \"C\"

		";
	}

	$content = $content."
//------------------
// DEventProcessor_${classname} (Constructor)
//------------------
DEventProcessor_${classname}::DEventProcessor_${classname}()
{

}

//------------------
// ~DEventProcessor_${classname} (Destructor)
//------------------
DEventProcessor_${classname}::~DEventProcessor_${classname}()
{

}

//------------------
// init
//------------------
jerror_t DEventProcessor_${classname}::init(void)
{
	// Create histograms here
	return NOERROR;
}

//------------------
// brun
//------------------
jerror_t DEventProcessor_${classname}::brun(JEventLoop *eventLoop, int runnumber)
{
	return NOERROR;
}

//------------------
// evnt
//------------------
jerror_t DEventProcessor_${classname}::evnt(JEventLoop *loop, int eventnumber)
{
	// Fill histograms here

	return NOERROR;
}

//------------------
// erun
//------------------
jerror_t DEventProcessor_${classname}::erun(void)
{
	// Any final calculations on histograms (like dividing them)
	// should be done here. This may get called more than once.
	return NOERROR;
}

//------------------
// fini
//------------------
jerror_t DEventProcessor_${classname}::fini(void)
{
	// If another DEventProcessor is in the list ahead of this one, then
	// it will have finished before this is called. e.g. closed the
	// ROOT file!
	return NOERROR;
}

";
	print FILE $content;
	
}

###############
# Usage
###############
sub Usage()
{
	print "\n";
	print "Usage:\n\t mkprocessor [-plugin] name\n";
	print "\n";
	print "Generate the C++ source and header files to implement a new\n";
	print "event processor for use with the Hall-D analysis framework.\n";
	print "The files will define a class which inherits from.\n";
	print "JEventProcessor and can therefore be added to a program\n";
	print "using the the AddEventProcessor() method of JApplication.\n";
	print "\n";
	print "The \"name\" parameter specifies a unique name for the class.\n";
	print "The class will, by default, be called DEventProcessor_name.\n";
	print "This can lead to long names, but at least it is clear.\n";
	print "what they are.\n";
	print "\n";
	print "Event processors are starting (or end) points in the analysis\n";
	print "chain. They are typically used for creating histograms and trees.\n";
	print "Only one (of each type) of event processor object is created\n";
	print "in a program which is then used by all threads. This is in\n";
	print "contrast to factories which are created for each thread.\n";
	print "If you wish to generate data visible by other factories and\n";
	print "event processors, then see mkfactory.\n";
	print "\n";
	print "One can add code to easily make this a plugin via the\n";
	print "command line switch:\n";
	print "\n";
	print " -plugin \n";
	print "\n";
	print "If this switch is present on the command line, a \"InitPlugin\"\n";
	print "routine will be added to the .cc file creating a DEventProcessor\n";
	print "of this type and adding it to the JApplication.\n";
	print "\n";
	print "\n";
	print "\n";
}